| Abstract | Cassava to sago processing industries in India are one of the energy intensive and waste generating industries. These wastes can be converted into energy and this has a potential to reduce the greenhouse gas emissions. The identified wastes from sago industry were cassava peel, wet pulp and waste water. Due to the amount of wastes generated and by disposing huge amount of waste water without proper treatment, serious environmental impacts were caused.
This study considered the Ravi sago factory in samarlakota to analyze the waste to energy opportunities in a micro level. In this factory, the process includes peeling, washing, rasping, straining and sedimentation. Sago is made from the sedimented wet starch through an indigenous machine. Sago is roasted or fried heating systems before drying to maintain its consistency. Fire wood consumption for the heating systems were 2100 tpd. During 1 ton of sago of production, 0.246 ton peel and 2.91 ton wet pulp, 12.67 tons waste water is produced. The energy potential from the wastes of Ravi sago factory such as peel, pulp, waste water were found to be 6780.9 GJ/ year , 24336 GJ /year and 12030.98 GJ/year respectively. Electrical energy requirement was found to be 1546 GJ/year. The possible waste to energy options for each waste were identified and discussed in chapter 4. Among all options biogas option is selected based on the industry energy demand, status of technology and characteristics of waste. This study selected cogeneration option to use the produced energy in the process because cogeneration is the sequential generation of electricity and heat with same primary input which can be used by means of biogas as the input to the gas engine.
As a part of the study, biogas plants of various capacities which are currently using sago waste water, corn starch waste water, cow dung were visited in the near by areas of samarlakota and also in Salem or the land of sago. The electrical and thermal energy savings were found for different capacities of biogas plants for both high potential wastes such as cassava waste water and wet pulp. The details of biogas plant of cassava pulp were gathered from the Asia biogas consultancy company in Bangkok.
The financial viability and environmental analysis is done for 3 wet pulp different input substrate capacities such as 50 tpd and 100 tpd ,160 tpd which indicate the negative NPV and low B-C ratio and low IRR with 25% feedstock availability. For cassava waste water, five different capacities are 50 m3/day,100 m3/day,200 m3/day,400 m3/day and 550 m3/day and results shows the positive NPV for all the 5 ventures with low pay back period and high B-C ratios because of 75% feedstock availability. The GWP by replacing fire wood for three wet pulp substrate plants of 50 tpd,100 tpd and 160 tpd is 371,744 and 1702 ton CO2 equivalent with carbon credits 4422$, 8850$ and 14180$ respectively. Similarly, for cassava waste water, GWP of five different capacities are 50 m3/day,100 m3/day,200 m3/day,400 m3/day and 550 m3/day were 351,526, 877 and 1138 ton CO2 equivalent with carbon credits 2917,4375, 7292 and 9463 $ respectively |