Performance of laboratory-scale aerobic and anaerobic systems treating food-processing wastewater was investigated. The results obtained showed that BOD and COD of wastewater discharged from a potato-chips factory can be reduced by 86% and 82% using UASB reactor at an organic loading rate (OLR) of 2.9 kg BOD/m3·d and a hydraulic retention time (HRT) of 18 hr. Corresponding results for an activated sludge system, operated at an OLR of 8.9 kg BOD/m3·d with a HRT of 6hr were 86% and 84%, respectively.
Treatment of confectionery wastewater using UASB at a HRT of 12hr and an OLR of 4.4 kg BOD/m3.d gave satisfactory results. COD and BOD removals were 92.4% and 91.5%, respectively. The use of completely activated sludge system at a HRT of 6 hr and ORL of 8.4 kg BOD/m3.d gave lower results as compared to UASB reactor. However, characteristics of the effluents produced using the two systems were in agreement with the standards regulating discharge of industrial wastewater into the sewerage system. Based on the technical and economic evaluation of the results, engineering designs were made for the selected systems.