Treatment of surface water by autonomous solar powered

Treatment of Surface Water by Autonomous Solar-Powered Membrane

CellsBy

Raed Waked Al-Qutub

SupervisorDr. Abdelrahim Abusafa

``

April,2010April,2010

An-Najah National UniversityClean Energy & Energy Conservation Engineering

2 Business Ally LLC.Your Driving Force to Success

INTRODUCTIONINTRODUCTION

WATER TREATMENT METHODSWATER TREATMENT METHODS

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SOLAR ENERGY & PV CELL SIZINGSOLAR ENERGY & PV CELL SIZING

EXPERIMENTAL WORKS & RESULTSEXPERIMENTAL WORKS & RESULTS

ECONOMIC EVALUATIONECONOMIC EVALUATION

PV-RO SYSTEM.PV-RO SYSTEM.

REVESE OSMOSIS PROCESSREVESE OSMOSIS PROCESS

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88 CONCLUSIONS&RECOMMENDATIONCONCLUSIONS&RECOMMENDATION



WATER TREATMENT METHODS WATER TREATMENT METHODS

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INTRODUCTION

Why is Water Important?Why is Water Important?

Water resources are essential for satisfying human needs, health, and ensuring food production, energy and the restoration of ecosystems, as well as for social and economic development and for sustainable development.

According to UN World Water Development Report in 2003, it has been estimated that two billion people are affected by water shortages in over forty countries, and 1.1 billion do not have sufficient drinking water.

INTRODUCTION

Energy Sources in Surface water treatment Energy Sources in Surface water treatment

Power grid, AC powered system is economic and takes minimum maintenance.

Diesel Generator, require frequent site visits for refueling and maintenance, and furthermore diesel fuel is often expensive.

Renewable energy sources by using Photovoltaic and wind turbine….etc.

A water treatment system needs a source of power to operate.

Water and Energy Crisis in Palestine

Palestine does not contain a lot of water sources which is not enough with ever increasing population. The Israelis and the Palestinians share interrelated water systems:1.Groundwater•Western Aquifer : Recharge area lies in the West Bank, The entire storage area lies in Israel and 95% of its water is used by Israel.•The Northern Aquifer : its recharge and storage areas essentially located within the West Bank. However, Israel extracts about 70% of the water.•The Eastern Aquifer: which is entirely within the West Bank, has 37% of its water consumed by Israel - mostly by settlers .


2. Springs and Wells

The number of measurable springs in the West Bank is 146 and the number of non measurable springs, hardly reached or low discharge is 163

There are 561 wells; 519 Palestinian wells and 42 wells under Israeli control. Out of Palestinian wells, there are 18 new wells and 148 wells out of order. Out of the working wells, 308 wells are used for irrigation (55.4%) and the (44.6 %) are used for domestic purposes.


Palestine lacks conventional energy resources such as oil and gas, and therefore must import all its energy from Israel at a relatively high cost. Presence of the Israeli occupation and drained of water and energy resources over the years of occupation. Many of the surface water in Palestine suffer from Fecal, Kᶧ and not suitable for drinking.

For this previous reasons, we searched for alternative energy sources for water treatment such as solar energy, which is considered a key determinant of economic and social development.



WATER TREATMENT METHODS WATER TREATMENT METHODS

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EXPERIMENTAL WORK.EXPERIMENTAL WORK.


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EXPERIMENTAL WORK.EXPERIMENTAL WORK.


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WATER TREATMENT METHODS

Objectives of Water Treatment

Provide potable water that is chemically and biologically safe for human consumption. It should also be free from unpleasant tastes and odors.

Water treatment aims at producing water that satisfies a set of drinking water quality standards.

Classification of water treatment processes

The water entering the system is preheated, and gross solids removed.

The water is entered through heat exchanger where the water is boiled into vapor. A mixture of water and vapor exit the heat exchanger and enter the separator.

The compressor draws the vapor from the separator and compresses it to about 0.35 bar, thereby increasing its temperature. The superheated vapor is then pumped into the condenser.

DistillationVapor Compression


As the hot vapor releases its latent heat, it condenses into distilled water, which is then discharged from the system.

The heat exchanger used to boil additional water in the evaporator side.

As additional water is evaporated during the process, the remaining water becomes more concentrated. When the desired level of concentrate is reached, the concentrate is discharged.


DistillationVapor Compression

Classification of treatment of water processes

Multistage Flash Distillation (MSF)Low Pressure (chamber)


Distillation

Multieffect Boiling Distillation (MEB)Use vapor in next champer


Distillation

1.1. Definition:Definition:A Filtration Membrane is a physical

boundary over which a solute (TDS) can be separated from a solvent (water) by applying energy in the form of pressure or electric potential.


Membrane Processes Technology

A cross section in a membrane.

2. 2. Membrane process types:The main membrane processes used in water treatment are:A. Microfiltation (MF)B. Ultrafiltation (UF)C. Nanofiltration (NF)D. Reverse Osmosis (RO)

2. 2. Membrane process types:The main membrane processes used in water treatment are:A. Microfiltation (MF)B. Ultrafiltation (UF)C. Nanofiltration (NF)D. Reverse Osmosis (RO)



Membrane Process

Typical Operating Range µm

Permeate description

MF 0.8-2.0 Water, dissolved solute

UF 0.005-0.2 Water, small molecules.

NF 0.001-0.01 Water, very small molecules, ionic

solutes

RO 0.0001-0.001 Water, very small molecules, ionic

solutes




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Reverse Osmosis Process

Osmosis is the process in which water moves from a lower concentration to a higher concentration.

Principles of Osmosis

Reverse Osmosis is the process in which water moves from a higher concentration to a lower concentration, the amount of force or pressure applied must exceed the osmotic pressure

Principles of Reverse Osmosis

Reverse Osmosis Process

Process Description and Terminology




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Solar Energy and Photovoltaic Cell Sizing

Solar Radiation

Palestine enjoys over 2500 sunlight hours every year, with an annual average solar radiation intensity exceeding 5.3 kWh/m2.day as shown in table 4.1.


Photovoltaic Module

A single PV cell produces an output voltage less than 1V, about 0.6V for crystalline silicon (Si) cells.

thus a number of PV cells are connected in series to achieve a desired output voltage.

Most of commercially available PV modules with crystalline-Si cells have either 36 or 72 series-connected cells.


Sizing of System Components

The sizing of PV Panel, by using the peak power of the PV generator to cover the total load demand is obtained as in equation

(Where is the daily energy consumption in kWh, PSH is the peak sun hours (PSH= 5.4); , are the efficiencies of charge regulator and inverter respectively ( = 0.92, =0.9) and is the safety factor for compensation of resistive losses and PV-cell temperature losses =1.15

FRv

lpv XS

XPSHX

EP

RvvR

fS

lE




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PV-RO SYSTEM PV-RO SYSTEM


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Assembly diagram of the PV-RO system

PV-RO system

Input Voltage: DC 24 VPressure Up to 4 BarPrime Self-Priming up to 2~3 meterCapacity 378 L/day

Specification of the DC pump

the main source of this water is Shraish spring located in Nablus city in west bank

1. Feed Water

Characteristics of shraish spring

pH TDS

(mg/L)

Fecal

(cfu/100ml)

Turbidity

(NTU)

K+

(mg/L)Shraish 7.62 397 600 0.26 30Standar

d6.5-8 <50 0 <1 12

2. DC pump

PV-RO system

3. photovoltaic cell

The specification of the photovoltaic is listed below in table

Solar module SM55(Siemens)Electrical parameters Maximum power rating Pmax [Wp] 55Rated current Impp [A] 3.15Rated voltage Vmpp [V] 17.4Short circuit current Isc [A] 3.45Open circuit voltage Voc [V] 21.7

PV-RO system

5 micron filter, removes sedi ment, clay and particulate matter to 5 micron range.

1-2 micron carbon filter removes chlorine, harmful chemicals.

1-2 micron filter compacted carbon block, to reduce or eliminate a wide range of contaminants

4. Pretreatment filters

PV-RO system

The reverse osmosis membrane was made with a polyamide thin film composite membrane in spiral wound configuration.

4. Reverse Osmosis Membrane

5. Membrane Configurations

Spiral Wound Modules

It consists of membrane envelopes (leaves) and feed spacers which wound around a perforated central collection tube.




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EXPERIMENTAL WORKS

MEASURING INSTRUMENTS Description

Ammeter Current

Voltmeter Voltage

Pressure gauge Pressure output from the DC pump

Conductivity meter Dist 1, HANNA H198301

pH meter pH 211, microprocessor based, Bench pH/mV/Cº meters

Turbidity meter Cole Palmer, model 8391-45

Membrane Filtration Technique.

Fecal Coliform (FC)

The experimental results were measured by using many appropriate devices

1. Effect of Solar Radiation

The system was operated in a sunny day in June 2009 at 9:00 AM when the solar radiation was in the range of (478.75) W.hr/m2, and all other parameters constant.

Solar radiation , Power output from PV , Power input to the Pump

Effect of solar radiation on power input to the pump


The pressure output of the pump exit is directly proportional to the power input to the pump.

Relationship between the power input to the pump and pump pressure

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12

Power(w)

Pre

ssru

e(B

ar)


Power input to the Pump permeate flow rate

0

1

2

3

4

5

6

7

8

3 5 7 9 11

Power(W)

Per

mea

te f

low

rat

e (

L/h

)

Effect of power input to the pump on permeate flow rate


Summary

The PV panel provides electrical current directly to the high pressure pump whose speed increases as the power from the PV panel increases.

2. Effect of Pump Pressure on the Permeate Water Flow rate

•Permeate flow rate , pressure drop across membrane •When the feed pressure increased from 0.63 bar to 1.2 bar, the permeate production increased by 83%.

0

1

2

3

4

5

6

7

8

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3

Pressrue (Bar)

Per

mea

te f

low

rat

e (L

/h)

Effect of membrane Pressure on permeate flow rate

Water Quality

pH, TDS decrease and Kᶧ ,turbidity increases when the flow rate of permeate water increased

6.4

6.6

6.8

7

7.2

7.4

7.6

7.8

8

3 4 5 6 7 8

Permeate Flow rate (L/h)

pH

Effect of permeate flow rate on permeate pH

Water Quality

pH, TDS decrease and K ,turbidity increases when the flow rate of permeate water increased

4

5

6

7

8

9

10

4 4.5 5 5.5 6 6.5 7 7.5 8

Permeate Flow rate (L/h)

K+

(m

g/L

)

Effect of flow rate of permeate water on K+ concentration

Water Quality

pH, TDS decrease and K ,turbidity increases when the flow rate of permeate water increased

0

10

20

30

40

50

60

70

80

4 4.5 5 5.5 6 6.5 7 7.5 8

Flow rate of permeate water (L/h)

To

tal

dis

so

lved

so

lid

s(m

g/L

)

Effect of flow rate of permeate water on total dissolved solids

Water Quality

pH, TDS decrease and Kᶧ ,turbidity increases when the flow rate of permeate water increased

0

0.05

0.1

0.15

0.2

0.25

4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00

Permeate flow rate (L/h)

Tu

rbid

ity

Effect of flow rate of permeate water on turbidity

3. Effect of Feed Water Temperature on Permeate Flowrate

• water temperature increase , Permeate flow rate increase

0

2

4

6

8

10

12

14

16

30 32 34 36 38 40 42 44

Water Tempreture(C)

Perm

eate

flo

w r

ate

(L

/h)


The main reason for this trend is the reduction in viscosity with temperature increase. As viscosity decrease the mass transfer through the membrane surface is enhanced.

0

2

4

6

8

10

12

14

16

30 32 34 36 38 40 42 44

Water Tempreture(C)

Perm

eate

flo

w r

ate

(L

/h)


The effect of feed water temperature on product quality is generally very small

Feed Water Temp (ºC)Permeate Quality

33 35 38 40 44

Flow rate (L/h) 8.6 10.0 10.8 12.0 15.0

pH 6.1 7.3 6.3 5.9 6.7

TDS (mg/L) 48 50 49 50 51

Fecal (cfu/100ml) 0 0 0 0 0

Turbidity (NTU) 0.15 0.14 - - -

Kᶧ (mg/L) 7.1 7.5 8.4 8.4 8.3

4. Effect of Feed water Salinity on Permeate flow rate

• The input water salinity was adjusted by adding NaCl to produce solution concentrations of 500, 650 and 800 ppm. All other parameter were kept constant.

• The osmotic pressure does not depend on the solute type, or its molecular size, but only on its molar concentration.

• Higher operating pressures are needed to overcome the osmotic pressure.

4. Effect of Feed water Salinity on Flow rate Salinity of Permeate Water

0

20

40

60

80

100

120

140

0 2 4 6 8 10 12

Permeate flow rate (L/h)

To

tal

Dis

so

lved

so

lid

(mg

/l)

• When the feed water contains high salt concentration, The permeate flow rate decrease.

5. Effect of Recovery on Permeate Water Quality

• adjustable valve at the retentate exit• The permeate flow rate increase, the fecal was observed for the first time

when the recovery changed

Power (W)

Permeate flowrate

(L/h)

Retentate flowrate

(L/h)

Permeate water properties

pH TDS (mg/L)

Fecal(cfu /100ml)

K (mg/L)

8.73 5.88 22.73 5.97 35 10 6.1

7.98 13.04 13.95 6.1 43 17 6.6

8.17 14.15 6.98 6.2 63 45 6.8




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ECONOMIC EVALUATION

7.1 Cost Analysis

The product cost is strongly correlated with unit capacity, quality of feed water, pretreatment, types of water treatment technology, site condition, costs of land.

Average daily water flow rate can be calculated as the following:

During June, the average flow rate 44.32 L/d and the monthly average solar radiation was 8.25 kWh/m².

ECONOMIC EVALUATION

The average water flow rate = 9

)/(36.360 dL

=40.04 L/d

According to other months, the average water flow rates were calculated corresponding the monthly average solar radiation as shown

ECONOMIC EVALUATION

Common Economic Parameter :

Plant life time is 25 years.Operating days per year are 270 days.Feed water TDS is 400mg/L (normal case).Operating and maintenance (O&M) costs are 20% of the system annual payment.Annual rate of membrane replacement is 20%.Interest rate is 5%.Plant availability (f) is 90%.Capacity(M)=40 L/d Salvage value of the units will be zero.

ECONOMIC EVALUATION

7.1.1 Capital Cost

Total capital cost of PV module = 11Watt X 7.27 $/Watt. =80$

Item CostPV module (Siemens SM55, 55Wp) 80$

Reverse Osmosis Membrane 100$Booster Pump (12VDC) 150$3 stages pretreatment filters, accessories

100$

Total 430$

• Capital cost (CC) summary

ECONOMIC EVALUATION

Fixed Charges

To determine the fixed charge value of the capital costs, these costs are multiplied by an amortization factor (a)

1)1(

)1(

n

n

i

iia

10.070952 ya

Annual fixed charges

fixedA = (a) X (CC) = 0.070952X430$ =30.5$/year

Annual Operating Costs

Annual operating cost covers all expenses after commissioning and during the actual operation

ECONOMIC EVALUATION

Operating and Maintenance (O&M) Costs

The annual O&M costs are estimated at 20% of the plant annual payment

mAo & = (20%) X (Afixed) = 20% X 30.5$/year =6.1$/year

Annual O&M Costs

ECONOMIC EVALUATION

Membrane Replacement

Replacement rate may vary between 5%–20% per year

ntAreplaceme = (20%) X (membrane cost) = 20% X 100$ =20$/year

Annual O&M Costs

•Unit production cost (Aunit)

)270)()((

)(

Mf

AA total

unit

)/270)(/04004.0%90(

/$6.563 yeardaydaym

yearAunit

Aunit = 5.8$/m³

Total annual cost (Atotal)=Afixed+Areplacement+AO&M=56.6$/year




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The looming water crises in Palestine can be significantly reduced by the exploitation of the abundant brackish and surface water resources.

The combination between renewable energies specially (photovoltaic cells) and RO Water Treatment Processes very suitable in Palestine for remote sites lacking of electric grids where water scarcity is a big problem .

Economically, it was found that although the energy is free, the water production cost from the PV–RO unit is $5.23/m3 which is still expensive and can not be economically viable, only in catastrophes and remote areas and far.

CONCLUSIONS

One source of renewable energy was not economically viable and could be used as another source assistant as hybrid system which is economical and available for 24h/day along the year.

The effect on product quality is generally a very small change compared to the Change observed in productivity when the feed temperature increased from 33°C to 44°C.

They are not recommended to make Recovery in biologically unsafe water because the Fecal was observed for the first time when the recovery changed

.

CONCLUSIONS

RECOMMENDATIONS

It is recommended that future work be focused on another Power source assistant as hybrid system (Diesel Generator) which is available for 24h/day along the year.

Other sources of water with different characteristics can be also tested. The effect of fecal concentration can be investigated by changing the source of water.

Different membrane arrangement such series and parallel configurations can be also tested to see the effect of recovery.

Design of solar heaters that can heat the feed water prior to membrane treatment is highly recommended.

Treatment of surface water by autonomous solar powered

Technology

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