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

Joanna Struk-Sokołowska,Joanna Rodziewicz,B Kaźmierczak,K Piekarska,H Jouhara,J Danielewicz,M Kutyłowska

doi:10.1051/e3sconf/20172200169

Joanna Struk-Sokołowska, Joanna Rodziewicz + Show 5 more

Open Access

https://doi.org/10.1051/e3sconf/20172200169

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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 mgO 2 ·L -1 (efficiency wastewater treatment from 96.0 to 98.6%).

Highlights

The dairy industry is one of the biggest sources of industrial wastewater in Europe [12]. It generates wastewater characterized by a high content of organic compounds expressed as biochemical oxygen demand (BOD) or chemical oxygen demand (COD)
The SS fraction may be used by the microorganisms directly, while the XS requires a previous hydrolysis under the influence of extracellular enzymes, thanks to which these substances are transferred into the dissolved fraction
The COD value of the SI and XI fractions undergoes the smallest changes as a result of the activity of microorganisms

Summary

Introduction

The dairy industry is one of the biggest sources of industrial wastewater in Europe [12]. It generates wastewater characterized by a high content of organic compounds expressed as biochemical oxygen demand (BOD) or chemical oxygen demand (COD). The biodegradability of wastewater depends, among other things, on the availability of organic compounds (in the forms of dissolved compounds or suspensions) for microorganisms, substrate type, adaptation of the system, presence of toxic compounds, and temperature [34]. The most frequently used parameters characterizing the biodegradability of wastewater include the COD/BOD5 ratio. Its value above 2.5 indicates a high share of hardly biodegradable or non-biodegradable impurities, while a value below 1.8 indicates the susceptibility of wastewater to biological decomposition [5].

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