Small and Large scale Community composting structures:
Each urban household approximately generates half kg wet waste per day which can be composted using the locally built cement structures for large communities or barrels for smaller communities as detailed below.
Cement structures based composting at a commercial complex:
There are 10 compost cement tanks of 5 ft x 3 ft x 2.5 ft (L x W x H) dimensions which can take in 800-900 kgs of shredded food and garden waste. Two more tanks, almost double in length, are meant for storage. Each tank has an outlet to release the leachate. All the 10 outlets are connected to a drain which takes the leachate out of the composting area and then gets connected to a series of water treatment channels and ends up finally in two tanks which supply water to the entire campus.
- No rodent and odour issues.
- Top layer if covered with dry leaves stops flies infestation and less leachate loss due to the mixing of dry leaves.
- That said, easy to handle large quantities. Anything beyond 250 kgs this method works well.
- Location inside the community cuts the transportation cost.
- Cost effective since it’s a onetime investment and long lasting.
Cost Estimate done by CTC for Nochi Nagar model community:
|Daily Wet waste quantity||Cost||Space required|
|2000 homes – 1 ton / day||Rs.5,60,000||840 SqFt|
|800 homes – 425 Kgs
100 homes – 50 Kgs
- So roughly for the estimated 425 kg per day wet waste from the 850 homes in the area (Nochi Nagar plus the adjoining street with 200 homes) it will cost around Rs 2,80,000.
- Space required will be around 400 sqft only and it is available within the Nochi Nagar Slum Clearance Board colony.
- The above calculation is based on the 5 ton compost Yard built for corporation in the cemetery opposite Loyola College.
Another detailed look at the design, cost and how to keep it low using local resources:
(from the popular blog savitahiremath.com – its got details about a variety of community composting methods):
With the help of a local mesthri (mason) who had built tanks at KVK and ample support from the resident association’s Management Committee, I got three tanks built in our 15ftx15ft compost room. The size: 10ft x 3ft x 3ft. The cost: Around Rs 35,000. The base of the tanks has a slope to help excess water drain out through an outlet fitted with a mesh. The mesh is necessary to prevent earthworms being washed away through it. With the help of three connectors, a single 1.5-inch pipe is connected to the tanks. All the excess water collected in this pipe flows out through a tap fitted with a valve which can be turned on and off, as required. When turned on, the water falls into a bucket placed in a small 1.5-foot-deep sump.
This excess water is nothing but nutrient-rich vermi-wash that can be diluted and used to water plants.
Large barrels for smaller communities:
Large barrels as shown below could work on the same model as above at a smaller scale for small apartments with half a dozen or a dozen households. It can even be placed on roof top.
Make it local to cut cost:
This can be made locally to cut the transport cost which could be significant. The stand can be manufactured locally using local welders. The barrels are available in plenty at Petrol bunks (which tranport engine oil using them) at Rs.500 each. Ot its available in some shops at Rs.900. There are smaller barrels for Rs.250 each available for even smaller apartments.