SWM Digital Library - Calculator of Suchitwa Mission

No. of Households

Nos

Per capita waste generation

gm/day

In the absence of actual data, per capita waste generation per day may be taken as 300 gms for Rural areas, 350 gms for Municipalities and 450 gms for Corporation area

Population (on an average 4 members per house)	Nos
Total quantity of Biodegradable waste generation	kg/day
Incoming waste volume	m³/day
Volume of water to be added (The solid waste is mixed with equal qty of water - volume ratio of 1:1)	m³/day
Volume of digester tank for 45 days (retention time) =(Volume of waste + Vol. of water ) x 45	m³
Volume of gas holder tank (Digester size: gas holder size = 75 : 25)	m³
Biogas plant Size	m³
Say	m³
Height of biogas plant (m) Assuming depth of biogas plant as 3 m	3 m
Diameter of biogas plant (m)	m
Volume of inlet tank	1 m³
Volume of inlet tank	1 m³
Volume of filter tank (Filter tanks are provided for more than 200 kg/day capacity plants)	m³
Volume of Septic tank (Septic tanks are only provided for more than 200 kg/day capacity plants)	m³

Feedstock Quality

Daily Total solids 20% of incoming waste quantity	kg
Daily Volatile solids 80% of Total Solids	kg
Volatile solids per daily feed stock	kg/m³
Organic Loading Rate Organic Loading Rate (OLR) = Flow Rate ∗ Feedstock Concentration / Digester Volume	kg VS/m³.D
Check OLR< 2 kg VS/m3.D is OK
The pH in the biodigester tank should be as close to neutral as possible. Since the anaerobic processes in a biodigester produce acids. The most common pH problem is one of acidity. Beneficiary can do a simple litmus test on the biodigesters content. If the results are below 7, beneficiary must add a small amount of lime or grounded lime stone to normalize the digester's pH. Since excessive amounts of lime will not be soluble in the mixture and may harm the bacteria, beneficiary should never exceed a lime concentration of 500mg for every litre of mixture in the biodigester tank.

Biogas Generation

Biogas yield from 1kg food waste is about 80-100 litres Biogas yield from 1kg food waste is about 80-100 litres	m³
3 hrs storage as per IS Code, Recommended duration of storage for raw biogas could be as per design and local utilization requirements for medium and large scale biogas plants.
One cubic biogas can produce 4-5 kWh electricity depends on efficiency of genset and average methane content in raw biogas

No. of stoves

Nos

Cooking Potential

Hours of cooking for biogas stove
Assuming the average consumption of a biogas stove to be 0.4 M3/hour

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Biogas

Design Considerations

Density of biodegradable waste

500 kg/m³

Retention time

45 days