From Kitchen Scraps to Clean Energy:

CSIR's AGR Technology Converts Waste to Wealth

Rapid urbanisation and changing lifestyles have led to significant solid waste management issues, with open landfills causing environmental harm through greenhouse gas emissions. Nearly half of this waste is biodegradable organic matter, which can be transformed into a valuable resource.

CSIR-Indian Institute of Chemical Technology (CSIR-IICT) has developed the Anaerobic Gas Lift Reactor (AGR) technology to address this problem. Led by Dr. A. Gangagni Rao, the AGR system, developed since 2013, is designed for Indian conditions and transforms organic waste into biogas through anaerobic digestion. This biogas serves as a clean energy source for cooking and off- grid electricity.

Additionally, the AGR process produces bio- manure or Fermented Organic Manure (FOM), enhancing soil fertility and crop yields. Replacing chemical fertilizers with FOM supports sustainable agriculture.

AGR technology offers numerous environmental benefits by diverting organic waste from landfills, reducing methane emissions, and minimising pollution. It accommodates various feed-stocks, including food waste, market vegetable waste, slaughterhouse waste, and animal manures. With 31 installations across 11 Indian states, the AGR system handles capacities from 250 kg to 10 tons of waste daily, demonstrating its versatility and effectiveness in sustainable waste management.

The adoption of AGR technology offers a multitude of environmental benefits. By diverting organic waste from landfills, AGR based biogas plants can significantly reduce methane emissions, a potent greenhouse gas. Furthermore, by processing organic waste, AGR technology promotes cleaner landfills, minimising environmental pollution and safeguarding public health.

The versatility of AGR technology is proven for variety of feedstocks such as food waste, market vegetable waste, mulberry waste, slaughterhouse waste, landfill leachate, animal manures, Organic Fraction of MSW (OFMSW) etc. There are about 31 installations across India in 11 states with varying plant capacities from 250 kg to 10 ton of waste treatment every day.

Mention in PM’s ‘Mann ki Baat’ Programme

The potential of organic waste to be a resource rather than a burden has not gone unnoticed. In January 2021, the CSIR- IICT high rate biomethanation technology based on Anaerobic Gas Lift Reactor (AGR) received a special mention in Prime Minister Shri Narendra Modi's Mann Ki Baat address. This recognition highlighted the groundbreaking nature of this innovation and its potential to revolutionise waste management practices.

A Case Study in Action: AGR based Biogas plant at the Bowenpally Vegetable Market Yard

Dr. B R Ambedkar Vegetable Market Yard in Bowen-pally, Hyderabad, serves as a prime example of the successful implementation of CSIR- IICT's AGR technology. Being the largest vegetable market yard in Hyderabad, it grapples with the challenge of managing a significant amount of organic waste - approximately 10-12 tons every day.

Beyond Electricity: Reducing LPG Consumption

The AGR system at Bowenpally also replaces about 30 kg of LPG daily in the market canteen, resulting in significant cost savings and promoting sustainable cooking.

CSIR- IICT's first commercial AGR- based biogas plant at The Akshaya Patra Foundation (TAPF) converts food waste into biogas for cooking, reducing LPG usage. The plant generates 120-140 cubic meters of biogas daily, replacing about 60 kg of LPG. The bio- manure produced is used as organic fertilizer, exemplifying a closed- loop system and earning the title "Wealth from Waste." This model showcases the potential of converting "waste to energy from kitchen to kitchen," highlighting the effectiveness of AGR technology in sustainable waste management.

Scaling Up: Decentralised Waste Management for a Sustainable Future

The success of TAPF highlights the potential of AGR technology. CSIR- IICT aims to expand AGR systems in urban and semi- urban areas struggling with solid waste management. These modular AGR systems are scalable, making them suitable for communities of all sizes. Decentralised waste management with AGR technology enables communities to manage waste disposal and energy generation independently.

CSIR- IICT, led by Dr. A. Gangagni Rao and Dr. S. Sridhar, has developed an integrated system combining AGR and Nano Filtration (NF) technology. This innovation efficiently treats sewage and organic waste, generating biogas, bio- manure, and clean, reusable water. It addresses waste management and water scarcity, promoting sustainability.

AGR and NF technologies are designed for scalability and affordability, making them ideal for developing countries facing similar waste management challenges. Their success in India can serve as a model globally, promoting sustainable waste management practices.

Future Prospects

CSIR- IICT's technologies transform waste into valuable resources, fostering sustainable development. Decentralised waste management empowers local communities, promotes circular economy principles, and improves public health by reducing landfill-related disease risks. The sale of excess biogas or bio-manure can generate additional income, enhancing economic well-being.

INTERVIEW

Dr. Srinivasa Reddy

Director, CSIR- IICT

Q. What challenges have you encountered in scaling up and implementing AGR technology across various regions, and how is CSIR- IICT addressing these challenges to ensure widespread adoption?

A. One of the major challenges that we have encountered is the non-availability of segregated organic waste although there are huge volumes of waste is generated on a daily basis. We propose the deployment of biogas plants at the source of waste generation to prevent logistic issues and also advice the clients to ensure the utility of biogas either for heat and/or power applications near the plant premises. Secondly, the temperature in the colder regions of India poses an economical issue due to the inclusion of heating elements. The microbial consortia are classified based on the digestion temperature and as mentioned above the temperature in the colder regions of India also demands suitable microbial cultures for efficient anaerobic digestion to take place for biogas generation. The potential of biogas generation depends on the type of feedstock, and hence the techno- economic feasibility.

Q. Please elaborate the environmental and economic benefits observed from the deployment of AGR technology.

A. Rotting food creates methane (CH4), a greenhouse gas with 21 times the global warming potential of CO2. Our AGR technology converts organic waste to biogas, which can replace LPG or generate power, reducing Green House Gas (GHG) emissions. Managing waste at the source benefits the environment and promotes sustainability by replacing fossil fuels with renewable energy.

A ton of organic waste can release 280- 296 kg of CO2 daily. Decentralised biogas plants capture CO2 and CH4, using them as fuel, thus reducing the carbon footprint and pollution from landfills. A 1-2 ton/day biogas plant can create jobs for 10-15 people during fabrication, installation, and operation.

Economically, the ROI for biogas plants varies. If used for power generation, the ROI is longer; if replacing LPG, the ROI is 3-3.5 years due to higher LPG costs (Rs. 90/kg) compared to electricity (Rs. 11/kWh). One cubic meter of biogas replaces about 0.4 kg of LPG or 0.7- 0.85 units of electricity.

We advocate a distributive model, setting up plants where waste is generated. This reduces hazardous effects from waste collection and landfilling. Large kitchens in hotels, hospitals, and institutions can adopt this technology to become self- sufficient in fuel and energy needs.

Q. How the AGR technology was indigenously developed at CSIR- IICT, and what were the key innovations and research milestones that contributed to its success?

A. Over a decade ago, CSIR- IICT began indigenising AGR technology to suit Indian conditions. European high- rate digesters, though impressive, were not economically feasible or suitable for India's waste types. Thus, CSIR-IICT developed the Anaerobic Gas Lift Reactor (AGR) technology, featuring efficient mixing, delinking of hydraulic and solids residence time, ammonia inhibition control, and scum cutting.

Field trials in 2013 at a 1- ton/day biogas plant in Toofran, Medak, involved treating various wastes and resolving operational issues like rapid acidification, biomass washout, pH maintenance, and C/N ratio adjustments. The AGR, a slurry digester with a three- phase separation mechanism, evolved over ten years to improve design, feedstock versatility, process efficiency, and yield. Customised designs are provided based on client needs, with a focus on the crucial element of operation and maintenance to ensure the success of biogas plants.

Contributed by: Science Media Communication Cell, CSIR-NIScPR, New Delhi.