India’s Silicon Valley, and once upon a time, the city of lakes, Bengaluru will be uninhabitable by 2025, scientists of the Indian Institute of Science warned in 2016.
According to the scientists in the study, rapid urbanization and expansion between 1973 and 2016 caused a 1,000% increase in paved surfaces and a decline of 88% in the city’s vegetation, while Bengaluru’s water bodies declined by 85% between 2000 and 2014.
Six years after the study, not much has changed. The city’s largest remaining lake in the city, Bellandur, spread across 950 acres, and the second largest, Varthur, spread across 500-acres were recorded frothing even at the end of 2021.
“Almost all lakes that are part of Bengaluru’s three water valleys are in bad shape. Untreated and partially treated sewage loaded with chemicals and petrochemicals freely flows into them causing the formation of biofilms and frothing,” says Leo Saldanha, environment activist and founder of NGO Environment Support Group (ESG) in Bengaluru.
Experts point out that this crisis stems largely from the fact that the city’s civic bodies have been unable to connect all households and industrial units with sewer networks.
The city’s population has almost doubled in two decades, from 5.77 million in 2001 to 12.76 million in 2021, according to the World Population Review which considers it as the 24th most populous city in the world and the fastest-growing Indian metropolis behind New Delhi, growing a whopping 38% from 1991 to 2001.
Meanwhile, the city’s sewage and sanitation infrastructure are struggling to keep pace.
Fats and Phosphates
Studies conducted over the past few years by the Centre for Ecological Sciences at the Indian Institute of Science (IISc), Bengaluru, say the frothing observed on lake surfaces is a consequence of nutrient enrichment (Nitrogen and Phosphorus) in the lakes due to the mixing of untreated sewage, mostly from household waste, detergents, agricultural waste, and industrial effluents.
“Extra phosphorus gets trapped in the sediment and with high-intensity winds, the churning of lake water happens, leading to the release of phosphorus from sediments, forming froth,” finds the lead author Prof TV Ramchandra of the IISc study.
Phosphates and Fats, oils, and grease (FOG) (also known as lipids) are the most common pollutants in wastewater and are classified as slowly biodegradable surfactants, added Professor Harini Nagendra, who leads the Center for Climate Change and Sustainability at Azim Premji University.
Sewage Fat To Energy
Bangalore generates 1440 MLD wastewater and has 33 Sewage Treatment Plants (STPs) with a total treatment capacity of 1370 MLD, the Bengaluru Water Supply and Sewerage Board (BWSSB) website claims.
Environmental activist Leo Saldanha claims “most STPs are malfunctioning due to overload, poor maintenance, and the use of wrong technology.” Much of the sewage – treated and untreated – is finding its way into the city’s lakes, he said.
But even fully functional STPs that produce “treated wastewater” leave in some amount of lipids; the STPs that are currently being used in India don’t fully degrade the fats. Typical STPs can remove only 70-92% of fat content depending on the technology, Chilean scientists have shown in a 2019 study.
Bengaluru-based entrepreneur Julesh Bantia, who runs a biodiesel plant-Eco Green Fuels-based on used cooking oil (UCO) and other vegetable feedstocks, has developed a process by which lipids present in fecal matter and sewage can be converted into biodiesel.
Biodiesel is a renewable, biodegradable, and low-cost fuel manufactured from vegetable oils, animal fats, or used cooking oil and is one of the most attractive among the options explored for alternative energy sources. Using biodiesel as a vehicle fuel increases energy security, improves air quality and the environment, and is safe to handle, as per the US department of energy.
Another benefit, of course, is that the raw material is abundant. As Bantia explains, “Every person on average defecates about 300 g poop every day. The fat content in the poop is approximately 3% that doesn’t degrade easily in the STP plants,” said Bantia.
Besides, sewage also contains lipids from other sources as well, such as edible oil, used cooking oil, and industrial oil – from home kitchens, restaurants, commercial and industrial sources. Hence, the total fat content in sewage is likely much higher.
In fact, the content of lipids present in active sewage could be as high as 12.3%, Chinese scientists revealed in a 2017 study.
“Sewage lipids can be put to good use. Ideally, they need to be removed from the sewage sludge before it enters the clarifier (constructed downstream of the STP to separate the treated wastewater from the biological mass). If we don’t remove the lipids at this level, they get miscible in water and flow into lakes and then to irrigated farmland. These lipids are responsible for microbial growth in lakes and also foaming.”
In 2019, Bantia submitted a proposal to enable separating the lipids at the STPs at the office of Bellandur lake STP. STPs in the city are managed by the Bangalore Water Supply and Sewerage Board (BWSSB).
Bantia says his plans are scalable as per the volume of sewage. He did not receive a response from BWSSB.
This reporter also attempted to reach the Board’s Chairman and IAS officer N Jayaram via phone and email several times in the past two weeks but he remained unavailable for comment.
At last, the chairman's office asked this reporter to speak with Chief Engineer (Wastewater Management, BWSSB) BC Gangadhar who didn’t respond till the time of publishing this story.
Mr. Gangadhar told The Dialogue, "I have taken over the charge only two years ago so I am unaware of Bantia's proposal. Please ask him to submit the proposal to me now. I will surely look into the prospects of his project."
On the presence of fat in sewage that might be going out of the STPs along with treated wastewater, Gangadhar said, “I don’t have an idea on the presence of fat in treated wastewater. We have not looked into this aspect."
“Over 95 percent of the sewage in the city is being treated. The rest 5 percent of drains are also being linked to STPs. Moreover, most of the treated wastewater is being sent to land refill in the Kolar district which is far away from Bengaluru. So, it is unlikely that the wastewater is contaminating the lake," Mr. Gangadhar claimed.
The STP (Active Sludge System, that is normally used in India) typically follows three major stages of treatment:
Primary Treatment: Floating debris such as plastic bags, leaves, paper, etc. are removed from the raw sewage.
Secondary Treatment: In this stage, oxygen (air) is mixed into the sewage to activate the microbes and convert the solid waste into sludge (biomass). The sludge can be removed, de-watered/ dried, and used as manure for agriculture and garden purposes. The water-free from sludge is sent to a clarifier.
Tertiary Treatment: Sludge-free water is filtered through a pressure sand filter and an activated sand filter to remove suspended impurities. Then it is disinfected to kill all the bacteria present in it by either chlorination or ozonation or with ultraviolet light. This treated water is then pumped into storage tanks or water bodies.
Bantia proposes installing a tricanter in between the secondary and tertiary treatment processes. “A clarifier can only separate solids from liquids because of its slow centrifugal speed (45 minutes per rotation). Since oils and water both are liquids, they remain miscible and come out of the STP together,” he said.
“Lipids can be separated at the STP by putting a tricanter before the clarifier. The tricanter is a type of centrifuge that can separate and discharge three different constituents-oil, water, and sludge-simultaneously due to their different densities. After drying, the fat can be converted into biodiesel by using a simple chemical process-transesterification. But instead, it is being mixed in the lakes causing health and environmental hazards,” explained Bantia.
Tricanters are not generally used in the STPs in India. The cost depends upon the size of the centrifuge, speed of its rotation, and other features. As per e-commerce portal Alibaba, an industrial tricanter for wastewater treatment can cost up to Rs 18 lakh.
Bantia said, “Tricanters would increase the cost of STPs for sure, but considering environment and health hazards and prospects of renewable energy source, the investment would be value for money.”
The conversion of sewage fat into biodiesel could be a game-changer not only for Bengaluru but for the entire country where many rivers and lakes often froth and make headlines.
Currently, about 3/4 of India’s total energy demand is met by three fossil fuels – coal (44%), oil (25%), and natural gas (6%), as per the 2020 statistics from International Energy Agency. Modern renewable energy has a merely 3 percent share and the rest is met by biomass and other means, says the report.
But, countries can cut down carbon emissions by 50-85% using biodiesel, one study finds.
Fecal Fat: A big pollutant for wetlands
Fecal matter is considered one of the worst pollutants in water bodies as it represents an increase in nutrient load and a potential spread of waterborne diseases. Fecal lipids or sterols (β-stanols that are products of cholesterol) are indicators of anthropogenic sewage pollution in the environment.
A recent study by German scientists suggests fecal lipids or sterols (5β-stanols) a43 one of the factors behind the “eutrophication” of the Baltic Sea and associated rivers apart from Phosphorus and Nitrogen derived from agriculture fertilizers.
Eutrophication is defined as the enrichment of water by nutrients, which causes accelerated growth of algae and cyanobacteria and plants that release extracellular polymeric substances (EPS) causing a disturbance in water ecology. EPS are known to form biofilms on water surfaces that act as biosurfactants and contribute to the frothing of water bodies. This biofilm also lowers the oxygen content, killing off aquatic life that is essential to maintain the quality of water.
But even algal microfilms can also be used to produce biodiesel, recent studies have proposed.
Utilizing lipids in sewage
Bantia’s proposal (a win-win approach that would help rid these ecosystems of pollutants while producing energy) is not without precedent.
A 2017 study published in the Journal Biotechnology noted: The utilization of fecal waste for the production of biofuels is environmentally and economically beneficial.
Extensive research is being conducted all over the world to produce fuels from renewable biomass. After all, lipids in sewage sludge (after treatment at STP plant) are considered to be high-class raw materials for biodiesel or other valuable products and are readily available at no cost.
In 2020, Chinese scientists highlighted this potential in their study published in Nature, and Korean scientists demonstrated the extraction of lipids from sewage sludge in a paper published in Energies.
In the US, Dr. Asanga Padmaperuma, Senior Research Chemist in the Energy Processes and Materials Division at Pacific Northwest National Laboratory (PNNL) under the United States Department of Energy, recently wrote an article “The Economics of Poop for Creating Biofuels”.
Published on the US government portal on energy in October 2021, the article notes, “The energy, nutrients, and metals contained in the untreated sludge at thousands of the nation’s wastewater resource recovery facilities have the potential to be transformed into a renewable, cost-effective feedstock for liquid transportation biofuels.”
The PNNL has developed an efficient thermochemical waste-to-energy conversion technology (hydrothermal liquefaction, or HTL) that can rapidly convert solid sludge and other biosolids directly into versatile biocrude.
The technology benefits the wastewater sector because it is more efficient at destroying solids and recovering carbon than traditional sludge treatment processes and creates a new source of revenue—fuel sales—that helps offset costs and improve environmental services, he noted.
The lab also determined that integrating HTL into the existing fleet of treatment facilities could increase total national energy recovery from wastewater sludge by 188% and reduce total disposal biosolids costs by 43%—or $1.4 billion per year—from current practice.
Meanwhile, in Israel, a company called Enzymocore has been making biodiesel from wastewater’s “brown grease” for the past six years.
The Indian context
For India, the potential is immense. India generates 62 million tonnes of waste (mixed waste containing both recyclable and non-recyclable waste) every year which is projected to rise to about 150 million tonnes by 2030.
A large part of this goes to water bodies such as lakes, rivers, and seas. Disposal of domestic sewage from cities and towns is the biggest source of pollution of water bodies in India, says a recent report of CPBC.
In fact, Indian scientists from Chandigarh College of Technology and Chandigarh Engineering College, Chandigarh too have proposed a similar technology to convert the lipids present in Sewage sludge into biodiesel in their paper published in June 2021.
When it comes to Bangalore, with its nearly 1.2 crores (12 million) population, on average, generates 36 lakh kg (3.6 million kg) of excreta every day.
In 36 lakh kg fecal matter, fecal lipid content could be around 1 lakh kg (100,000 kg) which can generate up to 92,000 liters of biodiesel every day, estimated Bantia.
Bantia conducted experiments by collecting “treated sewage water” that was being discharged in the lake and managed to obtain biodiesel. He has been running a plant on the outskirts of Bengaluru since 2008 that has the capacity to produce 40,000 liters of biodiesel every day using vegetable, and animal fat. It was recognized as one of the first biodiesel plants in Karnataka.
“The STP officials denied me even a pilot project to show them how useful this process could be to address the long-pending problem. On top of that, they would want me to pay for the fecal fat that I propose to convert into biodiesel. This shows the administration and the government’s lack of interest in addressing the lake pollution and generating biofuel from waste,” alleges Bantia, who followed up a couple of times to pursue this project but to no avail.
Bantia’s proposal continues to gather dust, even as the BWSSB and the state government have been battling court cases for their alleged negligence to protect the city lakes from sewage.
“There is no biofuel plant on any of the lakes under BBMP,” confirmed Bhuprada, BBMP executive engineer.
When asked about the presence of fat in treated water and the feasibility of the process to convert sewage fat into biodiesel, she said, “I have no idea about it.”
The Karnataka State Pollution Control Board (KSPCB) officials also denied having any idea of lipids present in the treated water. In Bangalore, the KSPCB shares responsibility for the quality of water supply with the BWSSB.
Why is biodiesel important?
“Harvesting reusable energy products from all forms of waste should be prioritized, provided the costs are economically viable and the process is not polluting. Karnataka and other governments must encourage such innovations which not only offer solutions to the environmental and clean water crisis but also help meet India’s renewable energy needs in the future,” said Charmaine Fernandes Sharma, a renewable energy expert based in Bhadohi city of Uttar Pradesh who is also the Member of Task Force on Best Practices for India’s cleanliness drive Swachh Bharat Mission.
Sharma, who is herself a biodiesel entrepreneur and managing partner at Observing I Ecotech, lauds Bantia’s efforts, recognizing that India’s energy security will remain vulnerable until alternative fuels are developed based on renewable feedstocks.
Fossil fuel resources are non-renewable and at the current rate of extraction, petroleum oil will run out in 53 years, natural gas in 54, and coal in 110, as per a 2015 World Energy Outlook study by the International Energy Agency.
India consumes 102 billion liters of diesel annually. As per the Biofuel policy 2018, the country aims to blend 5% biodiesel by 2030. That means nearly 5 billion liters of biodiesel are needed per year to meet the targets. However, it blended a dismal 0.16%, as per the United States Department of Agriculture report, 2020.
Biodiesel is predominantly obtained from vegetable oils such as rapeseed, palm oil, and others. However, the high cost of cultivation of oil crops and shrinking of agricultural lands for growing biodiesel feedstocks has contributed to the increase of food prices over the past few years, raising the concerns of food shortage versus fuel crisis.
Used cooking oil (UCO) is a renewable feedstock but India lacks a proper network to dispose of UCO in a traceable manner and hence most of it goes back to the food chain instead of biodiesel production. The Dialogue has extensively covered this issue in 2021.
That is why proposals such as Bantia’s hold promise. Municipal sewage sludge is an inevitable waste and can be envisaged as a no-cost, readily available, and non-edible feedstock, which can make biodiesel production more viable. IISC’s Dr. Ramchandra said, “All innovators who wish to work for the environment and upkeep of the water bodies should be welcomed.”
Overall, very little work has been done in India on garbage to energy projects, admits Karthik Ganesan, Fellow, and Director - Research Coordination, Council On Energy, Environment And Water (CEEW), New Delhi.
Sharma agrees. She says she’s been trying hard for many years to cut the red tape in many states to get approval for a waste-to-energy plant that uses all kinds of garbage to produce biodiesel through a pyrolysis process.
In pyrolysis, shredded waste is converted into Hydrocarbons (as per their composition) in a high-temperature reactor without incineration of any material and hence no emission of carbon dioxide, Dioxins, and Furans.
After much struggle, Sharma and her team have established one pyrolysis plant at the Indian Navy establishment in Vizag in 2021. Being part of India’s ambitious scheme Swachh Bharat Abhiyan, she has access to many government frontals and has been sensitizing the state governments to focus on garbage to energy projects for many years.
“It is almost impossible to cut the red tape and corruption network and get this RE project approved despite the fact that many large cities like Delhi, Mumbai, and Surat have piled up mountains of stinking garbage and don’t know what to do about it,” Sharma said.
Multiple Agencies in Rejuvenation works
Although they do not seem to be prioritizing waste-to-energy solutions, the agencies responsible for maintaining the health of Bengaluru’s lakes do have rejuvenation projects in the pipeline, mostly the result of various orders issued by courts and the National Green Tribunal (NGT), a statutory body that handles environmental disputes. (In 2021, the NGT imposed a Rs 24 crore fine on various government agencies for their failure to upkeep a Bengaluru lake.)
Activist Leo Saldanha alleges, “These efforts are being carried out by different agencies. The plans are created in a silo, are not executed well, and even work at cross purposes at many places. There is no comprehensive approach to deal with such a big environmental disaster.”
For instance, while Bruhat Bengaluru Mahanagara Palike (BBMP), the city’s civic body, manages 167 lakes, BDA (the Bengaluru Development Authority) manages 33 lakes including Varthur and Bellandur lakes, and the Bengaluru Water Supply and Sewerage Board (BWSSB) manages the sewage treatment plants set up across the city including at lakes.
Nevertheless, the three major approaches being applied are:
*Desilting: The National Green Tribunal (NGT) set up a committee of experts headed by Justice Santosh Hegde. As per the NGT order, BDA, the lake’s custodian, is responsible for de-weeding and desilting the lake by May 2022.
So far, over 22 percent of the desilting work has been completed in Bellandur lake and 35 percent in Varthur lake.
“The work got delayed due to the pandemic and objections by some activists who raised the presence of heavy metal in Bellandur. We hope that the work will be completed within the deadline”, says Dr Ramchandra, one of the three members in the panel appointed by the NGT to oversee the lakes rejuvenation work.
*NEERI Master Plan: As per the Karnataka High Court directives, the BBMP has roped in CSIR-National Environmental Engineering Research Institute (NEERI). NEERI has proposed RENEU (in-situ drain treatment of the lake) and Phytorid (a wetland system-based sewage treatment) for the draining treatment of the lakes.
Upgradation of STPs: In response to several orders issued by NGT, Karnataka State Pollution Control Board (KSPCB), and courts, Bengaluru Water Supply and Sewerage Board (BWSSB) is upgrading 20 STPs for the removal of biological nutrients, phosphorus, potassium, and nitrates, that spur the growth of water hyacinth.
Other 13 STPs that have been constructed over the past three years have the necessary modifications for the removal of biological nutrients. Moreover, BWSSB is also undertaking a survey to identify drainage lines that are letting out sewage into the stormwater drain network. These lines are being connected to big lines connecting the STPs.
Karnataka State Pollution Control Board’s response
While scientists like Dr. Ramchandra and activist Saldanha insist that a significant amount of the untreated sewage is still being discharged into Bellandur’s catchment area every day creating a toxic environment fertile for disasters like fires and foam, the Karnataka State Pollution Control Board (KSPCB) refutes their claims.
As the government agency responsible for ensuring the compliance to standards related to discharges to the environment in the state of Karnataka, KSPCB has regulatory oversight over BWSSB, BBMP, and BDA on the issue of sewage in Bengaluru’s lakes. It is tasked with inspecting effluent treatment plants for their effectiveness and advises other government bodies to take corrective measures where necessary.
Syed Khaja Mohiddin, Senior Environment Officer and member of the KSPCB insisted, “Almost 90 percent sewage in Bengaluru is being directed to STPs now. Our STPs are working on the technology approved by the Central Pollution Control Board.”
Khaja didn’t respond to questions on the possible reasons behind froth and fire in many lakes across Bengaluru.
However, he said he will look into Bantia's proposal. “If Bantia submits his proposal to us, the technical advisory committee would surely evaluate the process developed by him.”
When informed about Khaja’s positive response, Bantia says he will submit the proposal to KSPCB.
This story was produced with support from Internews' Earth Journalism Network. It was originally published on 20 February 2022 in The Dialogue and has been lightly edited for length and clarity.
Banner image: Varthur Lake / Credit: Pradeep KS.