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SECTION-6 Limnology, Watershed Hydrology and Monitoring
PAPER-9
AN OVERVIEW OF HUMAN ACTIVITIES POLLUTING BELLANDUR TANK IN BANGALORE
Sreekantha and K.P. Narayana


ABSTRACT
INTRODUCTION
LITERATURE SURVEY
OBJECTIVES
STUDY AREA
METHODOLOGY
COLLECTION OF SECONDARY DATA FROM GOVERNMENT AGENCIES
COLLECTION OF PRIMARY DATA
DEVELOPMENT OF METHODOLOGY FOR SAMPLING SURVEY
DOMESTIC WASTEWATER ESTIMATION
QUALITATIVE ANALYSIS
SAMPLING METHODOLOGY
RESULTS AND DISCUSSIONS:-METEOROLOGICAL PARAMETERS
WASTEWATER ESTIMATION FOR THE INDUSTRIAL CLUSTERS
TABLE 1: DETAILS OF INDUSTRIAL SAMPLING IN CLUSTER I.
TABLE 2: DETAILS OF INDUSTRIAL SAMPLING IN CLUSTER II
TABLE 3: DETAILS OF INDUSTRIAL SAMPLING IN CLUSTER III
DEMOGRAPHIC STUDIES
TABLE 4: POPULATION GROWTH IN THE LAST FEW DECADES AND FUTURE ESTIMATION
Fig.1: Population growth pattern of the region
COMMERCIAL ACTIVITIES IN THE CATCHMENT-Estimation of wastewater generated by hospital
TABLE 5: DETAILS OF SAMPLE SURVEY CONDUCTED FOR HOSPITALS IN THE REGION
Estimation of wastewater generated by vehicular service centres
TABLE 6: DETAILS OF SAMPLE SURVEY CONDUCTED FOR VEHICULAR SERVICE CENTRES
Total Wastewater Contribution
TABLE 7: INDIVIDUAL AND TOTAL WASTEWATER GENERATION IN THE REGION
Treatment facility
TABLE 8: GEOGRAPHICAL FEATURES OF BELLANDUR TANK
Qualitative Analysis
TABLE 9: TEST RESULT OF SAMPLES OF DRY WEATHER FLOW INTO BELLANDUR TANK
RECOMMENDATIONS AND CONCLUSIONS
REFERENCES


ABSTRACT: up | previous | next | last

The physico-chemical analysis of various parameters in Bellandur tank exhibited considerably high values, revealing the lake unfit for human consumption. Residential, industrial and commercial activities in the catchment have been recognized as the source of pollution and their individual roles have been estimated. Suitable and feasible environmental strategies, for the restoration and management of the tank, have also been suggested.

INTRODUCTION: up | previous | next | last

The continuous migration of people from rural areas and smaller towns to metropolitan and megacities, in search of employment, educational facilities, commercial and trade opportunities and good infrastructure has resulted in rapid urbanization. Though urbanization helps in the growth process to a large extent, the clear deterioration in the physical environment and quality of life in urban areas always overshadows this positive aspect. For better and healthy living, safe drinking water supply and hygienic sanitation are a must. However, due to the ever-increasing population, it is becoming extremely difficult to cope with the demand for these basic amenities (Abbasi, S.A., 1997). Almost all the cities at present are facing severe problems of managing wastewater. Formerly designed wastewater management systems are incapable and inefficient in the present scenario. Thus, wastewater gets discharged into natural water bodies indiscriminately, deteriorating the quality of surface and groundwater day by day (Carpenter et. al., 1996).

The increasing population is posing a great threat to the ecology and well being of the aquatic ecosystem, especially lakes. Bellandur tank is under serious threat due to damaging land use practices in its catchment. The tank, choking with weeds, silting up, and encroached from all sides, is shrinking in size, with deterioration in its quality and loss of its rich and varied faunal, floral, and other resources. Many precious wetlands have either gone extinct or are in the throes of death.

LITERATURE SURVEY: up | previous | next | last

It is evident that over the last four decades, the quality of the watercourses has undergone a drastic deterioration that can be linked to industrial and demographic transformation. Analysis of the quality of surface water in Parma Valley of Italy over three decades (1951 - 1981) show that, there was a 360 % increase in the pollution load by human activities with much of the increase occurring between 1961 and 1971. This was due to wastewater from four sources - domestic, industrial, commercial and agricultural activities. (In this catchment, agricultural activity can be hardly seen and only the first three are significant). De, et al (1991) in their study of Calcutta Metropolitan city have shown that the Hoogly river is polluted severely by domestic waste (52 m. gallons per day) as well as industrial waste (100 m. gallons per day). In addition, there are discharges with pathogens from Tolly's Nullah, and shipping wastes of Calcutta Port. A large part of Kidderpore and garden reach sewerage system carry toxic and heavy metal discharge of industrial origin. The unscientific method of dumping garbage by filling swamps and marsh lands has also affected the ground water of Calcutta. The concern over the problem is not a new one. Rai et al (1993) studied pollution of Nainital Lake and the results showed that the lake was unfit for any purpose. They identified factors such as human settlement in catchment area, tourism and other recreational activities, which deter the quality of the lake.

Analysis of chemical and fisheries data from the Willow Brook, Northamptonshire, UK, a stream polluted mainly by ammonia and zinc, and found it without fish for over a 3-year period. High bacterial population and BOD values in the Varuna river, could be attributed to the discharge of untreated wastewater and industrial effluents into the river at Varanasi (Joshi, G and Adoni, A.D, 1993).

OBJECTIVES: up | previous | next | last

The objectives of the present study are:

  • Identification of various activities in the command area, that are responsible for pollution, and estimation of individual wastewater contribution by each activity.
  • Physico-chemical characteristics of the Bellandur tank.
  • STUDY AREA up | previous | next | last
    Geographically, the study area is located between 77o 35´ west and 77o 45´ east and latitude 12o 50´ south and 13o 00´ north (toposheet 57 H/9, scale: 1:50,000). The catchment covers the eastern part of Bangalore, an area of about 148 sq. Km. The terrain of the region is relatively flat and sloping towards south of Bangalore city. Relative slope of the region is found to be very gentle to gentle slope. The relative contour height is 930 m above mean sea level and the lowest is 880 m. The height is found to be 870 m above mean sea level near the tank. The drainage pattern is dentric type and is characterized by gneiss and gneiss granite rocks. Three main streams join the tank, which form the entire watershed. One of the streams originates at the northern part of the region, Jayamahal and covers the eastern portion and is referred to as the eastern stream. Another stream originates from the central part of the city, Krishna Raja Market and covers the central part of the region before joining the tank and is called the central stream. Another stream commands southwestern part of the region called the western stream. Further, before the confluence with Bellandur Tank, all the streams come across two to three tanks.

    METHODOLOGY: up | previous | next | last
    Initially, a team of environmental engineers conducted a brief exploratory study of the catchment, which mainly included discussions with the local people, field observations, and study of the literature available on the catchment, etc. The outline for further study was developed with this background. The data obtained from the sample survey were subjected to comparative analysis with the field experiments in order to validate the results obtained.

    COLLECTION OF SECONDARY DATA FROM GOVERNMENT AGENCIES up | previous | next | last

  • Meteorological information such as temperature, rainfall, humidity and wind direction was collected from the Meteorological Centre and Directorate of Economics & Statistics.
  • Industrial details were obtained from Karnataka Industrial Area Development Board and Directorate of Economics & Statistics.
  • Data on area wise demography was based on Census Books collected from the Census Department.
  • Two types of toposheets were used in the present study. 1:50,000 scale toposheets were collected from the Survey of India department and 1:20,000 scale toposheets were collected from the Bangalore Development Authorities.
  • Physical features of the Bellandur Tank were obtained from the Minor Irrigation Department.
  • COLLECTION OF PRIMARY DATA up | previous | next | last

    Primary data relating to industries, hospitals and major vehicular service centers were collected through a sample questionnaire survey. The questionnaire data was generalized to estimate the total wastewater generation by all these activities in the area.

    DEVELOPMENT OF METHODOLOGY FOR SAMPLING SURVEY up | previous | next | last

    A stratified sampling methodology has been developed for the present study. Industries with more than 100,000 rupees investment were selected for the industrial survey. Based on the distribution of the industries, several clusters were identified. Each cluster was classified into several categories considering the type of production. Under each category, survey was conducted so as to cover at least 20 % of the total industries. Also the selected industries were distributed equally over the total range of investments under each category. The methodology was extended to hospitals in the catchment. About 40 % of the hospitals were surveyed randomly all over the catchment (the capacity ranging from 8 to 1000 beds). The wastewater contribution by the hospitals in total has been estimated by generalisation of the data obtained. As the data regarding the total number of vehicular service stations and their location could not be obtained from any of the authorized organizations, the sampling methodology has been slightly modified. Here, two sampling stations having one sq. km of individual area were chosen. One is located at the periphery of the city and the other is located at the densely populated central part of the city. All the service stations coming under the sampling area were surveyed and finally averaged.

    DOMESTIC WASTEWATER ESTIMATION up | previous | next | last

    The population data of 1991 census, obtained from the Census Department was used to estimate the present and extrapolate the future population. With this population data, total domestic wastewater generation was estimated. The per capita water consumption has been considered based upon detailed literature survey and discussions with the concerned authorities. The quantity of wastewater generation has been projected for the future 20 years with the corresponding increase in population.

    QUALITATIVE ANALYSIS up | previous | next | last

    A complete analysis of the wastewater sample was done to check the pollution load qualitatively, and to verify, whether they meet the wastewater parameter limits prescribed by statutory boards before discharging the same into fresh water bodies. For this purpose, the grab samples were collected from various points and were subjected to analysis.

    SAMPLING METHODOLOGY up | previous | next | last

    Water samples were collected gently in two litre black-polythene cans. The pH, temperature, dissolved oxygen, free carbon dioxide and total alkalinity were determined in the field. For other analysis, the samples were preserved by adding a few drops of chloroform, taken to the laboratory and stored in a refrigerator for further analysis.

    RESULTS AND DISCUSSIONS:
    METEOROLOGICAL PARAMETERS
    up | previous | next | last

    The rainfall data is available for the last 100 to 110 years. Rainfall varies from 725.5 mm to 844.8 mm. The district receives 51 % of the total annual rainfall in the southwest monsoon period, i.e. June to September. The average annual rainfall in the catchment was 859 mm in 1999. April is usually the hottest month with the mean daily maximum and minimum temperature of 33.4o C and 21.2o C respectively. December is generally the coolest month with the mean daily maximum and minimum temperature of 25o C and 15.3o C respectively. The temperature drops down to 8o C during January nights. Relative humidity is high from June to October (80 to 85 %). Thereafter, it decreases and from February to April becomes 25 to 35%. The relative humidity in the morning is higher than in the evening, giving rise to the formation of fog.

    WASTEWATER ESTIMATION FOR THE INDUSTRIAL CLUSTERS up | previous | next | last

    The growth pattern of the industries formed three clusters in the region. All the three clusters are located at the periphery of the city. The urban encroachment has affected these industrial clusters, giving rise to mixed land use pattern. The area around Koramangala and HAL forms cluster I, the area along Bannerghatta road forms cluster II and the area around Hosur road forms cluster III.

    Cluster I: Out of 42 identified industries in this cluster, 21 were subjected to sampling. Most of the industries were found to be wet processing, discharging 121,073.7 L/day of wastewater to the catchment (Table1).

    TABLE 1: DETAILS OF INDUSTRIAL SAMPLING IN CLUSTER I. up | previous | next | last

    Sl No.

    Type of Industries

    Total No of Industries

    No. of Industries Surveyed

    Percentage of Sampling

    Wastewater Discharge for the Sampled Industries (L/day)

    Estimation of Total flow (L/day)

    1

    Engineering

    13

    5

    38.46

    8090

    21067.7

    2

    Rubber

    1

    1

    100

    480

    480

    3

    Textile

    1

    1

    100

    4500

    4500

    4

    Bricks/Granites

    2

    1

    50

    80

    160

    5

    Dyeing

    1

    1

    100

    4160

    4160

    6

    Miscellaneous

    24

    9

    37.5

    34015

    90,706

     

    Total

    42

    21

       

    121073.7

    Cluster II: Out of 72 industries identified in this cluster, 22 were selected for the survey. Engineering industries are more in number. The total wastewater contribution is found to be 45,444 L/day (Table 2).

    TABLE 2: DETAILS OF INDUSTRIAL SAMPLING IN CLUSTER II up | previous | next | last

    Sl No.

    Type of Industries

    Total No of Industries

    No. of Industries Surveyed

    Percentage of Sampling

    Wastewater Discharge for the Sampled Industries (L/day)

    Estimation of Total flow (L/day)

    1

    Engineering

    13

    4

    30.7

    2260

    7362

    2

    Rubber/Plastic

    1

    1

    100

    160

    160

    3

    Textile

    6

    3

    50

    4200

    8400

    4

    Electronic/

    Electrical

    5

    2

    40

    750

    1875

    5

    Bricks/Granites

    4

    2

    50

    440

    880

    6

    Chemical

    2

    1

    50

    1000

    2000

    7

    Miscellaneous

    41

    10

    24

    5944

    24767

     

    Total

    72

    23

       

    45444

    Cluster III: In Cluster III, 42 industries were identified, out of which 17 were selected for the sample survey. Industries along the Bannerghatta road come under this cluster. In this cluster also, engineering industries are more in number. The total wastewater generation in this cluster is found to be 24,938 L/day (Table 3).

    TABLE 3: DETAILS OF INDUSTRIAL SAMPLING IN CLUSTER III up | previous | next | last

    Sl No.

    Type of Industries

    Total No of Industries

    No. of Industries Surveyed

    Percentage of Sampling

    Wastewater Discharge for the Sampled Industries (L/day)

    Estimation of Total flow (L/day)

    1

    Engineering

    11

    3

    27.2

    1930

    7096

    2

    Rubber/Plastic

    6

    2

    33.3

    400

    1212

    3

    Textile

    3

    2

    66.6

    3700

    5555

    4

    Bricks/Granites

    1

    1

    100

    1500

    1500

    5

    Dyeing

    1

    1

    100

    1600

    1600

    6

    Miscellaneous

    20

    8

    40

    3190

    7975

     

    Total

    42

    17

       

    24938

    All the three industrial clusters, in total, contribute 191,455.7 litres of wastewater everyday to the catchment.

    DEMOGRAPHIC STUDIES up | previous | next | last

    Population data for the last 6 decades was collected from the Census Books and the growth pattern have been analyzed. With this growth pattern the present (2001) and future population for the year 2011 is estimated (Table 4).

    TABLE 4: POPULATION GROWTH IN THE LAST FEW DECADES AND FUTURE ESTIMATION up | previous | next | last

    Year

    Population

    Density (persons/km)

    1941

    99,322

    671

    1951

    141,222

    954

    1961

    243,225

    1643

    1971

    487,493

    3293

    1981

    867,375

    5860

    1991

    13,23,124

    8940

    2001

    23,89,694

    16146

    2011

    43,16,026

    29162

    Using Geometrical Increase Method, the population in the catchment is estimated for the years 2001 and 2011 (Fig 1). For the year 2001, it is found to be 23,89,694 and it becomes 43,16,026 by 2011. Data compiled from various literatures show the per capita water consumption for purely domestic purposes as about 135 litres per day. The literatures also show that 80 % of the total water consumption becomes wastewater. Thus, considering all these aspects, the present wastewater contribution by domestic activity is estimated to be 2,58,087 m3/day. In 10 years the quantity will increase to 4,66,130 m3/day. Thus, a significant amount of wastewater is being generated in the region and it has become a major concern to collect, transport, treat and discharge.

    FIGURE-1: POPULATION GROWTH PATTERN OF THE REGION up | previous | next | last

    FIGURE-1

    COMMERCIAL ACTIVITIES IN THE CATCHMENT
    Estimation of wastewater generated by hospitaLS:
    up | previous | next | last

    There are totally 65 hospitals identified in the region, of which 32 were sampled and the data generalized to get the total wastewater contribution by hospitals (Table 5).

    TABLE 5: DETAILS OF SAMPLE SURVEY CONDUCTED FOR HOSPITALS IN THE REGION up | previous | next | last

    Bed Range

    Number of Hospitals

    Number of Sampled Hospitals

    Percentage of Sampled Hospitals

    Obtained Quantity by Sampling (L/day)

    Estimated Total Quantity (L/day)

    1 – 50

    41

    18

    43.9

    378900

    863098

    51 – 500

    18

    9

    50

    181000

    362000

    501 – 1000

    6

    6

    100

    332000

    332000

    Total

           

    1557098

    The above results show that the major contribution among these three categories is by small hospitals.

    Estimation of wastewater generated by vehicular service centres: up | previous | next | last

    Sampling survey reveals the number of service centers per square kilometer of the area as 5 and the daily discharge of wastewater by them as 9632.25 liters. From the sampling survey, it can be estimated that the catchment contains 740 service stations, and they discharge 14,25,573 liters of wastewater everyday (Table 6).

    TABLE 6: DETAILS OF SAMPLE SURVEY CONDUCTED FOR VEHICULAR SERVICE CENTRES up | previous | next | last

    Sample Station

    No of Service Stations

    Wastewater Generation (L/day)

    1

    7

    10,592.5

    2

    3

    8,672.0

    Average

    5

    9,632.25

    Total Wastewater Contribution: up | previous | next | last

    The total wastewater generation in the catchment is found to be 2,61,274.17 m3/day. The individual contribution by residential sector is found to be 98 % of the total wastewater and as the population increases at such a fast rate, there will be tremendous increase in wastewater generation in the coming years (Table 7).

    TABLE 7: INDIVIDUAL AND TOTAL WASTEWATER GENERATION IN THE REGION up | previous | next | last

    Sl. No.

    Type of Activity

    Individual Contribution in m3/day

    Percentage Contribution

    1

    Industrial

    191.50

    0.073

    2

    Residential

    258100.00

    98.00

    3

    Commercial

    Hospitals

    1557.10

    0.595

    Service Centres

    1425.57

    0.55

     

    Total

    261274.2

     

    Treatment facility: up | previous | next | last

    On the northwestern side of Bellandur tank, the Koramangala and Challaghatta valley sewage treatment plant is situated. The designed capacity of the plant is 163,000 m3/day of wastewater. But currently it is treating only 100,000 m3/day. The incapability of the network of pipes to transport the generated wastewater is one of the main reasons for less flow in to the sewage treatment plant (STP). The remaining 161,274.17 m3/day of wastewater requires complete treatment. At present, this wastewater is directly entering various tanks in the catchment, polluting them.

    Bellandur tank is a rainfed tank. The central stream joins the tank from the northwestern part. Before the confluence of the central stream, it joins with the western stream and finally flows as one and joins the tank. Though the actual area of the tank is about 328.87 hectares, the growth of weeds, siltation and slush formation have reduced it to 154.34 hectares (Table 8). For the last few decades, treated, partially treated and untreated wastewater has been discharged to this tank. The Minor Irrigation Department is using the water of this tank for irrigating agricultural lands, coconut trees, etc. Many episodes of diseases in coconut trees have been reported due to this contaminated water.

    TABLE 8: GEOGRAPHICAL FEATURES OF BELLANDUR TANK up | previous | next | last

    Parameter

    Value

    Longitude

    13o00´ north – 12o 50´ south

    Latitude

    77o35´ west – 77o 45´ east

    Annual Rainfall in the catchment

    859 mm

    Maximum Temperature (oC)

    35 in April

    Minimum Temperature (oC)

    14 in January

    Surface Area (ha)

    328.87

    Area engulfed with slush and weed (ha)

    174.33

    Catchment Area (ha)

    8,868.83

    Area irrigated by the tank (ha)

    10,271.15

    Human Population in the catchment (1991 Census)

    13,23,124

    Qualitative Analysis: up | previous | next | last

    Maximum values of BOD and COD may be attributed to the heavy input of variety of nutrients such as sulphates and phosphorous to the tank, creating a favorable environment for microbial activity. Hazardous substances such as cyanide were not detected, which is an indication of the absence of hazardous industrial discharge. The alkalinity at the outfall is an indication of prevailing concentration of the parameter (Table 9). The high values of sewage at the inflow are a clear indication of the pollution of the tank.

    TABLE 9: TEST RESULT OF SAMPLES OF DRY WEATHER FLOW INTO BELLANDUR TANK up | previous | next | last

    Sl No.

    Parameters

    Sample at the central stream inlet

    Sample at the eastern stream inlet

    Sample at the outfall of the tank

    1

    Temperature

    28o C

    28o C

    28o C

    2

    Colour

    Black

    Brownish

    Light black

    3

    Odour

    Pungent

    Pungent

    Pungent

    4

    pH

    7.3

    9.4

    7.1

    5

    Alkalinity (mg/L)

    362.00

    348.00

    230.00

    6

    Total Dissolved Solids (mg/L)

    420.00

    498.00

    418.00

    7

    Total Phosphorous as phosphates (mg/L)

    2.10

    1.80

    0.6

    8

    COD (mg/L)

    396.00

    456.00

    122.00

    9

    BOD3 (mg/L)

    278.00

    294.00

    84.00

    10

    Nitrates (mg/L)

    0.387

    0.347

    0.124

    11

    Sulphates (mg/L)

    62.00

    68.00

    49.00

    12

    Cyanide

    ND

    ND

    ND

    13

    Lead

    ND

    ND

    ND

    RECOMMENDATIONS AND CONCLUSIONS: up | previous | next | last

    It is a highly complex task to bring out a feasible and environmentally sustainable solution to restore the original quality of the tank and the streams.

  • Previously designed wastewater conveyance systems and treatment facilities for a flow of 163,000 m3/day are presently out dated because of their incapability to handle the present quantity. The sewer networks are to be completely reestablished and the dimensions of the pipelines upgraded keeping in view the future growth of the population. All the lines should be desilted and efficient underground facility should be provided for the entire region.
  • Improper maintenance of the sewer lines is one of the reasons for their blockage and breakage, and their ultimate opening into the natural streams. The tank and the streams should be completely desilted.
  • Unauthorized settlements along the streams and in the catchment such as slums and unsewered layouts contribute large quantity of wastewater.
  • During the field visits it was observed that, residents along the banks of the streams opened their wastewater outlets into the natural streams and prevention of such things can be a tedious task. Stringent rules and regulations can minimize these problems to a large extent. Unplanned growth of the city further prevents the upgrading of the sewer systems.
  • Though the task is not a simple one, there is no alternative. As the daily discharge of wastewater in to the tank is found to be 1,61,274.17 m3/day, another treatment plant can be suggested instead of upgrading the existing one. The treatment should be done up to the tertiary level and as far as possible the treated effluent should be used for beneficial purposes.
  • Wastewater should not be allowed to enter the natural streams at any point while storm water should be allowed to flow into the natural streams to the maximum extent.
  • Creating awareness among the public through media, workshops, etc., can simplify the problem to a large extent.
  • The studies reveal the contribution of wastewater by residential activities to be significant and with the current growth rate of population, wastewater generation can increase in the future.
  • REFERENCES: up | previous | next | last

  • Abbasi, S.A., 1997. Wetlands of India - Ecology and Threats. Discovery Publishing House.
  • Carpenter, S., Frost, T., Persson, L., Power, M and Soto, D., 1996. Freshwater Ecosystems: Linkages of Complexity and Processes. Functional Roles of Biodiversity; a Global Perspective; John Wiley and Sons Ltd.
  • De, N.K. and Bose, A.K., 1991. Environmental Crisis in Calcutta Metropolitan City. Environment Design and Development, Conflict or Harmony? A Geographical Appraisal. Scientific Publishers, Jodhpur.
  • Joshi, G and Adoni, A.D., 1993. Studies on Some Water Quality Parameters of Two Central Indian Lakes and Evaluation of their Trophic Status. Ecology and Pollution of Indian Lakes and Reservoirs. Ashish Publishing House.
  • Rai, J.P.N. and Rathore, V.S., 1993. Pollution of Nainital Lake Water and its Management. Ecology and Pollution of Indian Lakes and Reservoirs. Ashish Publishing House.
  • Address: up | previous

    1.) Centre for Ecological Sciences,
    Indian Institute of Science,
    Bangalore,
    560 012,
    India

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