Treatment of domestic sewage in horizontal flow anaerobic immobilized biomass (HAIB) reactor

This paper focuses on the evaluation of the start-up period and the perform ance 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 fi ve stages of 2.88 m each. Polyurethane foam cubic matrices with 1 an sides were used as support for biomass immobilization. The reactor was operated a t the mean hydraulic detention time of 4.3 hours and the experimental resul ts presented refer to 15 weeks of operation at mean sewage temperature of 2 5 degreesC and mean liquid flow rate of 20 l h(-1). The mean chemical oxyge n demand (COD) of the sewage, based on composed samples, was found to be 35 0 mg l(-1). A short start-up period lasting nearly 8 weeks was observed by monitoring several parameters such as COD, biogas composition, methane conc entration and total volatile acid (TVA) concentration By the end of the sta rt-up period onward, the effluent COD attained approximately constant value s of 100 mg l(-1) and 75 mg l(-1) for non-filtered and filtered samples.