標準活性汚泥法の浄化機能からみた施設余裕度に関する研究

抄録

This paper discusses the characteristics of the design and operation factors of activated sludge process which have been determined experimentally and of the treatment capacity of the process. A new kinetic model of substrate removal and metabolism has been developed. It is composed by 7 parameters, such as DNA, RNA and substrates including recalcitrant organic matter. The flow of aeration tank is described by a series of 4 complete-mixing tanks and that of final sedimentation tank is expressed using the limiting flux theory on the behavior of sludge blanket zone. By this model the changes of data obtained from the municipal sewage treatment plant were well simu lated.
The performance of activated sludge process is discussed based on the stationary state analysis using this process model. The concentration of recalcitrant organic matterincreases with the increase of the retention time of aeration tank. When the retentiontime is 20 hours, the recalcitrant organic matter is shown to be contained byabout 40% in the effluent organics. The allowance degree:λ of the facility is introduced in the following form, λ=(maximum daily flow rate under the condition of which effluent total BOD₅=20mg/l)/(design maximum daily flow rate) Conclusively, it becomes apparent that the allowance degree ranges from 1.15 to 1.65 when the standard operation values, such as retention time of aeration tank=6-8 hrs and the hydraulic surface loading=20-30m/day, are applied to the facilities of waste water treatment.