1

CHAPTER 1

INTRODUCTION

Food and beverage industry is one of the largest industry sectors and is

essential to all economies. It has its dominating role in satisfying basic needs and

requirements of every person. The last 5 decades has seen a dramatic increase in

the demand for food due to the rapid growth in world population. Annual dairy

production accounts for 514 million tonnes; cereal production (including rice, wheat

and coarse grains) is approximately 2 billion tonnes where as meat production is in

the order of 200 million tonnes.

With the development in the industrial sector consequently there is

increase in raw material usage. Water is an inevitable raw material for food

industries. The main sources for the industrial sector are groundwater and surface

water. Ground water has emerged as an important source to meet the water

requirements of the industries in recent years. According to World Development

Report (WDR) of 2003, in developing countries, 70 percent of the industrial waste

water are dumped without proper treatment, thereby polluting the usable water

supply. According to Centre for Science and Environment (CSE) report in 2004 on

an average each litre of wastewater discharged further pollutes 5-8 litres of fresh

water.

Meat industry is one of the highly polluting industries which require great

concern with the environmental aspect. The primary steps in poultry processing

includes bleeding, scalding or skin removal, evisceration, washing, chilling, cooling,

packaging and cleaning. In all these processes water plays a key role. Poultry

processing expels a more difficult waste stream to treat. The killing and rendering

2

processes creates blood by-products and waste streams, which are very high in

BOD (1200-3800 mg/L) and COD (2650-6720 mg/L) values.

Waste streams from poultry processing can be generalised in to

carcasses, skeleton waste, rejected or unsatisfactory animals, fats, animal faeces,

eviscerated organs, blood and waste water. All the solid waste are subjects to

rendering and are converted to useful by-products. They are rich in protein, nitrogen

and minerals like phosphorus. They are used to produce animal feed, cosmetics,

fertilizers fish and pet feed.

In conventional system of poultry waste water system follows

coagulation, flocculation, aeration, flotation and biological treatment. Most of the

times it is treated waste water is discharged into nearby water bodies or open

lands. Sometimes it is used for irrigation of garden and lawns. Improper processing

and discharging of wastewater in water bodies is a severe thread to aquatic lives.

Whereas discharging it in open land leads to outspread of diseases. Drawbacks

associated with this conventional wastewater treatment system are high sludge

production which is difficult to process further. If resins or membranes are used for

wastewater treatment it has to be recharged or changed periodically. And also this

conventional system is less efficient remove some of the biological compounds and

colour to make it reuse into the production process.

The advent of various technical developments led to the discovery of

various treatment processes. One among them is Advance Oxidation Process. It

refers to chemical treatment a process which employs oxidation techniques to

degrade biologically toxic and non degradable chemicals. This treatment process is

based on the production on highly reactive hydroxyl radicals as the primary oxidant.

Advance oxidation process is broadly classified into Fenton process, Photo-Fenton

process, UV based process, photo catalytic redox process, sonolysis, Electro

Fenton process etc., The main function of this AOP is generation of highly reactive

free radicals primarily Hydroxy radicals which are effective in destroying number of

organic chemicals because they are reactive electrophiles that react rapidly and

non selectively.

3

Fentons Reagent system of AOP is an attractive and effective

technology because it uses only Iron and Hydrogen peroxide. Iron is an abundant

material in nature and hydrogen peroxide is environmentally safe. Fentons method

is capable of degrading large number of hazardous organic pollutants and there are

no toxic reagents are involved in this process it also leaves no residues and the

technology of this process is so simple. But the ferrous ions consumed in this are

regenerated at a very slower rate. And it becomes a rate limiting step in this

process.

Electrochemical advanced oxidation processes (EAOP) based on

Fentons reaction chemistry are eco-friendly methods that have received much

attention for water treatment. The most popular EAOP is the electro Fenton

process. Electro fenton process has two different configurations. In the first one

Fenton reagents are added to the reactor from outside and inert electrodes with

high catalytic activity are used as anode material while in the second configuration,

only hydrogen peroxide is added from outside and Fe2+ is provided from sacrificial

cast iron anodes. Compared to conventional Fenton process, the electro Fenton

process has the advantage of allowing better control of the process.

In the presence of ferrous ions and in acidic aqueous medium the

oxidation power will be enhanced due to the production of very reactive one

electron oxidizing agent hydroxyl radical (OH) from the Fenton reaction. This

electro Fenton process can generate OH by the simultaneous electrochemical

reduction of O2 in the presence of catalytic amounts of ferrous ions. And this

method is found to be effective for the degradation of number of organic pollutants.

4

CHAPTER 2

REVIEW OF LITERATURE

This chapter deals with review of literature for industrial water usage,

poultry wastewater, wastewater treatment, advance oxidation processes and

electro fenton process.

2.1 GLOBAL WATER AVAILABILITY

70% of the earth surface is covered with water, which amounts to 1400

million cubic kilometres (m km3). However, 97.5% of this water being sea water, it

is salty. Fresh water availability is only 35 m km3. Out of the total fresh water,

68.7% is frozen in ice caps, 30% is stored underground and only 0.3% water is

available on the surface of the earth. Out of the surface water, 87% is stored in

lakes, 11% in swamp and 2% in rivers. As all the sweet water is not extractable,

only 1% of the total water can be used by human beings. As water was available in

plenty, it was considered as a free resource since generations. However, with

growing demand for water and depletion of the available water, assured supply of

good quality water is becoming a growing concern. (Anon., 2006).

2.2 INDUSTRIAL WATER USAGE

The World Bank estimates that the current industrial water use in India is

about 13 percent of the total freshwater withdrawal in the country and the water

demand for industrial uses and energy production will grow at a rate of 4.2 per cent

per year, rising from 67 billion cubic metres in 1999 to 228 billion cubic metres by

2025. All these estimates reveal that the industrial water demand is not negligible in

India and that it is bound to grow in the coming years.

5

Industries not only consume water but also pollute it. In developing

countries, 70 percent of industrial wastes are dumped without treatment, thereby

polluting the usable water supply. Note that industrial water demand is not the

demand for water as in other sectors, as a large part of the water withdrawn for

industrial use is discharged as polluted water by the industries. According to Centre

of Science and Education (CSE, 2004) report on an average, each litre of

wastewater discharged further pollutes about 58 litres of water which raises the

share of industrial water use to somewhere between 3550 percent of the total

water used in the country. (World Development Report, 2003)

2.3 POULTRY PROCESSING INDUSTRY AND WATER USAGE

Food processing industry can be divided into four major sectors

including fruit and vegetable processing, meat, poultry and sea food, beverage and

bottling and dairy operations. All of these sectors consume huge amount of water

for processing food. A considerable part of these waters are potential wastewaters

to be treated for safe disposal to the environment.

Poultry processing industries offer a more difficult waste stream to treat.

The killing and rendering processes create blood by-products and waste stream,

which are extremely high in BOD. The primary steps in processing chicken include

1. Rendering and bleeding

2. Scalding and skin removal

3. Internal organ evisceration

4. Washing, chilling and cooling

5. Cleaning

Solid wastes which include skin, fat, faeces, muscles etc, are subjected

to rendering process and converted to useful by-products. Wastewater is tedious to

treat and Discharge of this effluent without proper treatment in water bodies is a

severe threat to aquatic lives and affects the ground water.

6

2.4 POULTRY AND WASTE WATER TREATMENT

Number of methods has been studied previously for the treatment of

meat industry wastewater. The maximum of 85% of COD removal is obtained in

Upward-flow anaerobic sludge blanket (UASB) reactor treatment for poultry

wastewater (Anna Kwarciak-Kozowska, et al., 2011). And a COD removal of 54-

67% is obtained in the treatment of meat industry waste water using dissolved air

flotation (Rennio F. De. Sena, et al., 2009)

2.5 ADVANCE OXIDATION PROCESSES (AOPS)

Advance Oxidation processes (AOPs) are an attractive for treatment of

contaminated grounds, surface and wastewaters containing heavy pollutants.

These technologies generate hydroxyl radical (OH) which is a highly reactive

oxidant (E = 2.8 V versus SHE) (Farre et al., 2006; Guinea et al., 2008; Pera-Titus

et al., 2004). These methods are attractive because of the possibility of the

mineralizing the target compounds (Zoh and Stenstrom, 2002). The main

interesting of OH radicals are also characterized by a non selectivity of attack

which is a useful attribute for an oxidant used in wastewater treatment and to solve

pollution problems. OH is the second strongest oxidant after fluorine.

Methods based on chemical and photolytic catalysis have been included

in a group of new technologies denominated. AOPs generated highly degrading

OH radicals. As OH radicals are so reactive and unstable, they must be produced

continuously. These radicals are produced by several methods such as hydrogen

peroxide/ultraviolet irradiation (H2O2/UV), hydrogen peroxide/ozone (H2O2/O3),

ozone/ultraviolet irradiation (O3/UV), TiO2-catalyzed UV oxidation, and also the

combination of H2O2 with ferrous ions (Fenton reagent).

7

Oxidation Species Oxidation power (V)

Fluorine (F2) 3.03

Hydroxyl radical (OH) 2.80

Atomic Oxygen 2.42

Ozone (O3) 2.07

Hydrogen peroxide (H2O2) 1.77

Permanganate (KMnO4) 1.67

Chlorine (Cl2) 1.36

Table No.2.1 Oxidation power of selected oxidizing species (Beltran et al., 1998)

2.6 FENTON PROCESS

Fenton process is known to be very effective in the removal of many

hazardous organic pollutants from water based on an electron transfer between

H2O2 and iron. The reactivity of this process was first observed in 1894 by its

inventor H.J.H. Fenton, its utility was not recognized until the 1930s when a

mechanism based on hydroxyl radicals was proposed. The main advantage is the

complete destruction of contaminants to harmless compounds, e.g. CO2, water and

inorganic salts. The Fenton reaction causes the dissociation of the oxidant and the

formation of highly reactive OH that attack and destroy the organic pollutants. The

reaction mechanism can be described by means of the following reactions: the

generation of hydroxyl radicals (OH) between H2O2 and Fe2+ (Reaction 2.1), the

degradation of organic substance by the OH (Reaction 8). In the mean time, some

reversed reactions and side reactions (Reactions 2.2, 2.3, 2.5, and 2.6) also occur

(Kang et al., 2002; Kang and Hwang, 2000; Neyens and Baeyens, 2003; Oturan et

al., 2001).

Fe2+

+ H2O2 Fe3+ + OH + OH- (Reaction 2.1)

Fe2+

+ OH Fe3+ + OH- (Reaction 2.2)

Fe3+

+ H2O2 FeOOH2+ + HO2 + H+ (Reaction 2.3)

8

OH + Organic Products (Reaction 2.4)

H2O2 + Organic Products (Reaction 2.5)

OH + H2O2 HO2 + H2O (Reaction 2.6)

OH + OH H2O2 (Reaction 2.7)

FeOOH2+

Fe2+ + HO2 (Reaction 2.8)

HO2 + Fe2+

HO2 - + Fe3+ (Reaction 2.9)

HO2 + Fe3+

O2 + Fe2+ + H+ (Reaction 2.10)

The reaction rate of reaction 2.3 is much slower than that of reaction 2.1

meaning that Fe2+ is consumed quickly, but reproduced slowly. Thereby, the

oxidation rate of organic compounds is fast when large amount of Fe2+ is present

because large amount of OH is produced (Behnajady et al., 2007). Numerous

competing reactions which involve Fe2+, Fe3+, H2O2, OH, hydroperoxyl radicals

(HO2) and radicals derived from the substrate, may also be involved. OH radicals

may be scavenged by reacting with Fe2+ or H2O2 as seen in reactions 2.2 and 2.6.

Fe3+ formed through reactions 2.1 and 2.2 can react with H2O2 following a radical

mechanism that involves OH and HO2 with regeneration of Fe2+ as shown in

reactions 2.3, 2.8, 2.9 and 2.10 (Lucas and Peres, 2006).

The Fenton reaction also has several important advantages such as

short reaction time among all advanced oxidation processes, iron and H2O2 are

cheap and non-toxic, and the process is easily to run and control (Argun et al.,

2008).

However, in Fenton process, a large amount of sludge will be produced

during the neutralization process, especially when the high strength wastewater is

treated (Oturan et al., 2001; Qiang et al., 2003; Zhang et al., 2007). To solve this

problem, the Fenton reaction efficiency can be enhanced in the presence of UV

9

irradiation and electrochemical as commonly called photo-Fenton and electro-

Fenton process, respectively.

2.7 ELECTRO-FENTON PROCESS

The application of electrochemical method in Fenton process, named

electro-Fenton process, could be generally divided into four categories (Khataee et

al., 2009; Ting et al., 2009; Zhang et al., 2006). In the first one, H2O2 is externally

applied while a sacrificial iron anode is used as Fe2+ source. In the second

category, Fe2+ ion and H2O2 are electro-generated using a sacrificial anode and

cathode via the two electro reduction of sparged oxygen, respectively. In the third

category, Fe2+ ion is externally applied, and both of H2O2 and Fe2+ are concurrently

generated at cathode, but primarily focusing on H2O2 generation on mercury pool,

carbon felt, reticulated vitreous carbon, graphite, activated carbon fiber, stainless

steel plate or carbon-PTFE cathode. In the fourth category, Fentons reagent is

utilized to produce OH radicals in the electrolytic cell, and Fe2+ ion is regenerated

via the reduction of Fe3+ ion or ferric hydroxide sludge on the cathode.

Fenton reaction involves several sequential reactions as shown in

reaction 2.1-2.10. The well known Fentons reaction (reaction 2.1) constitutes a

source of OH radicals production by chemical means. The H2O2 and Fe2+ ions are

simultaneously generated on the working electrode, according to the following

electrochemical reactions.

On the cathode side

O2 + 2H+ +2e

- H2O2 (Reaction 2.14)

Fe3+ + e

- Fe2+ (Reaction 2.15)

H2O + e- H2 + OH- (Reaction 2.16)

10

On the anode side

2H2O 4H+ + O2 + 4e- (Reaction 2.17)

Fe2+

Fe3+ + e- (Reaction 2.18)

Fentons reaction (reaction 2.1) takes place then in homogeneous

medium leading to the formation of OH radicals.

The anodic reaction is the oxidation of water to molecular oxygen

(reaction 2.17) which is used for optimal production of H2O2 (reaction 2.14)

necessary for Fentons reaction. Figure shows two catalytic cycles taking place

during this process. Electrochemical reactions 2.14 and 2.15 can take place when

the aqueous solution is maintained under oxygen saturation by bubbling

compressed air.

The electro-Fenton process can be considered very efficient and much

cleaner techniques than chemical ones for improving the quality of water resources

and eliminating organic compounds in water.

In this study, a novel electro-Fenton process, in which Fentons reagent

was utilized to produce OH in the electrolytic cell and Fe2+ ion is regenerated via

the reduction of Fe3+ ion on the cathode was investigated.

2.8 OPERATIONAL PARAMETERS

It has been proved that the Fentons reaction is a chain reaction. Various

factors were found to have significant impacts on the electro-Fenton performance.

11

2.8.1 pH

pH is one of the most important factors for the electro-Fenton process. It

has been confirmed that the optimum value of pH is 2-4. In addition, when the pH

increases, the iron ions especially the Fe3+ precipitate. Therefore, the amount of

catalyst of Fentons reaction decreases. When pH is lower than 2, H2O2 cannot be

effectively decomposed to OH by Fe2+. This can be explained that in lower pH, the

scavenging effect of the OH by H+ is severe to form an ozonium ion such as H3O2

+; result in reducing the generation of OH (Sun et al., 2008). H3O2 + is electrophilic

leading to the decreasing rate of reaction between H2O2 and Fe2+. The optimum pH

for removal aniline and 2,6 dimethylaniline was 2 (Anotai et al., 2006; Ting et al.,

2009). At the pH above 3 the composition rate of synthetic dyes decreased

because the oxidation potential of OH and also the dissolved fraction of iron

species decrease with increasing pH (Panizza and Cerisola, 2009).

In fact, the optimum pH indicates a disadvantage of electro- Fenton

process because the pH of most water is not within the optimal range. There are

two ways to decrease the pH of wastewater. One is to add acid, and then other is to

mix the target wastewater with some acidic wastewater. Some researchers

investigated the wastewater treatment at neutral pH and the organics can also be

removed successfully. But, in that case, the wastewater is treated mainly by

coagulation rather than by degradation of OH

2.8.2 DISTANCE BETWEEN ELECTRODES

The decrease of the distance between the electrodes leads to a

decrease of the ohmic drop through the electrolyte and then an equivalent decrease

of the cell voltage and energy consumption (Fockedey and Lierde, 2002). It can be

concluded that the closer the electrode are, the better the performance. However, it

is necessary to keep appropriate distance between the electrodes for installation

and avoidance of short circuit between anode and cathode.

12

2.8.3 TIME

Time is one of the important parameters in the electro Fenton treatment

of waste water. The treatment efficiency, COD, Turbidity and Colour removal is

progressive as the time increases. And after a period of time it reaches a stable

point after which there is very low or no removal of COD.

2.8.4 H2O2 CONCENTRATION

H2O2 Concentration is a crucial factor for electro Fenton treatment.

Although Fe2+ can react with H2O2 to generate OH and greater OH radicals could

be generated with increasing Fe2+ concentration. Fe2+ and H2O2 cannot be

excessive unilaterally because of the occurrence of undesired side reactions

(reaction 2.2 and 2.6). In reaction 2.6, the HO2 is also an oxidant, but has an

oxidation potential much less than OH. COD removal efficiency increased with the

increasing Fe2+ to H2O2 molar ratio (Zhang et al., 2007). Increasing the H2O2

concentration from 10 to 25 mM increased the removal efficiency, 46% of 2,6-

dimethyaniline but increase from 25 to 30 mM decrease in removal efficiency , 35%

(Ting et al., 2009).

13

CHAPTER 3

MATERIALS AND METHODS

This chapter deals with material and methods involved in Electro Fenton

treatment, coagulation and water parameter analysis. The parameters like pH, TDS,

COD, BOD, Turbidity, Color, Sulphide and chloride contents are analyzed.

3.1 METHODOLOGY

Wastewater from poultry processing industry was collected from poultry

processing industry and stored at refrigerated conditions at pH 2. Initial

characteristics of the wastewater were analysed. And after adjusted to necessary

pH the electro fenton treatment was carried out. Then characteristics of the treated

water was analysed and optimisation was carried out. And then combined

coagulation and electro fenton was done and the results were compared.

3.1.1 PROCESS FLOW CHART

Raw wastewater collection

Storage of wastewater at pH=2 under refrigerated condition

Study of initial characteristics

Electro fenton treatment

14

Optimisation

Combined coagulation and Electro fenton

Analyse and compare the results

3.2 ELECTRO FENTON REACTOR

The reactor used in this study is a batch type lab scale reactor made of

glass. The total volume of this reactor is 500ml. And 300 ml of waste water is

measured and treated in this reactor for specified operational parameters. pH,

Electrode distance, time and amount of H2O2 are the parameters changed and

studied in this experiment. pH is changed using 0.1N HCl and 0.1NaOH with the

help of digital pH meter. A constant DC current of 0.1 Ampere is maintained

throughout the treatment with the help of lab scale Regulated Power Supply (RPS).

Iron is used as electrode in this treatment to produce Fe2+ ions. Effective electrode

area is about 42cm2.

3.3 COAGULATION

In wastewater treatment coagulation process is particles adhesion

process with formation of large flocs, as a result of addition of a chemical reagent

(coagulating agent) for the purpose of destabilization of suspended colloidal

particles and their subsequent coagulation (aggregation). In this experiment alum

(aluminium sulphate) is used for coagulating agent. Alum is easily available and

cheap in cost. And optimum amount of alum for coagulating meat industry

wastewater is found to be 250 mg/L (Vanerkar A. P. et al).

15

3.4 PHYSIOCHEMICAL ANALYSIS

3.4.1 CHEMICAL OXYGEN DEMAND (COD)

Chemical oxygen Demand test is used to indirectly measure the amount

of organic compound in water. It is expressed in mg/L which indicates the amount

of oxygen consumed per litre of solution for complete oxidation of pollutants in the

solution.

The organic matter present in the sample gets oxidized completely by

potassium dichromate (K2Cr2O7) in the presence of sulphuric acid (H2SO4), silver

sulphate (AgSO4) and mercury sulphate (HgSO4) to produce CO2 and H2O. The

sample is refluxed with known amount of K2Cr2O7 in sulphuric acid medium and the

excess of K2Cr2O7 in determined by titration against ferrous ammonium sulphate,

using ferroin as an indicator. The amount of O2 required oxidizing the organic

matter.

Take 1 ml of sample in two COD vials and 1 ml of distilled water in

another COD vial. Add 10 ml of 0.25N K2Cr2O7 to all the COD vials. Add 11 ml of

sulphuric acid-silver sulphate reagent to all the vials. Add a pinch of mercury

sulphate to all the vials. Place all the vials in COD digester and digest it at 80C for

2 hours. After digestion transfer the contents to conical flasks and add 33 ml of

distilled water and 3 drops of ferroin indicator to each of the conical flasks. Then

titrate it against 0.1N ferrous ammonium sulphate solution. The end point is sharp

colour change from blue green to reddish brown.

Chemical Oxygen Demand = A B N 8 1000

Volume of sample taken mg/L

A Blank titre value

B Sample titre value

N Normality of ferrous ammonium sulphate

16

And COD removal is calculated using the formula

COD removal percentage = COD of RWW COD of treated wastewater

COD of RWW*100

RWW Raw wastewater

3.4.2 BIOLOGICAL OXYGEN DEMAND (BOD)

The Biological oxygen demand is a chemical procedure for determining

the amount of dissolved oxygen needed by the aerobic organisms in a water body

to break the organic materials present in the given water sample at certain

temperature over a specific period of time. BOD is the principle test to give an idea

of biodegradability of any sample and the strength of the waste. Hence the amount

of pollution can be easily measured.

The sample is filled in an airtight bottle and incubated at specific

temperature for five days. The dissolved oxygen (DO) content of the sample is

determined before and after five days of incubation at 20 C and the BOD is

calculated from the difference between initial and final DO. The initial DO is

determined shortly after the dilution is made all the oxygen uptake occurring after

this measurement is included in the BOD measurement.

Add 10 ml of sample to each of two BOD bottles and fill the remaining

quantity with the dilution water. Dilution water is prepared by adding 5ml of Calcium

chloride solution, 5ml of magnesium sulphate solution, 5 ml of ferric chloride

solution and 5ml of phosphate buffer solution to five litres of high quality organic

free water and aerated for 12 hours and allowing it to stabilize by incubating it at 20

C for four hours. Then add dilution water alone to another two BOD bottles (for

blank). Preserve one of the sample and blank solution at in a BOD incubator at 20

C for five days. Measure the dissolved oxygen content of that blank and sample

solution by digital DO meter (for initial DO and blank correction). And after five days

17

measure the dissolved oxygen content of stored sample and blank bottles (for DO

after five days and blank correction).

Biochemical Oxygen Demand = ((DO-D5-BC) Volume of the diluted sample)

mg/L

Volume of the sample taken

DO Initial DO of the diluted sample, mL

D5 DO at the end of 5 days for the diluted sample, mL

BC Blank correction (blank initial - blank final), mL

And BOD removal percentage is calculated using the formula,

BOD removal percentage = (BOD of raw wastewater BOD of treated wastewater) 100

BOD of raw wastewater 3.4.3 SULPHATE ESTIMATION

Sulphate content is estimated by gravimetric method. Sulphate is

precipitated as barium sulphate on reacting with barium chloride in the presence of

hydrochloric acid. The precipitate barium sulphate is dried, ignited and weighed as

BaSO4.

BaCl2 + SO42- BaSO4 + 2Cl-

Take 200 ml of sample in a beaker and adjust the pH of the sample to

4.5 to 5.0 with HCl. Then add additional 2 ml HCl. Boil this solution for one minute

and add 10 ml of hot barium chloride slowly using a pipette. Keep the beaker on a

water to digest the precipitate at 80 to 90 C for two hours. Filter the contents of the

beaker through an ashless filter paper. And place the filter paper in a previously

18

weighed crucible and char the filter paper by heating with a loosely closed lid on the

top. And weigh the ash in the crucible for amount of BaSO4.

mg/L sulphate as SO42- =

mg BaSO 4

Vol .Sample taken in ml 411.5

3.4.4 CHLORIDE ESTIMATION

Silver nitrate reacts with chloride ions to form silver chloride. The

completion of reaction is indicated by red colour produced by the reaction of silver

nitrate with potassium chromate solution which is added as an indicator.

AgNO3 + Cl AgCl + NO3-

2AgNO3 + K2CrO4 Ag2CrO4 + 2KNO3

Take 100 ml of sample in a conical flask. Adjust the pH of the sample in

the range of 7 to 9.5 using sulphuric acid or sodium hydroxide. Add 1ml of

potassium chromate as indicator. Titrate against standard silver nitrate solution until

a slight perceptible reddish colour persists.

Chloride (Cl-) mg/L = Sample titre Blank titre Normality of AgNO 335.451000

ml of sample taken for estimation

3.4.5 COLOUR REMOVAL MEASUREMENT

To measure the colour reduction efficiency the max of filter raw waste

water is calculated using the UV spectrometer. And it is found to be 403nm. Then at

this wave length the absorbance of treated sample is measured. And colour

reduction percentage is calculated using the formula,

19

Colour removal percentage

=(Absorbance of RWW Absorbance of treated wastewater)

Absorbance of RWW 100

RWW Raw wastewater 3.4.6 pH

The pH was determined by using a digital pH meter. The pH meter was

standardized with double distilled water of pH 7.0 and buffers at pH 4.0.

3.4.7 TURBIDITY

The turbidity was measured using the digital turbidity meter. And it was calibrated using standard naphthalene solution. 3.4.8 TDS

TDS was measured using hand TDS meter. It was calibrated using

standard sodium chloride solution.

20

CHAPTER 4

RESULTS AND DISCUSSION

In this chapter the results and discussions of the study are presented. It

deals with the raw water characteristics, preliminary studies, optimisation of electro

fenton treatment and combination of coagulation and electro fenton and

comparisons.

4.1 INITIAL WASTEWATER CHARACTERISTICS

pH 7.4

Chemical oxygen demand 4960 mg/L

Biological oxygen demand 2800 mg/L

Turbidity 210 NTU

Sulphate 600 ppm

Chloride 665 ppm

Protein 1160ppm (1.16gm/L)

TDS 1800 ppm

Table 4.1 Initial water characteristics

21

Initial analysis of wastewater shows that it has very high values of COD

and BOD. So it has high amount of pollutant in it. And Turbidity value is about 210

NTU which shows that it has high amount of suspended solid particles than the

normal water. It is found that the wastewater has only 1.16gm/L of protein. And

salts like sulphate, chloride values are slightly above the normal water value. TDS

value was about 1800ppm.

4.2 POSSIBILITY FOR PROTEIN RECOVERY

The amount of protein present in the wastewater is very low (1.16gm/L).

It is due to efficient screening of wastewater in industries before discharge. And the

screened solid particles are subjected to rendering process and are converted into

useful by products. And most of the protein present in the wastewater is water

soluble hemeprotein. So only there is very low amount of protein is discharged

through wastewater. If some more water is used for cleaning process then

obviously the amount of protein in the wastewater is going to decrease. So recovery

of protein from the wastewater is not feasible as it built up unnecessary increase in

cost.

22

4.3 PRELIMINARY STUDIES

The preliminary analysis is done to study whether the electro fenton

treatment is suitable for treatment of poultry wastewater and to screen out the

parameters and their range which can give high treatment efficiency for the

treatment.

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8

Rem

ov

al

Eff

icie

ncy

%

pH

pH Vs Removal Efficiency

pH Vs COD

removal

pH Vs

Turbidity

removal 40

45

50

55

60

65

70

75

80

85

0 30 60 90 120R

emo

va

l E

ffic

ien

cy %

Time (min)

Time Vs Removal Efficiency

Time Vs

COD

removal

Time Vs

Turbidity

removal

Time- 15min

H2O2- 5ml

ED- 3cm

Time- 15min

H2O2- 5ml

ED-3cm

Fig. 4.2a Preliminary analysis pH Vs

Removal Efficiency

Fig. 4.2b Preliminary analysis Time Vs

Removal Efficiency

23

From the preliminary analysis we come to know that all the parameters

have considerable effect on the treatment efficiency of electro fenton. For pH the

maximum COD and turbidity removal is obtained in the range 2-4. And the treatment

efficiency increases with increase in time till 90 min after which it tends to reach a

stable condition. So the time range for maximum removal is selected as 75-105min.

For electrode distance and amount of hydrogen peroxide the maximum removal of

turbidity and COD is achieved in the range 2-4cm and 10-20ml respectively.

40

50

60

70

80

90

100

0 2 4 6

Rem

ov

al

Eff

icie

ncy

%

Electrode Distance (cm)

Electrode Distance Vs Removal

Efficiency

Electrode

Distance Vs

COD

removal

Electrode

Distance Vs

Turbidity

removal

80

82

84

86

88

90

92

94

0 5 10 15 20 25

Rem

ov

al

Eff

icie

ncy

%Hydrogen Peroxide (ml)

Amount of Hydrogen peroxide Vs

Removal Efficiency

H2O2 Vs

COD

removal

H2O2 Vs

Turbidity

removal

pH- 3

Time- 90min

H2O2- 5ml

pH- 3

Time- 90min

H2O2- 5ml

Fig. 4.2c Preliminary analysis ED Vs

Removal Efficiency

Fig. 4.2d Preliminary analysis H2O2 Vs

Removal Efficiency

24

4.4 OPTIMISATION

4.4.1 pH OPTIMISATION

Interactive effect of pH with other parameters for the removal of

Chemical oxygen demand is shown in this figure. The maximum removal of COD is

obtained at the pH 3.

This optimum pH is a disadvantage for electro fenton treatment because

the pH of effluent is around neutral pH. So acid has to be added to get this optimum

60

65

70

75

80

85

90

95

0 2 4 6

CO

D r

em

ov

al

%

pH

ED=1cm

ED=2cm

ED=3cm

60

65

70

75

80

85

90

95

0 2 4 6

CO

D r

em

ov

al

%pH

H2O2=10ml

H2O2=15ml

H2O2=20ml

60

65

70

75

80

85

90

95

0 2 4 6

CO

D r

em

ov

al

%

pH

Time=75min

Time=90min

Time=105min

Fig. 4.3a Effect of pH with other parameters for COD

removal

25

pH. Adding incoming water with the treated water can be a solution to decrease the

pH of wastewater.

In the above figure the interactive effect of pH with electrode distance,

volume of hydrogen peroxide and time for the turbidity removal is shown. The

maximum turbidity removal is achieved at pH 3.

60

65

70

75

80

85

90

95

0 2 4 6

Tu

rbid

ity

Rem

ov

al

%

pH

ED=1cm

ED=2cm

ED=3cm

60

65

70

75

80

85

90

95

0 1 2 3 4 5

Tu

rbid

ity

Rem

ov

al

%

pH

H2O2=10ml

H2O2=15ml

H2O2=20ml

60

65

70

75

80

85

90

95

0 2 4 6

Tu

rbid

ity

Rem

ov

al

%

pH

Time=75min

Time=90min

Time=105min

Fig. 4.3b Effect of pH with other parameters for turbidity

removal

26

The effect of pH with other parameters for colour removal is shown in

the above figure. And the maximum colour removal is achieved in pH 3.

So pH 3 is taken as optimum pH for the electro fenton treatment of

poultry wastewater. The decrease in pH below 3 affects the conversion of Fe3+ to

Fe2+. So there is decrease in efficiency of the treatment. Increase in pH will lead to

the production of ferric hydroxide which is undesirable and decrease the efficiency

of treatment.

60

65

70

75

80

85

90

95

100

0 1 2 3 4 5

Co

lou

r R

emo

va

l E

ffic

ien

cy %

pH

ED=1cm

ED=2cm

ED=3cm

60

65

70

75

80

85

90

95

100

0 2 4 6

Co

lou

r R

emo

va

l E

ffic

ien

cy %

pH

H2O2=10

ml

H2O2=15

ml

82

84

86

88

90

92

94

96

0 2 4 6

Co

lou

r R

emo

va

l E

ffic

ien

cy %

pH

Time=75 min

Time=90min

Time=105min

Fig. 4.3c Effect of pH with other parameters for colour removal

27

4.4.2 ELECTRODE DISTANCE OPTIMISATION

Electrode distance is an important parameter for electro fenton

treatment. If the distance is low there is decrease in power consumption because of

decrease in ohmic drop and vice versa. Also it is necessary to keep certain

distance between the electrodes to prevent short circuit.

From this interactive study of effect of electrode distance with other

parameter we get the maximum colour removal at electrode distance of 2cm.

60

65

70

75

80

85

90

95

0 1 2 3 4

CO

D r

emo

va

l ef

fici

ency

%

Electrode distance (cm)

pH=2

pH=3

pH=4

60

65

70

75

80

85

90

95

0 1 2 3 4

CO

D r

em

ov

al

effi

cien

cy %

Electrode distance (cm)

H2O2=10ml

H2O2=15ml

H2O2=20ml

80

82

84

86

88

90

92

94

0 1 2 3 4

CO

D r

em

ov

al

effi

cien

cy %

Electrode distance (cm)

Time=75min

Time=90min

Time=105min

Fig. 4.4a Effect of Electrode distance with other parameters for COD

removal

28

From this graph we come to know that at the electrode distance of 2 cm

we can obtain the maximum turbidity removal.

60

65

70

75

80

85

90

95

0 1 2 3 4

Tu

rbid

ity

rem

ov

al

effi

cien

cy %

Electrode distance (cm)

pH=2

pH=3

pH=4

60

65

70

75

80

85

90

95

0 1 2 3 4

Tu

rbid

ity

Rem

ov

al

effi

cien

cy %

Electrode distance (cm)

H2O2=10ml

H2O2=15ml

H2O2=20ml

78

80

82

84

86

88

90

92

0 1 2 3 4

Tu

rbid

ity

rem

ov

al

effi

cien

cy %

Electrode distance (cm)

Time=75min

Time=90min

Time=105min

Fig. 4.4b Effect of Electrode distance with other parameters for

turbidity removal

29

The maximum colour removal is obtained at the electrode distance of

2cm. So the optimum electrode distance is 2cm. And overall treatment efficiency is

high at this electrode distance.

60

65

70

75

80

85

90

95

100

0 1 2 3 4

Co

lou

r R

emo

va

l E

ffic

ien

cy %

Electrode Distance (cm)

pH=2

pH=3

pH=4

80

82

84

86

88

90

92

94

96

0 2 4

Co

lou

r R

emo

va

l E

ffic

ien

cy %

Electrode Distance (cm)

H2O2=10

ml

H2O2=15

ml

82

84

86

88

90

92

94

96

0 1 2 3 4

Co

lou

r R

emo

va

l E

ffic

ien

cy %

Electrode Distance (cm)

Time=75min

Time=90min

Time=105min

Fig. 4.4c Effect of Electrode distance with other parameters for colour

removal

30

4.4.3 AMOUNT OF HYDROGEN PEROXIDE OPTIMISATION

The amount of hydrogen peroxide is a very important factor for electro

fenton treatment. The treatment efficiency increases with the increase in amount of

hydrogen peroxide. But if it exceeds a level it will lead to unwanted side reactions.

And favours the production of ozonium ion which is a very weak oxidizing agent

compared to hydroxyl ion. From the above figure the maximum removal of COD is

obtained at 50ml/L of hydrogen peroxide.

60

65

70

75

80

85

90

95

0 10 20 30

CO

D r

em

ov

al

effi

cien

cy %

Amount of H2O2 (ml)

pH=2

pH=3

pH=4

60

65

70

75

80

85

90

95

0 10 20 30C

OD

rem

ov

al

effi

cien

cy %

Amount of H2O2 (ml)

ED=1cm

ED=2cm

ED=3cm

80

82

84

86

88

90

92

94

0 10 20 30

CO

D r

em

ov

al

effi

cien

cy %

Amount of H2O2 (ml)

Time=75min

Time=90min

Time=105min

Fig. 4.5a Effect of Hydrogen peroxide with other parameters for COD

removal

31

From the above graph we come to know that the maximum turbidity

removal is achieved at 50ml/L of hydrogen peroxide.

60

65

70

75

80

85

90

95

0 10 20 30

Tu

rbid

ity

rem

oa

l ef

fici

ency

%

Amount of H2O2 (ml)

pH=2

pH=3

pH=4

60

65

70

75

80

85

90

95

0 5 10 15 20 25

Tu

rbid

ity

rem

ov

al

effi

cien

cy %

Amount of H2O2 (ml)

ED=1c

m

ED=2c

m

80

82

84

86

88

90

92

0 5 10 15 20 25

Tu

rbid

ity

rem

ov

al

eff

icie

ncy

%

Amount of H2O2 (ml)

Time=75min

Time=90min

Time=105min

Fig. 4.5b Effect of Hydrogen peroxide with other parameters for turbidity

removal

32

The maximum colour removal is also achieved at 50ml/L of hydrogen

peroxide. So the best treatment efficiency for the electro fenton treatment of poultry

waste water is achieved at 50ml/L of hydrogen peroxide.

80

82

84

86

88

90

92

94

96

0 10 20 30

Co

lou

r R

emo

va

l E

ffic

ien

cy %

Amount of H2O2 (ml)

pH=2

pH=3

pH=4

80

82

84

86

88

90

92

94

96

0 10 20 30

Co

lou

r R

emo

va

l E

ffic

ien

cy %

Amount of H2O2 (ml)

ED=1cm

ED=2cm

ED=3cm

78

80

82

84

86

88

90

92

94

96

0 5 10 15 20 25

Co

lou

r R

emo

va

l E

ffic

ien

cy %

Amount of H2O2 (ml)

Time=75min

Time=90min

Time=105min

Fig. 4.5c Effect of Hydrogen peroxide with other parameters for colour

removal

33

4.4.4 TIME OPTIMISATION

The efficiency of the electro fenton treatment increases with increase in time.

But after a certain period of time it reaches a stable value. Beyond that time there is no COD

removal or very low removal.

From the graph we come to know that up to 90min there is increase in COD

removal. And after that time there is no significant change in removal of COD.

78

80

82

84

86

88

90

92

94

0 50 100 150

CO

D r

em

ov

al

effi

cien

cy %

Time (min)

pH=2

pH=3

pH=4

80

82

84

86

88

90

92

94

0 50 100 150

CO

D r

em

ov

al

effi

cien

cy %

Time (min)

ED=1cm

ED=2cm

ED=3cm

80

82

84

86

88

90

92

94

0 50 100 150

CO

D r

em

ov

al

effi

cien

cy %

Time (min)

H2O2=10ml

H2O2=15ml

H2O2=20ml

Fig. 4.6a Effect of Time with other parameters for COD removal

34

The turbidity removal increases with increase in treatment time up to 90min.

After 90 min there is no significant increase in turbidity removal. So treatment of wastewater

more than 90min will lead to unnecessary loss in time.

60

65

70

75

80

85

90

95

0 50 100 150

Tu

rbid

ity

rem

ov

al

effi

cien

cy %

Time (min)

pH=2

pH=3

pH=4

78

80

82

84

86

88

90

92

0 50 100 150

Tu

rbid

ity

rem

ov

al

effi

cien

cy %

Time (min)

ED=1c

m

ED=2c

m

80

82

84

86

88

90

92

0 50 100 150

Tu

rbid

ity

rem

ov

al

effi

cien

cy %

Time (min)

H2O2=10ml

H2O2=15ml

H2O2=20ml

Fig. 4.6b Effect of Time with other parameters for turbidity removal

35

The colour removal tends to increase with increase in time till 90min. But after

90min there is no significant increase in colour removal. Prolonging the treatment time more

than 90min will lead to unnecessary waste of time. So the optimum time for electrode fenton

treatment is taken as 90min.

82

84

86

88

90

92

94

96

0 50 100 150

Co

lou

r R

emo

va

l E

ffic

ien

cy %

Time (min)

pH=2

pH=3

pH=4

82

84

86

88

90

92

94

96

0 50 100 150

Co

lou

r R

emo

va

l E

ffic

ien

cy %

Time (min)

ED=1cm

ED=2cm

ED=3cm

78

80

82

84

86

88

90

92

94

96

0 50 100 150

Co

lou

r R

emo

va

l E

ffic

ien

cy %

Time (min)

H2O2=10ml

H2O2=15ml

H2O2=20ml

Fig. 4.6c Effect of Time with other parameters for colour removal

36

4.5 OPTIMISED POINT

From the above graphs the optimised point is found as

Parameter Optimised point

pH 3

Electrode distance 2

Hydrogen peroxide 15ml/300ml (50ml/L)

Time 90 min

4.6 TREATED WATER CHARACTERISTICS

Characteristics

Raw waste water

Electro Fenton

Coagulation and Electro Fenton

Chemical Oxygen Demand (mg/L) 4960

360

(93% reduction)

160

(96.8% reduction)

Biological Oxygen Demand (mg/L) 2800

200

(92.85% reduction)

60

(97.85% reduction)

Turbidity (NTU) 210

19

(91% reduction)

7

(96.67% reduction)

Sulphate (ppm) 600

320

(46.67% reduction)

440

(26.67% reduction)

Chloride (ppm) 665

260

(60.9% reduction)

180

(72.93% reduction)

TDS (ppm) 1800

990

(45% reduction)

840

(53.33% reduction)

Amount of sludge production - 7.8 gm 36.7 gm

Table 4.3 Characteristics of treated water treated by Electro fenton and

combined coagulation with electro fenton

Table 4.2 Optimised point for electro fenton treatment of poultry wastewater

37

4.7 ELECTRO FENTON AND COMBINED COAGULATION WITH ELECTRO

FENTON

The above figure shows a comparison between electro fenton and combined

coagulation with electro fenton. It shows that electro fenton has a good effect for the

treatment of poultry wastewater. And combined coagulation with electro fenton is more

efficient than electro fenton. But the sludge production is more in this combined technique.

So this sludge has to be treated further through landfill or some other techniques. Also the

sulphate content of the water treated through the combined technique is higher because the

addition of alum (aluminium sulphate) which have certain interruption in the sulphate

content of the treated water.

86

88

90

92

94

96

98

100

COD BOD Turbidity Colour

Rem

ov

al

%

EF Vs Combined Coagulation and EF

Electro Fenton

Coagulation and Electro

fenton

Fig. 4.7 Characteristics of treated water treated by Electro fenton and

combined coagulation with electro fenton

38

CHAPTER 5

SUMMARY AND CONCLUSION

Wastewater from the meat industry is very difficult to purify due to its specific

characteristics; irregular scatter; and considerable amounts &organic, mineral and biological

matter. This investigation shows that electro fenton treatment can be successfully applied to

the treatment of poultry effluent with minimal sludge production. Combined coagulation

with electro fenton is more efficient when compared to electro fenton. But the sludge

production is higher in this combined technique which has to be disposed or treated further

through landfill or some other technique. And the waste water has very low amount of

protein content. So the recovery of protein from the wastewater is not feasible as it increases

the cost of recovery.

39

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