AMMONIA REMOVAL AND DISCHARGES DURING STORM EVENTS - INTEGRATED APPROACH FOR A SMALL WWTP AND ASSOCIATED CSOS

An experimental research has been carried out in a small WWTP in order to study the impact of storm events, with a global approach including all CSOs. Special attention has been devoted to the ammonia removal a nd discharges into the receiving water during storm events. More than 100 rainfalls have been measured between September 1993 and December 1 994. The main results are: -the mass of ammonia discharged by overflow s without any treatment ranges from 50 to 90 % of the total mass trans ferred in the sewer system during rainfall periods. -the mass of ammon ia treated in the WWTP ranges from 70 to 140 % of the dry weather mass during the same duration, but with a mean concentration ranging from 24 to 76 % of the dry weather concentration due to the dilution effect . -the ammonia removal efficiency remains above 90 % even for strong o r long rainfall periods, thanks to the overdesign of the WWTP. (C) 199 7 IAWQ. Published by Elsevier Science Ltd.