Denitrification of groundwater: pilot-plant testing of cotton-packed bioreactor and post-microfiltration

摘要

The use of raw cotton as carbon source in the denitrification of drinking water was tested in a field pilot-plant. The reactor treated water from a well in which the concentration of nitrate varied from 22 mg N l~(-1) in summer to a minimum of 9 mg l~(-1) in winter. The experimental reactor had a capacity of approximately 9m~3 and could be packed with up to 1500 kg of unprocessed cotton. The highest rate of denitrification observed was 0.36 kg N m~(-3) d~(-1), at a feed rate of 6 m~3 h~(-1). However, this performance could be sustained only temporarily as the relatively high water pressure caused serious compression of the bed. The long-term (six months) performance of the system was studied at feed rates of 0.8 and 1.5 m~3 h~(-1). The process was stable and 80-100