Nitritation-denitritation Study In Wastewater Treatment CAST Process

With the development of the living standard of the people, C/N of wastewater had become low, case sewage biological denitrification lacked carbon source, reduced nitrification efficiency etc. Shortcut nitrification-denitrification process, a new-type of microbial nitrogen removal process, not only decrease energy consumption (measured as O2) and carbon sources (measured as methanol) by about 25% and 40% respectively, but also can cut down reaction time as well as sludge production substantially, thus this technology is considered as a research focus at home and overseas. A pilot-scale experimental set-up of Cyclic Activated Sludge Technology (CAST) was constructed to investigate implementation of this technology systematically and to explore various factors as well as control means for it through actual domestic wastewater and artificial domestic wastewater treatment respectively.Via controlling DO concentration, the shortcut nitrification-denitrification sludge in the CAST pilot-scale plant treating actual domestic wastewater was started up rapidly at normal temperature(18-20℃) and pH values 7.18～8.63. Results showed that the rapid start-up operation of the shortcut nitrification-denitrification sludge was performed following a 28-day's continuous cultivation under operating conditions: Influent/Aeration(3h)-Settle(0.5h)-Decant/Idle(0.5h); SRT: 11d; DO concentration: 0.4-0.9mg/L.With simulation of muncipal wastewater for treatment object, the effects of DO,temperature,C/N and alkalinity on nitrification denitrification were investigated. The DO was divided into three cases DO>1.0mg/L,0.5mg/L