Treatment of high strength wastewater from fruit juice industry using integrated anaerobic/aerobic system

Abstract

This work aimed to study the treatment of wastewater generated from fruit juice industry (24–30 m 3/batch). Three treatment schemes have been investigated. The first treatment scheme was a batch activated sludge (AS) system and was operated at different aeration time up to 48 h. The second scheme was two-stage up-flow anaerobic sponge reactors (UASRs). Two-stage UASRs were operated at a total hydraulic retention time (HRT) of 13 h corresponding to an organic loading rate (OLR) of 8.7 kg COD/m 3 d. While, the third treatment scheme consisted of a two-stage UASR followed by an AS system which was operated at three different HRTs namely 10, 12, and 14 h. Long term experiments indicated the superiority of the third treatment scheme which operated at a total HRT of 23 h (UASRs: 13 h and AS: 10 h) in terms of chemical oxygen demand (COD), biochemical oxygen demand (BOD 5), total suspended solids (TSS) and oil & grease removal. The integrated system achieved an overall removal efficiency of 97.5% for COD, 99.2% for BOD 5, 94.5% for TSS and 98.9% for oil & grease. The treated wastewater produced from the UASR–AS system complied with the standards set by the Egyptian law regulating the reuse of treated wastewater in agricultural purposes.