Anaerobic Wastewater Treatment in the Food Processing Industry: Two Case Studies

This article relates two experiments with wastewater treatment in the food processing industry. One of them refers to the use of an anaerobic filter (meat processing industry) and the other to the use of an upflow anaerobic sludge blanket reactor-UASB (vegetable and fruit processing industry). In the first case, the study describes the performance of an anaerobic filter which has been working for 6 years and provides COD removal efficiency (including primary treatment) equal or better than 80% with an organic loading of 1.4 kg of COD/m³ day. The reactor has a bed of broken stones with size of 0.75 m having a medium hydraulic detention time of 13 h. Discharges of accumulated sludge in a false bottom below the filter are made at intervals of 2 or 3 months.In the second case, the study describes the performance of an upflow anaerobic sludge blanket reactor (88 m³) during 255 days of operation including the adaptation phase or startup. This reactor receives wastewater from vegetable and fruit processing including tomato , corn, guava and peach. At the end of each operational phase studied, the COD removal efficiency was about 80%. In the last phase (7.5 h hydraulic detention time), the organic loading was 1.4 kg of COD/m³ day and the hydraulic loading was 3.2 m³/m³ day.