The pollution problem of solid waste disposal is not different. Landfills and garbage overflow in most cities create another set of problem. There is also the problem of disposal of hospital waste. India generates around 25 million tonnes of municipal solid waste per year.
Municipal waste has a very high proportion of biomass. Because of high amount of biomass present in the garbage, pellets obtained from garbage have heating value of 4000 k cal/kg and bulk density of 500 kg/cubic meter. It is estimated that about 100 kg of moist garbage yields around 30 kg of fuel pellets. The fuel pellets burn without smoke. The ash residue is only 5 per cent of pellet weight and is a good potassium fertilizer.
Earthworms have been used to treat the waste. They provide ideal temperature, pH and oxygen concentration for speedy growth of useful aerobic and actinomycetes. The worm also produces enzymes which break complex biomolecules present in the garbage into simple compounds which are utilized by the microorganisms.
The oxygen provided to the microorganisms accelerates various bioprocesses speeding up the decomposition of organic wastes. The oxygen rich micro environment eliminates anaerobic micro-organisms preventing the formation of foul smelling, obnoxious compounds like hydrogen sulphides and mercaptons.