SEWER SYSTEM ODOR CONTROL IN THE LAKE BALATON AREA

In order to stop eutrophication and protect the water quality of Lake Balaton, the canalization and wastewater treatment system was redesigned in the late 70 s. Hence, regional sewer systems leading to subcentral treatment plants were established. Long retention times and long pressure sewer section, however, combined with the high sewage temperatures created a new environmental problem: the production of odorous and corrosive compounds such as hydrogen sulphide. In the present study, a preventive procedure to control anaerobic biodegradation processes in the sewage has been developed. It is based on the metabolic advantage of nitrate reduction over sulphate consumption. In a model experiment, problems deriving from the inappropriate application of nitrate addition were discovered, e.g. decreasing effectiveness by initiating undesired attached microbial growth, and denitrification and subsequent sludge loss in the secondary clarifier. The main concern of the system-specific procedure developed is to avoid local and general nitrate overdosing by an optimum arrangement of the dosing stations. This cost-effective procedure which prevents odour and corrosion problems has been successfully implemented in the Lake Balaton area.