Biological treatment of papermill wastewater by sequencing batch reactor technology to reduce residual organics

Sequencing Batch Reactor (SBR) experiments have been conducted in the laboratory to study factors affecting the composition and concentration of residual organics in the effluent of biological wastewater treatment plants. Wastewater discharged by a papermill was used to feed four SBRs. The influence of process conditions, like duration of filling phase (FILL) or duration of reaction phase (REACT) could be demonstrated. The degree of elimination was dependent on the sludge age and on optimized process strategy. The highest COD removal and the best sludge settling properties for the papermill wastewater were obtained at a sludge age of 20 days with REACT period of 12 hours and duration of FILL phase of 0.5 hours. Pyrolysis GC/MS studies showed that the residual CODfrom the treated papermill wastewater consisted of refractory organic compounds such as lignins.