Sewage infrastructure in West Bengal, India. A case study of the waste water treatment plant situated at Kalyani

Bachelor Thesis 2016 73 Pages

Environmental Sciences



1. Acknowledgement

2. List of Figures

3. List of Tables

4. List of Abbreviations

5. Introduction

6. Review of Literature

7. Review of Literature Historical Background

8. Review of Literature Technical Overview

9. Satellite Imagery Kalyani Town

10. Field Visit

11. Satellite Imagery Kalyani STP

12. Summary & Conclusion

13. References


I express my heartfelt gratitude and sincere appreciation to Prof. D. Das, Ph. D., Department of Environmental Science, University of Kalyani, for his inspirational guidance, constructive criticism and affectionate encouragement during the total study period which helped me to execute my project work.

I also take this opportunity to convey my sincere gratefulness to Dr. Seema Kapoor, Professor, Dr. Shanti Swaroop Bhatnagar University Institute of Chemical Engineering and Technology (Dr. SSB UICET), Panjab University, Chandigarh for her compassionate support and motivating inspiration right from the beginning of this project.

I would also like to express my deepest sense of gratefulness towards Shri Mihir Bhatta, Senior Research Fellow, Department of Environmental Science, University of Kalyani for his liberal guidance and sympathetic supervision which helped me complete this project work.

I am obliged to Shri B. Chakraborty, Executive Officer and Shri S.N. Chatterjee, A.E., Kalyani Municipality, Kalyani, Nadia for their whole hearted cooperation and assistance.

I also express my heartfelt thankfulness to Mr. D. Kumararajan, Project Manager, L&T, Kalyani Sewage Networks & WWT Project for his exceptional guidance on our field visit, Mr. G.M. Khan, Project Coordinator L&T, Kalyani Sewage and WWT Project, for his excellent coordination and support, to successfully conduct the field visit without any problems whatsoever. I also thank the entire LNTECC team and L&T Limited for allowing us to visit the under renovation sewage treatment plant and arranging our safety through the entire duration of our visit.

Finally, I express my deepest gratitude and regards to my parents and friends whose eternal blessings were the inspiration on the way of my life.

I am very much thankful to the researchers and scientists whose publications enriched me to accomplish this meaningful study in such a logistic manner.

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List of Figures

1.1 Graph of population rise over a hundred years.

1.2 Demand of fresh water by various sectors in upcoming years.

1.3 Pie-charts showing the extent of sewage generation and treatment in Class I cities and Cass II towns in India.

2.1 Ancient sewage system in Indus Valley Civilization.

2.2 Sanitary sewers, storm sewers, separate and combined arrangements in a municipality.

2.3 Septic tank used to treat small volume of waste.

2.4 Flowchart of waste water treatment in a plant.

2.5 Typical waste water treatment facility and the stages employed.

2.6 Bar screens (Photo courtesy: Uma Wirutskulshai Colorado State University, 1996)

2.7 Grit removal in a constant velocity grit channel.

2.8 Round tanks utilized for settling of suspended solids.

2.9 Graphical representation of biological growth phases in secondary treatment.

2.10 Aerated activated sludge tank utilized in secondary treatment.

2.11 Trickling filters utilized in secondary treatment.

2.12 Rotating biological contactors (RBCs) utilized in secondary treatment.

2.13 Submerged aerated filters utilized in secondary treatment.

2.14 Excess sludge from biological treatment being de-watered before disposal.

2.15 Treated water being used for recreational and aesthetic beautification of Abu Dhabi (Photo courtesy: Prof. Debasish Deb, University of Kalyani, 2016).

3.1 The satellite imagery of Kalyani Sewage Treatment Plant.

3.2 Lifting stations used to pump sewage onto higher altitudes.

3.3 Old screening chamber with new screens yet to be placed at Kalyani STP.

3.4 Main pumping station at Kalyani STP

3.5 Blueprint of primary clarifier.

3.6 Blueprint of four armed trickling filters (TF).

3.7 Recirculation pump house in Kalyani STP.

3.8 Our examination of the recirculation pumps at Kalyani STP.

3.9 Blueprint of secondary clarifier.

3.10 Sludge ponds used after secondary clarifiers.

3.11 Chlorine disinfection used chamber as a tertiary treatment.

3.12 Blueprint of sludge drying beds used as dewatering mechanism.

3.13 Schematic diagram of Waste Stabilization Pond Process (WSP).

3.14 Anaerobic ponds used a primary treatment in WSP.

3.15 Facultative aerated lagoons used as secondary treatment is WSP.

3.16 Mr. K. guiding us at Kalyani STP.

5.0 Satellite area of Kalyani Town which serves as the catchment area for the Kalyani STP.

List of Tables

1.1 Table showing the tentative costs of setting up a sewage treatment plant with various stages.

1.2 Table showing the discharge (directly or indirectly) of waste water from West Bengal.

1.3 Table showing the generation of sewage by Class I cities in West Bengal, their population and available treatment capacities.

1.4 Table showing the generation of Class II towns in West Bengal, their population and available treatment capacities.

1.5 Table showing the performance evaluation of sewage treatment plants in West Bengal funded by NRCD.

1.6 Table showing the treatment capacity and actual treatment capacity of Sewage Treatment Plants in West Bengal.

2.1 Table containing types and descriptions of all subparts of Total Suspended Solids (TSS).

2.2 Table containing the stages and descriptions of various treatments employed in a waste water treatment plant.

2.3 Table containing types and definitions of various mechanisms for particle settling.

2.4 Table containing the various types of secondary biological treatments employed in a waste water treatment plant.

4.1 Table showing the average daily flow reaching STP, its capacity and upgraded capacity.

4.2 Table showing the quality of sewage water reaching the Kalyani STP (in terms of BOD, COD and TSS levels).

4.3 Table showing the parts of conventional treatment process at Kalyani STP, their dimensions and other specifications.

4.4 Table showing the parts of traditional treatment process at Kalyani STP, their dimensions and other specifications.

4.5 Table showing the result of treatment analysis after subsequent stages of treatment in case of conventional treatment at Kalyani STP.

4.6 Table showing the result of treatment analysis after subsequent stages of treatment in case of traditional treatment at Kalyani STP.

4.7 Table showing the percentage (%) reduction in characteristics of sewage water after treatment (in terms of BOD, COD and TSS levels).

List of Abbreviations

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Indian economy is presently in a transition phase, from being a developing nation to a developed one. At this chronological juncture, our country faces primarily two problems, the lack of infrastructure and ever increasing urban population. Over a period of a hundred an ten years, from 1901 to 2011, Indian urban population has exploded from 25.8 million to estimated 387 million [53]. This has put extreme pressure on the fresh water resources of the nation due to concurrent expansion of agricultural sector, industrialization and urbanization [54]. Thus, a self- perpetuating problem has been generated, overload of sewage and lack of fresh water. By 2050, it is projected that 50% of the Indian population is going to reside in urban establishments [53], while even now, public services are not able to keep up with the demand of the fast urbanization. The graph (Fig. 1.1) below shows the increase in urban population of India over a hundred years from 1901 to 2011, helping us to predict the future population [56].


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Figure 1.1. Increase in Indian population over a hundred years.

This rapid increase in urban population is a result of extreme immigration of population from rural areas or small towns to cities and suburbs. Unfortunately, majority of these cities lack sewerage infrastructure or sewage treatment plants. Major cities in India have extended beyond metropolises and incorporated nearby villages and small towns. However, most of these urban agglomerations still remain under rural administration with no capacity for sewage handling and treatment. Thus, sewage and other domestic and commercial wastes are discarded into rivers or pond or in open dumps away from cities.

The chart (Fig. 1.2) below represents the projected demand of fresh water in billion cubic meters (BCM) by different sectors in India in the upcoming years of 2025 and 2050, based on the usage statistics of 2010 [61].

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Figure 1.2. Projected increase in fresh water demand in future.

Approximately 38,254 million liters per day (MLD) of waste water is produced by urban agglomerates consisting of Class I and Class II cities, each having a population of 50,000 each, which constitute about 70% of the total urban population in India [53]. In India, 27 cities have only primary treatment facility, while 49 cities have both primary and secondary treatment facilities, with the efficiency of treatment ranging from 2.5% to 89% [55]. About 23% of waste water generated comes from the state of Maharashtra, while the Ganga river basin contributes to about 31% of the generated waste water, which in total is 54% of all the waste generated in India. Only 74% of the generated waste water is collected [55]. Presently, India can treat up to 31% of the total waste water generated by these cities, which amounts to 11,787 MLD. It is projected that by 2051, waste water generated from these urban agglomerate may increase to 120,000 MLD and the waste water generated by rural India will not be less than 50,000 MLD [53]. According to studies by Central Pollution Control Board (CPCB), out of 269 sewage treatment plants in India, only 231 are optional, causing only 21% of the sewage generated to be effectively treated [53]. The untreated waste water is the main cause of water pollution in India [56].

The pie charts below (Fig. 1.3) shows graphically the extent of sewage generated and sewage treatment capacity of Class I cities (A) and Class II towns (B) in India respectively in MLD [62].

Figure 1.3. Extent of sewage generated and treatment capacity.

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The most common mode of waste water treatment in Class I cities of India is the Activated Sludge Process (ASP), which includes up to 59.5% of the entire installed capability. This is followed by the Up flow Anaerobic Sludge Blanket (UASB) technology which encompasses 26% of the entire installed capability. Series of Waste Stabilization Ponds (WSP) technologies is equally important as it is used in 28% of all sewage treatment plants in India. However, the collective capability of all such ponds is only 5.6% of the total installed capacity [57].

Series of Waste Stabilizing Ponds (WSP) technologies is primarily employed in Class II towns of India, encompassing 71.9% of the entire installed capability, and is prevalent in 72.4% of all the STPs in this category. Next comes ‘Up flow Anaerobic Sludge Blanket’ (UASB) technology which encompasses 10.6% of the entire installed capability and is prevalent in 10.3% of all STPs in India under this category [57] [58].

The reason for preference of Activated Sludge Process (ASP) in major cities in India is due to the fact that this technology requires less area and space compared to other methods, specifically UASB and WSP technologies because they both require large ponds in their treatment process. This is because in the conventional type of ASP, both the primary sludge and secondary sludge are treated in a common anaerobic sludge reactor. Only the secondary sludge from the anaerobic sludge digesters need to be handled by deposition on sludge drying beds. Again, in the Extended-Aerated type of the ASP there is an omission of the primary settling tank and anaerobic sludge digester and the entire secondary sludge is taken to the sludge drying bed directly. The Extended Aerated type of the ASP is less in use due to its high operational cost for big systems [57].

The UASB treatment technology is considered by and large an economical form of waste water treatment in terms of operation, with a benefit of generated biogas which can be used as an energy resources.

This comprises of grit removal and polishing ponds having a retention time of 1 day. The disadvantage of such technology is that it is very susceptible to environmental variations, which are greatly aggravated by anthropological issues like power cuts. As polishing ponds have been included as a part of this treatment process, it naturally requires a large land area and is thus inconvenient to be designed within cities due to paucity of available land. Also correct and efficient grit removal facilities must be present for better efficiency of the UASB reactors as the BOD levels of the treated water are greatly dependent on the TSS levels after primary treatment [57] [58].

The Series of Waste Stabilization Ponds (WSP) technologies is ideally used to treat waste water from Class II towns in India because its operation is economical. However, no biogas or other energy resources are recovered in this method. However, the advantage of WSP over USAB is that the former is less susceptible to operational quality and it also provides improved quality of bacteria. There are usually three stages to this technology namely, anaerobic pond, facultative pond and maturation pond, where the sewage water is retained for a total hydraulic period of 5 to 7 days [58].

There are 234 functional sewage treatment plants in India and majority of them are in only 5% of the cities and towns and were developed under various river action plans from 1978­79 onwards. In Class I cities, generally treatment methods like oxidation ponds and activated sludge processes are employed [53].

Industries also contribute to the aggravating problem with industrial waste water of 13468 MLD generated, of which only 60% of the effluent is treated [54].

Thus it is evident that a large difference exists between the generated waste water and the treated waste water. Adding to that problem, inefficient infrastructure and unsatisfactory operation, and irregular maintenance has led to about 39% of all the sewage treatment plants not meeting the prescribed effluent standards as set by the Environment (Protection) Rules before being discharged into streams, according to a survey report by Central Pollution Control Board (CPCB).

Among the metropolitan cities in India, Delhi has the maximum treatment capacity of around 2330 MLD which is 30% of the treatment capacity of all metropolitan cities. After Delhi comes Mumbai with a treatment capacity of 2130 MLD which is nearly 26% of the treatment capacity of all metropolitan cities. Thus the above two cities constitute to about 55% of all the waste water treatment capacity in the country. In some cities like Hyderabad, Chennai, Vadodara, Ludhiana and Ahmedabad, the available treatment capacity meets the volume of the generated waste water. Some cities like Delhi and Dhanbad have more than 50% of the capacity while all other cities have less than 50% capacities [55].

According to a survey by Central Pollution Control Board (CPBC) in 2013, the maintenance and operational quality of sewage treatment plants in India depend on primarily three factors:

- Regular and continuous supply of energy
- A collection trained and skilled labor force
- Systematic maintenance and proper preventive measures and checking [57].

In cases where natural systems are involved, the requirement of energy is minimal. Conventional treatment systems however, require high amount of energy. Only a little number of personnel are required to control the natural treatment systems, while, conventional and conventional advanced technologies require more workforce and trained labor [55].

According to ‘Performance Evaluation of Sewage Treatment Plants in India funded under NRCD [56], there are presently 34 sewage treatment plants (STPs) in West Bengal whose total installed capacity is around 457 MLD. However, the tangible utilization is only 49% off the said capacity, or 214 MLD. There are 3 STPs which have BOD limits exceeded above the prescribed limit. The COD limits of all the STPs were under the prescribed limits. The discrepancy between the said and actual utilization of the capacities is due to the fact that 13 STPs in West

Bengal are in a non-operational condition or are undergoing certain renovations to retro fit new equipment and more efficient technologies [57].

Table 1.1. The cost of setting up different stages of waste water treatment plant through conventional methods [62]:

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Table 1.2. The disposal of wastewater in river Ganga from Class I cities and Class II towns in West Bengal [57]:

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Table 1.3. The sewage generation in Class I cities in West Bengal has been summarized below [56] [58]:

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Table 1.4. The sewage generation in Class II Towns in West Bengal has been summarized below [56] [58]:

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Table 1.5. Performance evaluation of sewage treatment plants in West Bengal funded under NRCD [56]:

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Table 1.6. Treatment capacity and actual utilization capacity of Sewage Treatment Plants (STPs) in West Bengal [59]:

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According to a report by the Central Pollution Control Board [59], there are 13 sewage treatment plants (STPs) in West Bengal currently in a non-operational state, which is the highest among all states in the country. According to the same survey, though the total installed capacity of all of the 34 sewage treatment plants (STPs) is 457 MLD, the actual utilization capacity is only 214 MLD which is only 49% of the total sewage treatment potential in the state of West Bengal [55]. An estimated volume of 527 million liters of waste water is disposed into the river Ganga from fifteen Class I cities situated alongside the banks [57]. The number of Oxidation Ponds or Aerated lagoon technologies used in STPs in West Bengal are nine in total with plants present, comprising one at Nabadwip, South Suburban, Bahrampore, Bhatpara, Bally, Panihati, Kalyani and two at Titagarh. The number of Activated Sludge Process technologies used in West Bengal are four in total, with STPs present at Titagarh, Garden Reach, Bhatpara B and Cossipore- Chitpur (Bangur). The number of Trickling Filters employed at STPs in West Bengal are five in total with one plant each present at Baranagar and Kamarhati area, Howrah area, Chandannagore, Serampore and Kalyani. All the treated water from Sewage Treatment plants primarily in West Bengal drain into river Ganga, and there are some plants with provisions which allow the treated water to be used for supplementary irrigation water. These plants which have this provision for irrigation are present at Cossipore-Chitpur (Bangur), Titagarh, Panihati, Baranagar and Kamarhati, Kalyani, North Howrah- Kona (Bally). There also exists provision of waste water to be used in pisciculture in areas surrounding the plants in Panihati and Serampore.

The treatment capacity of the sewage treatment plant (STP) in Kalyani Block B2, B3 is 11 MLD while at the STP in Kalyani Town area has a treatment capacity of 6 MLD. The sewage treatment plant (STP) in Kalyani is under the administration of Kalyani Municipality and receives water from Kalyani town area which is a Class II town in West Bengal, with an area of 29.14 square kilometers and a population of 100,602 according to the 2011 census. The sewage treatment plant (STP) at Kalyani was chosen because it provided a perfect opportunity to assess the developments being commissioned by the central government and various state government in order to improve the efficiencies and treatment capacities of such treatment plants, through technological installation of modern developed systems and retro-fitting equipment with enhanced efficiencies to the already existing set ups.

The Government of West Bengal has commissioned LNTECC of Larsen & Toubro (L&T) through Kalyani Municipality to improve the already existing sewage treatment plant at Kalyani Town.

The purpose of this project is to visit the sewage treatment plant (STP) at Kalyani in West Bengal, India, and try to collect as much information as possible, on the various aspects of the treatment plant, such as demographic significance, sewerage conditions of surrounding areas, total area and individual areas of the various treatment and handling methods, plant capacity, energy requirements, treatment methods employed and number of such facilities, performance of the equipment and processes, quality (both chemical and physical), volume and location of the discharged water, presence of quality control mechanisms, methods of sludge disposal and so on.

After collecting the above information, these recorded parameters will be presented in tabular form and hence will enable one to compare this sewage treatment plant with other similar plants in West Bengal and rest of India. This will help us to assess the condition of such plant in the country and comment on the quality of the discharged water from these plants.

The collected information will also be used to compare the previous and latest results and efficiencies after the retro fitting is complete.

Review of Literature

Water is one of the most basic human necessities, available mainly in three aggregate forms on the globe, namely water or liquid state, ice or snow as solid state and steam or vapour state. Water is a wonderful liquid with innumerable properties that allow it to be indispensable to all activities of man and therefore critical to the existence of life on this planet and consequently to the human survival and development. Water is considered a universal solvent due to its high dielectric constant (relative permittivity) compared to other liquids with a value of 78.41 at 25 ° C [1] and polarity [2]. This property enables water to maintain the homeostatic and osmotic balance of blood. Water also has a high specific heat capacity, 75.375 ± 0.05 J/mol-K [3] that enables it retain large amount of latent heat energy and thus maintain balance of the temperature systems, ranging from the climatic conditions on the planet to that of the human body.

Thus it is evident that water fulfils the basis for natural habitats, apart from the needs of our society and serves more specifically for human activities such as domestic use, industrial use, agricultural use, fishing, transportation and recreation.

As a byproduct of anthropogenic usage, the water becomes polluted with constant discharge of contaminants from various sources, leading to an overall decrease in water quality at every stage of the water cycle and adversely affecting all life and processes dependent upon it.

According to Swiss Federal Institute of Aquatic Science and Technology (Eawag), Duebendorf, Switzerland, waste water is any volume of water that has been adversely affected in quality by anthropogenic elements and is incapable of natural rectification by physical or biological agents.

Waste water can generate from an amalgamation of domestic, industrial, commercial, agricultural activities and also as a result of soil erosion leading to surface run offs during heavy rainfall. The waste water that is predominantly generated by households from an urban or semi urban area is termed as municipal waste water or sewage and is usually conveyed to the treatment plant with the help of sewer systems.

Indian cities have been classified into Class I cities and Class II suburban towns. Class I cities are those urban agglomerations with a population of 1,000,000 residents and above. Class II suburban towns are areas with population more than 100,000 and less than 1,000,000 residents.

Historical Background

Mesopotamian and Indus Valley civilizations have been said to use basic sewer systems for waste removal, where vertical shafts used to transfer the household wastes generated into a gutter (Fig. 2.1) [43]. Modern sewer systems were constructed in the mid­nineteenth century when obnoxious conditions were created as a result of urbanization and industrialization, and disease outbreaks like cholera or foul smelling rivers like the Great Stink of Thames [4].

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Figure 2.1. Sewers in Indus Valley Civilization.

The sewage systems however did very little to actually treat the sewage, but simply carried the waste water away from populated regions. Attempts were made to divert sewage into fertilizing materials in 1840 [5]. The predecessor of the septic tank was cesspool, in which waste water was sealed in tanks to avert contamination. It was later improved into the modern septic tank. Chemical breakdown of waste was achieved in late 19th century, by using microorganisms. Sir Edward Frankland successfully demonstrated the filtration of waste water through porous gravel, where the filter remain unblocked over a long period of time [6]. A trickling filter was developed in 1890 by Lawrence Experimental Station in Massachusetts. Contact beds and bacterial beds were developed in 1905 by Joseph Corbett [7]. In 1912, The Royal Commission on Sewage Disposal of United Kingdom specified the ’20:30 standard’ applicable to BOD and suspended solids per litre of waste water [8].

Technical Overview

The sewer systems can be of three types, namely sanitary, storm and combined sewer system. Sanitary sewer systems usually carry waste water from household bathroom and kitchens and commercial establishments. Storm sewers carry mainly rain water during monsoon seasons. A combined sewer system is one which carries both storm water and waste water in the same pipe (Fig. 2.2) [44].

The pipe which carries the waste water in a separate sewer system is referred to as foul sewer. In a combined system sewer, the waste water is diluted by the storm overflow and thus has a lesser concentration than the waste water carried by a separate sewer system. Waste water treatment plant which collect waste water from combined system must make provisions for storage of excess water during storm events in vessels called storm tanks [9]. This excess storm water flow defines to a great extent the necessary hydraulic capacity of the waste water treatment plant [10].

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Figure 2.2. Sewer systems in cities.

However, wastewater can also be defined in details as a combination of one or more of:

- domestic effluent consisting of black water (excreta, urine and fecal sludge) and grey water (kitchen and bathing wastewater);
- wastewater as a result of commercial activities, and public health services like nursing homes and hospitals;
- industrial effluent, storm water and other urban run-off;
- agricultural, horticultural and pisciculture sewage, either, whether dissolved or as suspended solids [11]

Years ago, waste water was simply dumped into running water bodies where a natural process of rectification began. Firstly, the utter bulk of fresh water in the waterways diluted the wastes. Bacteria and other microbes consumed the organic matter in water, thereby producing new bacterial cells, and liberating harmless products like carbon dioxide and methane. However, the great size of the population today has put a dire stress on the natural purification capacity of waste water as due to huge amount of municipal wastes being produced every day. Thus, nature needs a ‘helping hand’ from human communities to counter the volume of waste and set the balance correctly again [12]. This is where waste water treatment comes into the picture.

The chief purpose of waste water treatment is to hasten the natural processes by which waste water is purified, in a manmade environment.



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Panjab University – Dr. S.S. Bhatnagar University Institute of Chemical Engineering and Technology
Wastewater Waste water management Sewage treatment plant Waste treatment in India Primary treatment Secondary Treatment Activated sludge process Trickling filters



Title: Sewage infrastructure in West Bengal, India. A case study of the waste water treatment plant situated at Kalyani