COD fractions changes in the SBR-type reactor treating municipal wastewater with controlled percentage of dairy sewage

¹ Bialystok University of Technology, Department of Technology in Engineering and Environmental Protection, 15-351 Wiejska St. 45a, Bialystok, Poland
² University of Warmia and Mazury in Olsztyn, Department of Environment Engineering, 10-719 Warszawska 117a, Olsztyn, Poland

^* Corresponding author: j.struk@pb.edu.pl

Abstract

The aim of study was to investigate the influence of percentage of dairy wastewater in the municipal wastewater on the changes of COD fractions during the cycle of SBR-type reactor. The scope of the research included physicochemical analyses of municipal wastewater without dairy wastewater, dairy wastewater, mixture of municipal and dairy wastewater as well as treated sewage. Both the concentrations and the proportions between COD fractions changed in the SBR cycle. In raw municipal and dairy wastewater - XS, insoluble hardly bio-degradable fraction of COD dominated (49.6 and 64.5% respectively). In treated wastewater SI, COD for dissolved compounds that are not biologically decomposed (inert) (from 62.1 to 74.6%) dominated, while XS fraction was from 19.1 to 24.4%. The consumption rate of organic compounds depended on the type of COD fraction, SBR cycle phase and the percentage of dairy wastewater. The highest rates of organic compounds consumption were noted in the phase of mixing. In the case of fraction SI, no differences in concentration in the SBR cycle time, were found. Concentration of COD in treated wastewater was from 34.8 to 58.9 mgO₂·L^-1 (efficiency wastewater treatment from 96.0 to 98.6%).