Journal of Scientific & Industrial Research

Vol. 58, July 1999, pp 475-5 1 6

Wastewater Management i n Cluster of Tanneries in Tamil Nadu through

Implementation of Common Emuent Treatment Plants+

Tapas Nandy, S N Kaul* , Sunita Shastry, U Manivel and C V Deshpande

National Environmental Engineering Research Institute, Nehru Marg, Nagpur 440 020

The Indian leather industry has gained substantial socio-economic significance due to its contributions to social equity and export contributions. Environmental concerns associated with leather processing, however, had placed the Indian leather sector under serious threat of survival in 1 996. Over 400 tanneries in Tamil Nadu were closed under the orders of the Hon'ble Supreme Court of India for reasons of inadequate compliance to environmental discharge norms of the State. National Environmental Engineering Research Insti­tute (NEERI) and the Central Leather Research Institute (CLRI); played a key role in providing critical technological solutions to the vexed problem in a span of 1 5 months. The outcome of the implementation of technology plans developed and delivered by the two CSIR laboratories to the All India Skin and Hide Tanners and Merchants Association (AISHTMA) enabled the tanners of Tamil Nadu to comply with the environmental norms of the State.

Introduction

Leather production involves tanning which is a chemi­cal process converting the semi-soluble protein called the 'collagen' present in the corium of animal skin and hides into though, flexible, insoluble and highly durable leather. The most common tannages are vegetable tan­nage and chrome tannage. Vegetable tanning is gener­ally adopted where certain desirable physical properties like solidity, feel, colour etc. are desired, viz., heavy leather or in-sole leathers, while leathers meant for shoe upper, glove, garment, luggage, etc. , are invariably pro­cessed by chrome tanningl . Tanning of hides and skins is basically a wet process, consuming 70- 100 I of water per kg of skin/hide processed. Tanneries generate waste­water in the range of 30-35 11kg skin/hide processed with variable pH and high concentrations of suspended sol- ­ids, BOD, COD, tannins including chromium.

There are over 900 tanneries in Tamil Nadu distrib­uted in the five Districts of the State, viz. North Arcot Ambedkar, Erode Periyar, Dindigul Annf\, Trichy and Chengai MGR. These tanneries mostly exist in clusters, and the untreated/partially treated wastewater being dis­charged into nearby surface water qody creating obnox-

I

* Author for correspondence +Work is based on authors' CSIR Technology Award

ious conditions and impairing the physical, chemical and biological quality of water in the rivers, and also con­taminating the ground water. The tanneries were under closure as per the orders of the Hon'ble Supreme Court for non-compliance to environmental effluent discharge norms of the State Pollution Control Board. Therefore, proper wastewater management was warranted to ensure compliance of the stipulated norms of the Statutory Board for restarting the tanneries.

NEERI conducted extensive field investigation in eleven operational common effluent treatment plants (CETPs) completing the following activities :

Site surveys in and around CETPs for updating the data­

base.

Estimation of quantity and characteristics of combined

wastewater

Bench scale treatability studies.

Delineation of measures for discernible improvement in

the performance of the CETPs through effective opera­tion and maintenance, and remodeling of CETPs.

Evaluation of CETPs and assistance in trouble shooting operations.

Integration of High Rate Transpiration System in the

CETP in order to achieve the containment of IDS in treated effluent, and zero effluent discharge.

476 J SCI IND RES VOL 58 JULY 1 999

Sludge management.

Training programme for chemists, plant operators and engineers of the CETPs for sustainable performance.

CLRI, Chennai implemented inplant measures in in­dividual tanneries by adopting cleaner technology pack­ages for the following pollution parameters in order to reduce the load on CETPs:

TDS (20-25per cent).

BOD/COD (20-35per cent).

Sulphide (50-6Oper cent).

Chromium (98-99per cent).

Hydraulic loading (20-25 per cent).

Implementation of common effluent treatment plant for wastewater management in cluster of tanneries is an economical solution to the problem due to economy of scale and concomitant, equalization and proportioning. The system also provides a basis for rational cost shar­ing. Implementation of CETPs for wastewater manage­ment in cluster of tanneries in Tamil Nadu through de­sign, commissioning, and upgradation of CETPs is ad­dressed.

Quantity and Characteristics of Wastewater Generation in Tannery

The quantity and characteristics of wastewater dis­charge in tanneries vary from to process to process, tan­nery, to tannery and from time-to-time. Tanning opera­tions though said to be continuous, are in the stricter sense in batches and the discharges of spent water are intermittent.

Apart from variation in the characteristics of the waste­water from different operations, there are wide range of fluctuations in the flow volume during different hours of the day, providing shock loading to an effluent treat­ment plant as a whole. The fluctuations in the flow of tannery waste also vary with the type of process adopted.

Process of tanning can be categorised and the prob­able quantity of wastewater expected out of each of them are as follows2:

Raw to E.I.

Raw to Wet Blue

Raw to Finishing

25-30 IIkg of raw skin/hide.

25-30 llkg of raw skin/hide.

30-40 llkg of raw skin/hide.

*For Tables 1-27 see pages 484-5 1 5

E.I. to Finishing

Wet B lue to Finishing

50-60 llkg of E.I. leather.

20-30 llkg of wet blue.

The waste load contributed per kg of hide processed is given in Table 1 * .

Cleaner Technologies of Production for Tanning Industry

Tannery wastes contribute to the pollution hazard in no small measures since they have a high proportion of putrescible organic and toxic inorganic wastes.

Tanning process is more or less a wet process from which a large volume of liquid waste is almost continu­ously discharged throughout the working hours of the day. Its discharge to the environment without adequate treatment can render soils sick, pollute surface and ground water and create air pollution problems by pro­ducing obnoxious gases.

Any form of tannery waste treatment, however simple, entails certain non-productive investment by the indus­try. The greater the volume and strength of the waste, higher will be the capital, operation and maintenance costs.

The cost of treatment, capital, as well as recurring, can be greatly reduced if the strength and volume of the waste is restricted to minimum at the source itself. In­plant control measures are best suited for this purpose and can effect significant reduction in pollutional load at a relatively low cost.

The single most important aspect of sound engineer­ing for successful pollution control starts with the in­plant control measures.

In-plant control measures for a tanning industry can be divided into the fol lowing four steps : · Reduction of water usage in a tannery. • Process modifications to reduce pollutional

load. · Segregation of effluent streams and its treat­

ment. Recovery and util ization of by-products. The choice of the appropriate step obviously depends

upon the benefits derived by the industry for the cost of enforcing that step. Some applications of cleaner tech­nologies in tanning industry are presented in Tables 2 and 3 .

j

NANDY et al. : WASTEWATER MANAGEMENT IN TANNERIES 477

Raw wastewater

Legend:

1 . Screen Chember 2. � Sump 3. Rotary Screen 4. Equelizetion Basin 5. Flash Mixer I 8. Bailie Chennel

. 7. Primllry Clluffier 8. ""-<obIc Lagoon 9. PrHoeIllUon Tank 10. Aelllllon Tank 1 1 . � Clariller 12. Aesh Mixer II 13. F\occu'-\or

" 14. Tube Sllll1er 15. Sludge Drying Beds 18. Sludge Thickener 17. Centrifuge AlB AIumIline C/O DAPlPolyeledrolyle + MIxer

Aoetlng Mllltor • FIXed Mllltor - SIudge Une 1- "1 Tertiary Tlllatment Units

Treated Ellluenl to River Palar

8

�r:;--t �- - - - � .. - 2 2�--� - - - - : : : : 8thte . . . . I .. .. .. .. : _ . . . . . 15

A B O ." . . .. . .. .. .. . . . . .. .... .. . . .. . ... . . R�d�

* * * 9

* *

NOT TO SCALE Figure I - Schematics of common effluent treatment plant

Treatability Studies for Treatment of Tannery Waste­water

In order to arrive at the most appropriate treatment scheme, and to establish design parameters for the unit processes and operations for the treatment of combined wastewater from tanning industry, detailed treatability studies were needed. NEERI carried out extensive labo­ratory studies to assess the feasibility of treating mixed tannery wastewater through physico-chemical route fol­lowed by anaerobic and aerobic bio-oxidation of chemi­cally treated tannery effluent3-6.

Studies on chemical treatment using various coagu­lants provided with development of relationship between coagulant dose and COD removal efficiency3. The ki­netic coefficients for the design of aerobic biological system, viz. yield coefficient (Y) and specific decay rate (kd) were estimated at 0.58 kg VSSlkg COD and 0.05 d- I , respectively. The oxygen requirement was estimated at 0.43 kgO/kg COD .d (ref. 6).

Common Effluent Treatment Plant (CETP)

Out of the 900 tanneries in the State of Tamil Nadu, about 1 00 tannery units have installed individual efflu­ent treatment plants, while others have formed compa­nies and co-operatives to establish common effluent treat­ment plants: The distribution of CETPs in the five dis­tricts of Tamil Nadu is presented in Table 4. Out of the

30 CETPs, 1 1 are under operation, five under construc­tion and 1 4 are proposed.

Design and Implementation of CETP - A Case Study

The common effluent treatment plant for treatment of tannery wastewater has been designed for 4000 m3/d, based on the combined wastewater flow generated from 76 small and medium scale tannery units. The design is based on pretreatment comprising settling, screening, and solar evaporation of soak and pickle liquor at individual tannery units. The tanneries connected to CETP involve process ing from raw to fin i shed leather, and semi-finished to finished leather based on vegetable tan­ning process , except for a few units which are based on chrome tanning 7

The CETP designed on the basis of laboratory treat­ability studies comprises screening, equal ization, physico-chemical treatment and biological treatment through anaerobic route (anaerobic lag�on), preaeration and aerobic route (extended aeration system). The sche­matics of the CETP is shown in Figurel . The unit sizes and basic design details of various unit processes and operations are presented in Table 5 .

Performance Evaluation of CETP

Performance evaluation of the CETP has been car­ried out after commissioning under the existing operat-

478 J SCI IND RES VOL S8 JULY 1 999

Flow, cumlh 1 50 Monitoring I 150

Flow. oumlh.

75

25

1200

Average flow ' 114.7 cum/h .

AYBrage flow · 92.4 cumIn:

1800 Time, h

2400 0500

- Inlet -- Outlet

125

75

50

25

Monitoring I I

1200

Alleraga flow ' 112.9 cumlh ..

Average flow ' 88.7 cumlh·

1800 Time, h :

2400 0500

- Inlat ......... Outlet

Flow, cum/h 1 50 r-�--------------------� 1 50

rFI�ow�,�c=um�/�h __________________ �

Monitoring I II

1 25 Average flow • 115.3 cum/h

75 Average flow ' 92.5 cumlh

50

25

O LL��'���������� 0600 1200 1800

Time. h· 2400 0500

- Inlet -- Outlet

75

50

25

Monitoring I V

1200

Awrage flow ' 117.6 cum/h'

Average flow ' 94.1 oumlh

1800 Time, h . .

2400 0500

- Inlet -- Outlet

Figure 2 - Hourly flow variation at inlet and outlet of CETP

ing conditions. In order to assess the quantity of waste­water being received at the CETP, flow was monitored for 24 h on different dates. Figure 2 presents the hourly flow variation . The combined wastewater received at the CETP ranged from 28 1 9.4 to 3572.5 m3/d.

The CETP was monitored to evaluate the performance of various unit processes and operations under existing operating conditions by identifying sampling points at various stages of treatment and collecting one hourly samples composited for six and 24 h. Table 6 presents the detailed analyses for samples collected at various stages of treatment. All analyses have been carried out as per Standard Methodsx.

The performance of various unit processes and op­erations of the CETP were not at its optimal level of

performance mainly attributed to improper equalization of wastewater flow and characteristics, improper dosing of coagulants due to manual dosing being practiced and irregular desludging of sludge from primary clarifier resulting in escape of suspended solids along with the clarified effluent.

After Proper Operation and Maintenance

Based on the evaluation, measures implemented to improve CETP performance were proper equalization through regular pumping and mixing of wastewater, regu­lar dosing of coagulants based on design doses of 450 mg/I each for alum and l ime through operation of the dosing tanks, and regular desludging of sludge from pri­mary clarifier. Evaluation of CETP after implementing the improvement measures is presented in Table 7 .

}

....

NANDY et at. : WASTEWATER M ANAGEMENT IN TANNERIES 479

The results indicate that the performance of the chemi­cal treatment could be improved with regular and proper dosing of coagulants in addition to proper desludging. The results are presented in Table 8 .

The design dosage of coagulants was based on labo­ratory studies using analytical grade chemicals. How­ever, further improvement in the performance of the chemical treatment was assessed by carrying out treat­ability studies using commercial grade chemicals being utilized at site to optimize the coagulant dosages.

Treatability Studies for Optimization of Dosage of Com­mercial Grade Coagulants

Laboratory treatability studies for treatment of com­bined wastewater were conducted to determine the op­timum coagulant dosage for alum and lime using com­mercial grade chemicals already in use at the plant site. Initially, alum was used in various doses ranging from 200 to 700 mg/1 . After optimizing the alum dose, lime was used in concentration ranging from 400 to 1 000 mgll in combination with optimum alum dose. The concentration of significant parameters in chemically treated effluent are given in Tables 9 and 1 0.

The results indicate an optimum dosage of alum : lime as 500 : 800 mg/l, achieving COD and SS removal of 74.9 and 84.0 per cent, respectively with treated ef­fluent pH of 8 .5 . The sludge generated was 1 50 mIll .

After Optimization of Chemical Treatment

Based on treatabil ity studies, optimum dosage of chemical coagulants were practiced for further improve­ment in the performance of chemical treatment.

Table 1 1 presents detailed analyses at various stages of treatment after implementation of the optimum co­agulant dosing. Optimum coagulant dosage resulted in further improvement in the performance of chemical treatment compared to earl ier monitoring and is presented in Table 1 2.

Performance of the extended aeration system dete­riorated as SRT in the aeration tank was estimated to be in the range of 60-63 d, which is high as compared to the design value of 20 d and the oxygen uptake rate of bio­mass (MLVSS) was 26.7 mg/I.h as compared to design value indicating low oxygen uptake rate of biomass. Fig­ure 3 presents the oxygen uptake rate during various monitoring period. SVI was 1 63 mIlg indicating poor sludge settleabil ity (Figure 4). Deterioration of the final treated effluent quality, despite improved performance

of the chemical treatment was attributed to non-optimum performance of the extended aeration system.

After Optimization of Extended Aeration System

Measures implemented to improve the performance of extended aeration system were wastage of biological sludge from the aeration tank to maintain SRT of 20 d, innoculating mixed liquor for volatile biomass (MLVSS) build-up, and regular sludge wastage from sludge recycle l ine.

After biomass build-up in the aeration tank, with MLVSS concentration in the range of 2245 to 2680 mgll, and achieving SVI and OUR values of 1 05 mgll and 40 mg/I.h, respectively, the evaluation data on plant performance is presented in Table 1 3 .

The concentration of COD in the final treated efflu­ent was in the range of 244 to 297 mg/l as compared to 329 to 524 mg/l as observed during the earlier monitor­ing exercises. Oxygen uptake rate in the aeration tank was 4 1 .3 mg/I.h compared to 26.7 mg/I.h during earlier monitoring, indicating presence of volatile biomass (MLVSS) in the system (Figure 3) .

The final treated effluent from CETP conform to the limits prescribed by the Statutory Board for inland sur­face water discharge except for the parameters COD, TDS and chlorides. Table 1 4 presents the data on char­acteristics of treated effluent during various stages of monitoring along with the discharge Standards of the Statutory Boards. The results indicate improvement achieved in the effluent characteristics through proper operation and maintenance of the plant.

To ensure removal of colour from the treated effluent to the maximum extent possible, and to bring down the concentration of major polluting parameters well within the stipulated Standards of the Statutory Board tertiary treatment was warranted. Treatability studies were con­ducted to optimize the dosage of coagu lants and coagulant-aid for tertiary treatment through physico­chemical route.

Treatability Studies for Tertiary Treatment

Laboratory treatability studies were carried out to evaluate the performance of tertiary treatment of sec­ondary treated effluent through physico-chemical route. Efforts were made to remove colour as far as possible and reduce the concentration of major polluting param-

480 J SCI IND RES VOL 58 JULY 1999

1 0 DO'-mg/l a DOr-:,_ma..:.I-'-I __________ --,

ArIW Commlsaionlng Arter Proper Operation & "'alntananc.

a

2 .. Oxygen Uptake .Rata • "5.7 mall .h· Spaclflc Oxygen Utllizatlcn

o Rat. · 15.1 rng/tI·h o 1 2 3 .. 5 8 7 8 a

Tlma, m: .

1 0 DO , mall

2

After Optlmlzatlcn of Chemical Treatment

Oxygen Upteke Rate · 28.7 mall .h: . Spaclflc Oxygen Utilization Rata • g ... mal g.h.

2 3 .. 6 8 7 8 g Tlme, m

8 *

..

2

. .

Oxyg.n Upt'" Rate · ..... 7 mall .h . Speolflc Oxygen Utilization Rate · 16." ma/g.h ·

O �������������� o 2 3 .. 5 8 7 a g . nme, m. :

a DO, mall

2

After Optimization of Aeration Syatem

•

Oxygen Uptake Rate · 41.3 mall .h Specific Oxygen U tlllution Rate • 18.5 mal g.h

o 0'---'--2'--3'--"'--5'--8'--7'--8,---Ig .

nme, m

Figure 3 - Estimation of dissolved oxygen uptake rate

eters below the Standards stipulated by the Statutory Boards for inland surface water discharge.

Commercial grade chemical coagulants, viz. alum and lime along with cationic polyelectrolyte as coagulant-aid, were used in the study. Initially, alum was used in vari­ous doses ranging from 1 00 to 500 mg/l, in increments of 50 mg/I. Optimizing the alum dose, lime was used in combination at varying doses. This was fol lowed by use of polyelectrolyte at various doses in combination with optimum doses of alum and lime.

The concentrations of major parameters in the treated effluent using various coagulants and coagulant-aid are in Tables 1 5 through 17 .

Treatab i l i ty data , ind icate opt imum dose of alum: lime :polyelectrolyte as 350:225 :0.4 mg/l, achiev­ing COD and SS removal of 54.3 and 48.9 per cent, re-

spectively, and reducing colour of the effluent from 1 95-220 to 66-70 Pt-Co units.

Upgradation of CETP

Based on treatability studies, construction of tertiary treatment units for treatment of secondary treated efflu­ent through physico-chemical route, comprising flash mixer, flocculator and tube settler was completed and commissioned. The plant was evaluated after imple­mentation of the complete treatment route comprising primary (physico-chemical), secondary (two stage bio­logical - anaerobic followed by aerobic) and tertiary treat­ment (physico-chemical). The combined wastewater flow varied in the range of 2025 .6 to 2258.2 m3/d.

The optimum chemical dosing using commercial grade coagulants, viz. alum:lime as 500:800 mg/l was practiced in primary treatment unit. OUR in the aeration

i

NANDY et al. : WASTEWATER MANAGEMENT I N TANNERIES 48 1

Sludge Volun'le', inl 1 200 ��----�------------�

After Comnilaalonlng SVI • 118 ml Ig MLSS • 3988 mgll ·

400 .

200

0 0 30 120

Time, m'

;:.SI�oo�g�e�v��· ume��, m�l_. __________ � 1 200 ,

1000

800

800

400

200

�ter Optimization of Chemloal Treatment SVI • 183 ml /g MLSS • 3980 mgll

O LL���LL���LL��� o 30 120

Time, m '

1 200 Sludge Volume, ml

After Proper Operation a Malntenanoe SVI • 138 ml.lg .

1000 ML8S · 31140 mgll ,

800

400

200

0 , 0 30

Time, m' .

1 200 8100ge Volume, ml

400

200

After Optimization of Aeration System SVI · 88 ml/g MLSS • 3264 mgll

O LL�����LLLL���� o � 120

Time, m '

Figure 4 - Sludge setting profile of MLSS from aeration tank

tank was 42.8 mg/l .h indicating the presence of volatile biomass (MLVSS) in the system. SVI was 98 mllg indi­cating sludge settleability. Optimum dosage of coagu­lants alum:lime:polyelectrolyte as 350:225 :0.4 mgll in the chemical treatment unit for tertiary treatment was practiced.

B ased on one hour ly samples co l l ected and composited for 6, 1 2, 1 8 and 24 h , detailed analyses of samples collected i s presented in Table 1 8 . Table 1 9 pre­sents detailed analyses of equalized influent and final tertiary treated effluent collected on different dates. The operating design parameters of the various units during the monitoring period are presented in Table 20. En­ergy consumption at various stages of treatment is pre­sented in Table 2 1 .

The secondary treated effluent characteristics from the extended aeration system conform to the l imits pre­scribed by the Statutory Board for inland surface water discharge, except for TDS and chlorides parameters. Additional tertiary treatment ensures removal of colour in the final treated effluent with concentration of major polluting parameters wel l within the stipulated Stan­dards of the Statutory Board for inland surface water discharge, except for parameters TDS and chlorides. Concentration of TDS and chlorides in the effluent are to be controlled through the implementation of High Rate Transpiration System.

Util ization of Treated Tannery Effluent through High Rate Transpiration System (HRTS) for Control of TDS and Chlorides

482 J SCI IND RES VOL 58 JULY 1 999

The high rate transpiration system (HRTS) is a land application system wherein the wastewater is applied in specially designed field layouts with wide ridges and furrows, and planted with trees bestowed with higher transpiration capacity. The HRTS envisages the use of dynamic multicomponent soil system as a live filtra­tion device to renovate pretreated wastewater through adsorption, ion exchange, precipitation, and stabiliza­tion of pollutants through microbial degradation . Also the earthworms present in the system provide aerobic conditions for the stabilization of organic contents in the wastewater through a network of burrows.

The plants, e.g. Bamboo (Dendrocalamus strictus), Neem (Azadirachta indica) and Shishum (Dalbergia sissoo) transpire water equivalent of 7 to 1 3 -times of its potential evapo-transpiration rate from the soi l matrix alone. Thus, HRTS permits the disposal of 250-450 m3 of wastewater /ha of land/d. As all the wastewater is utilised in this process, the ground water pollution problem is avoided. The nutrients present in the waste­water are used by the plants and partly retained in the soil matrix with positive impact on the soil ecosystem.

Treatment and disposal of the tannery wastewater through HRTS was initiated at CETP. Two different designs of HRTS were provided as described subse­quently :

Design - /

Design - I of HRTS consists of ridges having bottom with of 1 .6 m, top width of 0.8 m and height of 0.5 m. The width of the furrow is 0.8 m. A layer of 1 5 cm of the filter media consisting of coconut peat/sawdust is given in the furrows and covered with 2-3 cm layer of clayey soil . The plant-to-plant spacing between the ridges is 2.4 m and 1 .0 m within the ridge. One hectare of area accomodates 4 1 furrows and 4 1 ridges of each 1 00 m length.

Design - II Design - II of HRTS consists of ridges having bottom

width of 1 .0m, top width of 0.5 m and height of 0.5 m. The width of the furrow is 0.5 m. A layer of 1 5 cm ofl the filter media consisting of coconut peat/sawdust is given in the furrows and covered with 2-3 cm layer of clayey soil . The plant-to-plant spacing between the ridges is 1 .5 m and 1 .0 m within the ridge. One hectare

of area accomodates 66 furrows and 66 ridges of each 1 00 m length.

Design - I planted with neem and karanj, and Design­II planted with casurina was adopted and demonstrated at the site.

After plantation, schedule of wastewater loading is as per the recommendations detailed in Table 22. The saplings was provided with fresh water in the pits for 3 months for their better establishment fol lowed by ful l loading with tannery wastewater as suggested to the CETP management.

Sludge Management

Present Status of Sludges from CETP

The chemical and biological sludges generated from CETP treating tannery wastewater fall under Hazard­ous Waste Category 1 2 (ref.9) . . It is essential to handle the sludges scientifically to minimize adverse impacts on health and environment. In view of the hazardous char­acteristics of the sludges, it is necessary to adopt Cradle to Grave principle in the management of the hazardous sludges generated from the CETP, including the sludge storage, transportation, treatment, and disposal .

The chemical and biological sludge generation were 650 m3 and 60 m3 /d, respectively. After dewatering, the total sludge generation was computed as 50.7 1 m3 /d, with moisture content of 30 per cent. The concentra­tion of heavy metals in the sludges are summarized in Table 23 .

The existing practice of sludge management was col­lection of sludges in a temporary disposal yard after de­watering. Part of the sludge so produced was disposed off in a LDPE lined concrete pit. However the landfill capacity was insufficient and the excess sludge was dumped on low lying areas in the CETP premises.

Approach to Design of Sludge Management System

The moisture content of sludge, as it comes out of the treatment units, was around 92 per cent. It was essential to remove moisture before disposal. The sludge must be subjected to dewatering employing vacuum filters. The maximum allowable moisture content prior to landfil l disposal is 30 per cent. This helps in minimizing the leachate generation and facilitates disposal.

During monsoon, sludge dewatering should be col­lected in drums and stored for a few days before dis-

;/

...

,

)

NANDY et al. : WASTEWATER M A N AGEMENT IN TANNERIES 4'83

posal in secure landfill . The storage should be discour­aged in other seasons. The drums should be stored in a shed to prevent entry of rain water. The shed should be on an elevated land, and should have impermeable floor­mg.

The site(s) for the establishment of the sludge dis­posal facilities should be very close to CETP to mini­mize the risk involved in transportation. The intermedi­ate storage facility at CETP should have adequate space for storing sludge generated in 1 0 d.

Secure Landfill for Sludge Disposal

The disposal of sludges generated from CETP must be through secure landfil l to prevent leachate genera­tion, and its subsequent migration into the soil and groundwater.

Following aspects have been considered while design­ing the secure landfill : location; landfil l layout; foun­dation; liners; leachate management; fil ling procedures; and closure. The details have been presented elsewhere 10.

Conclusions

Various unit processes and operations of the CETP designed to treat combined wastewater flow from clus­ter of tannery units, after commissioning and under ex­isting operating conditions, were not functioning at op­timum level of performance as per design. This was attributed mainly to poor operation and maintenance of the plant. Table 24 presents the problem associated with various units in the CETP, and reasons thereof.

The performance of the CETP was improved by opti­mizing the operating parameters in the individual units. During the period of evaluation efforts were made to improve the performance of the plant through optimiza­tion of commercial grade chemical coagulant dosage and build-up of active biomass in the extended aeration sys­tem. In addition, proper maintenance activity in the plant was also initiated. This included maintaining regular pumping schedule for various pumps, regular coagulant dosing through operat ion of dosing tanks, regular desludging, and regular operation of mixers and sur­face aerators.

The overall performance of the CETP was further im­proved by upgrading the CETP through implementation

of tertiary treatment units and optimizing the operating parameters.

The characteristics of treated effluent as achieved af­ter commissioning, proper operation and maintenance, optimization of chemical treatment, optimization of ex­tended aeration system, and upgradation of CETP along with the discharge Standards are presented in Table 25, indicating improvement in treated effluent char­acteristics. The concentration of major polluting param­eters in the final treated effluent were well within the Standards stipulated by the Statutory Board for Inland Surface Water discharge including removal of colour, except for parameters TDS and chlorides. The concen­tration of BOD, COD and SS, and colour unit in the final treated effluent were in the range of 2-7, 96- 1 73 and 38-45 mgll, and 80- 1 1 5 Pt-Co unit.

The treated effluent cost after secondary treatment and tertiary treatment are estimated at Rs 1 1 .82/m3 and Rs 14 . ] 81m3, respectively considering the cost of chemical coagulants, energy and manpower requirements.

Concentration ofTDS and chlorides in the final treated effluent are to be c�ntrolled through utilization of treated effluent through High Rate Transpiration System (HRTS) . The implementation ofHRTS has already been initiated.

The chemical and biological sludges generated from CETP treating tannery wastewater fal l under Hazardous Waste Category 1 2 (ref. 9) . Disposal of sludges gener­ated is recommended through secure landfi l l to prevent its leakage and subsequent migration into soil and ground water.

Similar studies were carried out for the implementa­tion of additional ten under operation CETPs in Tamil Nadu. The brief details of the CETPs are presented in Table 26 and the final treated effluent characteristics are presented in Table 27. Implementation of CETPs and optimization in the performance of the various unit pro­cesses and operations have enabled to comply within the environmental norms of the Statutory Boards. The timely S&T intervention has led to recommissioning of the tanneries, thereby averting unemployment of the vul­nerable section of the workforce and loss of substantial foreign exhange earnings from exports.

484 /

Operation/ Process .

Pickling/ Depickling

Tanning

Post tanning operations­- rechroming - basification - neutralisation - dyeing - fat liquoring Finishing

EHluent treatment

Raw material preservation and transportation Hide/skin cur ing

Beamhouse operations­

Soaking

Fleshing

Unhairing

Liming

Deliming Degreasing

Process control and partial automation of tannery operation

Beamhouse, tanning and post-tanning operations Design engineering of tanneries Process flow sheeting, piping and instrumentation, layout, utility diagrams, equipment specificatiOns and operational safety

J SCI IND RES VOL 58 JULY 1 999

Table 1 - Average pollution loads in tannery wastewater per tonne of hide/skin processed

Parameter

Biological Oxygen Demand (BOD) 5 d @ 2Q°C

Chemical Oxygen Demand (COD)

Chlorides (as el)

Total Dissolved Solids

Suspended Solids

Sulphides (as S)

Total Chromium (as BCS)

Table 2 - Modem and clean technologies for leather processing

Pollution load in kg

70 1 80

270 600 1 00

4

30

Conventional technology

New option(s) Availab ility of new technological options

Chromium

Chemicaf addition in installments

Solvent based chem icals/technolo gies Aerobic

Salt

Pit

Mechanical! mar.ddl Sodium sulphide and lime

Pits

Ammonium SolvenV suriactants

Manual (Chemical, water and pH)

No systematic approach

a . Recycle b. Saltless Pickling c. Alternate tannage (AI, Ti etc) d. C h romium recovery and recycle e. High chrome exhaust aids f . Complexing of mineral with natural

tannins g . Wet white h. W hite crust Process control systems for controlled addition and pH control

Solvent free and water based

a. UASB b. Biotechnological c. Membrane technology a . Saltless or less salt curing b. Chilling and biocide combination c. Drying

a. Mechanical desalting

b. Paddle method c. Drum

Green fleshing

a. Enzymatic b. Hari saving

c. Enzymatic/ pressure technique a. Paddle b. Lime liquid recycle c. Separation of liming and unhairing baths

Carbondioxide a. Bbiodegradable suriactants b. Enzymatic

Instruments or micro process controls

Application of process design engineering concepts to leather processing

Indian Foreign Germany

CLRI C L R I CLRI Italy, France,

Denmarrk etc. CLRI

CLRI Italy

Italy, U K , Germany

C L R I Netherlands

C L R I U K African countries

Indian Foreign CLRI Westem countries CLRI

CLRI UK, France, Germany, Italy

CLRI Australia

CLRI CLRI Germany, Italy

Europe, USA Germany, USA

CLRI Italy and Switzerland

CLRI

'''T'

.... -

•

)

NANDY et at. : WASTEWATER M A N AGEMENT IN TAN N ERIES

Table 3 - Emerging options in making leather chemicals greener

Leather process stage Curing and Preservation

Unhairing

Deliming

Degreasing

Pretanning

Tanning! Retanning

Fat liquoring

Finishing

Conventional chemicals Sodium chloride

Pentachlorophe nol

Sodium sulphide

Ammonium chloride! sulphide Alkyl phenyl ethoxylate

Basic chrome sulphate

Mineral Tannages! Retannages

Chemical fillers

Synthetic fat liquors Surfactants from petrochemicals Cd and Pb chrome pigment Nitrocellulose and lacquer emulsions Water proofing agents Formaldehyde for casein fixation Solvent based finished (acrylic and PU) Benzidine dyes

Ecofriendly option(s)

i) Chilling+biocide ii) I rradiation i) TCMTB ii) OITZ

Proteolytic enzymes

i) Linear or branched ethoxilate from oxo and fatty alcohols. ii) Lipase enzymes Aluminium tannage for wet white or white crust

I) Partial or total Cr replacement with AI, Zr, Ti, Fe. ii) Partial substitution with vegetable tanning(s) Compounds based on poultry feathers or animal hair Oleochemical based fat l iquors Fatty acid oxylate based surfactants Organic alternatives

Water based Pus

Fluorinated acrylic copolymers Polytunctional crosslin king agents

Water based or low solvent counterparts

Non-benzidine dyes

Disadvantages! Advantages

Expensive: not always feasible More expensive; anti fungal and bacterial properties not present in one compound Not fully effective for hides; not active below certain temperature High affinity for lime; buffers in float; cost effective on higher operation scale Higher efficiency; do not form persistent metabolites; biodegradable

Leather characteristics not yet comparable to chrome leather; poorer heat resistance. Leachability problems; Economically less attractive

Biodegradable; promotes chrome exahustion.

Loss environmental damage

Absence of phenolic constituents Covering power and light fastness deficiencies Poor flow properties; large quantity application

Slower drying, oil and grease repellents Specific to protein material; Good Rub fastness

Application techniques need refinements

Better results on upholstery and auede leather

485

-

486 J SCI IND RES VOL 58 JULY 1 999

Table 4 - Distribution of CETPs in tannery clusters, Tamil Nadu

District Distribution as per existing status of CETPs Total No. Operational Under Proposed of CETPs

construction

North Arcot Ambedkar

- Ranipet 3 3 2 8 - Ambur 1 4 6 - Pemambut 1 2 3 - Vaniyambadi 2 3 6 Erode Periyar

- Erode 1 Dindigul Anna

- Dindigul

Trichy

- Trichy 2 3 Chengai MGR

- Chrompet Area 1 1 - Madhavaram 1 Total 1 1 5 1 4 30

NANDY et al. : WASTEWATER MANAGEMENT IN TANNERIES

Table 5 - Unit sizes and design details of various unit processes and operations of CETP

unit

Design Flow

Screen Chamber * S creen Bars 'It Spacing * No . of Bars Mechanical Screen

Receiving Sump

Equalization Basin

Flash Mixer I

Baffle Channel * No . of Baffles * Size * Spacing

Primary Clarifier

Anaerobic Lagoon

Pre -Aeration 'Tank

Aeration Tank

Sizes

2 . 0 x 1 . 0 x 3 . 0m 10 x 5 0mm 12\1111\ 93 1 No .

Dia SWD

9 . 0m 2 . 0m

42 x 2 0m Depth : 3 . 0m FB : 0 . 5m

2 . 5 x 2 . 5 x 2m FB : O . 4m

11 . 2 x 1 . 2 x 1 . 0m 18 0 . 7 5 x 1 . 2 0m 0 . 4 Sm

Dia . : 15m SWD 3 . 0m FB O . 5m

1 0 0 x 7 8 . 6m Depth : 3 . 5m FB 0 . 5m

1 0 0 x 3 9 . 2Sm Depth : 3 . 1m FB O . Sm

6 0 x 2 8 x 3m FB O . Sm

Des ign Details · based on Design Flow

4 0 0 0 m3/d

Velocity through s creen : 0 . 8 m/s

Drum Motor : 3 HP

Flow : 4 0 0 m3 /h DP : 2 0 min Pump : 2 + 1 , 3 0 HP

DP : l S . 12 h Mixers : 2 x 2 5 HP ( float ing) Pump : 1+1 , 15 HP

DP : 4 . 5 min Mixer : 5 HP

DP : 4 . 8 3 min

DP 3 . 2 h SOR 2 2 . 6 3 m3 /m2 . d WLR 84 . 9 m3 /m . d Sludge Pump : 1+1 , 1 0 HP

DP - 6 . 88 d OUt : 0 . 2 1 8 kgBOD/m3 . d Inf . BOD : l S 0 0 mg/ I BODr : 6 0 Per cent

DP : 3 . 04 d MLSS : 2 5 0 mg/l Aerators : 5 x 20 HP ( floating)

F/M : o . ls /d MLSS : 4 0 0 0 mgl l MLVS S : . 32 0 0 mg/l PP : 3 0 . 2 4 h

.

OLR : 0 . 7 5 0 kgBOD/m3 . d HP provided : 6 x 2 0

487

Contd . ...

488

Table 5 contd . . . .

Secondary Clarifier

Flash Mixer I I

Flocculator

Tube Settler

Sludge Drying Beds

Sludge Thickener

Centrifuge

J SCI IND RES VOL 58 JULY 1 999

Dia . : 15m SWD 2 . 5m FB O . 5m

2 . 5 x 2 . 5m Depth : 2 . 1m

6 . 0 x 6 . 0m Depth : 2 . 5m

6 . 0 x 6 . 0m Depth : 1 . 5m

15 x 8 x 1m Nos . 4 5

Dia . : 6m SWD 2 . 0m FB 0 . 5m

Capacity : 12 m3 /h Solids conc . : 5 -10 D�um dia . : 85 0mm

SOR WLR SLR

2 2 . 6 m3 /m2 . d 84 . 9 m3 /m . d 9 0 . 54 kg/m2 . d

DP : 2 . 6 5 h Sludge Pump

DP : 4 . 7 3 min Mixer : 5 HP

1+1 , 7 . 5 HP

DP : 32 . 4 ·min Paddle Motor : 2 HP

Details not available Sludge Pump 1+1 , 5 HP

Drying period : 8 d Application depth : 4 0 em Primary sludge : 3 6 0 m3 /d at 2 Per cent conc. Secondary sludge : 143 . 2 7 m3 /d at 1 . 5 Per cent conc. Sludge application 2 4 0 m3 /d

.

Wt . of sludge @ 1 . 5 Per cent conc . . : . 4343 : 9 kg/d SLR : 150 kg/m2 . d Vol . of sludge after thickening at 5 Per cent conc.

: 78 . 98 m3 /d

Make : Humbol l Wedge · Media Ltd .

Operating period : 6 h Machine Motor : 2 5 HP

SWD - Side water depth; TO - Total depth ; DP - Detention period ; FB - Free board ; SOR - Surface overflow rate ; WLR - Weir loading rate ; OLR - Organic loading rate ; F/M - Food/Micro-organism ; SLR - Solids loading rate

)..

Parameters

Colour , P t - Co pH

Temp . , oc

Alkal inity SS TDS COD BOD Sulphates Sulphides Chlorides Ammoni cal N Kj eldhal N Nitrate N' Nitrite N Phosphates Phenol s oil & Grease Heavy Metals

;.

1*

183 0 8 . 7 -9 . 3

2 5 -2 9

1742 3 8 6 0

....- -;

Table 6 - Perfonnance evaluation of common effluent treatment plant (After commissioning)

).- ...

Receivina Sumo Eff . f rom Eaualization Basin Eff . from Pri m� ry Cl �r; r i �r

2 *

1460 7 . 8 -9 . 0

2 7 -2 9

2272 3024

3 *

1 3 5 0 8 . 0 -8 . 2

2 8 -2 9

2 02 0 2 8 7 8

4 *

1080 7 . 7 -8 . 3

2 7 -28

5+

1450 7 . 7 -9 . 3

2 5 -2 9

1978 2 0 04 3290 3255

1*

9 8 0 7 . 8 -8 . 2

2 5 -2 8

2 042 3 0 72

2 * 3 * .

995 985 7 . 8 - ' 7 . 6 -8 . 3 8 . 4

2 7 - 2 7 -2 9 2 8

1 9 0 8 3 2 0 8

2 1 96 3190

4 * 5+

1 0 0 0 . � 9 0 7 . 5 - 7 . 5 -7 . 9 8 . 4

2 6 - 2 5 -2 8 2 9

2 0 50 3 06 5

2 0 10 3 1 7 0

1*

4 8 5 7 . 5 -7 . 8

2 5 -2 8

1 6 6 0 971

2 *

4 6 0 8 . 3 -8 . 5

2 7 -2 9

1580 8 8 5

3 *

495 7 . 9 -8 . 4.

2 7 -2 8

1600 8 96

4*

4 9 0 7 . 7 -7 . 9

2 6 -2 7

1572 1064

5+

490 7 . 5 -8 . 5

2 5 -2 9

1603 9 3 5

2 5 012 2 0819 2 2 84 6 . 16867 2 18 3 6 1 9 7 4 5 1 96 7 8 1 9 2 0 0 1 9 8 3 9 1 9 5 3 8 1 8 3 04 1 8 3 4 0 1 8 1 0 6 18133 1 8 2 0 7 9 4 94 8589 7 3 6 8 5 3 6 4 8 1 3 8 5 9 7 0 6 12 4 6 2 5 7 5 8 0 8 6 1 6 7 3 8 5 0 3 9 2 7 3 7 8 6 3 923 3 94 7 3 02 4 2 6 3 3 2 2 1 0 1936 2 56 1 155i 1 6 3 5 1715 1 6 2 6 1688 1324 142 0 1408 1325 1 3 9 3 1800 1 6 0 0 1 2 8 0 1 0 6 5 1475 1590 1 5 6 5 1 5 8 2 1 5 6 0 1 5 7 0 1248 1 2 4 4 1260 1 2 4 0 1 2 6 0

1 2 2 7 0 8 4

1 2 4 149

2 9 . 1 5 . 2

1 9 . 5 6 . 0

10 . "0

143 6244

136 122

23 . 6 3 . 6

16 . 3 5 . 1 8 . 5

138 5 113

98 150

2 8 . 9 4 . 4

1 5 . 2 5 . 7 9 . 0

110 4710

108 186

14 . 4 2 . 5

14 . 1 3 . 2 7 . 2

134 120 5843 5443

113 115 150 150

2 3 . 3 2 1 . 9 4 . 3 4 . 3

17 . 3 15 . 2 5 . 3 5 . 6 9 . 3 9 . 2

140 5 6 8 3

117 151

2 3 . 5 4 . 4

1 5 . 0 5 . 3 9 . 5

137 5 02 6

114 152

2 2 . 5 4 . 3

14 . 9 5 : 5 9 . 4

1 2 9 5 6 7 0

1 1 1 1 4 8

2 4 . 1 4 . 5

15 . 3 5 . 2 9 . 3

133 562 0

114 1 5 0

23 . 0 4 . 3

15 . 1 5 . 3 9 . 3

103 4 8 1 7

98 1 2 7

2 1 . 8 4 . 2

1 1 . 3 4 . 8 8 . 3

113 4 9 0 5

98 128

2 3 . 4 4 . 3

11 . 0 4 . 7 8 . 3

112 5057

96 127

2 2 . 3 4 . 2

11 . 1 4 . 8 8 . 4

111 4 8 8 2

9 5 124

2 3 . 9 4 . 3

1 1 . 3 4 . 6 8 . 3

110 4 8 9 5

9 6 1 2 7

2 2 . 8 4 . 2

11 . 1 . 4 . 7 8 . 3

Chromium 2 1 . 4 16 . 9 15 . 4 12 . 1 1 7 . 2 16 . 2 1 6 . 1 16 . 3 1 6 . 9 16 . 5 6 . 0 5 . 9 6 . 1 6 . 0 6 . 0 Copper BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BOL BDL Cadmium BDL BDL BOL BDL BDL BDL BOL BDL BDL BDL BDL BDL BDL BOL .BDL Manganese 0 . 316 0 . 3 11 0 . 2 8 8 0 . 2 74 0 . 3 0 8 0 . 3 04 0 . 3 1 0 0 . 3 0 6 0 . 3 02 0 . 3 0 5 0 . 175 0 . 18 5 0 . 18 9 0 . 18 8 0 . 1 8 7 Zinc 0 . 22 2 0 . 19 7 0 . 18 9 0 . 184 0 . 1 98 0 . 193 0 . 194 0 . 195 0 . 1 9 2 0 . 194 0 . 172 0 . 1 73 0 . 1 73 0 . 16 5 0 . 16 9 Lead 0 . 2 5 1 0 . 2�9 0 . 2 3 5 0 . 212 0 . 23 7 0 . 23 8 0 . 2 3 9 0 . 2 40 0 . 2 3 5 0 . 2 3 8 0 . 22 0 0 . 2 1 9 0 . 2 18 0 . 223 0 . . 2 2 2 Ni9kel BDL BOL BDL BDL BDL BDL BDL BDL BOL BDL BDL BDL BDL BDL BDL . I ron . 3 . 2 0 2 . 91 2 . 8 1 2 . 6 8 2 . 93 2 . 92 2 . 93 . 2 . 9 5 2 . 9 7 2 . 94 1 . 6 9 1 . 6 8 1 . 6 7 1 . 6 9 1 . �6

Contd . . .

z � Z tl -< � � -

� en -'l t'I'l � t'I'l � 2: � z � C) t'I'l 2: t'I'l Z -'l Z � Z Z t'I'l � @ en

.j>. 00 \0

Table 6 Contd . . .

Parameters

Colour , Pt -Co pH

Temp . , oC

Alkal inity SS TDS COD BOD Sulphates Sulphides Chlorides Ammonical N Kj eldhal N Nitrate N Nitrite N Phosphates Phenols oil & Grease Heavy Metals

Chromium Copper Cadmium Manganese Zinc Lead Nickel . Iron

Eff . from Anaerobic Lagoon Eff . fro� Pre.- aeration Tank

1*

3 8 5 7 . 4 -7 . 6

2 8 -2 9

1 8 9 0 1 6 8

2 *

3 6 5 7 . 5 -7 . 8

2 7 -2 8

1866 166

3 *

3 9 5 7 . 7 -7 . 8

2 6 -2 8

1910 1 7 7

4*

3 9 5 7 . 7 -7 . 8

2 6 -2 7

183"0 165

5+ 1 * .

3 9 0 3 3 5 7 . 4 - 7 . 7 -7 . 8 7 . 8

2 6 - 2 7 -2 9 2 8

1 8 8 8 1330 167 245

2 *

3 15 7 . 7 -7 . 8

2 7 -2 8

1 3 0 6 2 52

3 *

3 5 0 7 . 7 -7 . 8

2 5 -2 7

1 2 92 2 7 5

4*

340 7 . 7 -7 . 8

2 5 -2 6

1 3 0 0 2 6 9

5+

345 7 . 7 -7 . 8

2 5 -2 8

1310 2 6 7

Eff . from Secondry Clarifier

1*

2 0 5 6 . 5 -6 . 7

2 6 -2 7 126 1 0 8

2 *·

210 6 . 5 -6 . 6

2 5 -2 6 1 3 0 1 0 6

3 * 4 *

200 195 6 . 6 - 6 . 7 -6 . 7 6 . 8

2 5 - 2 5 -2 6 26 122 120 110 1 12

5+

200 6 . 5 -6 . 8

2 5 -2 7 1 2 8 109

17224 17203 17183 1 7 118 17169 16397 1 6 4 8 0 1 6 5 8 2 16673 1 6 5 8 5 1 5 3 4 8 1 5 3 1 0 15056 1 4 8 8 9 15042 2482 2 560 2415 2 5 86 2 56 6 1295 . 1 3 0 0 1254 1125 1246 5 2 6 507 4 95 4 7 5 510

8 3 8 986 922 9 0 0 962 313 2 9 2 226 2 5 3 243 3 7 35 32 36 34 34 29 35 2 5 31 765 780 750 785 772 530 525 510 515 525

180 196 2 12 190 200 8 9 1 0 8 9 1 . 6 1 . 8 2 . 1 1 . 8 1 . 8 4 8 18 4807 4 9 51 4 7 8 9 4 8 07 4 7 3 2 4 7 14 4 8 9 2 4 7 0 0 4 7 5 9 4 2 9 5 4 3 5 2 433 9 4423 4 2 5 9

108 110 106 103 107 6 6 6 8 64 6 1 6 5 24 2 5 23 2 8 2 5 1 4 2 1 4 5 1 3 9 135 1 3 9 86 8 9 8 3 79 84 3 2 3 3 30 3 8 3 3

1 1 . 6 1 1 . 4 11 . 2 11 . 8 1 1 . 5 14 . 6 14 . 0 14 . 1 14 . 4 13 . 6 8 . 6 9 . 3 8 . 8 8 . 4 8 . 5 2 . 2 2 . 1 2 . 1 2 . 1 2 . 1 BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL 6 . 5 6 . 6 6 . 3 6 . 4 6 . 6 6 . 2 6 . 3 6 . 2 6 . 2 6 . 3 2 . 2 2 . 3 2 . 1 2 . 2 2 . 1 3 . 3 3 . 4 3 . 5 3 . 5 3 . 4 3 . 2 3 . 3 3 . 4 3 . 3 3 . 3 BDL BDL BDL BDL BDL 5 . 9 5 . 8 5 . 8 5 . 8 5 . 8 5 . 7 5 . 7 5 . 8 5 . 7 5 . 7 4 . 5 4 . 5 4 . 6 4 . 5 4 . 5

1 . 12 1 . 1 0 1 . 11 1 . 1 0 1 . 12 0 . 7 75 0 . 778 0 . 782 0 . 7 8 3 0 . 7 79 0 . 6 8 3 0 . 6 87 0 . 692 0 . 678 0 . 6 89 BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL . BDL

0 . 0 8 1 0 . 082 0 . 0 8 0 0 . 0 82 0 . 08 1 0 . 076 0 . 076 0 . 07 7 0 . 0 79 0 . 078 0 . 064 0 . 06 5 0 . 067 0 . 06 5 0 . 06 6 0 . 16 6 0 . 162 0 . 15 8 0 . 16 0 0 . 162 0 . 153 0 . 152 0 . 154 0 . 150 0 . 151 0 . 13 5 0 . 13 6 0 . 137 0 . 13 5 0 . 13 6 0 . 162 0 . 163 0 . 1 5 9 0 . 16 0 0 . 161 0 . 13 9 0 . 13 8 0 . 13 5 0 . 13 6 0 . 13 8 0 . 06 6 0 . 06 5 0 . 063 0 . 06 7 0 . 066

BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL 0 . 73 1 0 . 73 0 0 . 72 5 0 . 73 5 0 . 72 9 0 . 595 0 . 5 9 9 0 . 5 9 6 0 . 5 9 7 0 . 598 0 . 44 0 0 . 44 6 0 . 44 8 0 . 44 6 0 . 443

All values are expressed in mg/] except colour , pH and temperature ; * 6 h ' compos ite samples :

BDL - Below detectable limits

1 - 0 6 0 0 h to 1100 h 2 - 1200 h to 1700 h ; 3 - 1 8 0 0 h + 24 h composite sample

� �

to 2 3 0 0 h 4 - 2 4 0 0 to 0500 h

).. ...

� o

.... en o z o

al en

<: o r VI 00 .... C � \0 \0 \0

J

Parameters

Colour � P t - Co pH

Temp " oC

Alkal inity SS TDS COD BOD Sulphates Sulphides Chlorides Ammonical N Kj e ldhal N Nitrate N Nitrite N Phosphates Phenol s Oil & Grease Heavy Metals

v" .... )...

Table 7 - Performance evaluation of common effluent treatment plant (After proper operation and maintenance)

#'

Receiving Sump Eff . from Equalization Basin Eff . from Primary Clar i f ie r

1* 2 * 3 * 4* 5+ 1 * 2 * 3 * 4* 5+ 1* 2 * ' 3 *

146 0 1 4 8 0 1430 1450 1450 995 1 0 0 0 975 985 1000 4 9 0 485 490 7 . 3 - 7 . 9 - 6 . 9 - 7 . 0 - 7 . 0 - 7 . 6 - 7 . 6 - 7 . 4 - 7 . 3 - 7 . 3 - 7 . 4 - 7 . 4 - 7 . 4 -9 . 5 9 . 1 7 . 7 7 . 3 8 . 8 7 . 8 7 . 8 7 . 7 7 . 4 7 . 8 7 . 6 7 . 6 7 . 5

2 5 - 2 7 - 2 7 - 26 - 2 6 - 2 5 - 2 7 - 2 6 - 2 7 - 2 5 - 2 5 - 2 7 - 2 7 -26 2 � 2 9 2 7 2 9 2 8 2 9 2 8 2 8 2 9 2 7 2 9 2 8

2660 2 4 0 0 2 2 7 2 2 2 8 0 2 2 8 8 2 0 6 0 2 0 3 8 1 9 92 2 0 0 0 2 0 2 5 1 6 6 8 1552 1540 3790 4 2 6 0 2 50 0 3000 3 8 2 0 3 6 6 0 3 3 6 0 2 4 7 0 3 0 3 0 3 100 750 709 652

17804 1 6 8 9 0 2 4 8 0 8 2 14 8 8 2 0 2 3 6 1 8 9 0 0 2 0 0 1 0 1 9 0 8 6 19546 19232 1 7 6 1 5 18129 17578 8452 8 04 8 7306 7221 7922 6167 6 113 5 919 6315 6237 2658 3 2 1 5 2 9 8 0 2236 2 662 2 1 0 0 2 0 9 6 2 3 0 7 1665 1 6 5 0 1598 1 7 05 1 6 8 4 1 2 3 4 1213 1 0 9 9 1 6 7 0 1 7 8 0 1 2 7 0 1525 1 4 9 2 1 4 7 2 1 4 8 0 1450 1 5 3 0 1450 1160 1 2 4 2 1180

122 145 1 5 8 ' 135 144 150 14 0 136 133 141 110 8 9 100 5924 4391 7690 5535 5744 5773 5715 5608 5443 5613 5080 5086 4952

100 98 126 110 117 115 116 116 1 0 9 116 82 86 85 150 118 1 5 0 145 1 5 1 1 5 0 152 152 148 152 1 0 8 116 117

22 . 4 15 . 6 2 6 . 8 2 2 . 3 2 2 . 6 2 0 . 3 2 1 . 5 2 1 . 9 2 2 . 3 2 2 . 6 2 0 . 2 2 0 . 4 21 . 7 2 . 5 4 . 4 3 . 3 6 . 4 4 . 4 4 . 5 4 . 4 4 . 3 4 . 4 4 . 4 4 . 4 4 . 3 4 . 3

14 . 6 18 . 2 15 . 1 19 . 4 17 . 8 15 . 5 14 . 7 14 . 3 15 . 6 15 . 2 1 1 . 5 10 � 9 11 . 1 6 . 8 5 . 7 3 . 9 5 . 2 5 . 5 5 . 3 5 . 5 5 . 2 5 . 4 5 . 3 4 . 5 4 . 4 4 . 4

12 . 6 7 . 4 10 . 4 8 . 6 9 . 3 9 . 3 9 . 5 9 . 2 9 _ 5 9 . 4 8 . 5 8 . 7 8 . 6

4 *

4 5 0 7 . 3 -7 . 5

2 6 -2 7

1 5 9 8 764

5+

4 8 0 7 . 4 -7 . 6

2 5 -2 9

1608 713

17845 17913 3 14 7 3 1 12 1096 ' 1 2 04 1194

1 0 1 4 8 5 0

84 113 .

2 2 . 0 4 . 4

11 . 3 4 . 3 8 . 7

1170 98

4 962 86

1 1 0 2 2 . 6

4 . 4 1 1 . 2

4 . 4 8 . 5

Chromium 16 . 9 1 9 . 3 14 . 8 17 . 4 16 . 8 16 . 8 17 . 1 16 . 5 16 . 2 16 . 7 5 . 8 6 . 0 5 . 9 6 . 0 5 . 9 Copper BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL Cadmium BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL Manganese 0 . 2 64 0 . 42 6 0 . 2 8 2 0 . 3 15 0 . 3 04 0 . 3 0 3 0 . 3 05 0 . 3 02 0 . 3 04 0 . 3 0 3 0 . 1 79 0 . 18 5 0 . 178 0 . 18 9 . 0 . 1 86 Zinc 0 . 2 2 5 0 . 198 0 . 2 2 1 0 . 15 7 0 . 195 0 . 190 0 . 192 0 . 18 9 0 . 1 90 0 . 190 0 . 16 5 0 . 17 0 0 . 166 0 . 172 0 . 16 8 Lead 0 . 34 0 0 . 242 0 . 1 94 0 . 2 03 0 . 2 42 0 . 2 3 7 0 . 2 3 8 0 . 2 3 9 0 . 22 9 0 . 2 3 8 0 . 2 1 9 0 . 2 1 8 0 . 22 5 0 .. 2 1 9 0 . 22 0 Nickel Iron

BDL BDL 1 . 95 2 . 64

BDL 3 . 46

BDL 3 . 05

BDL BDL 2 . 96 2 . 94

BDL BDL 2 . 90 2 . 92

BDL 2 . 98

BDL 2 . 94

BDL 1 . 6 9

BDL 1 . 6 7

BDL 1 . 6 8

BDL 1 . 6 5

BDL 1 . 6 7

Contd . . .

z :> z o -< � I:> -

:E :> en -l tTl :E � tTl " � :> z :> Cl tTl � tTl Z -l Z

� Z Z tTl � tTl en

� 'D

Table 7 Contd . . .

Parameters

Colour , Pt - Co pH

Temp . , oC

Alkal inity SS TDS COD BOD Sulphates Sulphides Chlorides Anunonical N Kj eldhal N Nitrate N Nitrite N Phosphates Phenols O i l & Grease Heavy Metal s

Chromium Copper Cadmium Manganese Zinc Lead Nickel ' Iron

E f f . from Anaerobi c Lagoon E f f . from Pre - aeration Tank E f f . f rom Secondry Clarif ier

1 * 2* 3 * 4 * 5+ 1* 2 * 3 * 4 *

3 9 5 3 9 0 4 0 0 3 6 5 .3 8 5 345 3 3 5 3 15 3 2 0 7 . 4 - 7 . 2 - 7 . 1 - 7 ; 1 - 7 . 1 - 7 . 4 - � . 3 - 7 . 3 - 7 . 3 -7 . 6 7 . 7 7 . 2 7 . 2 7 . 6 8 . 0 7 . 5 7 . 4 7 . 4

2 6 - 2 7 - 2 7 - 2 7 - 2 7 - 2 6 - 2 7 - 2 5 - 2 6 -2 7 2 9 2 9 2 8 2 9 2 8 28 2 7 2 7

1 7 9 0 1 8 3 8 1802 1 7 8 6 1 8 12 1208 1196 1200 1 2 3 6 157 155 160 1 6 5 1 5 8 349 2 5 5 3 2 1 2 3 4

1 6 7 1 7 17005 1 6 7 6 9 1 6 8 2 8 16942 1 6 3 4 9 16240 16182 1 6 1 7 2 1940 2170 2 107 2 1 7 8 2147 1 0 4 0 1070 1126 1 0 6 7

8 0 7 807 736 7 3 7 7 96 2 1 1 2 1 0 234 2 2 2 3 5 2 5 3 0 3 5 3 0 7 9 0 750 7 6 9 7 5 0

1 8 9 1 6 7 184 1 8 0 1 7 6 8 7 8 9 4 744 4897 4825 4 6 3 8 4 8 6 3 4 7 0 0 4 8 0 8 4 76 5 4 5 5 0

1 1 0 111 1 1 2 105 1 1 0 6 7 6 2 6 7 6 9 1 4 3 1 4 6 1 4 8 1 3 7 140 8 7 81 8 8 9 1

10 . 5 10 . 6 1 1 . 7 10 . 9 1 1 . 3 13 . 4 13 . 2 13 . 1 1 3 . 7 2 . 2 2 . 1 2 . 0 2 . 1 2 . 0 BOL BDL BOL BDL 6 . 9 6 . 0 6 . 8 6 . 3 6 . 5 6 . 7 5 . 9 6 . 7 6 . 3 3 . 7 3 . 6 3 . 6 3 . 5 3 . 6 3 . 6 3 . 5 3 . 5 3 . 4 5 . 8 6 . 0 5 . 9 6 . 1 5 . 9 5 . 7 5 . 9 5 . 8 6 . 0

5+

3 3 0 7 . 3 -8 . 0

2 6 -

1 *

2 1 0 6 . 1 -7 . 0

2 6 -

2 * 3 *

2 2 0 2 0 5 6 . 1 - 6 . 1 -6 . 2 6 . 3

2 5 - 2 5 -

4* '

210 6 . 3 -6 . 9

2 5 -

5 +

210 6 . 1 -6 . 9

2 5 -2 8 2 7 2 7 2 6 2 6 2 7

1216 1 2 8 1 2 2 1 2 6 1 2 2 124 278 105 9 2 100 8 9 98

1 6 3 3 5 14534 14 3 0 8 1 4 6 93 14814 14678 1070 4 3 7 4 0 8 4 2 6 433 424

217 2 8 3 1 2 4 2 7 3 0 765 5 2 0 5 3 0 5 5 0 540 530

8 4 6 2 6

6 6 86

13 . 3 BOL 6 . 1 3 . 5 5 . 8

1 . 8 4178

26 34

8 . 9 BOL 2 . 5 BOL 4 . 7

1 . 5 4 3 0 7

2 7 3 5

9 . 5 BDL 2 . 0 BOL 4 . 8

1 . 9 1 . 8 4212 4263

2 5 2 7 3 3 3 6

9 . 9 9 . 7 BDL BOL 2 . 6 2 . 7 BOL BOL 4 . . 8 4 . 9

1 . 8 4 2 3 7

2 6 3 5

9 . 6 BOL 2 . 5 BOL 4 . 8

1 . 12 1 . 0 5 1 . 15 1 . 13 1 . 14 0 . 782 0 .. 771 0 . 7 90 0 . 7 8 1 0 . 78 1 0 . 6 8 2 0 . 6 8 7 0 . 6 7 9 0 . 6 85 0 . 6 80 BOL BOL BOL BOL BOL BOL BOL BOL BOL BDL BDL BDL BOL BOL BOL BOL BOL . BOL BOL BOL BOL BOL BOL BOL BOL BDL BDL BOL BOL BOL

0 . 08 0 0 . 082 0 . 083 0 . 082 0 . 08 1 0 . 075 0 . 076 0 . 079 0 . 08 0 0 . 078 0 . 062 0 . 0 6 5 0 . 06 7 0 . 070 0 . 06 0 0 . 16 5 0 . 16 2 0 . 157 0 . 1 5 8 0 . 16 0 0 . 156 0 . 1 52 0 . 15 6 0 . 15 0 0 . 152 0 . 13 7 0 . 13 5 0 . 13 8 0 . 14 0 0 . 142 0 . 16 5 0 . 16 2 0 . 158 0 . 162 0 . 16 1 0 . 14 0 0 . 13 8 0 . 13 6 0 . 14 1 0 . 13 9 0 . 06 8 0 . 06 S 0 . 06 2 0 . 063 0 . 06 8

BOL BOL BOL BOL BOL BOL BOL BOL BOL BDL BOL BOL BOL BOL BOL 0 . 735 0 . 73 8 0 . 736 0 . 73 0 0 . 73 3 0 . 6 03 0 . 6 0 9 0 . 5 8 9 0 . 6 1 0 0 . 6 0 1 0 . 4 5 5 0 . 46 3 0 . 46 5 0 . 458 0 . 46 0

Al l values are expre s s ed i n mg/ l . except * 6 h compos ite samples :

colour , pH and temperature ; BOL - Below detectable l imits ·

1 - 0 6 0 0 h to 1100 h; 2 - 1200 h + 24 h compos ite sample

� .... ,

to 1700 h ; 3 - 1800 h toO 2 3 0 0 h ; · 4 - 2 4 0 0 h toO - 0 5 0 0 h

, . "

.j:>. '" N

..... c.n 0. Z o

::tl t"I1 c.n

<: o " VI 00

c " . ;..c: '" '" '"

NANDY et al. : WASTEWATER M ANAGEMENT I N TANNERIES 493

Table 8 - Improvement in the performance of the chemical treatment unit

Parameter Concentration

After commissioning After proper 0 and M

Influent Effluent per cent Influent Effluent percent Removal Removal

BOD, mg/l 1 552- 1 71 5 1 324-1 420 1 3. 1 - 1 8.5 1 598-1 705 1 096-1 234 25.9-35.7

COD,mg/l 5808-6257 3786-3927 32.4-39.5 591 9-63 1 5 2658-321 5 47.4-56.9

SS, mg/lL 3065-3208 885-1 064 65.3-72.4 2470-3660 652-750 73.6-79.5

1

494 J SCI IND RES VOL 58 JULY 1 999

Table 9 - Treatability studies for combined wastewater

(Physico-chemical route with alum as coagulant)

Paramet ers Raw waste E f f luent concentrat ion - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Coagulant dose - 'a'lum in mg/I - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .

2 0 0 3 0 0 4 0 0 5 0 0

Appearance Dark Brown Brown Brown LiqJa'� Brown Brown

Colour , Pt - Co 1 0 0 0 8 1 5 7 9 9 7 4 5 7 0 0 pH 7 . 8 7 . 2 7 . 0 6 . 6 6 . 1 SS 3 1 0 0 2 3 8 4 2 1 5 8 1 8 6 3 1 6 1 8 COD 6 2 3 7 5 0 2 1 4 5 5 9 3 4 9 9 3 1 8 7 TDS 1 9 2 3 2 1 6 9 4 3 1 6 8 6 6 1 6 7 3 2 1 6 5 4 0 S ludge Volume , mL/ L 2 0 3 0 3 7 4 3 57

Al l value s except colour , pH, and s ludge volume are in mg/l Opt imum a lum dose : 5 0 0 mg/ l

Table 1 0 - Treatability studies for combined wastewater (Physico-chemical route with alum and l ime as coagulant)

Parameters Raw waste Effluent concentrat ion

6 0 0

Light Brown

6 7 5

6 . 0

1 5 4 1

3 1 1 2

1 6 5 0 1

7 5

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Coagulant doose - a�lum : l ime in mg/ l

7 0 0

Light Brown

6 6 0

5 . 7

1 4 7 9

3 0 3 1

1 6 6 3 6

9 5

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

5 0 0 : S O D : 5 0 0 : 5 0 0 :

4 0 0 5 0 0 6 0 0 7 0 0

Appearance Dark Light Light Light Faint Brown Brown Brown Brown Brown

Colour , Pt - Co 1 0 0 0 6 1 5 5 9 5 5 7 5 5 5 0

pH 7 . 8 7 . 2 7 . 5 7 . 8 8 . 1

SS 3 1 0 0 9 3 0 8 6 5 73 5 6 1 1

COD 6 2 3 7 2 9 6 9 2 8 1 0 2 4 2 0 2 0 3 3

TDS 1 9 2 3 2 1 5 73 2 1 5 7 8 9 1 6 0 9 7 1 6 4 4 3

Sludge Volume , mL/L 2 0 8 5 9 0 1 0 5 1 2 0

Al l values exc-ept colour , pH and s ludge volume are in mg/ l Opt imum dose o f Alum : Lime - 5 0 0 : 8 0 0 mg/ l

5 0 0 : 5 0 0 : 5 0 0 :

8 0 0 9 0 0 1 0 0 0

Faint Faint Faint Brown Brown Brown

4 9 5 4 7 5 4 6 0

8 . 5 9 . 0 9 . 8

4 9 6 4 5 6 4 2 8

1 5 6 0 1 3 4 7 1 1 3 2

1 6 8 8 0 1 7 1 3 6 1 7 4 4 3

1 5 0 1 5 5 1 6 5

,

-'

�

.�

,-

r � ..... ../

Table I I - Performance Evaluation of Common Effluent Treatment Plant (After Optimization of Chemical Treatment)

Parameters Receiving Sump Eff. from Equalization Basin Eff. from Primary Clarifier

I ' 2' 3' 4' 5+ l ' 2' 3' 4' 5+ I ' 2' 3' 4' 5+

Colour, Pt-Co 1 05 1 1 595 1 20 1 1 685 1 400 980 990 1 006 985 1 000 480 495 485 465 480 pH 8.2- 8.0- 7.0- 7.3- 7.0- 7.7- 7.9- 7.9- 7.7- 7.7- 7.7- 7.9- 7.9- 7.9- 7.7-

9.2 8.5 8.2 9.0 9.2 7.8 8 . 1 8.0 8.0 8 . 1 7.8 8.2 8.0 8.0 8 .2 Z ;J>

Ternp.,"C 25- 27- 27- 27- 25- 25- 27- 27- 27- 25- 25- 27- 27- 26- 25- Z 28 28 29 28 29 28 29 28 28 29 28 29 28 27 29 t:I -<

Alk�\ in.i ty 2260 2 1 20 1 9 1 0 1 990 20 1 0 2095 2 1 60 2 1 68 1 946 2008 1 655 1 5 1 5 1 672 1 468 1 555 � S S 4620 5500 1 490 7800 4730 3 4 1 9 3 362 3 3 1 8 3420 3392 485 535 547 424 500 �

-

TDS 1 943 1 1 5880 1 8694 2 1 5 23 1 8980 1 9337 1 8960 1 9004 1 9430 1 9 1 85 1 7307 1 7273 1 8836 1 7254 1 7458 COD 79 1 2 5464 6868 9847 7385 6677 6465 6738 63 1 0 6539 2 1 03 1 940 1 927 2070 2058 � BOD 2335 1 645 2099 29 1 4 2238 1 780 1 725 1 797 1 653 1 760 7 2 1 726 704 757 7 1 7 ;J>

CI:l Sulphates 1 550 1 385 1 730 1 1 36 1 400 1 1 50 1 1 20 1 1 75 1 1 35 1 1 50 948 930 920 940 932 -'l tTl Sulphicles 1 34 1 58 1 22 1 26 1 30 1 36 1 28 1 35 1 30 1 32 1 07 1 09 1 1 0 1 1 1 1 08 � Chlorides 62 1 8 4370 5975 7057 6 1 90 5936 5895 5943 6254 60 1 5 5343 5464 5366 5343 5400 � A mmonical N 1 02 1 1 6 1 24 1 33 1 1 6 1 09 1 1 4 1 1 7 1 1 4 1 1 5 83 86 83 78 84 tTl :;o::l Kjeldhal N 1 36 1 5 2 1 62 1 73 1 50 1 48 1 50 1 5 1 1 50 1 5 1 1 1 0 1 1 2 1 08 1 06 1 08 s:: N itrate N 2 1 .2 20.6 2 1 .8 22.7 22. 1 20.9 2 1 .3 22.4 23. 1 22.6 20.6 20.6 2 1 .9 2 1 .8 22.0 ;J> Nitrite N 4.4 5 .3 3 .5 4.2 4.3 4.4 4.3 4.5 4.3 4.4 4.3 4.2 4.3 4.2 4.3

Z ;J> Phosphates 1 4.3 1 5 .2 1 8 .4 1 9.0 1 7 .3 1 5. 2 1 5 .0 1 4.9 1 5 . 1 1 5 . 1 1 1 .3 1 1 . 1 1 1 .2 1 0.8 1 1 . 1 Cl tTl Phenols 4.3 5.5 7.6 3 .3 5 .4 5 .3 5 .6 5 .5 5 .4 5 .5 4.4 4.6 4.6 4.5 4.5 s:: Oil & Grease 1 0.2 8.9 9. 1 7.2 9.2 9.3 9.3 9.3 9.2 9.3 8.2 8.2 8.3 8.2 8 .3 tTl

Z Heavy Metals -'l -Chromium 1 7.0 1 7.3 1 6.8 1 7 .4 1 7 .2 1 6.4 1 6.5 1 6.9 1 6.3 1 6.5---� 5.4 5 .8 5 .9 5 .3 5 .6 Z -Copper BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL B DL BDL BDL BDL BDL -'l ;J> -Cadmium BDL BDL BDL BDL B DL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL Z -Manganese 0.304 0.308 0.306 0.3 1 0 0.308 0.303 0.304 0.307 0.3 1 0 0.306 0. 1 76 0. 1 85 0. 1 88 0. 1 89 0. 1 87 Z tTl -Zillc 0.203 0. 1 97 0. 1 98 0. 1 95 0. 1 98 0. 1 94 0. 1 95 0. 1 96 0. 193 0. 1 95 0. 1 7 3 0. 1 72 0. 1 73 0. 1 65 0. 1 70 :;o::l -Lead 0.242 0.240 0.234 0.233 0.238 0.237 0.239 0.24 1 0.236 0.239 0.22 1 0 .2 1 9 0.2 1 7 0.224 0.223 tri

CI:l -Nickei SOL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL -Iron 2.90 2.92 2.94 2.97 2.94 2.93 2.94 2.96 2.98 2.95 1 .66 1 .67 1 .68 1 .69 1 .66

Colour, PI-Co 375 385 355 380 370 3 20 340 333 335 3 30 205 220 225 230 220 pH 7.3- 7.4- 7.4- 7.4- 7.3- 7.4- 7.5- 7.5- 7.5- 7.4- 6.4- 6.3- 6.4- 6.3- 6.3-

7.4 7.5 7.5 7.5 7 .5 7.5 7.7 7.6 7.6 7.7 6.5 6.4 6.5 6.6 6.6 Te·mp.,o 28- 27- 26- 26- 26- 28- 27- 25- 25- 25- 27- 25- 25- 25- 25-

Contd . . . .l>-'D l.Il

Table 1 1 Contd . . .

29 29 27 27 29 29 28 27 27 29 28 27 26 Alkalinity 1 865 1 800 1 772 1 768 1 785 1 2 1 5 1 242 1 226 1 240 1 230 1 02 1 00 1 1 8 SS 1 1 1 1 1 3 1 07 1 0 1 1 1 0 235 205 2 1 9 258 235 1 1 2 1 05 1 09 IDS 1 6303 1 6565 1 7555 1 6478 1 6550 1 6058 1 6 1 0 1 1 6993 1 6 1 65 1 6203 1 5544 1 4909 1 5 5 1 5 COO 1 354 1 277 1 360 1 280 1 35 2 649 656 636 648 650 343 329 363 BOO 45 1 460 482 455 453 1 19 1 20 1 22 1 1 5 1 1 8 3 1 34 34 Sulphates 35 32 33 37 34 690 680 685 695 695 5 1 0 520 550 Sulphides 1 52 1 48 1 60 1 40 1 45 1 0 1 2 1 3 1 4 1 2 1 .9 1 .8 2.0 Chlorides 5247 5265 5248 5266 5295 5 2 1 0 52 1 8 52 1 5 5 222 5250 4595 4587 4574 Ammonical N 1 10 1 03 1 07 1 06 1 08 68 66 64 65 67 30 35 32 Kje\dhal N 1 45 1 35 1 39 1 42 1 39 79 89 86 83 84 42 43 46 Nitrate N 1 1 .2 1 0.9 1 0.2 1 1 .4 1 0.8 1 4.5 1 3 .7 1 3 . 3 1 4.2 1 3 .9 1 0.3 1 1 .2 1 0.9 Nitrite N 2.2 2. 1 2.3 2. 1 2.3 BOL BOL BOL BOL BOL BOL BOL BOL Phosphates 6.5 6.7 6.8 6.7 6.6 6.3 6.5 6. 1 6.4 6.3 3.2 3 .6 4.2 Phenols 3 .6 3.8 4.2 3 .7 3 .7 3.2 3.5 3.7 3 .6 3 .6 BOL BOL BOL Oil & Grease 5 .8 5 .7 6.2 5.8 5.9 5.7 5 .6 6.0 5 .5 5 .6 4.7 4.6 4.7 Heavy Metals -Chromium 1 . 14 1 .20 1 . 1 5 1 . 1 2 1 . 1 3 0.782 0.783 0.801 0.7 8 1 0.782 0.665 0.663 0.673 0.675 0.670 -Copper BOL BOL BOL BOL BOL BOL BOL BOL BOL B OL BOL BOL B OL -Cadmium BOL BOL BOL BOL B OL BOL BOL BOL BOL BOL BOL BOL BOL -Manganese 0.080 0.08 1 0.083 0.084 0.082 0.076 0.077 0.079 0.08 1 0.079 0.063 0.066 0.068 -Zinc 0. 1 62 0. 1 65 0. 1 57 0. 1 58 0. 1 6 1 0. 1 57 0. 1 53 0. 1 47 0. 1 5 1 0. 1 53 0. 1 36 0. 1 34 0. 1 37 -Lead 0. 1 65 0. 1 58 0. 1 62 0. 1 62 0. 1 6 1 0. 1 40 0. 1 42 0. 1 38 0. 1 37 0. 1 39 0.068 0.065 0.063 -Nickel BOL BOL BOL BOL B OL B OL BOL BOL B OL BOL BOL BOL BOL -Iron 0.738 0.735 0.736 0.730 0.733 0.603 0.605 0.602 0.60 1 0.602 0.454 0.462 0.466

All values are expressed in mgll except colour, pH and temperature; BOL - Below detectable limits * 6 h composite samples: 1 - 0600 h to 1 1 00 h; 2 - 1 200 h to 1 700 h; 3 - 1 800 h to 2300 h; 4 - 2400 h to 0500 h + 24 h composite sample

\ J (- " ""

27 28 1 05 1 00 1 14 1 1 0

1 5 1 63 1 5263 347 339

35 33 540 535 1 .8 1 .9

4860 4620 33 3 1 39 40 1 1 .6 1 0.5 BOL BOL 4.6 3.9 BOL BOL 4.8 4.7

BOL BOL BOL BOL

0.Q7 1 0.067 0. 1 39 0. 1 38 0.063 0.065 BOL B OL

0.460 0.460

Contd . . .

,

.j>. \D 0\

...... en 0 Z � � tTl en -< 0 " V1 00 ...... c £< \D \D \D

)

NANDY et ai. : WASTEWATER M ANAGE M ENT I N TANNERIES

Table 1 2- lmprovement in the performance of chemical treatment plant with optimum coagulant dosage

Parameter

BOD, mgll COD, mgll SS, mgll

Concentration After proper 0 and M After Optimising Chemical

Treatment Influent

1 598-1 705 591 9-63 1 5 2470-3660

Effluent 1 096-1 234 2658-321 5

652-750

%Removal 25.9-35.7 47.4-56.9 73.6-79.5

Influent 1 653-1 797 631 0-6738 331 8-3420

Effluent 704-757

1 927-21 03 424-547

%Removal 54.2-60.8 67.2-71 .4 83.5-87.6

497

Parameters

I '

Colour, Pt-Co 1 3 85 pH 7.8-

9 .8 Temp. ,oC 26-

27 Alkalinity 2360 SS 5 2 1 0 TDS 1 8487 1 8560 COD 1 00 1 2 BOD 3 1 04 Sulphates 1 620 Sulphides 1 22 Chlorides 7794 Ammonical N 1 1 0 Kjeldhal N 1 43 Nitrate N 22.3 Nitrite N 4.4 Phosphates 1 7.5 Phenols 5 .6 Oil & Grease 9.4 Heavy Metals -Chromium 1 7. 3 -Copper BDL -Cadmium BDL -Manganese 0.3 1 5 -Zinc 0.224 -Lead 0.343 -Nickel BDL -Iron 2.90

Table 1 3 - Performance Evaluation of Common Effluent Treatment Plant (After Optimization of Extended Aeration System)

Receiving sump Eff. from equalization basin

2' 3' 4' y I ' 2' 3' 4' y

1 456 1 398 1 284 1 3 80 980 990 1 000 985 1 0 1 5 9.2- 8 .0- 7.3- 7.3- 8.0- 8.2- 8. 1 - 7.7- 7.7-9.9 8.5 8.0 9.9 8.2 8.5 8.2 8.2 8.5 27- 27- 27- 26- 25- 27- 27- 27- 25-

29 29 28 29 26 30 28 28 30 2585 2448 1 896 2380 2368 2459 2224 20 1 5 2298 4926 5468 5 1 00 4823 4460 4240 39 1 0 4040 4263 1 69 1 2 22486 1 72 1 6 1 9996 20686 2 1 1 25 20960 1 9865 20292

9826 1 1 025 95 1 9 9968 9728 9898 7480 7540 866 1 2663 3528 2837 30 1 0 30 1 6 3068 2545 2594 2750 1 320 1 460 1 570 1 495 1 600 1 450 1 395 1 560 1 485 1 3 1 1 56 1 05 1 28 1 22 1 26 1 3 8 1 30 1 3 1

5924 9609 6835 8780 6484 6238 6 1 1 3 6505 6409 1 20 1 04 1 1 1 1 1 5 1 1 4 1 1 8 1 1 6 1 1 4 1 1 8 1 66 1 39 1 40 1 5 2 1 49 1 53 1 52 1 50 1 5 3

2 1 .9 2 1 . 5 20.5 22.6 22.3 2 1 .5 2 1 .9 20. 3 22.0 4.3 4.5 4.3 4.4 4.4 4.3 4.5 4.3 4.4 1 6.3 1 8 .9 1 5 .5 1 6.3 1 5 .3 1 5 .9 1 4.9 1 6 . 1 1 5 .4 4.9 5.7 4.2 5.5 5.4 5.2 4.8 5.5 5.3 7.4 9.2 6.5 8.5 8.6 9.2 9.4 8.9 9. 1

1 6.9 1 9.4 1 2. 3 1 6. 8 1 7 . 1 1 6. 8 1 6. 5 1 6. 3 1 6.7 BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL

0.408 0.207 0.3 1 0 0. 309 0.304 0.303 0.3 1 1 0.307 0. 307 0. 1 97 0.205 0. 1 28 0. 1 98 0. 1 98 0. 1 95 0. 1 98 0. 1 98 0. 1 97 0.201 0.333 0. 1 34 0. 238 0.240 0.239 0.234 0.234 0.238 BDL BDL BDL BDL BDL BDL BDL BDL BDL

2.92 1 .94 3 .00 2.93 2.95 2.90 2.93 2.98 2.95

...

I '

495 8.0-8.2 27-

28 1 630 477 1 8742

2878 1 23 8 1 260 1 04

58 1 5 85 1 1 2

22. 1 4.3 1 1 . 3 4.3 8.6

5.4 BDL BDL

0. 1 80 0. 1 70 0.2 1 8 BDL 1 .67

Eff. from primary clarifier

2' 3 ' 4' 5+

485 500 530 495 8.0- 8. 1 - 8.2- 8.0-8. 1 8 .3 8 .3 8 .3 27- 27- 27- 27-

30 28 28 30 1 606 1 595 1 528 1 580 564 606 570 547 1 8675 1 8675 1 8 1 76

2702 22 1 4 2270 2598 1 1 69 1 1 1 5 1 1 44 1 1 00 1 1 70 1 1 65 1 1 95 1 1 95 1 02 1 1 4 1 08 1 1 0

5765 5606 5760 5 7 1 0 79 86 82 85 1 07 1 1 3 1 09 1 1 2

20.9 2 1 .8 20.2 2 1 .9 4.2 4.4 4.2 4.3 1 1 . 1 1 1 . 3 1 0.9 1 1 .0 4.2 4.4 4.5 4.3 8.3 8.7 8 .5 8 .6

5.8 5 .9 5 .2 5 .6 BDL BDL BDL BDL BDL BDL BDL BDL

0. 1 84 0. 1 79 0. 1 90 0. 1 86 0. 1 65 0. 1 66 0. 1 72 0. 1 67 0.225 0.2 1 9 0.220 0.220 BDL BDL BDL BDL 1 .68 1 .65 1 .69 1 .67

Contd . . .

.....

.j:>. 'D 00

"-

CIl (j -

Z I:) it' tTl CIl

< 0 r V\ 00 '-c:: � 'D 'D 'D

;( )Y -( - '-- .¥

Table 1 3 Contd . . .

Parameters Receiving sump Eff. from equalization basin Eff. from primary clarifier

r 2' 3' 4' 5- I ' 2' 3' 4' 5- I ' 2' 3' 4' 5'

Colour, Pt-Co 360 365 380 355 360 320 325 3 35 300 325 1 95 2 1 5 220 1 90 1 95 pH 8.0- 8 .0- 8.0- 8. 1 - 8.0- 8. 1 - 8 . 1 - 8 . 1 - 8 . 1 - 8 . 1 - 6. 1 - 6. 1 - 6.4- 6.4- 6. 1 - Z

8 . 1 8 . 1 8 .2 8.2 8 .2 8.2 8.2 8.2 8 .2 8 .2 6 .2 6.2 6.6 6.5 6.5 >-

Temp.,"C 24- 27- 28- 26- 24- 24- 26- 26- 26- 24- 25- 25- 25- 25- 25- Z 0

27 30 3 1 27 3 1 27 27 27 27 27 26 27 26 26 27 -< Alkalinity 1 762 1 798 1 865 1 826 1 785 1 222 1 206 1 200 1 2 1 6 1 2 1 0 1 08 1 1 2 1 07 1 09 1 08 � SS 1 09 1 1 3 1 07 1 1 2 1 1 1 28 1 263 332 309 29 1 87 82 93 90 88 � IDS 1 7655 1 7667 1 7872 1 7304 1 7630 1 7337 1 73 3 1 1 7443 1 7 1 48 1 7307 1 5326 1 5685 1 5332 1 5656 1 549 1 � COD 1 767 1 770 1 6 1 6 1 47 1 1 649 769 7 1 7 7 7 1 752 755 244 29 1 265 297 269 >-BOD 770 738 802 761 750 224 209 228 207 230 27 26 24 24 26 en

� Sulphates 34 35 39 38 37 695 690 670 682 688 532 539 5 27 545 537 trl

� Sulphides 1 58 1 30 1 35 1 48 1 39 9 1 2 1 1 8 1 0 1 .5 1 .4 1 .9 2.0 1 .7 � Chlorides 5692 5648 5527 5666 5622 5600 5580 5585 552 1 5555 5 1 52 5 292 4964 5 1 23 5 1 04 trl Ammonical N 1 04 1 1 0 1 08 1 09 1 08 69 66 67 65 68 23 25 28 27 26 ::tl Kjeldhal N 1 35 1 43 1 42 1 40 1 40 90 87 86 85 88 34 34 38 36 34 3::

>-Nitrate N 1 0.9 1 1 .7 1 0.6 1 0.5 1 1 .3 1 6. 1 1 8 .7 1 6.5 1 5 . 8 1 6.7 9.6 8.7 8.6 7.9 8.6 Z Nitrite N 2.2 2. 1 2.4 2.2 2.3 BDL B DL BDL BDL BDL BDL BDL BDL BDL BDL >-

a Phosphates 6.9 7.2 6.2 6.5 6.7 6.5 6.4 6.2 6.0 6.3 2.5 3 .0 2.8 3 . 1 2.9 trl Phenols 3 .5 3.4 3.8 2.9 3.4 3.2 3 .4 3 .5 3.0 3 . 1 BDL BDL BDL BDL BDL 3:: trl Oil & Grease 6. 1 5.8 5 .5 6.2 5.9 6.0 5 .8 5 .2 5 .7 5 .7 4.9 4.2 3.9 4.6 4.3 Z Heavy Metals

-l -

-Chromium 1 .20 1 . 1 5 1 . 1 2 1 . 1 4 1 . 1 3 0.783 0.782 0.785 0.784 0.783 0.653 0.668 0.670 0.663 0.665 Z -Copper BDL BDL BDL B DL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL � -Cadmium BDL BDL BDL B DL B DL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL Z

Z -Manganese 0.080 0.083 0.084 0.08 1 0.082 0.079 0.082 0.D78 0.079 0.D78 0.068 0.067 0.070 0.072 0.069 trl ::tl -Zinc 0. 1 58 0. 1 57 0. 1 62 0. 1 65 0. 1 6 1 0. 1 53 0. 1 54 0. 1 52 0. 1 5 1 0. 1 52 0. 1 40 0. 1 38 0. 1 37 0. 1 4 1 0. 1 39 -trl -Lead 0. 1 62 0. 1 58 0. 1 65 0. 1 58 0. 1 6 1 0. 1 4 1 0. 1 40 0. 1 39 0. 1 42 0. 1 40 0.063 0.065 0.064 0.065 0.064 en -Nickel BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL BDL B DL BDL BDL BDL -Iron 0.735 0.736 0.738 0.73 1 0.733 0.603 0.602 0.602 0.60 1 0.60 1 0.463 0.465 0.463 0.464 0.464

All values are expressed in mg/! except colour, pH and temperature; BDL - Below detectable limits * 6 h composite samples: I - 0600 h to 1 100 h; 2 - 1 200 h to 1 700 h; 3 - 1 800 h to 2300 h; 4 - 2400 h to 0500 h + 24 h composite sample

.j::o. \0 \0

500 J SCI IND RES VOL 58 JULY 1 999

Table 14 - Characteristics of final treated effluent obtained during different monitoring periods

Concentration as Monitored on Parameters

Colour, Pt-Co pH Temp . , OC Alkalinity S5 TDS COD -BOD Sulphates Sulphides Chlorides Ammonical N Kjeldhal N Nitrate N Nitrite N phosphates Phenol s Oil & Grease

Chromium

1# _ _ _ _ _ _ _ _ � � M _ _ _ _ _ _ _ _

Range* Average+

195-210 200

6 . 5-6 . 8

25-27

120-130 128

106- 112 ill 14889- 15348 15042

475- 524 510

32 - 37 34 510-530 525

1 . 6 -2 . 1 1 . 8

4295 -4423 42 59 23-28 25 30-38 3 3

8 . 4- 9 . 3 8 . 5 BDL BOL

2 . 1 - 2 . 3 2 . 1

BDL SOL 4 . 5 -4 . 6 4 . 5

0 . 6 78-0 . 692 0 . 6 89

!I## - - - - _ . _ - - - - - - - - - - - -

Range t Average+

205-220 210

6 . 1-6 . 9

2 5-27

122 - 128 124

89-105 9.S 14308-14814 14678

408-437 ill 24-31 30

520-550 530 1 . 5-1 . 9 1 . 8

4178-4307 4237

25-27 26 3 3 - 36 3 5

8 . 9- 9 . 9 9 . 6 BOL BDL

2 . 0 -2 . 7 2 . 5 30L BDL

4 . 7 -4 . 9 4 . 8 0 . 679- 0 . 68 7 0 . 6 80

All values except colour I pH, and temperature are in mg/l SDL - Below detectable limits

II After commissioning ## After proper operation and maintenance @ After optimization of chemical treatment 1}19 After optimization of extended aeration system

III@ - - - - - - - - - � - � - - - - - - �

Range t Average +

205-230 22 0

6 . 3- 6 . 6

2 5 - 28

100- 11S 100

l.Qi:ill 110 14909- 15544 15263

3 2 0 - 363 339 31-35 33

510-550 535 1 . 8- 2 . 0 1 . 9

4574-4 860 4620

30-35 3 1

3 9 - 4 6 40 10 . 3 - 1 1 . 6 10 . 5

BDL BDt 3 . 2 - 4 . 6 3 . 9

SDL BDL 4 . 6 - 4 . 8 4 . 7

0 . 663 - 0 . 675 0 . 670

" Hourly samples collected and composited for 6 h over a period of 24 h + * * ( t )

+ + ( t t )

Hourly samples. collected and composited for 24 h Standards for inland . surface water discharge Removal to the extent possible Should not exceed 5°C above the receiving water temperature 400C at the point of discharge

.

StandardsH

IV@@ MEF TNPCB � - - - - - - - - - - - - - - - - - -

Range* Average+

190-220 195 (t) 6 . 1- 6 . 5 5 . 5-9 . 0 5 . 5- 9 . 0

25-27 ++ (ttl 107 -112 lOS 82 -93 88 100 100

15326-15685 15491 2 100

244-297 269 250 250

24-27 26 3 0 3 0 527-545 537 1000 1 . 4-2 . 0 1 . 7 2 . 0 2 . 0

4 964- 5292 5104 1000

23-28 26 50 5 0

34 - 3 8 3 4 1CO 100 7 . 9- 9 . 6 8 . 6 1 0

BDL BDL 2 . 5 -3 . 1 2 . 9

BDL SDL 1 . 0 1 . 0 3 . 9-4 . 9 4 . 3 10 10

0 . 6 5 3 - 0 . 6 7 0 0 . 6 6 5 2 . 0 2 . 0

-I

.,.

{

Parameters

'*" �

Table 1 5 - Treatabi lity studies for tertiary treatment of secondary treated effluent (Physico-chemical route with alum as coagulant)

Raw w :aste E f f luent concent rat i on - - - - - - - - - - - - - - - - - 7 - - - - - - � - - - - - - - - - - - � - - - - -

Coagulant dose - alum : lime in mg/l

3 0 0 : 3 2 5 : 3 5 0 : 3 7 5 : 4 0 0 : 4 5 0 : 2 0 0 2 0 0 2 2 5 2 5 0 2 7 5 3 0 0

Colour , Pt - Co 1 9 5 1 2 2 1 0 7 9 3 8 8 8 3 7 8 pH 6 . 4 6 . 8 6 . 8 6 . 8 6 . 5 6 . 5 6 . 6 SS 8 8 5 9 5 8 54 5 3 5 0 4 7 COD 2 6 9 1 6 9 1 5 6 14 8 1 4 3 1 4 0 1 3 4 TDS 1 5 4 9 1 1 3 6 1 7 1 3 5 7 0 1 3 5 2 5 1 3 6 7 9 1 3 8 3 3 1 4 0 3 5 S ludge Volume , ml\l 5 0 5 5 6 2 7 0 7 9 8 5

Al l values except colour , pH and s ludge-vOlume are in mg/l Opt imum dose - a lum : lime 3 5 0 : 2 2 5 mg/ l

�

z >­z Cl -< � :::. -

� C/.l -'l tTl � � tTl iO

3:: >­z >­o tTl 3:: tTl Z -'l -Z

� Z Z tTl iO -tTl C/.l

U1 o

Parameters

Table 1 6 - Treatability studies for tertiary treatment of secondary treated effluent (Physico-chemical route with alum and lime as coagulant)

Raw waste Effluent concentration - - - - - - - � - - - - - - - - - - - - - - - .. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ,

a lum lime Polyelectrolyte - doses in mg/ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .

350 : 350 : 350 : 350 : 350 : 350 : 350 : 350 : 350 : 350 : 225 : 225 : 225 : 225 : 225 : 225 : 225 : 225 : 225 : 225 : 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 0

Colour , Pt - Co 195 78 74 6 9 6 7 6 7 · 66 65 65 64 63 pH 6 . 4 6 . 6 6 . 6 6 . 6 6 . 7 6 . 7 6 . 7 6 . 7 6 . 8 6 . 8 6 . 9 as 88 49 48 48 45 45 44 43 43 42 41 CQD 269 135 12 9 126 123 123 122 121 120 118 117 TDS 15491 13446 13353 13245 1313 6 13136 13121 13121 13136 13136 13152 Sludge Volume , m: l/l 61 6 0 6 0 5 8 58 58 57 57 55 54

All values except colour , pH and sludge volume are in mg/ l Optimum dose - alum : lime : p olyelectrolyte 350 : 225 : 0 . 4 mg/l

:{ '- .J.. -..:

Ut o tv

"-en 0 Z 0 ::0 m en

< 0 r-Ut 00 "-c:: t< \0 \0 \0

Parameters

Colour , Pt-Co pH SS

COD

y ,� '-

Table 1 7 - Treatability studies for tertiary treated of secondary treated effluent (Physico-chemical route with alum and lime as coagulant and cationic polyelectrolyte as coagulant aid)

Raw waste E f fluent concentration

�

- - - - - - - - - - - - - - - - - - - - - - - -. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ,

a lum : lime : Polyelectrolyte - d oses in mg/l - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - . - - - - - - - - - - - - - - - - - - - - - - - - - - - .

3 5 0 : 350 : 3 50 : 3 5 0 : 350 : 3 5 0 : 350 : 350 : 3 5 0 : 225 : 2 2 5 : 225 : 225 : 2 2 5 : 225 : 22 5 : 225 : 2 2 5 : 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9

195 78 74 69 67 6 7 . 66 65 65 64 6 . 4 6 . 6 6 . 6 6 . 6 6 . 7 6 . 7 6 . 7 6 . 7 6 . 8 6 . 8

88 49 48 48 45 45 44 43 43 42 269 135 129 126 123 123 122 121 120 118

3 5 0 : 2 2 5 : 1 . 0

6 3 6 . 9

41 117

TOS 15491 13446 13353 13245 13136 13136 13121 1312 1 13 136 13136 13152 Sludge Volume , mill 61 6 0 60 58 58 58 57 5 7 55 54

All values except colour , pH and sludge volume are in mg/ l Opt imum dose - alum : lime : p olyelectrolyte 3 5 0 : 225 : 0 . 4 mg/l

z :> z " -< � �

� en ...:j t'I1 � � t'I1 �

s:: :> z :> a t'I1 s:: t'I1 Z ...:j -z

� z Z t'I1 � -t'I1 en

u. o w

Parameter

1*

Table 1 8-- Performance evaluation of common effluent treatment plant (After upgradation of CETP)

Receiving Sump Ef f . from Equalization Basin Eff . from Primary Clarifier

2 * 3'* 4* 5 * 1 * 2 * 3

* 4* 5* 1* 2 * 3 * 4 * 5 *

Colour, Pt-Co 16 9 0 1 6 5 0 1 8 9 5 12 8 0 1 4 5 0 1 0 90 1 000 10 1 5 102 0 1020 535 510 pH B . 8 9 . 8 - 7 . 7 - 7 . 5- 7 . 7 - 7 . 8 7 . 8 - 7 . 8 - 7 . 5 - 7 . 5 - 7 . 7 7 . 6 -

545 7 . 6 -

8 . 2 2 8 -

5 5 0

7 . 6 -8 . 2

2 9 -

5 3 0 7 . 6 -B . 2

2 8 -

9 . 0 9 . 0 9 . 0 7 . 9 8 . 2 8 . 2 8 . 2 B . 2 7 . 7 Temp . 1 °C 3 0 3 0 - 3 0 - 2 8 - 2 8 - 3 0 3 0 - 3 0 - 2 8 - 2 8 - 3 0 3 0 -

Alkal inity SS TDS COD BOD Sulphates Sulphides ' Chlorides Ammonical N Kj eldahl N Nitrate N Nitrite N phosphates Phenols Oil & Grease Chromium

31 31 3 1 31 31 3 1 3 1 3 1 3 1 31 3 1 3 1

1740 19 5 0 2 0 7 0 17 3 0 2004 1 9 0 8 2 04 0 2 1 9 0 2 0 5 0 2 0 1 0 16 0 0 1 5 7 0 1 5 8 0 1 6 6 0 1 6 0 0

4 2 8 0 5 1 8 0 4 2 83 4 9 8 0 43 5 0 4 2 0 0 44 8 0 4 1 5 0 4 8 5 0 4 2 8 0 6 0 1 5 8 2 656 5 7 7 6 3 8 1253 0 15 96 0 1 0 1 0 0 I1BOO 12 3 4 8 144 0 0 12 862 12 0 0 3 11999 1 2 3 0 0 1 1344 11310 1 0 803 1 0 991 1 1 1 93

546 9 5743 612 0 4810 5950 6 8 4 0 4979 5 3 8 6 5600 513 8 1 8 54 1494 1 4 6 0 1 6 3 5 1 5 8 3 2 13 5 1 6 70 12 5 0 1 0 8 0 1 5 3 4 1 7 1 0 1 5 9 0 1 5 6 2 1 7 3 6 1644 6 5 2 7 0 6 656 6 6 3 6 5 8

2 0 50 1 6 0 0 15 0 0 1 2 5 0 1 6 0 0 2 0 5 0 1 8 8 0 1 8 5 0 2 1 5 0 2 0 5 0 15 8 0 15 1 0 1 5 0 0 1 7 6 5 1 5 7 5 77 6 3 74 72 74 5 S 83 . 7 0 82 60 3 5 62 51 4 9 4 3

5 3 6 9 4 12 0 54 5 0 6 2 1 5 53 6 9 5 5 6 0 5125 5 6 7 0 5 9 5 0 5 6 7 5 54 3 0

130 112 14 5 110 1 3 0 132 12 8 1 2 9 126 12 7 1 1 7 1 90 1 9 2 1 8 5 150 1 8 3 1 8 5 1 8 3 1 7 9 1 8 0 1 8 2 1 6 5

2 3 . 0 2 1 . 6 20 . 8 18 . 5 2 1 . 3 2 1 . 5 2 0 . 9 2 1 . 7 2 2 . 5 2 1 . 6 ' 2 0 . 5

5 . 5 3 . 6 4 . 9 4 ; 3 4 . 5 5 . 7 4 . 2 4 . 7 4 . 4 4 . 6 4 . 0 12 . 1 18 . 7 20 . 4 18 . 8 1 8 . 3 1�. 6 1 5 . 8 16 . 2 15 . 9 15 . 5 1 1 . 4

2 . 5 3 . 1 3 . 0 2 . 9 3 . 0 3 . 0 3 . 0 3 . 2 2 . 8 3 . 1 2 . 1

1 0 . 3 11 . 2 8 . 8 6 . 5 9 . 0 9 . 3 9 . 2 9 . 1 9 . 3 9 . 2 8 . 3 3 8 . 3 24 . 4 3 0 . 1 3 2 . 8 3 0 . 4 3 2 . 0 2 8 . 9 2 9 . 3 32 . 6 3 1 . 9 4 . 9 2

� ....

5 02 5

1 1 3

5 5 3 0

114 5 7 1 0

113 5 5 6 0

1 1 4 1 5 3 160 161 158

2 0 . 4 2 0 . 3 21 . 7 2 0 . 5 4 . 5 4 . 3 4 . 3 4 . 2

1 0 . S 11 . 0 11 . 4 11 . 3 2 . 2 2 . 1 2 . 1 2 . 1

8 . 1 8 . 0 8 . 4 8 . 3

5 . 5 1 5 . 56 4 . 7 0 5 . 0 5

Contd " "

--<

lI\ o +>-

C/) Q z CJ � tTl C/)

< o r lI\ 00 '-c: � -.0 'D \D

)l.-' -..(

conto. .

Parameter Eff . from �aerobic Lagoon

1 * 2 * 3 * 4 * 5 *

Colour , Pt - Co 3 6 0 3 90 3 6 5 3 7 0 3 5 5 pH 7 . 5 7 . 5 - 7 . 5 - 7 . 5 - 7 . 5 -

7 . 8 7 . 9 7 . 9 7 . 9 Temp . , oC 3 0 3 0 - 3 0 - 2 9 - 2 9 -

3 1 3 1 3 1 3 1

Alkalinity 1 8 6 0 1 8 9 0 1 9 1 0 18 8 5 1 8 3 0

SS 1 4 1 1 3 4 1 4 6 134 1 4 9 TDS 1 0 6 7 5 1 0 7 1 0 1 0 3 7 0 1 0 4 7 0 1 0 5 43 COD 1104 1 1 0 6 1 0 6 4 1 0 4.6 93 3 BOD 4 6 8 4 3 9 4 66 4 7 6 441

Sulphates 7 5 73 6 9 7 7 5 7 Sulphides B O 8 7 8 9 9 0 75 Chlorides 5 12 0 5 0 0 6 5 1 0 6 54 6 5 5 1 13

Ammonical N 1 05 1 1 8 107 1 1 3 1 1 0 Kj eldahl N 1 5 0 165 152 156 1 5 5

Nitrate N 1 1 . 5 1 0 . 3 1 0 . 3 1 1.. 3 1 0 . 8 Nitrite N 2 . 0 2 . 1 2 . 3 2 . 1 2 . 1 Phosphates 9 . 8 9 . 6 9 . 2 8 . 9 9 . 3

Phenols 1 . 2 0 . 8 1 . 1 0 . 6 0 . 8 Oil &: Grease 6 . 1 5 . 7 5 . B 6 . 0 5 . 9

Chromium 1 . 4 1 3 1 . 5 2 8 1 . 4 9 5 1 . 54 2 1 . 5 44

""

Eff . from Pre -aeration Tank

1 * 2 * 3 * 4* 5*

3 05 3 5 0 3 1 0 3 2 0 3 1 5 7 . 8 7 . 1 - 7 . 6 - 7 . 6 - 7 . 6 -

8 . 2 B . 2 8 . 2 8 . 2 3 1 3 0 - 3 0 - 3 0 - 3 0 -

3 1 3 1 3 1 3 1 1 2 9 0 1 3 0 0 13 1 0 13 5 0 1 3 1 0

2 6 4 2 9 0 3 3 0 3 2 0 2 9 5 1 0 3 9 6 1 0 5 7 0 1 02 7 8 1 0 3 4 0 1 0 2 7 9

6 6 6 5 7 5 5 3 2 5 7 5 5 6 7

1 4 8 1 6 7 1 6 6 1 5 9 1 5 4 5 S 0 5 9 0 5 8 2 5 8 8 5 8 3

BDL BDL BDL BDL BDL 4 82 4 4 9 3 0 4 9 3 2 5 2 3 5 5 0 7 9

95 8 4 8 6 9 0 9 2

12 6 12 0 1 1 9 1 2 8 124 14 . 6 1 3 . 9 14 . 2 14 . 3 1 4 . 2

1 . 5 1 . 9 L 6 L 3 1 . 4 8 . 2 8 . 3 8 . 1 8 . 5 8 . 2 0 . 5 0 . 4 0 . 1 0 . 1 0 . 2 4 . 3 4 . 2 5 . 1 4 . 5 4 . 4

1 . 0 1 8 1 . 0 1 7 1 . 0 1 5 1 . 02 0 1 . 019

�

Contd . . . .

z > z 0 -< � � � > CIl -l tTl � � -tTl � :s: > z > 0 tTl :s: tTl Z -l z -l > z z tTl � tTl CIl

1Il o 1Il

v. 0

Table 1 8 Contd . . . . 0\

Parameter Eff . f rom secondary c lari fier · Eff . from t ube sett l er - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

�* 2* 3 * 4 * 5 * � * 2 * 3 * 4 * 5*

Colour, P t - Co �85 2 1 5 2 � O 2 2 0 2 0 5 � O O 1 � 5 � l S ��O �1 5 pH 7 . 4 7 . 4 - 7 . 4 - 7 . 4 - 7 . 4 - 8 . 0 7 . 8 - 7 . 7 - 7 . 7 - 7 . 9 -

7 . S 7 . 6 7 . 6 7 . 6 8 . 9 7 . 8 8 . 0 8 . 9 Temp . , oc 3 0 2 9 - 2 9 - 2 9 - 2 9 - 3 0 2 9 - 2 9 - 2 9 - 2 9 -

3 1 3 0 3 0 3 2 3 0 3 1 3 2 3 2 Alkal inity 2 4 0 2 3 6 2 2 0 2 3 0 2 2 0 2 4 5 2 4 7 2 3 0 2 3 5 2 3 0 SS 8 2 9 0 9 8 8 8 8 6 3 7 4 8 5 2 4 3 4 4 TD S 99 1 3 9 7 10 9 5 3 5 9 9 0 0 9 8 6 7 972 0 9 6 � 0 9 3 5 3 97 9 9 9 7 0 � ..... COD 2 6 0 2 5 2 2 3 5 2 5 3 2 5 0 1 5 0 1 7 3 1 6 0 l. 7 2 1 5 9 en (') BOD 2 l. 18 1 9 1 7 1 6 6 5 7 6 5 -Sulphates 4 3 0 4 3 5 4 2 0 4 4 0 4 3 0 4 5 0 4 6 0 4 7 0 4 6 5 4 6 3 Z Sulphides BDL BDL BDL BOL BDL BDL BDL BDL BDL BDL 0 Chlorides 4 7 7 1 4 8 ], 7 4 8 5 5 502 0 4 8 8 5 4 6 8 8 4 7 8 0 4 6 0 0 4 9 6 0 4 7 5 8 ::0

tTl Ammonical N 1.0 . 1. 8 . 7 ],0 . 9 8 . 3 1. 0 . 0 1 . 5 2 . 3 1 . 7 1 . 4 1 . 7 en Kj eldahl N 14 . 1 1 2 . 3 �S . 1 �2 . 5 J. 3 . 4 2 . 2 3 . 1 2 . 4 1 . 9 2 . 3 < \ Nitrate N 9 . 6 9 . 1 9 . 8 9 . 2 9 . 2 8 . 1 8 . 0 8 . 9 8 . 5 8 . 5 0 Nitrite N BDL BOL BDL BOL BDL BDL BDL BOL BDL BDL t-

v. Phosphat.es 4 . 0 4 . 1. 4 . 2 3 . 9 4 . 0 2 . 0 1 . 8 2 . 1 2 . 0 1 . 9 00

Phenols- BOL BOL BDL BDL BDL BDL BDL BOL BDL BDL ..... c::::

Oil 6< Grease 3 . 2 3 . 5 3 . 2 3 . 1 3 . 2 2 . B 2 . $ 2 . 5 2 . 7 2 . 6 � Chromium 0 . 57 2 0 . 5 6 0 0 . 5 8 0 0 . 5 7 5 0 . 5 7 7 0 . 1 6 5 0 . 1 6 9 0 . 16 2 0 . 17 0 0 . 1 6 8

'" '" '"

All values except colour , pH and temperature are in mg/ l

BDL - Below detectable limits * ]. - Zero h ; 2 - 6 h compos ite ( 1 0 0 0 - 1. 5 0 0 h ) i 3 - 12 h composite

( 1 0 0 0 - 2 1 0 0 h ) ; 4 - 18 h compos ite ( 1 0 0 0 - 0 3 0 0 h ) ; 5 - 24 11 composite ( 1 0 0 0 - 0 9 0 0 h )

'r- � ... �

� " \.

Table 1 9 - Perfonnance data of CETP after upgradation during different monitoring periods

Parameter Equa l i zed Inf luent F inal Treated e f fluent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - � - - - - - � - - -

1 * 2 * 3 * 4 * 5 * 6 * 1 * 2 * 3 * 4 * 5 * 6 *

Colour , · Pt - Co 1 0 5 0 1 0 0 0 1 0 0 5 1 0 7 0 9 3 5 1 0 2 5 1 0 5 1 0 5 1 0 0 9 0 90 80 pH 8 . 0 - 7 . 8 - 7 . 8 - 7 . 9 - 7 . 8 - 8 . 0 - 7 . 9 - 7 . 9 - 7 . 6 - 7 . 7 - 7 . 7 -:- 7 . 7 -

8 . 1 8 . 2 8 . 2 8 . 1 8 . 1 8 . 2 8 . 2 8 . 1 8 . 3 8 . 4 8 . 0 8 . 0 Temp . , oC · 3 0 - 3 0 - 2 9 - 3 0 - 3 1 - 3 1 - 3 0 - 3 0 - 3 0 - 3 0 - 3 0 - 3 0 -

3 1 3 1 3 1 3 1 3 3 3 2 3 1 3 1 3 1 3 1 3 1 3 1 Alkal inity 2 3 6 0 2 4 3 0 2 4 5 0 2 2 2 0 2 3 15 2 3 2 0 2 7 5 2 1 0 1 1 5 1 1 7 1 2 0 125 S S 4 94 0 4 9 5 2 4 4 6 5 4 2 6 0 4 8 1 7 4 6 1 5 4 2 4 0 4 5 3 8 3 9 3 8 TDS 1 2 7 4 0 1 2 1 6 0 1 1 4 0 2 1 2 4 0 0 1 2 5 2 0 12462 1 0 0 0 8 1 0 2 1 9 9 0 7 6 9 8 4 3 1 0 0 4 1 9 8 3 0 COD 5 3 4 3 6 0 8 1 5 9 9 6 5 7 5 1 6 6 8 5 6 5 5 6 146 125 124 118 98 96 BOD 1 6 04 1 5 2 0 1 7 3 3 1 6 1 0 1 7 3 8 1 7 8 9 7 5 3 2 2 3 Sulphates 2 0 0 0 1 4 7 2 1 5 8 5 14 5 0 1 4 5 0 1 1 3 5 4 5 0 4 5 0 4 6 0 4 5 0 4 2 0 4 5 5 Sulphides 9 0 5 5 92 78 94 70 BDL BDL BDL BDL BDL BDL

. Chlorides 5 9 0 5 5 7 1 0 594 0 574 0 5 7 3 0 5 7 2 0 4 8 2 3 4 5 13 4 72 6 4 6 8 0 4 7 2 0 4 6 70 Ammonical N 1 0 3 1 0 9 8 8 1 1 5 1 3 5 1 0 8 0 . 5 0 . 7 1 . 3 2 . 0 0 . 1 2 . 1 Kj eldahl N 143 14 0 1 1 9 1 5 0 1 8 8 14 9 0 . 7 1 . 0 2 . 0 3 . 0 0 . 2 3 . 0 Nitrate N 2 0 . 7 2 2 . 3 2 1 . 5 2 2 . 1 2 0 . 1 22 . 5 8 . 0 8 . 4 9 . 4 8 . 2 8 . 1 8 . 2 Nitrit e N 4 . 3 4 . 4 4 . 5 4 . 5 4 . 7 4 . 6 BDL BDL BDL BDL BDL BDL Phosphates 1 5 . 3 1 9 . 6 1 9 . 5 2 0 . 1 2 0 . 0 2 0 . 3 2 . 2 3 . 0 2 . 1 2 . 3 1 . 9 2 . 2 Phenols 3 . 3 5 . 5 4 . 1 5 . 0 5 . 1 4 . 8 BDL BDL BDL BDL BDL BDL Oil &t Grease 9 . 4 8. . 6 9 . 3 8 . 9 7 . 2 8 . 9 3 . 2 3 . 0 2 . 9 3 . 3 3 . 4 2 . 5 Chromium 3 2 . 8 2 9 . 3 3 2 . 1 3 3 . 3 3 4 . 0 2 9 . 9 0 . 15 1 0 . 15 9 0 . 16 2 0 . 153 0 . 15 6 0 . 164

. All values are expressed in mg/l except colour , pH and temperature * Hourly samples col lected and composited for e ight hours on different dates BDL - Below detectable l imit s

z > z 0 -< � ... I:l !"-

� > en -l m � � m �

3: > z > 0 m 3: m z -l -z

� Z Z m �

til en

Vl o -..J

IJ\ 0 00 Table 20 - Design parameters for unit processes and operations at varying operating conditions

particulars Des ign Operating values as .monitored v alue - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - _ .

Performance After After After After Up-e:"aluation proper . optimization optimization gradation of CETP operation of Chemical of extended of CETP after comm- main- treatment ae.ration iss ioning tenance system

Flow, m3 /d 4 0 0 0 2 7 52 . 6 2 7 1 0 . 2 2 7 6 8 . 2 2 8 2 3 . 1 2 02 5 . 6 - 2 2 58 . 2

Chemical d ose "-en

Alum, mg/l 450 4 5 0 4 5 0 5 0 0 5 0 0 5 0 0 Q Lime , mg/ l 4 5 0 4 5 0 4 5 0 S O O .S O O 8 0 0 Z

0 Primary c·larifier � DP , h 3 . 2 4 . 6 2 4 . 7 0 4 . 6 0 4 . 5 1 5 . 64 - 6 . 2 8

SOR, m3 /m2 . d 2 2 . 6 3 1 5 . 5 8 15 . 34 1 5 . 6 6 15 . 9 8 11 . 4 6 - 1 2 . 7 7 <: WLR, m3 /m . d 84 . 9 5 8 . 4 1 57 . 51 5 S . 74 5 9 . 91 42 . 9 9 - 4 7 . 93 0 r

IJ\ Chemical .t ,:eatment

00

(Removal 'e ffic�ency) C BODr , Per' cent 2 5 . 0 14 . 7 - 1 8 . 5 2 5 . 9 - 3 5 . 7 54 . 2 - 6 0 . 8 5 5 . 9 - 6 1 . 9 55 . 8 - 6 2 . 0 � SSr ' Per cent 7 9 . 5 6 5 . 3 - 72 . 4 73 . 6 - 7 9 . 5 8 3 . 5 - 8 7 . 6 84 . 5 - 8 9 . 3 84 . 8 - 8 9 . 4 -

\0 CODr , Per cent 3 5 . 5 - 3 7 . 4 4 7 . 4 - 5 6 . 9 6 7 . 2 - 71 . 4 6 9 . 5 - 72 . 7 6 9 . 6 - 72 . 9 \0 \0

Extended aeration 'system

DP , d 1 . 2 6 1 . 8 3 1 . 8 6 1. . 8 2 1 . 7 9 2 . 2 3 - 2 . 4 9 F/M Ratio d 0 . 1 5 0 0 . 04 4 0 . 04 1 0 . 02 5 . 0 . 052 0 . 02 0 - 0 . 0 2 8

OLR , kgBOD/l!'3 . d 0 . 792 0 . 13 3 0 . 1 1 9 0 . 06 5 0 . 12 9 ·· 0 . 0 56 - 0 . 0 8 3

MLSS , mg/I 4 0 0 0 3 9 8 8 3 8 4 0 3 9 8 0 3264 3 5 0 0 - 3 86 6 MLVSS , mgll 3 2 0 0 3 0 3 4 2 9 0 8 2 5 96 2498 2 7 4 7 - 3 1 0 0

MLVSS/MLSS 0 . 8 0 0 . 76 0 . 7 6 0 . 6 5 0 . 7 7 0 . 7 8 - 0 . 8 0 02 Reqd . , kg/d 7980 1340 1176 655 1 3 0 0 5 5 9 - 8 3 2

Aerators 120 104 . 1 0 103 . 6 0 1 04 . 2 0 102 . 5 0 102 . 6 - 1 0 3 . 5

Capacity, HP (provided) ( actual ) (actual ) (actual ) ( actual) ( actua l )

Contd . . . . . .

\

Table 20 Contd . . . . . .

Secondary clarifier DP , h SOR, m3 jm2 . d WLR , m3 jm . d SLR , kgjm2 . d

Biologica:t, treatment (Removal e'fficiency)

2 . 6 5 2 2 . 6 84 . 9 9 0 . 5 1

BODr , Per cent 9 0 SSr ' Per cent 5 0 CODr , Per cent

¥

4 . 7 8 �2 . 54 4 7 . 0 3 6 2 . 14

8 5 . 8 - 8 8 . 2 5 5 . 9 - 6 5 . 7 57 . 8 - 6 � . 0

�

4 . 98 4 . 7 8 12 . 5 5 �2 . 5 6 4 5 . 16 4 7 . 10 5 8 . 9 62 . 3

8 5 . 1 - 8 9 . 7 6 9 . 5 - 73 . 9 6 2 . 0 - 6 9 . 9 4 8 . 8 - 5 5 . 8 5 8 . 0 - 6 2 . 3 . . 4 2 . 9 - 4 9 . 8

DP - detention period; SOR - surface overf�ow rate ; WLR - weir loading rate ; OLR - organic loading rate ; SLR - solids loading rate

4 . 6 9 �2 . 8 0 4 7 . 03 52 . 1

8 7 . 6 - 8 9 . 4 6 8 . 8 - 72 . 0 5 9 . 4 - 6 8 . 3

.I,

5 . 6 9 - 6 . 4 6 9 . 2 8 - 1 0 , 54 3 7 . 04 - 3 9 . 52 3 1 . 4 8 - 3 2 . 6 7

8 6 . 2 - 93 . 5 6 8 . 7 - 72 . 4 6 0 . 6 - 6 7 . 3

z > Z o -<

�

�

� en -l tTl � � tTl '" ::: > z > C') tTl ::: tTl Z -l -Z

� Z Z tTl '" ti1 en

VI o \C)

5 1 0 J SCI IND RES VOL 5 8 JULY 1 999

Table 21 - Energy consumption at various stages of treatment

Treatment stages

Primary and Phys ico - chemical Treatment *

AIiaerobic Treatment * *

Aerobic Treatment#

Tert iary Physico� chemical Treatment##

Energy consumption (EC) kw

.

6 8 . 62

1 1 0 . 56

19 8 . 5 8 ·

2 1 5 . 2 3

EC kwhlm3 of wastewater t reated@

0 . 72 9 - 0 . 8 1 3

1 . 1 7 5 - 1 . 3 1 0

2 . 1 1 1 - 2 . 3 54

2 . 2 8 8 - 2 . 5 5 1

* Mechanical Screening + Equalizat ion + Physico- chemical Treatment

* * Mechanical Screening + Equalizat ion + Physico- chemical Treatment + Anaerobic Treatment + Preaeration

# Mechanical Screening + Equalizat ion + Physico- chemical Treatment + Anaerobic Treatment + �reaeration + Extended Aeration System

## Mechanical Screening + Equali zat ion + Physico- chemical Treatment .+ Anaerobic Treatment + Preaerat ion + Extended Aerat ion System + Physico- chemical Treatment

@ Flo.w range 2 0 25 . 6 - 22 5 8 . 2 m3 /d .

Design .

I - 2 . 4m

NANDY et al. : WASTEWATER MANAGEMENT IN TANNERIES

Total No . of furrows ( 1 0 0m./ l

4 1

Table 22- Wastewater loading schedule

Recommended loading for 2 0 m furrow l ength/d

1/ 5th of full loading rate weekly once upto 3 months

2 9 2 1

Full loading'"

1464 1

I I - i . 5m 66 180 1 9 1 0 1 ·

I I I - 6 . 0m 1 6 7 5 0 1 3 7 5 0 1

... Ful l loading . i s recommended after 3 months of plantation

Table 23-- Concentration of heavy metals in sludges from CETP

Parameters

Chromium · as Cr

Z:inc as Zn

Lead as Ph

Cadmium as Cd

Nickel as Ni

Manganese as Mn

Iron as Fe

Copper as Cu

Chemical ·s ludge (mg/kg)

2 4 7 6 - 2 854

4 . 6 - 6 . 6

3 . 8 -4 . 2

BDL

BDL

2 0 - 2 8

2 5 9 - 3 04

BDL

BDL - Below detectable l imit

B�r logical ·s ludge (mg/kg) . .

2 7 - 3 2

2 . 2 - 4 . 5

18 . 8 - 24 . 4

�DL

BDL

2 . 5 - 5 . 0

3 5 - 4 ?

BDL

5 1 1

5 1 2 J SCI IND RES VOL 58 JULY 1999

Table 24- Problems associated with various units in CETP, and probable causes

Observations

Improper equali zat ion of wastewater flow anQ characteri stics in equalizat ion basin

Poor performance efficiency of chemical treatment system

Sol ids escaping from primary clarifier

Performance of anaerobic lagoon not as per design

Low DO concentration in the eff luent f rom pre - aerat ion tank

Performance of extended aerat ion system decl ining during third round of monitoring

Sludge drying beds ful l

Probable Causes

- Irregular pumping schedule from rece iving sump to equali zation basin

- Poor mixing in equa l i z ation basin

- Regular dosing not be ing pract ised

- Chemical coagulants dosing not opt imi zed

S ludge pump capac ity inadequate

- Irregular pumping schedule

- Proper seeding of the lagoon has not been done

- Sludge accumulation at the bottom of lagoon

- Lagoon functioning as sett l ing tank due to higher detention period

All five aerators not operational

- Capacity of aerators inadequate

- System works as a facultative pond

- No sludge wastage pract iced Higher SRT maintained in

.

aeration tank - Fall in oxygen uptake rate

, indicat ing low concentration of act ive biomass (MLVSS)

- Low sludge sett leab i l ity - High concentration of

mineral ised s ludge in aeration tank

- Regular removal of dried s ludge not practiced

- Number of s ludge drying beds insufficient

- Sludge drying period of 10 days considered · in design whereas actual ( at field condit ions) drying period required was 20 days

- Sludge thickener and centri fuge not operated regularly

',. Al l BOL .. + (I

# .. .. ( + ) ++ ( ++ )

NANDY e t al. ; WASTEWATER MANAGEMENT IN TAN NERIES

Table 25 - Comparison of final treated effluent characteristics as monitored during various storages of investigations

concentrations as monitored Standards " " Parameter

Before upgradation After upgradation

Colour , , Pt - Co pH Temp . , OC , Alka l inity � .IJ2.'2 � llQI2 Sulphates Sulphides Chlorides Ammonical N Kj eldahl N Nitrate If Nitrite N . Phosphates

Phenols Oil & Grease Chromium

Range *

1 9 0 - 2 3 0 6 . 1 - 6 . 9

2 5 - 2 8 1 0 0 - 1 3 0

8 � -.l.li. 14308-15685 ,

244 -� 2 4 -ll

5 1 0 - 5 5 0 1 . 4 - 2 . 1

4178-5292 2 0 - 3 5 3 0 - 4 6

7 . 9 -1..!....§ BOL

2 . 0 - 4 . 6

BOL 3 . 9 - 4 . 9

0 . 6 53 - 0 . 692

Average+

2 0 5

1 1 2 9 5

� .lJlQ

2 9 5 2 5 1 . '6

iTIQ 2 5 3 5

9 . 6 BOL 3 . 1

BOL 4 . 0

0 . 6 7 0

Range8

8 0 - 1 15 7 . 7 - 8 . 9

2 9 - 3 2 1 1 5 - 275

3 8 - 4 5 9076-10575

9 6 -173 2 - 7

4 2 0 - 4 6 3 BOL

4513-4823 0 . 1 - 2 . 1 0 . 2'- 3 . 0 8 . 0 - 9 . 4

BOL 1 . 8 -3 . 0

BOL 2 . 5 ": 3 . 4

0 . 1 5 1 - 0 . 1 6 8

values except colour , pH , and temperature are in mg/T . - Below detectable l imits

Average#

95

1 7 0 4 0

.2li.Q. 124

4 4 4 8 BOL

� 1 . 2 , 1 . 7 8 . 4 BOL 1 . 9

BOL 3 . 0

0 . 13 6

MEF

( + ) 5 . 5 - 9 . 0

+ +

l.QQ

� l.Q.

2 . 0

5 0 1 0 0

l..Q.

1 . 0 1 0

2 . 0

Hourly samples collected and composited for 6 h over a period of 24 h Hourly samples collected and composited for 24, h Hourly samples collected and composited for 4. h . 6 h , a h , 1 2 h, 1 8h, and 24 h Ho�rly samples collected and compos ited for 4 h" , 8 h , and 24 h Standards for inland surface water discharge Removal to the extent possible Should not exceed SoC above the receiving water temperature 4 00C at the point of discharge

TNPCB

5 . 5 - 9 . 0 ( + + )

l.QQ nQQ

� l.Q.

1 0 0 0 2 . 0

lJ2j1Q 5 0

1 0 0

1 . 0 1 0

2 . 0

5 1 3

5 1 4 j SCI IND RES VOL 5 8 JULY 1 999

Table 26 : Details of oommon effluent treatment plants (CETPs) under operation in the State of Tamil Nadu f

Location of CETP No. of tannery units HideslSkins Design flow (m3/d) Unit processes and operations of CETP associated with CETP processing capacity

(Kg'd) SIDCO. Industrial Estate. Total : 87 Screen+Equalization basin+FIash mixer+Primary Ranipet. NM Connected : 87 83000 2500 clarifier+Aeration tanks 1&II+Secondary

clarifier+Sludge drying beds MeMsharam Sector. Total : 36 Screen+Equalization basin+Flash Ranipet. NM Connected : 19 82450 3400 mixer+CIarifiocculator+Aeration tanks

1&II+Secondary ctarifier+PoIishing pond+Sludge thickener+ Sludge drying beds

Thuthipet Sector. Ambur. Total : 44 Screen+Equalization basin+FIash NM Connected : 41 85000 2219 mixer+CIarifiocculator+Preaeration tank +

Oxidation ditches (4 Nos.)+Secondary darifier+ Sludge drying beds

Valayambattu. Total : 1 10 Screen+Equalization basin+Flash mixer+Primary Vaniyambadi.NM Connected : 1 10 83600 3120 clarifier+Anaerobic lagoon + Aeration tanks

1&II+Secondary clarifier+ Sludge drying beds Udayendiram. Total : 10 Screen+Grit chamber+Equalization basin+Flash Vaniyambadi.NM Connected : 10 8000 200 mixer+Static flocculator+ Primary darifier+Aeration

tank+ Secondary darifier+ Sludge drying beds

Bakkalpalli. Pemambut. Total : 18 Screen+Equalization basin+Flash NM Connected : 16 30000 890 mixer+CIarifiocculator+Preaeration tanks

Proposed : 2 1&II+Aeration tank+Secondary darifier+ sludge drying beds

Contd.

PammaJ-Pailavaram. Total : 138 Screen+Grit chamber+Equalization basin+Rash Chrompet Area Chengai Connected : 100 100000 3000 Mxer+CIarifioculator+Aeration tank+ Secondary � MGR Proposed : 38 ctarifier+Sludge thickener+ Sludge drying beds Dindigul. Total : 36 Screen+Grit chamber+Equalization basin+Rash Dindigul Connected : 36 124000 2500 mixer+Flocculation tank+Primary clarifier+

Anaerobic Lagoon+Aeration tank+Secondary ctarifier+ Sludge drying beds

Madhavaram. Chengai Total : 14 9500 800 Screen+Equalization cum Mxing Basin+ Primary MGR Connected : 1 4 clarifier+ Aeration tank+ Secondary

ctarifier+Poiishing pond+ Sludge drying beds Ramji Nagar. Total : 5 15000 525 Presettiing Tank+Equalization basin+Dissolved air Trichy Connected : 5 flotation Unit 1+ Aeration tank+Dissolved air

flotation Unit 11+ Sludge drying beds

.( ..J.. -.I

Table 27 - Characteristics of treated effluent from CETPs in Tamil N adu

Parameters Location of C ET Ps·

2 3 4 5 6

pH 7.5-8.4 7.6-7.8 7 . 1 -7.4 8.0-8.2 7.6-7.8 6.5-7.0

Suspended solids 84 78 1 1 0 95 93 90

Total dissolved 4496 1 1 390 1 1 872 7200 6720 1 9650 Solids

B O D 1 5 5 1 1 0 1 9 23 22

COD 245 222 596 295 2 1 5 1 40

Sulphates 839 1 8 952 950 9 1 5 630

Sulphides 1 .2 B D L 2.8 B D L 1 . 1 B D L

Chlorides 986 3960 5918 2965 3740 7200

Ammoniacal 38 24 0.3 52 55 32 N itrogen

Kjeldahl nitrogen 54 40 9.2 65 7 1 46

All values are in mg/l except p H ; B D L Below Detectable Limits

. 1 S I D C O Industrial Estate, North Arcot Am bedkar (NAA)

2 Melvishararm Sector, Ranipet, N AA

3 Thuthipet Sector, Ambur, N AA

4 Valayambattu, Vaniyambadi, N AA

5 Udayendiram , Vaniyambadi, N AA

6 Bakkalapalli , P e rnambut, N AA

7 Pam m al Pallavaram , Chrompet Area, Chengai M G R

8 Dindigul, Dindig u l Anna

9 Madhavaram, Chengai M G R

1 0 Ramji Nagar, Trichy

7 8 9 1 0

7 . 1 -7.2 7.5-7.8 7.6-7.8 7.3-7.5

2 1 6 92 68 70

5564 1 9042 4026 8440

28 24 8 5

248 1 360 1 46 1 44

2400 995 2460 8

1 .7 1 .8 B D L B D L

1 836 1 0700 1 1 78 31 20

25 45 4 1 2

37 60 6 22

.(

Standards for inland s u rface water discharge

M E F T N P C B

5.5-9.0 5.5-9.0

1 00 1 00

2 1 00

30 30

250 250

1 000

2 2

1 000

50 50

1 00 1 00

Z ;l> Z 0 -< � �

� en -l tTl � � tTl ::0 � ;l> Z ;l> 0 tTl � tTl Z -l ..... Z

� Z Z tTl ::0 tTl en

Vl Vl

5 1 6 J SCI IND RES VOL 5 8 JULY 1999

References

Sastry c.A. & Madhavakrishna W, Pollution Problems in Leather Industries in India, Environ India Rev Ser 2 ( 1 984).

2 Rajamani S, Madhavakrishna W & Thyagarajan G, Environ­mental Impact Assessment and Effluent Management in Leather Industries, Paper presented at Natn Semin Impact Environ Pro­tect Future Dev India, Nainital, April 6-8 ( 1 987).

3 Cheda P V, Mandlekar U V, Handa B K & Khanna P, Joint Wastewater Management for a Cluster of Tanneries at Kanpur, Proc 39th Ind. Waste Conf, Purdue University ( 1984).

4 Kaul S N & Nandy T, Treatment of Tannery Wastewaters with recourse to Energy and Chromium Recovery, NEERI Report,

1 99 1 .

5 Kaul S N and Nandy T, Tanning Industry - State-of-the-art, (Pub­lished by Ministry of Non-conventional Energy Sources, New Delhi) 1 994.

6 Nandy T, Kaul S N and Daryapurkar R A, Aerobic Bio-oxida­tion of Post-Anaerobic Tannery Effluents, 1m J Environ Stud­ies, 43 ( 1 993) 7- 19.

7 Wastewater Management in Cluster of Tanneries in Tamil Nadu­Phase I NEERI Report, 1 997.

8 Standard Methods for Examination of Water and Wastewaters, APHA, AWWA WPCF, 17th ed. 1 989.

9 Hazardous Waste Category, MEF Notification No. 465 Gaz In­

dia, Part -II, Section -3, Sub-section (ii), 1 989.

1 0 Wastewater Management in Cluster of Tanneries ill Tamil Nadu - Phase II NEERI Report, 1 997.