Treatment of high strength wastewater in thermophilic anaerobic-aerobic moving bed biofilm reactors

Moving bed biofilm reactors were used for the thermophilic (55 degreesC) an aerobic-aerobic treatment of a constructed high strength wastewater based o n molasses. The anaerobic reactors were started with mesophilic inoculum, w hile the subsequent aerobic reactors were started without inoculation. The total amount of anaerobic biomass (suspended and attached) in the reactors stabilised at around 3 g VSS l(-1). Substrate utilisation rates up to 4.2 k g soluble chemical oxygen demand (SCOD) (kg VSS.d)(-1). were obtained at lo ading rates, to the anaerobic biomass up to 16.4 kg SCOD (kg VSS d)(-1). Vo lumetric removal rates up to 7.6 kg SCOD m(-3)d(-1) were achieved at loadin g rates up to 30 kg SCOD m(-3)d(-1) in the anaerobic reactors. The maximum loading capacity however, was not evaluated during the study. Average sludg e yields of 0.25-0.28 kg VSS (kg SCODremoved)(-1) were achieved in the anae robic reactors. The total amounts of aerobic biomass varied between 1.1 and 2.5 g VSS l(-1). A maximum aerobic substrate utilisation rate of 4.6 kg SC OD (kg VSS.d)(-1) was achieved at an aerobic biomass loading rate of 18.4 k g SCOD (kg VSS.d)(-1). Volumetric removal rates up to 6.8 kg SCOD m(-3)d(-1 ) were achieved at loading rates up to 27 kg SCOD m(-3)d(-1) in the aerobic reactors. The maximum obtainable removal rates per biomass or volume were not reached during the study.