SULFIDE REMOVAL FROM ANAEROBIC WASTE TREATMENT EFFLUENT OF A PAPER-MILL

A labscale (20 l.) upflow reactor and a labscale (6 l.) biorotor reactor, which have been previously tested using composite wastewaters, were investigated for their suitability for sulphide removal from anaerobically treated papermill wastewater. Upon treating this wastewater, clogging problems occurred, in the upflow reactor, with all types of carrier material, and in the biorotor, only with the polyurethane sheets. These problems did not occur with systhetic wastewater without organic compounds using the same reactors. Due to these problems we concluded that the upflow reactor, at least in the configuration investigated, was not suitable for this type of wastewater. In the biorotor reactor sulphur reduction and clogging could be prevented by using Rasschig rings as carrier material at a rotation speed of 46 rpm. In this configuration of the biorotor reactor a sulphide removal rate of 620 mg/l.h was found at a hydraulic retention time (HRT) of 13 min with a removal efficiency of 95%. At lower rotation speeds the removal efficiency deteriorates seriously. Using polyurethane sheets or particles instead of the Rasschig rings the removal efficiency also decreased in the biorotor reactor. © 1990.