Electronic Industry Waste Water

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CHAPTER 1

INTRODUCTION

1.1 GENERAL

Wastewater treatment is a process to convert wastewater which is water no longer needed or

suitable that can be either returned to the water cycle with minimal environmental issues or

reused. The principal objective of wastewater treatment processes is generally to allow

human and industrial effluents to be disposed of without danger to human health or to the

natural environment. Wastewater treatment is closely related to the standards and/or

expectations set for the effluent quality. Such treatment processes are designed to achieve

improvements in the quality of the wastewater after making use of different processes. By-

products from wastewater treatment plants, such as screenings, grit and sewage sludge may

also be treated in a wastewater treatment plant. If the wastewater is predominantly from

municipal sources (households and small industries) it is called sewage and its treatment is

called sewage treatment and if it is from the manufacturing plant or other facilities in the

form of effluent then it is called as effluent treatment. Wastewater treatment plants may be

distinguished by the type of wastewater to be treated, i.e. whether it is sewage, industrial

wastewater, agricultural wastewater or leachate.

Conventional wastewater treatment consists of a combination of physical, chemical, and

biological processes and operations to remove solids, organic matter and, sometimes,

nutrients from wastewater. General terms used to describe different degrees of treatment, in

order of increasing treatment level, are preliminary, primary, secondary, and tertiary and/or

advanced wastewater treatment.

Industrial effluent is any wastewater generated by an industrial activity. Such an

industrial activity is any process that involves the creation of any object or service for profit.

This process involves various steps of manufacturing which further make use of water. The

wastewater generated from such facilities comes in the form of effluent wastewater. Because

of the increase of the demand, industrial output is forced to increase day by day. This further

led to a substantial increase in the demand of water. However, for the sustainability of the

http://water.worldbank.org/water/node/83330

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manufacturing processes wastewater produced is now widely being treated before

discharged in to the stream.

The electronics industry, especially meaning consumer electronics, emerged in the 20th

century and has now become a global industry worth billions of dollars. Contemporary

society uses all manner of electronic devices built in automated or semi-automated factories

operated by the industry. The size of the industry and the use of toxic materials, as well as

the difficulty of recycling has led to a series of problems with electronic waste. International

regulation and environmental legislation has been developed in an attempt to address the

issues.

1.2 Electronics Industry in India

Indian Electronics industry dates back to the early 1960's. Electronics was one industry

initially restricted to the development and maintenance of fundamental communication

systems including radiobroadcasting, telephonic and telegraphic communication, and

augmentation of defense capabilities. Until 1984, the electronics Industry was primarily

government owned and then in 1980s witnessed a rapid growth of the electronics industry

due to sweeping economic changes, resulting in the liberalization and globalization of the

economy. In the year 2005 India's electronic consumption was around 1.8 %. It is likely to

touch 5.5 % in 2010. According to a study conducted by ISA and Frost Sullivan, India's

semiconductor market would grow by 2.5 times. The end user products of semiconductor

would include mobile handsets, desktop and notebooks, PCs, etc.

(Source: Indian Mirror)

The electronics market of India is one of the largest in the world and is anticipated to reach

US$ 400 billion in 2022 from US$ 69.6 billion in 2012. The market is projected to grow at a

compound annual growth rate (CAGR) of 24.4 per cent during 2012-2020. Total production

of electronics hardware goods in India is estimated to reach US$ 104 billion by 2020. The

communication and broadcasting equipment segment constituted 31 per cent, which is the

highest share of total production of electronic goods in India in FY13, followed by consumer

electronics at 23 per cent. The growing customer base and the increased penetration in

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consumer durables segment have provided enough scope for the growth of the Indian

electronics sector. Also, digitization of cable could lead to increased broadband penetration

in the country and open up new avenues for companies in the electronics industry.

(Source: India Brand Equity Foundation - IBEF)

1.3 Wastewater from Electronics Industry

Great quantities of harmful wastewater are produced during the production processes of

electronic products and components. If factories were to discharge wastewater into rivers or

arbitrarily into the streams, it would cause the serious harm to ecological resources in the

surroundings which can be very fatal. Wastewater treatment systems not only change

poisoned substances into non-poisoned substances, but also recycle water resources so they

can be used again. Because of the many chemicals used in the electronics industry for

numerous processes, wastewater generation is quite high in this industry. Waste may

include- organic and inorganic wastes, acids and alkalis, heavy metals, oil and grease,

biological wastes, etc. Organic waste is collected separately from wastewater systems.

Acids and alkalis are sent to onsite wastewater treatment facilities for neutralization after

segregation of heavy metal bearing streams. Treatment steps for electronics industry

wastewater may include precipitation, coagulation, sludge dewatering, sedimentation,

skimming, activated sludge process, filtering or membrane separation depending upon

wastewater streams, softening, demineralization, activated carbon process, cooling towers,

ultra filtration process and reverse osmosis, etc.

Heavy metals are also found in the wastewater from industrial discharges. Semiconductor

industries may contribute heavy metals like Selenium, Cadmium, etc. in the wastewater

streams. These are too harmful if not disposed properly and their treatment should be in the

line with standards. Electroplating industry also produces large amount of heavy metals in

various processes. There have been many incidents reported where wastewater from the

electronics industry caused serious problems to both humans as well as environment in the

surrounding. Therefore, wastewater from the electronics industry should be treated

efficiently and industries should try to make reuse of water generated from the various

manufacturing processes.

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1.4 Objective of the Study

The main objective of the study is to calculate the design parameters which affect the

efficiency of the wastewater treatment systems in the electronics industry. Working of these

parameters will point out the environment management system to be adopted for the

treatment of waste.

The specific aims of the study are to:

• To experimentally check the adequacy and efficacy of various treatment processes by

calculating design parameters at different points.

1.5 Scope of the Study

This study focuses on types of treatment processes used by the concerned electronic Industry

in treating the effluent wastewater. The efficiency of these processes needs to be known for

better management and disposal of waste. Study aims to suggest positive changes, if any, in

the processes for attaining the maximum efficiency.

Area of the Study- An effluent treatment plant of a reputed MNC in the field of electronics

manufacturing is chosen. This company is in electronics manufacturing field in India since

90s. A wide variety of electrical and electronics components are being manufactured in this

plant facility. Due to various products and processes involved in the manufacturing at this

plant facility it is found to be good for our experimental work. For the treatment of

wastewater this plant has 2 treatment facilities-

Effluent Treatment Plant (ETP)

Sewerage Treatment Plant (STP)

For our experimental study ETP is chosen as it would contain the wastewater from the

manufacturing units involving wide variety of waste materials.

Unit Processes in the Effluent Treatment Plant: Various unit processes involved in the

treatment plant are as follows:

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Skimming Tank

Primary Clarification

Equalization

Activated Sludge Process

Secondary Clarification

pH Correction

Filtration

Parameters considered in the experimental study: Various Parameters calculated in this

study are as follows:

pH

Conductivity

Total Dissolved Solids

Total Suspended Solids

Dissolved Oxygen

Biological Oxygen Demand

Chemical Oxygen Demand

Ammonical Nitrogen

Phosphate

Oil and Grease

Heavy Metals

These parameters are calculated at different stages of treatment plants.

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CHAPTER 2

LITERATURE REVIEW

Wastewater treatment can be defined by physical, chemical, and biological processes. Physical

parameters include color, odor, temperature, solids (residues), turbidity, oil, and grease.

Chemical parameters associated with the organic content of waste water include the biochemical

oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), and total

oxygen demand (TOD). Inorganic chemical parameters include salinity, hardness, pH, acidity,

alkalinity, iron, manganese, chlorides, sulfates, sulfides, heavy metals (lead, chromium, copper,

and zinc), nitrogen (organic, ammonia, nitrite, and nitrate), and phosphorus whereas the

bacteriological parameters include coliforms, fecal coliforms, specific pathogens, and viruses.

Electronics Industry Waste

The wastewater from electronics industries varies so greatly in both flow and pollution strength.

So, it is impossible to assign fixed values to their constituents. In general, wastewaters may

contain suspended, colloidal and dissolved (mineral and organic) solids. In addition, they may be

either excessively acid or alkaline and may contain high or low concentrations of colored matter.

Abdulrzzak Alturkmani (2013) has found that heavy metals like nickel, zinc, chromium and

cadmium are commonly found in the industries manufacturing electronics components.

According to World Bank group (2007) the electronics industry includes the manufacture of

passive components (resistors, capacitors, inductors); semiconductor components (discrete,

integrated circuits); printed circuit boards (single and multilayer boards); and printed wiring

assemblies. They also found that Effluents from the manufacture of semiconductors may have a

low pH from hydrofluoric, hydrochloric, and sulfuric acids (the major contributors to low pH)

and may contain organic solvents, phosphorous oxychloride (which decomposes in water to form

phosphoric and hydrochloric acids), acetate, metals, and fluorides. Effluents from the

manufacture of printed circuit boards may contain organic solvents, vinyl polymers; stannic

oxide; metals such as copper, nickel, iron, chromium, tin, lead, palladium, and gold; cyanides

(because some metals may be complexed with chelating agents); sulfates; fluorides and

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fluoroborates; ammonia; and acids. Effluents from printed wiring assemblies may contain acids,

alkalis, fluxes, metals, organic solvents, and, where electroplating is involved, metals, fluorides,

cyanides, and sulfates.

Impact of electronics industries on the downstream of a river:

Electronics industries located near to the river poses greater damage to aquatic life as well as

human life. Heavy metals from these industries become life threatening to the aquatic species

and severely affect the quality of wastewater. Angela Yu-Chen Lin*, Sri Chandana

Panchangam, Chao-Chun Lo (2008) conducted study on the influence of the semiconductor

and electronics industries on per fluorinated chemicals (PFCs) contamination in receiving rivers.

The distribution of PFCs in the receiving rivers was greatly impacted by industrial sources. Their

results suggest that these manufacturing facilities, located directly upstream of our sampling

spots, are the primary causes of PFC contamination in the Keya, Touchien, and Xiaoli rivers.

The Keya River in particular was found to be polluted with PFCs derived from effluents out of

Hsinchu Science Park (HSP). A plausible risk to human and aquatic life exists, as demonstrated

directly by the quantity of PFCs detected in these rivers and indirectly by the many drinking

water intake sites situated downstream of our sampling points.

Important parameters in the effluent treatment plant

There are many parameters which affects the efficiency of a treatment plant. A study conducted

by Megha S.Kamdi1, Isha.P.Khedikar ², R.R.Shrivastava (2012) in which they have determined

the physical and chemical parameters of the waste water or the effluent, at inlet and outlet of the

effluent treatment plant. Under this study the various parameters such as temperature, pH,

chemical oxygen demand(COD), suspended solids(SS), total dissolved solids(TDS), phosphorus

and heavy metals are determined by taking samples at inlet and outlet of effluent treatment plant

and compared with the Indian standards for effluent discharge into river. The variation in the

parameters at inlet observed to be, 7.4-7.9 for pH, 40-90 for COD and 180-70 for SS and at

outlet it is 7.1-7.5 for pH, 32- 68 for COD and 42-95 for SS. The average performance efficiency

of the plant is calculated for the period of study & observed to be 26.85% for COD, 26.69% for

TDS, 15.51% for Phosphate, and 22.81% copper.

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In a book series written by Mohidus Samad Khan, Jerry Knapp, Alexandra Clemett,

Matthew Chadwick, Mahbub Mahmood and Moinul Islam Sharif, it is mentioned the

importance of the evaluation of ETPs and their monitoring. They said that by law factories must

monitor the quality of their wastewater and stay within national limits for pollution. The

Environment Conservation Rules should provide national standards for the quality of industrial

wastewater being discharged into certain places including open water bodies, public sewers and

irrigated land. They should also provide specific discharge quality standards for key parameters

from certain industries. It is also necessary and useful to monitor these parameters in the

wastewater entering the ETP and at several stages in the ETP process. This enables the ETP

manager to optimize the ETP process by adjusting chemical inputs, retention time and other

factors. This can reduce costs by preventing excess chemicals from being used and will result in

a more efficient plant that produces effluent that complies with national standards. Good ETP

management therefore requires a certain level of understanding of the overall function of the

ETP, how individual units work, how to monitor their functioning, and how to diagnose and

address problems. And the parameters to be checked are BOD, COD, DO, TDS, TSS, etc.

Performance evaluation of common effluent treatment plants:

Anju Singh, Richa Gautam and Swagat Kishore Mishra (2010) conducted a study on the

performance of a CETP treating 3405 m3 day-1 wastewater from 450 synthetic textile mills.

Four criteria viz. design, operation, maintenance and administration was deployed to evaluate the

overall performance of CETP. Design data was collected from each unit operation of the CETP

and adequacy of design was assessed using a scoring method. They have suggested some

improvements like better mixing in equalization tank, modifications in HRT, SOR etc. in the

clariflocculator, increasing HRT in aeration tank, can be achieved by changing operational

parameters. The Lime and FeSO4 tanks have inadequate capacity and mixing which therefore

needs improvement. Existing sludge drying beds are only 27% of the area required and therefore

need further construction. The COD and BOD in the outlet exceeded the standards for effluents

from textile industries. The two aeration tanks need to improve in terms of performance. This

can be achieved by improving the biomass in the aeration tanks I and II and increasing the HRT.

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Other standards were met by the treated effluents. These parameters are important in the

calculation of efficiency of the treatment plant.

In an another study conducted by Gautam, S.P, Bundela, P.S. Kapoor, A. Awasthi, M.K.

Sarsaiya, S (2010). They identified the sources of wastewater generation and their approximate

quantities were estimated. Representative wastewater samples were collected from different

location of effluent treatment and brought to the laboratory for analysis of various environmental

parameters such as pH, BOD, COD, TSS, YDS and oil and Greece as per the standard methods.

The performance of ETP was evaluated by assessing the performance of each component based

on the pollution load, the required treatment efficiency and the monitoring results. The

characteristics of treated wastewater at final outlet of ETP are compared with discharge standard.

The characteristics of treated wastewater at final outlet of plant are compared with desired

characteristics of treated waste to be used in the process. Based on the pollution load on ETP and

required capacity of its each component adequacy of respective component of existing ETP has

been assessed. Further, the wastewater samples were collected and analyzed for inlet outlet of all

the ETP components to assess its efficacy. In the results, ETP failed to comply with the standards

and didn’t find efficient.

DIPALI H. CHAIUDHARI and R.M. DHOBLE (2010) have conducted a study on the

performance evaluation of effluent treatment plant of dairy industry. They have collected

samples from forth points; Raw effluent [P-1], Equalization tank [P-2], Aeration tank [P-3],

Oxidation ditch [P-4] to evaluate the performance of ETP. Parameters analyzed for evaluation of

performance of ETP are pH, COD, BOD at 27° C, TSS. The COD, BOD and TSS removal

efficiency of ETP was observed to be 94%, 95% and 93% respectively in spite of the fact that

raw sewage. BOD: COD ratio was 0.5. The performance of ETP is in terms of average change

(%) in the pollution parameters. % efficiency is given in average efficiency of aeration tank and

oxidation ditch. Efficiency of units (Aeration tank and oxidation ditch) is found out in terms of

percentage. The BOD/COD ratio of the industrial effluent is more than 0.6, it is biologically

treatable. If the BOD/COD ratio is less than 0.3 biological treatments is not necessary. Biological

treatment methods is used in this plant i.e. Oxidation Ditch.

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Heavy metals in wastewater:

The most commonly encountered toxic heavy metals in wastewater: Arsenic, Lead, Mercury,

Cadmium, Chromium, Copper, Nickel, and Zinc. Their source varies from Industrial sources

like Printed board manufacturing, metal finishing and plating, semiconductor manufacturing,

textile dyes, etc. Many heavy metals are essential trace elements for humans, animals and plants

in small amounts. In larger amounts they can cause acute and chronic toxicity. Heavy metals

have inhibitory effects on the biological treatment process at the wastewater treatment plants.

Activated sludge process does not remove most of the heavy metals efficiently. Heavy metals do

not disappear nor react – they are either in the water or in the sludge.

Asli Baysal, Nil Ozbek and Suleyman Akman determined the Trace Metals in Waste Water and

Their Removal Processes. They have described the Atomic Absorption Spectrometry as an

analytical method for quantification of over 70 different elements in solution or directly.

Procedure depends on atomization of elements by different atomization techniques like flame

(FAAS), electrothermal (ETAAS), hydride or cold vapor. According to them precipitation is the

most common method for removing toxic heavy metals up to parts per million (ppm) levels from

water. Since some metal salts are insoluble in water and which get precipitated when correct

anion is added. Ion exchange is another method used successfully in the industry for the removal

of heavy metals from effluents. Though it is relatively expensive as compared to the other

methods, it has the ability to achieve ppb levels of clean up while handling a relatively large

volume.

Rafiquel Islam, Jannat Al Foisal, Hasanuzzaman, Musrat Rahman, Laisa Ahmed Lisa and

Dipak Kumar Paul on their study on Pollution assessment and heavy metal determination by

AAS in waste water collected from Kushtia industrial zone in Bangladesh analyzed the Pb, Cd,

Cr, Cu and Mn heavy metals. The results indicate that the concentration of Mn (0.68 to 0.72

ppm) exceeded the standards, although Pb and Cu were found within the standard limit at 0.0045

to 0.0085 and 1.33 to 1.58 ppm, respectively. Interestingly, contamination of Cd and Cr

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identified were below detective level. This study points out the health risk status of waste water

for residents and aquatic living being, an ultimate concern for their survival in the region.

Mass balance concept in the treatment plant:

A mass balance is an accounting of a material for a specific system boundary. In other words, we

are keeping track of all sources of the material that enter the system, all sinks of the material that

leave the system, and all storage of the material within the system. A mass balance can be done

for four scenarios or combinations of those scenarios as follows:

Dynamic (flows change over time)

Steady State (flows do not change over time; the system is in equilibrium)

Conservative pollutants (the pollutant does not change form over time; no reactions)

Non-conservative pollutant (the pollutant changes form over time due to chemical,

physical, or biological reactions)

In a study conducted by Athar Hussain, Pradeep Kumar, Indu Mehrotra (2009) titled Nitrogen

biotransformation in anaerobic treatment of phenolic wastewater a nutrient mass balance was

done. The change in feed N is reflected proportionately in the effluent-N. The stoichiometric

nitrogen requirement for growing cells has been reported to range from 6 to 12%. The anaerobic

microbial cells (C5H7O3N) contain 11% N and 2.2% P; the experimental determinations are

close to the cell formulation reported by Rittman and McCarty. They have found that additional

nitrogen might be coming from cell-lyses or cell. Decay of cells is expected to release 11% of

nitrogen. A decay rate of 6.5 × 10−3 d−1 gives nitrogen which accounts for (i) 80% of nitrogen

in the effluent and (ii) nitrogen required for is 3.5% cell yield.

In an another study conducted by N. Gans, S. Mobini and X. N. Zhang named Mass and Energy

Balances at the Gaobeidian Wastewater Treatment Plant in Beijing, China, mass and energy

balances are carried out for the Gaobeidian wastewater treatment plant in Beijing, China, in order

to identify the needs for process optimization and energy conservation. The mass balance over

the sludge treatment was carried out both on theoretical values and based on measured values.

Due to a lack of information it was only calculated for SS. Mass balances are valuable tools for

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investigating the general performance of a wastewater treatment plant and an effective method to

assess the reliability of the available data. In the case of the Gaobeidian WWTP, the mass

balance calculations based on measured values suggest that there might be problems with the

measurements. From the mass balance over the Gaobeidian WWTP it could be concluded that

the present nutrient removal is not optimal and the sludge treatment seems to be overloaded.

Methods for the optimisation of the plant should therefore focus on these problems.

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CHAPTER 3

TREATMENT PLANT DESCRIPTION

3.1 Design Basis

The following characteristics have been considered for the design of the inlet and outlet

parameters of the Effluent Treatment Plant:

Sr. No. Parameter Inlet Outlet

1 Flow (m3/hr) 10 10

2 pH 7-8 7-8

3 Fe (ppm) 32.11 <3

4 Zn (ppm) 277.2 <5

5 Mn (ppm) 6.2 <2

6 Pb (ppm) 3 <0.1

7 Cu (ppm) 0.3 <3

(Table: 3.1 Design basis parameters)

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3.2 Flow Diagram of the treatment Plant

C BUILDING

COLLECTION

TANK

SKIMMING

TANK

AERATION

TANK

REACTION

TANK PRIMARY

CLARIFIER

HOLDING

TANK

EQUALIZATION

TANK

MULTI GRADE

FILTER

pH

CORRECTION

TANK

SECONDARY

CLARIFIER

OUTLET

Sludge

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(Figure: 3.1 effluent treatment plant)

(Figure: 3.2 way to secondary clarifier in the ETP)

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3.3 Technical Data

Technical Data of the treatment plant is summarized below in a table:

Sr. No. Description Size/Capacity Quantity Make

1 Collection cum oil removal

tank

4.2m x 0.5m x 1.0m 1 No. RCC

2 Equalization tank 4.5m x 4.0m x 3.5m 1 No. RCC

3 pH tank 3.5m x 1.0m x 1.8m 1 No. RCC

4 Sludge sump 2.5m x 2.5m x 1.6m 1 No. RCC

5 Lime dosing tank 1.4m x 1.5m x 1.6m 2 No. RCC

6 Oil collection tank 1 m3 1 No. MS

7 Fume absorber - 1 No. MSRL

8 Sludge transfer Pumps 5 m3/ hour @10 MWC 2 No. CI

9 Reaction tank 2.0 m x 1.8m x 1.6m 1 No. RCC

10 Multi grade filter 1.0 dia x 23 m H.O.S 1 No. MS

11 Pipe oil skimmer 80 NB x 500 mm long 1 No. MSEP

12 High rate solids contact

clarifier grade mechanism

Suitable for 4.0 m dia 2 No. MSEP

13 Air compressor 0.25 m3 / hr 2 No. CI

14 Coagulant dosing pumps 0-50 lph 2 No. PP

15 Centrifuge 5 m3 / hr 1 No. CI

(Table: 3.2 Technical data of the treatment plant)

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CHAPTER 4

MATERIALS AND METHODS

4.1 Sampling and Sample Preservation-

During our experimental work different experiments were performed to calculate various

parameters which affect the efficiency of the effluent treatment plant. All the experiments

were performed according to the standard procedure established by the regulatory bodies.

Instruments used in the experiments were from the reputed companies and comply with the

necessary standards. All necessary precautions were taken while performing the experiments.

Grab sampling has been done at different points of the treatment plant. One litre new PVC

bottles were used for all samples taken. Sample bottles were securely sealed following

sampling and stored securely. The wastewater sample preserved to about 4 degrees Celsius.

This refrigeration maintains the biochemical oxygen demand. Samples were protected from

direct heat and sunlight so as to reduce as the interferences as much as possible.

4.2 Materials and Methods used in the determination of various parameters-

List of various parameters and their determination methodology is given below-

4.2.1 pH-

In simple words, pH is a logarithmic measurement of hydrogen ion concentration. pH has

direct influence on wastewater treatability — no matter which treatment it is physical,

chemical or biological. A very low pH value requires less contact time as compared to a

higher pH value. Different chemicals have different reaction times, which further have a

major effect on pH. To minimize corrosion, optimum pH levels of the pH should be

maintained.

Method: Electrometric Method

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Instrument: Hach Portable Meter Package with pH electrode

Materials Required: pH Probe, Beaker, Measuring Cylinder, Tissue Paper

4.2.2 Electrical Conductivity

Electrical Conductivity (EC) is the measure of the ability with which water conducts

electricity in the wastewater. Different salts in water have a different capacity to conduct

electricity. This is due to the differences in charge and size and mobility of the different

ions. Electrical conductivity also gives an indication of the total dissolved salt (TDS)

content of the water. This is because EC is a measure of the ionic activity of a solution in

term of its ability to transmit current. In most of the dilute solution, TDS and EC are

comparable.

Method: Direct Conductivity Method

Instrument: Hach Portable Meter Package

Materials Required: EC Probe, Beaker, Measuring Cylinder, Tissue Paper

4.2.3 Dissolved Oxygen (DO)

Dissolved oxygen is a molecule of oxygen that is dissolved into the wastewater. It is

affected by the temperature. If the temperature of the water is high, DO concentration

will be less. And also if the plants population is high in the stream then also DO levels

will be lower. Various scientific studies suggested that 4-5 parts per million (ppm) of DO

is the minimum amount that should be present. In the activated sludge process a

minimum level of 6 ppm of DO should be present for the microorganisms.

Method: Direct DO Probe Method


Materials Required: DO Probe, Beaker, Measuring Cylinder, Tissue Paper

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4.2.4 Total Dissolved Solids (TDS)

Total Dissolved Solids is the amount of charged ions (minerals salts or metals) dissolved

in a given volume of water sample. It is directly related to the purity of water and quality

of purification systems. In general, the total dissolved solids are the sum of cations and

ions in any wastewater sample. Total dissolved solids are based on the electrical

conductivity of water. Pure water has almost zero conductivity. Some dissolved solids

come from organic sources; other comes from runoff at the streets. Solids also come from

inorganic materials such as rocks. Salts usually dissolve in water forming ions that can be

negative or positive.

Method: Direct TDS Method


Materials Required: TDS Probe, Beaker, Measuring Cylinder, Tissue Paper

(Figure: 4.1 Hach Portable Meter)

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4.2.5 Total Suspended Solids (TSS)

Total Suspended solids are solid materials that are suspended in the water. High

concentrations of these suspended solids can lower the water quality by absorbing more

light. Suspended solids can result from surface runoff, bank erosion, algae growth.

Method: Filter Paper Method

Materials Required: Beakers, Measuring Cylinder, Weighing Balance, Oven, Glass Filter

paper, and Desiccator.

Procedure:

Initially dry the filter in oven at 103-105 degree Celsius for 1 hour.

Place Filtration apparatus with weighed filter in filter disk.

Mix sample well and pour into a cylinder up to a known volume.

Pour the known volume in the filter flask.

Draw sample into the flask through the filter.

Rinse the cylinder with successive 10 ml portions and continue suction after the

last rinsing.

Dry filter in oven at 103-105 degree Celsius for 1 hour.

Cool the filter paper in the desiccator and weigh.

Total suspended solids (mg/L) = (A-B) X 1000/sample volume, mL

where:

A = weight of filter + dried residue (mg)

B = weight of filter (mg)

4.2.6 Mixed Liquor Suspended Solids (MLSS)

Mixed liquor in the treatment plant is a combination of sludge and water from the

clarifier in the treatment process. It is reintroduced into an earlier phase of the treatment

process. The mixed liquor contains microorganisms which digest the wastes in the raw

wastewater.

Mixed Liquor Suspended Solids is a test for the TDS in a sample of mixed liquor.

Method: Filter Paper Method

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Materials Required: Beakers, Measuring Cylinder, Weighing Balance, Oven, Glass Filter

paper, and Desiccator.

Procedure: This test is essentially the same as the test we performed for TSS in the last

step except for the use of mixed liquor as the water sample.

4.2.7 Oil and Grease

Oil and grease causes ecology damages for aquatic organisms and equally, mutagenic and

carcinogenic for human being. They discharge from different sources to form a layer on

the water surface that decreases DO. This layer reduces biological activities in the

treatment processes. This lead to decrease dissolved oxygen levels in the water. Also due

to this oxygen molecules are difficult to be oxidative for microbial on hydrocarbon

molecules. The conventional techniques of removal make use of skimming tanks and oil

and grease traps in treatment plants but their efficiency of removal is quite low.

Materials Required: Beakers, Measuring Cylinder, Weighing Balance, n- Hexane,

Hydrochloric acid, Filter paper, Desiccator, Water bath.

Procedure:

Transfer the sample to a separating funnel. Carefully rinse the sample bottle with 30 ml

of n-Hexane and add the solvent washings to the separating funnel. Shake for 2 minutes.

Let the layers separate. Drain the solvent layer through a funnel containing solvent

moistened filter paper into a clean distillation flask. Extract two more times with 30 ml of

solvent each time, but first rinse the sample container with the solvent. Collect the

extracts in a clean distillation flask and wash filter paper with an additional 10 to 20 ml of

the solvent. Distil solvent from distillation flask over a water bath at 70°C. Quantitatively

transfer the residue using a minimum quantity of solvent into a clean, dried beaker. Place

the beaker on water bath for 15 minutes at 70°C and evaporate off all the solvents. Cool

the beaker in a desiccator for 30 minutes and weigh.

Oil and Grease (mg/l) = (M / V) x 1000

where,

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M= Mass in mg of the residue

V = Volume of the sample

(Figure: 4.2 Oil and Grease determination)

4.2.8 Sludge Volume Index

Sludge Volume Index (SVI) is a very important indicator that determines your control or

rate of de-sludging and it is calculated by considering the volume, in milliliters, of 1 gram

of suspended solids after 30 minutes of settling. It actually serves as a very important

measurement that can be used as a guide to maintain sufficient concentration of activated

sludge in the aeration tank whereby too much or too little can be considered problematic

to the system’s overall health.

Materials Required: Beakers, Graduated Measuring Cylinder of 1L capacity.

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Procedure:

Obtain sample of mixed liquor and fill it to a 1 liter graduated measuring cylinder

until the 1.0 liter marking.

Allow it to settle for 30 minutes.

After the time period, read the marking to determine the volume occupied by the

settled sludge.

The reading of the settled sludge is expressed in terms of mL/L. This is known as

SV value.

SVI = (SV / MLSS) x 1000

4.2.9 Biological Oxygen Demand (BOD)

BOD determination is an empirical test in which relative oxygen demand is determined

over a period of five days at 20 degree Celsius. Another method is to determine BOD for

a period of 3 days at 27 degree Celsius. In general, it is the amount of dissolved oxygen

demanded by aerobic organisms to break down organic material present in a given

wastewater sample. BOD directly affects the amount of Do in rivers and streams. The

rate of oxygen consumption is affected by a number of factors like temperature, pH and

the presence of certain kinds of microorganisms. The greater the BOD, the more rapidly

oxygen is depleted in the stream.

Apparatus and Reagents:

Incubation bottles or BOD bottles

Incubator

Deionized water

Hach Glucose And Glutamic Acid solution

Nutrient buffers

24

Procedure:

To ensure proper biological activity during the BOD test, a wastewater sample:

o Must be free of chlorine. If chlorine is present in the sample, a chlorination

chemical (sodium sulfite) must be added prior to testing.

o Needs to be in the pH range of 6.5-7.5.

Add approximately 30 mL of deionized water to a 200 mL graduated cylinder.

A seed solution of bacteria is added along with an essential nutrient buffer solution

that ensures bacteria population vitality.

Dilute to the sample to 160 mL using deionized water wash bottle.

Specialized 300 mL BOD bottles designed to allow full filling. At least one bottle is

filled only with dilution water as a control or blank.

Measure the initial DO content in the BOD bottles.

Each bottle in then placed into a dark incubator at 20°C for five days.

After five the DO meter is used again to measure a final dissolved oxygen

concentration (mg/L).

The final DO reading is then subtracted from the initial DO reading and the result is

the BOD concentration (mg/L). If the wastewater sample required dilution, the BOD

concentration reading is multiplied by the dilution factor.

Dilution factor = Bottle volume (300 ml) / Sample Volume

BOD (mg/L) = DO (Initial – Final) x dilution factor

25

(Figure: 4.3 Seeds and BOD bottles in the Incubator)

4.2.10 Chemical Oxygen Demand (COD)

COD is a measure of the capacity of water to consume oxygen during

the decomposition of organic matter and the oxidation of inorganic chemicals such

as ammonia and nitrite. It is the amount of oxygen equivalent of dichromate, a specified

oxidant that reacts with the sample under controlled conditions. A commonly used

oxidant in COD assays is potassium dichromate (K2Cr2O7) which is used in combination

with boiling sulphuric acid.


Borosilicate culture tubes with screw caps

Block Heater

Spectrophotometer for use at 600 nm.

Digestion Solution (0.1 K2Cr2O7 + H2SO4)

H2SO4 Reagent

26

Potassium Hydrogen phthalate: Dissolve 425 mg in 1 L DW

Procedure:

Prepare standards of COD ranging from 100-500 µg/ml.

Transfer 2.5 mL of sample and standards to culture tubes.

Add 1.5 mL digestion solution and 3.5 mL H2SO4 Reagent.

Place cultural tubes in block digester preheated at 150 degree and reflux for 2

hours.

Cool sample and standards to room temperature slowly.

Measure absorbance of sample and standards at 600 nm.

(Figure: 4.4 COD Block heater and spectrophotometer)

4.2.11 Ammonical Nitrogen

Ammonical nitrogen (NH3-N), is a measure for the amount of ammonia, a

toxic pollutant often found in the wastewater. The values of ammonical nitrogen in water

or waste liquids are measured in milligram per liter and are used for specifying water

27

treatment systems and facilities. It can also be used as a measure of the health of water in

natural bodies such as rivers or lakes, or in man-made water reservoirs.


Spectrophotometer at 410 nm.

Beakers, Volumetric Flask

Standard Ammonical Solution

Nessler Reagent (mercury iodide + potassium iodide)

EDTA

Procedure:

Standard solution of 1,2,3,4,5 and 6 mg/L are prepared in 50 mL of Nessler tube.

50 mL sample is taken in Nessler tube.

2 mL of Nessler reagent was added into standard and sample both.

2 or 3 drops of EDTA indicator is added.

Leave the sample for 30 minutes for color development.

Absorbance was taken at wavelength 410 nm.

4.2.12 Phosphate

Phosphorous occurs in natural waters as orthophosphate, condensed phosphates and

organic bound phosphates. They occur in solution, in particles or bodies of aquatic

organisms. They are used in treatment of boiler feed waters. They are found in sewage or

wastewater due to body wastes and food residues.


Spectrophotometer at 690 nm.

28

Beakers, Volumetric Flasks.

Strong acid solution

Ammonium molybdate solution

Stannous chloride solution

Standard phosphate solution

Procedure:

Take 6 tubes and add standard phosphate. Add distilled water to make upto 100

mL. Take 100 mL of the sample or a portion of it and dilute it with distilled water

to 100 mL.

Add 4 mL ammonium molybdate solution, 10 drops of stannous chloride solution

and mix well.

Leave for 10 minutes and record the absorbance at 690 nm.

4.2.13 Heavy Metals

Due to the discharge of large amounts of industries wastewater, metals such as Cd, Cr,

Cu, Ni, As, Pb, and Zn, are found in the water. Because of their high solubility in the

aqueous environments, heavy metals can be absorbed by living organisms too. They can

cause serious health issues if enters our food chain. Heavy metal removal from inorganic

effluent can be achieved by conventional treatment processes such as chemical

precipitation, ion exchange, and electrochemical removal.

In our experimental study we have determined five heavy metals – Arsenic, Selenium,

Lead, Iron and Chromium from atomic absorption spectroscopy.

Instrument and Reagents:

Atomic absorption spectroscopy

Volumetric flasks, Beakers

3% HCL

29

Standard solutions of Arsenic, Selenium, Lead, Iron and Chromium

Procedure:

Standard solutions of all heavy metals are made in the range of 0ppm, 0.5ppm,

1.0ppm, 3.0ppm and 5.0ppm

Each heavy is found out using flame technology.

Blank correction is applied at the initial stage and at the end of the standards.

Data is recorded and calibration curve is plotted.

Actual concentration of the heavy metals is calculated.

(Figure: 4.5 Atomic Absorption Spectroscopy)

30

8.89

7.34 7.27

6.82

5

6

7

8

9

Inlet Equalization Tank Secondary Clarifier Outlet

pH

Sampling Point

CHAPTER 5

RESULTS & DISCUSSIONS

5.1 Determination of parameters at different locations:

Different parameters were calculated at four locations: Inlet, Equalization Tank, Secondary

Clarifier and Outlet. Readings were depicted below at all the locations.

5.1.1 pH

Sr. No. Sampling Point Method Observed Value

1 Inlet Electrometric method 8.89

2 Equalization Tank Electrometric method 7.34

3 Secondary Clarifier Electrometric method 7.27

4 Outlet Electrometric method 6.82

(Table 5.1.1: pH)

(Figure 5.1.1: pH values)

31

5.1.2 Electrical Conductivity

Sr. No. Sampling Point Method Observed Value

(µS/cm)

1 Inlet Direct Method 1189

2 Equalization Tank Direct Method 1136

3 Secondary Clarifier Direct Method 1132

4 Outlet Direct Method 955

(Table 5.1.2: Electrical Conductivity)

(Figure 5.1.2: Electric Conductivity values)

1189

1136

1032

955 950

1000

1050

1100

1150

1200


EC (

µS/

cm)

Sampling Point

32

5.1.3 Dissolved Oxygen

Sr. No. Sampling Point Method Observed Value (mg/L)

1 Inlet DO Meter 5.48

2 Equalization Tank DO Meter 4.66

3 Secondary Clarifier DO Meter 7.38

4 Outlet DO Meter 7.57

(Table 5.1.3: Dissolved Oxygen)

(Figure 5.1.3: Dissolved Oxygen values)

5.48

4.66

7.38 7.57

0

1

2

3

4

5

6

7

8


DO

(m

g/L

)

Sampling Point

33

5.1.4 Total Dissolved Solids


1 Inlet Direct Method-TDS Meter 589

2 Equalization Tank Direct Method-TDS Meter 449

3 Secondary Clarifier Direct Method-TDS Meter 271

4 Outlet Direct Method-TDS Meter 188

(Table 5.1.4: Total Dissolved Solids)

(Figure 5.1.4: Total Dissolved Solids values)

589

449

271

188

100

150

200

250

300

350

400

450

500

550

600


TDS

(mg

/L)

Sampling Point

34

5.1.5 Total Suspended Solids

Total suspended solids (mg/L) = (A-B) X 1000/sample volume

where:

A = weight of filter + dried residue (mg)



1 Inlet Filter paper Method 239

2 Equalization Tank Filter paper Method 216

3 Secondary Clarifier Filter paper Method 156

4 Outlet Filter paper Method 89

(Table 5.1.5: Total Suspended Solids)

(Figure 5.1.5: Total Suspended Solids values)

239

216

156

89

50

70

90

110

130

150

170

190

210

230

250


TSS

(mg

/L)

Sampling Point

35

5.1.6 Biological Oxygen Demand

BOD (mg/L) = DO (Initial – Final - Blank) x dilution factor


1 Inlet Respirometric Method 160.44

2 Equalization Tank Respirometric Method 132.91

3 Secondary Clarifier Respirometric Method 79.38

4 Outlet Respirometric Method 38.65

(Table 5.1.6: BOD values)

(Figure 5.1.7: BOD values)

160.44

132.91

79.38

38.65 30

50

70

90

110

130

150

170


BO

D (

mg

/L)

Sampling Points

36

5.1.7 Chemical Oxygen Demand


1 Inlet UV Spectrophotometer 267.33

2 Equalization Tank UV Spectrophotometer 201.05

3 Secondary Clarifier UV Spectrophotometer 148.68

4 Outlet UV Spectrophotometer 72.31

(Table 5.1.7: COD values)

(Figure 5.1.7: COD values)

267.33

201.5

148.6

72.3 50

100

150

200

250

300


CO

D (

mg

/L)

Sampling Point

37

5.1.8 Ammonical Nitrogen






(Table 5.1.8: Ammonical Nitrogen values)

(Figure 5.1.8: Ammonical Nitrogen values)

1

0.735

0.249

0.127 0

0.2

0.4

0.6

0.8

1

1.2


Am

. Nit

rog

en

(mg

/L)

Sampling Point

38

5.1.9 Phosphate






(Table 5.1.9: Phosphate values)

(Figure 5.1.9: PO4 values)

0.775

0.624

0.349

0.201

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9


PO

4 (m

g/L

)

Sampling Point

39

5.1.10 Oil and Grease

Oil and Grease (mg/l) = (M / V) x 1000

where,

M= Mass in mg of the residue

V = Volume of the sample


1 Inlet n-Hexane Method 7.289

2 Outlet n-Hexane Method 1.251

(Table 5.1.10: O&G values)

(Figure 5.1.9: O&G values)

7.289

1.251

0

1

2

3

4

5

6

7

8

Inlet Outlet

O&

G (

mg

/L)

Sampling Point

40

5.1.11 Heavy Metals

a. Arsenic

Sr. No. Sampling Point Method Observed Value (ppm)

1 Inlet AAS – Flame 0.423

2 Outlet AAS - Flame 0.264

(Table 5.1.11.a: Arsenic values)

(Figure 5.1.11.a.: Arsenic values)

b. Lead




(Table 5.1.11.b: Lead values)

0.423

0.264

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Inlet Outlet

Ar

(pp

m)

Sampling Point

41

(Figure 5.1.11.b.: Lead values)

c. Iron




(Table 5.1.11.c: Iron values)

(Figure 5.1.11.c.: Iron values)

0.321

0.205

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Inlet Outlet

Pb

(p

pm

)

Sampling Point

3.074

0.417 0

0.5

1

1.5

2

2.5

3

3.5

Inlet Outlet

Fe (

pp

m)

Sampling Point

42

d. Selenium


1 Inlet AAS – Flame Not detected

2 Outlet AAS - Flame Not detected

(Table 5.1.11.d.: Selenium values)

e. Chromium




(Table 5.1.11.e.: Chromium values)

(Figure 5.1.11.e.: Chromium values)

0.253

0.003 0

0.05

0.1

0.15

0.2

0.25

0.3

Category 1 Category 2

Cr

(pp

m)

Sampling Point

43

5.2 Determination of various design parameters involved in the Activated

Sludge Process:

5.2.1 Mixed Liquor Suspended Solids

It is given by-

MLSS (mg/L) = (A-B) X 1000,000/sample volume (L)

where:

A = weight of filter + dried residue after muffle furnace (mg)


MLSS = 0.00314 x 106 = 3140 mg/L

1

Also, MLVSS = 0.75 x MLSS = 2355 mg/L

5.2.2 Sludge Volume Index

It is given by-

SVI = (SV / MLSS) x 1000

SVI = 402 x1000 / 3140 = 128 (mL/g)

5.2.3 Yield Coefficient

Yield coefficient (Y) Y = 0.1 g VSS g = 0.1 x 60 = 0.492

BOD removed (121.79)

5.2.4 Substrate concentration

S = 1 (1/qc + kd)

qY

44

= 1 (1/5 + 0.07) = 14.50 mg/ L

(0.038 x 0.492)

5.2.5 Volume of the Aeration Tank:

VX = YQqc(SO - S)

1+ kdqc

where, X = 0.8(3140) = 2512 mg/l

2512 V = (0.49)(5)(240)(112-14.5)

[1 + (0.07)(5)]

V = 78 m3

5.2.6 F/M:

F/M = QSO / XV

= (112-14.5) x 240 = 0.101 kg BOD5 per kg MLSS per day

3140 x 78

5.2.7 Detention Period: t = 78 x 24 = 7.2 h

240

5.2.8 Return Sludge Pumping:

R = MLSS = 0.45

(10000)-MLSS

Qr = 0.45 x 240 = 108 m3/d

45

5.3 Removal Efficiency of the treatment plant:

5.3.1 BOD Removal Efficiency

It is given by –

BOD (inlet) – BOD (Outlet) x 100 = (160.44- 38.65) x100

BOD (inlet) 160.44

= 75.90%

BOD removal efficiency of primary clarifier = 160.44 – 120.21 x100 = 25.4 %

160.44

BOD removal efficiency of primary clarifier = 110.01 – 79.38 x100 = 31.8 %

110.01

5.3.2 COD Removal Efficiency

It is given by –

COD (inlet) – COD (Outlet) x 100 = (267.33- 72.31) x100

COD (inlet) 267.33

= 72.95%

5.3.3 TDS Removal Efficiency

It is given by –

TDS (inlet) – TDS (Outlet) x 100 = (589- 188) x100

TDS (inlet) 589

= 68.08%

46

5.3.4 TSS Removal Efficiency

It is given by –

TSS (inlet) – TSS (Outlet) x 100 = (239- 89) x100

TSS (inlet) 239

= 62.76%

5.3.5 Oil and Grease Removal Efficiency

It is given by –

O&G (inlet) – O&G (Outlet) x 100 = (7.289- 1.25) x100

O&G (inlet) 7.289

= 82.85%

5.3.6 Ammonical Nitrogen Removal Efficiency

It is given by –

N (inlet) – N (Outlet) x 100 = (1.00- 0.127) x100

N (inlet) 1

= 87.30%

5.3.7 Orthophosphate Removal Efficiency

It is given by –

P (inlet) – P (Outlet) x 100 = (0.775-0.20) x100

P (inlet) 0.775

= 74.19%

47

5.4 Comparison of effluent discharge quality with the standards prescribed:

5.4.1 BOD & COD

(Figure 5.5.1: COD & BOD discharge quality characteristics)

5.4.2 Oil and Grease & TSS

(Figure 5.5.2: O&G and TSS discharge quality characteristics)

38.65

72.31

30

250

0

50

100

150

200

250

300

BOD COD

Sta

nd

ard

(m

g/L

)

Parameters

Observed Values (Outlet)

CPCB Standard

1.25

89

10

100

0

20

40

60

80

100

120

O&G TSS

Sta

nd

ard

(m

g/L

)

Parameters

Observed Value (Outlet)

CPCB Standard

48

5.4.3 Ammonical Nitrogen & Phosphate

(Figure 5.5.3: Nitrogen & Phosphate discharge quality characteristics)

5.4.4 Heavy Metals

(Figure 5.5.4: Heavy Metals discharge quality characteristics)

0.264 0.417

0.205 0.003

0.2

4.4

0.1 0.1

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Arsenic Iron Lead Chromium

Sta

nd

ard

(m

g/L

)

Parameters


CPCB Standard

0.127 0.2

50

4.4 0

10

20

30

40

50

60

Ammonical Nitrogen Phosphate

Sta

nd

ard

(m

g/L

)

Parameters


CPCB Standard

49

CHAPTER 6

CONCLUSION

Results from the present study Adequacy and Efficacy of Treatment Plant Treating Electronics

Industry Wastewater has been discussed below-

BOD removal efficiency of Primary clarifier is 25% which is less than normal observed

efficiency (30%) and for the secondary clarifier it is 32%.

Treatment plant is efficient in removing heavy metals like Iron and Chromium as the

effluent values are below CPCB standards. But plant is not efficiently removing heavy

metals like Arsenic and Lead (effluent values found above CPCB standards).

BOD and COD removal efficiency of the treatment plant found to be 75.09% and 72.95%

respectively.

Treatment plant is capable of removing oil and grease, ammonical nitrogen and

phosphate efficiently.

Important design parameters of aeration tank MLSS and SVI are found in the acceptable

limit.

Volume of the Aeration tank required for the suspended growth process is less than the

design volume of the tank.

FUTURE SCOPE AND RECOMMENDATIONS:

In the concerned Effluent treatment plant volume of the aeration tank is not adequate to meet the

suspended growth process; therefore, its capacity should be increased for better efficiency.

Arsenic and lead content is beyond the acceptable limits which should be treated with tertiary

treatment processes. There should also a policy to be formed for better management and

operation of the unit processes.