Influence of phase separator design on the performance of UASB reactors treating municipal wastewater

Abstract

The objective of anaerobic sewage treatment is to maximize the fraction of influent organic material that is transformed into methane, thus minimizing the COD fractions that are discharged with the effluent or in the excess sludge production. Experimental data in this paper show that in the case of application of a UASB reactor for sewage treatment, the phase separator design has an important influence on digestion efficiency. An efficient phase separator leads to retention of a larger sludge mass, which means that the mean solids retention time is increased. The data show that the mean solids retention time or sludge age is the fundamental operational parameter that determines the efficiency of the anaerobic treatment. A simple way to improve the phase separator performance is to apply parallel plates in the settling section of the UASB reactor, above the conventional phase separator design of triangular prisms with an open base.