In urban areas, an unmistakable, overpowering stench often signals the presence of a waste processing facility in a neighbourhood. The foul odour emanating from these sites has long been a major concern for residents and civic authorities. It is also purportedly one of the main reasons behind the Greater Chennai Corporation’s (GCC) recent decision to shut down 168 Micro Composting Centres (MCC) and 88 Material Recovery Facilities (MRF) across the city.
Despite the challenges, these MCCs play a crucial role in Chennai’s decentralised waste management system. If foul odour and associated health concerns are the problem, a micro composting centre operated by the Namma Ooru Foundation in Pudupet offers a compelling solution.
Micro Composting Centre in Pudupet: A breath of fresh air
On a sunny afternoon, I visited the centre, tucked amidst a bustling mix of residences, a temple, a ration shop, and several commercial buildings. What stood out immediately was the absence of the usual stench. In fact, I could not even locate the facility at first.
More surprisingly, residents had no complaints whatsoever about the presence of a waste processing unit in their neighbourhood.
Over the past 1.5 years, this MCC has processed over 300 tonnes of waste, effectively diverting that amount of garbage from being sent directly to the landfill. The centre has sold around 50 tonnes of compost made from the waste to farmers in villages across Tamil Nadu.
So, what is the secret behind this odour-free composting in a dense urban locality?
Here is the step-by-step process of how Namma Ooru Foundation (funded through the Corporate Social Responsibility initiative of Indian Oil) runs their odour-free MCC.
Read more: Living with a ban on plastic: Tips from P Natarajan, Namma Ooru Foundation
Waste collection and segregation
The MCC has four staff supported by a Climate Associate, R Saravanan. Using the battery-operated vehicle given by GCC, the staff collect the vegetable waste from the nearby markets. To ensure nutrient-rich compost, they also gather bulk waste from public events, tea grounds from around 20 tea shops, and egg shells from about 15 fast food outlets. This forms the ‘green matter’.
The ‘brown matter’ is made from dry garden waste, sugarcane residue, tender coconut shells, and paddy straws, pulverised into a uniform mix.
Mix of green and brown matter is key to eliminating foul odour
To neutralise the odour, the green and brown materials are combined with horse dung in a 2:1 ratio. Inoculum bacteria (used to break down organic matter) are added to this mixture. “As the vegetable waste is directly mixed into the compost tanks without brown matter, it attracts bees and flies and becomes a health hazard for the community. Covering the green waste with brown matter prevents leachate and odour, making it non-intrusive for nearby residents,” explains Saravanan.
This mixture is added to the shredder. “Adding inoculum bacteria and shredding the mixed waste helps to speed up the composting process,” he adds.
Windrow composting: A balance of air, heat, and moisture
During the composting process, three main parameters — air, temperature and moisture — are critical. While many composting centres rely on tank systems that hinder aeration, this MCC uses the windrow composting method, laying the shredded waste in long rows on the open ground.
“At the beginning and end of the composting process, the shredded waste will be at room temperature. During the process, it will be more than 60 degree celsius. This helps to kill harmful bacteria while preserving beneficial microbes,” notes Saravanan.
Moisture levels are manually regulated to ensure consistency. After 4 to 6 weeks, it is moved to the maturing zone.
Read more: ‘Ellam Plastic Mayam’: Chennai’s solid waste problem and how to fix it
Community impact of the micro composting centre
After maturation, the final compost, now with an earthy smell, is ready for use. Any residual plastic is manually removed to ensure purity.
The compost is sold at ₹10 per kg, or ₹7 per kg when purchased in bulk. On average, only 15–20% of the waste ends up in landfills.
Challenges in operating a micro composting centre
Despite this well-thought-out process, challenges remain. P Natarajan, Founder of Namma Ooru Foundation, says that one of the major hurdles is ensuring a consistent supply of at least one tonne of waste per day. With most apartment complexes unwilling to segregate and give their waste to MCCs, markets are the primary source. But, building a rapport with vendors in these unorganised spaces took the team around one and a half years.
Labour shortage is another pressing concern, particularly for the labour-intensive segregation process. “We are trying to automate a few operations, but that raises concerns of potential job loss for these workers,” Natarajan notes.
A model worth replicating
The Pudupet MCC proves that it is possible to run an efficient composting centre by putting in some thought and using innovative methods. This model is worth replicating as,
- It is community-friendly
- It is odour-free
- Promotes a sustainable and scalable waste management process
- Makes effective use of resources from local markets.
Instead of shutting down decentralised waste management units, civic authorities can be more prudent to support and replicate clean, sustainable, and beneficial models like these.