A novel process using enhanced acidification and a UASB reactor for biomethanation of vegetable market waste

The processing of solid vegetable market waste was attempted in a two-stage digester. Initially, for the hydrolysis and acidification of waste, enhanc ed extraction process was carried out by continuous sprinkling of water ove r the bed of waste in a mild steel 1001 solid bed digester. The leachate ob tained after completion of acidification phase was further treated in 24.61 UASB reactor for biogas production. The effect of waste-liquid ratio, dilu tion and sprinkling rate on the digestion of waste were studied. A high str ength leachate, with a COD of 25,298 mg l(-1) and total volatile fatty acid s concentration of 11.3 g l(-1), was obtained as a result of hydrolysis and acidification in a very short retention time of 40 h. The COD reduction of 94% was achieved during UASB reactor operation at organic loading rate of 19.6 kg COD m day(-3). A minimum hydraulic retention time of 16 l(-1) was a chieved.