Gas production by accelerated bioleaching of organic materials

Abstract

A process for gas production and accelerated bioleaching of organic materials by acid forming bacteria in beds of organic solids, such as landfills, passing the leachate of hydrolysis and liquefaction products of microbial action of the microorganisms with the organic material to an acid phase digestion zone to regenerate an activated culture of acid forming microorganisms for recirculation to the bioleaching zone. The supernatant from the acid phase digestion zone may be passed to a methane phase digestion zone operated under conditions to produce methane rich gas. The supernatant from the methane phase digestion zone containing nutrients for the acid forming microorganisms and added sewage sludge or other desired nutrient materials may be circulated to the acid phase digestion zone or to the bioleaching zone. Low Btu gas is withdrawn from the acid phase digestion zone while high Btu gas is withdrawn from the methane phase digestion zone and may be upgraded for use in SNG. The process of this invention is applicable to small as well as large beds of organic solids, such as waste landfills, provides simultaneous disposal of municipal solid waste and sewage sludge or other aqueous organic waste in a landfill which may be stabilized much more quickly than an uncontrolled landfill as presently utilized.