Treatment of Domestic Sewage in Horizontal-Flow Anaerobic Immobilized Biomass (HAIB) Reactor

Abstract

This paper focuses on the evaluation of the start-up period and the performance of a pilot-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor treating pre-screened domestic sewage. The pilot-scale HAIB reactor comprises a 14.5 cm internal diameter PVC tube 14.4 m long divided into five stages of 2.88 m each. Polyurethane foam cubic matrices with 1 cm sides were used as support for biomass immobilization. The reactor was operated at the mean hydraulic detention time of 4.3 hours and the experimental results presented refer to 15 weeks of operation at mean sewage temperature of 25°C and mean liquid flow rate of 20 l h−1. The mean chemical oxygen demand (COD) of the sewage, based on composed samples, was found to be 350 mg l−1. A short start-up period lasting nearly 8 weeks was observed by monitoring several parameters such as COD, biogas composition, methane concentration and total volatile acid (TVA) concentration. By the end of the start-up period onward, the effluent COD attained approximately constant values of 100 mg l−1 and 75 mg l−1 for non-filtered and filtered samples.