Applicability of biological phosphorus removal process for kraft pulp mill wastewater treatment

摘要

Due to the stringent regulatory limits, Finnish pulp mills will require to lower phosphorus concentration in the effluent of wastewater treatment plants. Biological phosphorus removal (BPR) process, a cost-effective alternative for tertiary wastewater treatment, is widely used for the reduction of phosphorus from municipal wastewater. Characteristics of kraft pulp mill wastewaters were found suitable for BPR process. Applicability of BPR process for the treatment of kraft pulp mill wastewaters was studied using four laboratory-scale sequencing batch reactors (SBRs). One SBR was operated according to the conventional fully aerobic activated sludge (AS) principle. The other three SBRs were operated according to the BPR principle and an anaerobic/aerobic sequence was used for each reactor. Effluent phosphorus concentrations of the BPR reactors were significantly lower than that of the fully aerobic reactor and effluent soluble phosphorus concentrations below 0.3 mg/L were achieved. Other major effluent parameters such as BOD5, COD, AOX, pH of the BPR reactors were similar to those of the AS reactor. Moreover, values of these parameters were very close to those of the actual pulp mill AS wastewater treatment plant from which untreated wastewater was collected. This lab-scale study clearly demonstrated the potential for the application of the BPR process for the treatment of kraft pulp mill wastewater.