METHOD OF TREATING AMMONIA CONTAINING WASTE WATER BY WAY OF BIOLOGICAL DENITRIFICATION

摘要

PURPOSE:To provide a method of treating ammonia containing waste water by way of biological denitrification, comprising the step of subjecting the waste water to nitrifying treatment such that ammonia is left in waste water, circulating a portion of the nitrified liquied to a first denitrification process, and after completely nitrifying the remaining portion of the nitrified liquid at a second nitrification process, subjecting the same to denitrification treatment at a second denitrification process, whereby it is enabled to lower the running cost of the system. CONSTITUTION:Waste water 1 to be treated is introduced to a first denitrification process 7 together with sludge 6 restored from settling basin 4 after condensation and separation therein and a portion of nitrified liquid 11 supplied from a first nitrification process 8, so as to denitrify NO2 in the nitrification liquid by BOD components contained waste water 1. Ammonia contained in waste water 1 and the nitrified liquid is passed through the first denitrification process 7 as it is and introduced into a first nitrification process 8, where it is nitrified such that ammonia is left therein at a certain range of concentration (NO2 type nitrification). A portion of nitrified liquid 11 is recirculated to the first denitrification process 7, whereas its remaining portion is introduced to a second nitrification process 9, where residual ammonia is nitrified completely. Finally, at a second denitrification process 10, denitrification of waste water is completed.