Biological Denitrification Using Saw Dust as the Energy Source

Nitrate contamination is one of the major problems in groundwater, which is increasingly becoming a threat to groundwater supplies. Nitrogen in groundwater also results from human excreta, ground garbage and industrial effluents, particularly from food processing plants. In order to remove nitrate from a water source, such as ground water the biological denitrification technology can be applied for which a carbon and energy source is needed. The aim of this study was to construct an easy to operate reactor to treat the NO3 contaminated (ground) water to such qualities that it can be used as drinking water for cattle. To achieve this objective it was investigated whether saw dust as an alternative carbon source for the bacterial denitrification, could be used. For this purpose a low maintenance reactor, which was inoculated with anaerobic digester sludge, was fed with nitrate rich (100-200 mgN/L) water. A 100% nitrate removal was observed when the feed water contained 200 mg/• NO3-N at a Hydraulic Retention Time (HRT) of 1 day, operating a stable reactor system. It was shown that similar nitrate removal rates were obtained when the reactor was operated at room or mesophilic temperatures.