Varthur Lake

Varthur Lake

STATUS AND NEXT STEPS FOR LAKE VARTHUR

On May Day 2015, Bangalore’s Lake Varthur gripped the country’s attention as 12-ft-high “toxic foam” gathered on the lake surface.  The foam is just the tip of the iceberg:

  • The foam is generated by a mix of detergents, phosphates in urine content, industrial effluents and other chemicals found in sewage.
  • It is estimated that 250-500 MLD of untreated sewage flows into Lake Varthur on a daily basis
  • The quality of lake water is poor. For example, E.Coli count in the water ranges from 1600 to 3500 per 100ml. Permissible levels of E.Coli for recreational water use are at the most 600 per 100 ml.
  • Not only is surface water polluted, but pollutants are entering our precious ground water. Borewells as far as 1 km away from Lake Varthur have shown E.Coli counts ranging from 900-1200 per 100 ml
  • This is not a problem faced by only one lake in Bangalore. In fact, BWSSB treats at most 450 MLD of sewage while simultaneously supplying 1140 MLD of water.   It is estimated that at almost 600 MLD of raw sewage enters Bangalore’s lakes and rivers on a daily basis.
  • And this problem is not unique to Bangalore. Across the country, Indians generate 38,000 MLD of sewage while only treating 8,200 MLD (22%).  Lake Varthur’s problems are replicated in numerous lakes, rivers and waterbodies all over India.

There are dire public health consequences to living like this.   Most residents of Whitefield rely on water tankers for water supply.  These water tankers rely on borewells in Lake Varthur as a main source for water.  Groundwater carries high levels of pollutants and we are all at risk.  Farmers around Lake Varthur use water from the periphery of the lake for drinking and for watering their crops.  We are all consuming the vegetables grown along the path of the water flow.  Water hyacinth growing in the lake is used as fodder for cattle, likely contaminating the dairy products produced from these cows.   Research has shown a high incidence of gastro and stomach problems witnessed by doctors treating patients who live in the area.  Finally, the stench from the lake is becoming unbearable and can be experienced a good distance away from the lake.

Cleaning up Lake Varthur is a daunting task; however any successes at Varthur can be replicated around Bangalore, and eventually around the country.  Varthur could be the first in a series of sustainably rejuvenated lakes and rivers and a starting point for much improvement in our country’s water and sanitation systems.

To that end, we summarize Lake Varthur as having three main needs:

  • Survey and fence: a fence will prevent future encroachments and also deter disposal of waste into the lake
  • Stop sewage from entering the lake: BWSSB must treat the entire sewage load entering the K&C (KoramangalaChallaghata) Valley.  Build local STPs if necessary
  • Desilt: Lake was last desilited in 1971.  A proper desilting will increase lake capacity by one third and improve lake’s ability for rainwater harvesting

What has been done already?

  • We started working on this issue in early 2015 and managed to meet with representatives from BWSSB, BDA, LDA, KSPCB, Tehsildar’s office, DDLR and got lots of runaround. Elan has even met Ramalinga Reddy – minister in charge of Bangalore!
  • We have obtained a dated (circa 2008) DPR from BBMP. A DPR (Detailed Project Report) is the first step the government takes in implementing large projects.  It outlines the project and its needs.  The BBMP DPR can not be used any longer since the lake is now in the jurisdiction of the BDA.  BDA has told us that they will not re-use a BBMP DPR
  • We have met with experts to explore alternative solutions:
    • Tharun of Ecoparadigm has shared with us his expertise on anaerobic (and distributed STPs),
    • TV Ramachandra of the IISC has shared with us his expertise on Jakkur lake rejuvenation esp. the potential of wetlands
    • IIHS (Indian Institute of Human Settlement)
  • We have met with experts in the STP industry (eg. Strategy head for VA Tech Wabag) and learnt the basic chemistry of STPs (from our very own Byron Smith)
  • We have spoken with others who have rejuvenated Bangalore lakes. These include Suresh Nair (ex United Way – Lakes), Vibhutipura Lake Committee, Puttenahali Lake, and Jakkur Lake.  Our very own Gopal uncle has helped rejuvenate Munnekolala Lake
  • We have met with the “original guardians” of the lake – Principal Khan and his students from KK High School. These students have worked with Prof TVR to do exceptional research on the lake, water quality of borewells in the area and more
  • We are fortunate to have Upalokayukta Justice S. Adi supporting our efforts. He has been instrumental in getting government representatives to show up at meetings etc.  We hope that with his support we can pressurize Government to execute on the first step: survey the lake and fence it by year end
  • Lake Varthur finally had enough and started foaming excessively. We are hoping that the intense media attention we garnered in early May 2015 can be leveraged to pressurize Government

How can you help?  There are a few options:

  • OPTION ONE: Attend meetings with Government officials:  We meet with various government officials on a regular basis.  We post this information on our group lists and we always need support at these meetings.  Our immediate ask is for the lake to be surveyed and fenced.  We hope this work will be done by the end of 2015 latest.
  • OPTION TWO:Start becoming a technical expert on Lake Varthur. Once the lake is surveyed and fenced, we will push for the BDA to issue a DPR on the lake.   In order to make intelligent decisions on the DPR, we need to build relationships with experts in the field as well as do some primary research on our own:
  •  Understand STPs in K&C (Koramangala/Challaghatta Valley): Planned capacity vs. utilization, power costs, other costs, proposals for new STPs.  Work closely with BWSSB and LDA.
  •  Investigate alternative solutions and their applicability for Lake Varthur e.g. anaerobic/distributed systems, wetlands, phytotechnology, bioenzymesetc
  •  Learn from other lakes.  Visit and document experiences from Jakkur, Puttenahali, Kaikondrahalli, Munnekolala, Vibhutipura etc
  •  Map sewage lines coming in.  From where is sewage flowing into the lake.  Pictures and maps
  • Read the BBMP DPR. This is a good background document for everybody to read

Please let us know if working on this would be of interest to you.  mehasenthil@gmail.com

  1. 11206778_868111423262261_6223513484349643838_oBangalore generates ~1,200 MLD of sewage daily.  We have treatment capacity for 720 MLD, yet according to BWSSB data, on our best days, we treat just about 450 MLD.  Why can’t we at the very least use our capacity to its max?

 

The main problem is the fact that conventional STPs are energy intensive.  45-50% of operating costs are typically power.  BWSSB may simply not have enough power supply.   However, it is possible to build STPs that generate biogas from the sludge and use the biogas to run the plants.  For example, Kodungayur and Perungudi in Tamil Nadu add up to about 160 MLD and generate 1 MW biogas which can then be used to run the STPs.  Building STPs with the “power gen” option is slightly more capital intensive but useful given utility industry’s lack of funds for power supply for opex

 

  1. Are there other options to conventional STPs?

– wetlands:  wetlands have been used to treat sewage inflows but land needed is high.  Need ~100 acres of land for tertiary treatment of 1 MLD of water (STPs generally do primary and secondary treatment very well)

– Anaerobic STPs.  He called them UASB (Upflow Unaerobic Sludge Blanket).  They remove 65% of sludge compared to removal of 95% of sludge by aerobic treatment.  Most of the time, anaerobic STPs require an aerobic treatment stage after the first level of treatment.  Anaerobic STPs also find it difficult to handle fluctuating in incoming sewage.  Traditional, mechanical STPs require less intelligent operator intervention

  1. What advice do you give us for Lake Varthur?

– Varthur needs to be tackled much further upstream.  Capture any sewage coming into the valley system (K&C) and find a way for it to be treated.

– Consider the potential to “monetize” sewage:  e.g. STP output water can be sold for industrial purposes.  e.g. in Tamil Nadu, STP plants are selling their output to a nearby refinery

– consider that peak loads are from 6 to 10 AM

– consider the difference between dry and wet weather flows

– test every 3-6 months for COD, BOD, TSS at major inflow points. This will give you an indication of progress made

– re: dredging Lake Varthur:  Theoretically, you should dredge the lake only up to its clay level.  Soil from dredging can be used as manure or for building bunds.  Would not recommend using it as sand because of presence of organic matter.

– E.Coli – 3-10 days retention in a pond gets rid of E. Coli.

  1. What are Key Water Parameters and how are they measured?

BOD = Biological Oxygen Demand.  Gives you an indication of how much organics are in the liquid.  If organic matters is high, needs more oxygen to be broken down.  It is measured over 5 days.  Byron believes KSPCB standard is about 30 mg/litre of water for water going into lake or river.

COD = Chemical Oxygen Demand.  COD number would be similar to BOD number for water that only had domestic effluent.  If COD is different from BOD, its an indication that there may also be industrial waste entering the body of water

Also look at SS (suspended solids) and TSS (total suspended solids)

  1. How do STPs work?

Normal STPs use an activated sludge process.  Add sludge into the wastewater and aerate the fluid.  Takes 3-10 hours to break up the organics.

Activated sludge STPs are the industry convention and the bacteria breaking up the sewage need oxygen to work.  Output of this process is Co2

Anaerobic STPs use anaerobic bacteria to break up the sewage and these bacteria don’t need oxygen to survive and output is methane.

 

  1. Bangalore generates ~1,200 MLD of sewage daily.  We have treatment capacity for 720 MLD, yet according to BWSSB data, on our best days, we treat just about 450 MLD.  Why can’t we at the very least use our capacity to its max?

– 25% of operating expense of STPs is power.  You will find that BWSSB may be able to find the capex to build new plants but does not necessarily have the opex to pay for power and other running costs.  Therefore, plants are not optimally utilized

  1. Are there alternatives to conventional STPs?.

Yes.

  1. Wetlands – wetlands require a lot of land area in order to be effective.  They are not feasible as an only solution
  2. anaerobic STPs – have the advantage of having low power needs.  When considering this option, look at the “residence time” i.e. how long it takes to break up the organics.  (Residence time for conventional STPs is 3-10 hours).
  1. Load Variation – why exactly is it a problem to have your STPs being fed by stormwater drains that also carry sewage?

Background:  Most Bangalore STPs are fed by storm water drains/rajakulves which bring A MIX of sewage and rainwater into the STP plants.

It is true that conventional STPs should be able to work faster when the sewage is diluted by rainwater.  However, the problem arises from the fact that when you combine rainwater and sewage, the load on the plant will increase.  Therefore, the STP plant has to be oversized….

(aside: might be an interesting exercise to compare the cost of oversizing STP plants to the cost of laying an underground drainage system…)

 

One thought on “Varthur Lake”

  1. Vikas says:

    We are facing issues of excess water from STP even after using in flush tank and garden.You have mentioned that excess water can be sold to Refinery. Can you point to any Refinery who is willing to buy excess water.

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