Municipal wastewater treatment in the anaerobic-aerobic baffled filter reactor at ambient temperature

This paper presents the pilot-scale experiments with anaerobic-aerobic treatment of municipal wastewater. As the anaerobic part of the pilot-scale system, the combination of the anaerobic baffled reactor and the anaerobic filter was used. The aerobic part of reactor was designed as an activated sludge system with the carrier of biomass (polypropylene cords). Two pilot-scale reactors (AN-I and AN-II) under real conditions were monitored. All technological parameters were identical in both reactors, but the AN-I reactor was inoculated with the psychrophilic digested sludge. The HRT in the anaerobic and aerobic parts of reactors were about 15 hours and 4 hours, respectively. The temperature in both reactors varied during the year from 4.5 to 23 degrees C. During the yearly operation time both systems removed all monitored parameters with relatively high efficiencies (COD-78.6-83.0%, BOD5-92.5-94.0 and SS-80.9-92.7%). The intensive nitrification process was observed during the whole year in both reactors (under average temperature of 5.9 degrees C in January 2000, too). The average removal of the NH4-N varied during the year from 46.4 to 87.3%. In both systems the effective denitrification process was observed, too. In the real conditions it is possible to operate such systems for a long time without removing excess sludge.