Evaluation of TOC concept in industrial wastewater at SART AS

Abstract

Approximately 98 % of the industrial wastewater that SART receives comes from offshore activities. Unlike municipal waste water, this wastewater contains relatively high Total Organic Carbon (TOC), and very little Nitrogen (N) and Phosphorus (P). The objective is to reduce TOC, and therefore nutrients N and P are added to the biological reactor. For the chemical and the biological processes, Dissolved Air Flotation (DAF) units are coupled with activated sludge. Combining chemical and biological processes is effective in reducing harmful components in the wastewater. In order to follow biodegradation on samples with different TOC concentrations, three laboratory bench tests were considered. Sludge washing of activated sludge and flocculation tests on selected water samples was done before start up of the bench tests. Samples before start up and at the end of each bench test were sending externally for Hydrocarbon (HC) analyses. During bench experiments more than 90 % of the initial DOC concentration was degraded within 3 days showing good effectiveness of activated sludge process. GC/MS results showed that most of the compounds identified before cycles belonging to glycol and glycol ethers that are known to be rapidly degraded. Overview of Advanced Oxidation Processes (AOP) for treating slowly biodegradable components is given.