Analysis of Bakery Sewage Treatment Process Options Based on COD Fraction Changes

摘要

Municipal WWTP often receive industrial wastewater including bakery sewage. The effluent of bakery industry has a high biological oxygen demand (BOD). In addition to high BOD this wastewater contains high chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN) and dark color. The effect of bakery wastewater contribution on COD fraction changes in municipal sewage is presented in this paper. The study was conducted in July 2016 in WWTP located in Lipsk, East-North Poland. The sewage receiver is the Biebrza River. Volume contribution of bakery wastewater is 10%. Analytical results were used to compute the percentage value contribution of individual COD fractions in wastewater. During the study the following fractions were identified: SS – COD of readily-biodegradable dissolved organic matter, SI – COD of non-biodegradable dissolved organic matter, XS – COD of slowly-biodegradable non-soluble organic matter, XI – COD of non-biodegradable non-soluble organic matter. The method used for COD fraction determination in wastewater was developed based on ATV 131P guidelines (ATV-DVWK-A131P). The aim of the study was to determine the effect of bakery wastewater contribution on COD fraction changes during technical scale biological wastewater treatment with an activated-sludge process. The percentage contribution of individual COD fractions in wastewater were compared with shares in wastewater from other food industries (dairy, olive mill, tomato, sugar beet, potato processing, winery). In raw wastewater XS fraction was dominant 44.2%. SS fraction was 38.8%. In raw wastewater fractions SI, XI ranged from 2.3 to 14.8%. In the effluent the SS fraction wasn’t noted, which is indicative of microorganisms consumption. WWTP effluents were dominated (43.4%) by slowly-biodegradable non-soluble organic matter (XS). Non-biodegradable dissolved organic matter (SI fraction) had a high share of 42.3%.