Continuous Biological Treatment of Membrane Concentrates of Deinking Wastewater Streams from Pulp and Paper Industry

Abstract

Aims: The aims of this research paper is to investigate the elimination rates of chemical oxygen demand in 5 days (COD5), biochemical oxygen demand in 5 days (BOD5), suspended solids (SS or AFS) denoted as “food” (F) to biomass (M; microorganism) ratio (F:M), by targeting varying rates and concentrations of influent stream in a continuous biological treatment (CBT). Study Design: The experiment initially consisted of two acrylic cylinders with cone-shape bottom with an inner diameter of 20 cm and 65 cm, respectively. The setup is fitted with a heater and aeration system. Temperature of wastewater range is maintained at 30 – 36 degree Celsius to promote the growth mesophilic microorganism. Place and Duration of Study: Institute for Sanitary Engineering, Water Quality and Solid Waste Management, University of Stuttgart, Bandtale 2, 70569 Stuttgart, Germany, between January 2011 and August 2011. Methodology: The experiments were carried out in continuous activated sludge systems for short periods with variable feeds. COD5 is the main parameter which is used to evaluate the carbonaceous organic matter removal capacity. COD5 analysis was performed on the effluent of every experiment. CODmf was measured to assess the effect of SS content in the effluent on the COD5 elimination. CODmf analysis was performed in all stages of the experimental period and served as an indicator of true COD5 values. BOD5 is measured to evaluate whether the effluent is fully biodegraded after the experiments. Results: The COD5 result showed the highest elimination rate on day 89 at 45%.CODmf showed the highest elimination rate on day 89 at 44%. Biological oxygen demand in 5 days results showed the highest elimination rate on day 90 at 89%. Suspended solids (AFS) result showed the highest elimination rate on day 89 at 79% all parameters with Influent rate of 16.7 liters per day. DFZ436 showed the highest elimination rate on day 64 at 82%. DFZ525 and DFZ620 showed the highest elimination rate for both wavelengths recorded on day 64 at 84%, and 79%, respectively, with Influent rate of 7.2 liters per day. Conclusion: High level of elimination of non-biodegradable organics, inorganic and color constituents in the highly toxic and concentrated wastewater is ample proof of the effectiveness of the CBT in combination with the activated sludge system and membrane filtration technologies.