USE OF ACTIVATED CARBON TO POLISH EFFLUENT FROM METALWORKING TREATMENT PLANT:

COMPARISON OF DIFFERENT STREAMSNidal Hilala*, Gerald Buscab, Fernando Rozadac and Nick Hankinsa

a-Centre for Clean Water Technologies, The University of Nottingham UK

b- Environmental Technology Centre, The University of Nottingham UK

c-Institute of Natural Resources, University of Leon SpainINTRODUCTION

Waste metalworking fluids are toxics and with a very high COD. Waste metalworking fluids are toxics and with a very high COD. In response to stringent legislation and increasing disposal cost designed a complete In response to stringent legislation and increasing disposal cost designed a complete process for metalworking fluid remediation was design, using membrane technology and bioremediation. The system produces 2 streams, a recovered process for metalworking fluid remediation was design, using membrane technology and bioremediation. The system produces 2 streams, a recovered oil with a calorific value of oil with a calorific value of 42kJ/g 42kJ/g and an aqueous phase that post bioreactor has a COD and an aqueous phase that post bioreactor has a COD 98% lower98% lower then the original waste. Nevertheless, lowering then the original waste. Nevertheless, lowering further the effluent COD appeared to be essential for process water recovery. Therefore, the team proposed to study the feasibility of using Activated further the effluent COD appeared to be essential for process water recovery. Therefore, the team proposed to study the feasibility of using Activated Carbon to polish the aqueous effluent. 3 streams were simultaneously studied and compared:Carbon to polish the aqueous effluent. 3 streams were simultaneously studied and compared:

(-e) Before the bioreactor, (-eB) After Bioreactor and (-eBF) After Bioreactor effluent micro-filtered(-e) Before the bioreactor, (-eB) After Bioreactor and (-eBF) After Bioreactor effluent micro-filtered

Acknowledgments:We thank the UK Engineering and Physical Sciences Research Council and CARDEV International Ltd for funding this work.

eB

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eBF

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Co (mg/L)

Cs (mg/L)

feed average

1m

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0.7 l/day 500 l/dayInlet flow rate x 715

Outlet flow rate x 715

Surface x 715

Number of columns x 715

Flux kept constant

Lab scale Industrial scaleHeight : 1m 1m Diameter: 3cm 45cm Mass of AC: 0.190 kg 151 kg

1m

1m

0.7 l/day 500 l/dayInlet flow rate x 715

Outlet flow rate x 715

Surface x 715

Number of columns x 715

Flux kept constant

Lab scale Industrial scaleHeight : 1m 1m Diameter: 3cm 45cm Mass of AC: 0.190 kg 151 kg

Complete treatment system showing where Activated Carbon test were carried out

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Adsorbate Qº (mg/g) K L (L/mg) R 2 n K F

e 345.0 0.007 0.994 2.1 23.11eB 400.0 0.033 0.928 1.9 17.05

eBF 625.0 0.014 0.992 1.5 9.06

R 2

0.9290.9890.992

FreundlichLangmuir

Fittings to Langmuir’s and Freundlich’s models

Before activated carbon After activated carbon Effluent -e -eB -eBF -e -eB -eBF

pH 9.2 8.2 8.2 7.7 7.9 8.2

Turbidity (NTU) 1.3 17.6 0.05 5.5 15 1.1 COD (mg/l) 7300 1150 1000 840 85 350

Effluents characteristics before and after AC treatment

Scale-up of the activated carbon column to fit the industrial system

Conclusion

The activated carbon has been proven to be effective in removing the The activated carbon has been proven to be effective in removing the COD and the colour of each effluent.COD and the colour of each effluent.

The absorption column used straight after the membrane system, by-The absorption column used straight after the membrane system, by-passing the bioreactor, showed a good removal capacity but the column passing the bioreactor, showed a good removal capacity but the column has been subject to major bacterial development leading to a complete has been subject to major bacterial development leading to a complete blockage of the column.blockage of the column.

The results clearly show that using the activated carbon straight after the The results clearly show that using the activated carbon straight after the bioreactor bioreactor (-eB)(-eB) is the is the best solutionbest solution. Detached microorganisms from the . Detached microorganisms from the bioreactor colonise the AC column enhance considerably the column bioreactor colonise the AC column enhance considerably the column performance without over developing and without blocking the column.performance without over developing and without blocking the column.

Break through curve for the three different types of effluent

1 Effluent

2 Ultrafiltration

3 Nanofiltration (-e)

4 Bioreactor (-eB)

5 Concentrate treatment

6 Buffering tank

7 0.45 μm filter (-eBF)

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oil

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Activated Carbon columns

Bioreactor recycling loop

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3 Nanofiltration (-e)

4 Bioreactor (-eB)

5 Concentrate treatment

6 Buffering tank

7 0.45 μm filter (-eBF)

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oil

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-eB-e

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Activated Carbon columns

Bioreactor recycling loop

-eBF

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1 2