Anaerobic sewage treatment in a one-stage UASB reactor and a combined UASB-Digester system

Abstract

The potential of a novel technology consisting of a UASB complemented with a digester (UASB-Digester) for mutual sewage treatment and sludge stabilisation under low temperature conditions was investigated. The performance of the UASB-Digester system was compared with a one stage UASB. The UASB reactor was operated at a HRT of 6 hours and controlled temperature of 15°C, the average sewage temperature in the Middle East countries during wintertime, while the digester was operated at 35 °C. The UASB-Digester provided substantially better removal efficiencies and conversion than the one stage UASB reactor (p<0.05). The achieved removal efficiencies in the UASB-Digester and the one stage UASB for CODt, CODss, CODcol and CODdis are "66, 87, 44 and 30" and "44, 73, 3 and 5"% for both systems, respectively. The wasted sludge from the UASB-Digester is much more stabilised. The performance of the UASB digester is as good as that achieved in tropical countries. Therefore, the anaerobic sewage treatment at low temperature in a UASB-Digester system is recommended