Soft Drink and Cookie Industry Wastewater Treatment by Anaerobic Contact Sequencing Batch Reactors

Abstract

Wastewaters resulting from soft drink, cookie, and other food processing industries can have high concentrations of chemical oxygen demand (COD), suspended solids (SS). fats, oil and grease (FOG), as well as low pH values. Treatment is often required before discharging these wastewaters to either a receiving environment or the sewer. These high strength wastewaters have been treated under anaerobic and aerobic biological conditions and/or chemically as reported in previous studies. In the research reported herein, a new reactor type, the anaerobic contact sequencing batch reactor (AnCSBR), which is a combination of the anaerobic sequencing batch reactor and anaerobic contact process was used to treat soft drink industry (SDIW) and cookie industry (CIW) wastewaters. Results obtained in this study showed that SDIW is highly biodegradable under anaerobic conditions. Laboratory scale AnCSBRs were able to achieve 98% SCOD and 74 to 97% TCOD removal under organic loading rates ranging from 0.36 to 8.6g COD/L.day for SDIW. Organic loading rates of CIW between 0.6 and 3.4 g COD/L.day resulted in TCOD and SCOD removals of 75 to 95% and 82 to 98%, respectively. The ability of the AnCSBR to achieve high FOG removal under relatively high loading rates is also described. 85 to 98% FOG removal was obtained for CIW which had influent FOG concentrations ranging between 850 to 3,800 mg/L with an average of 2,030 mg/L