Abstract
The design of a city located in the Changjiang River Economic Development Zone,this paper is preliminary design of the the capacity of 50,000 tons of sewage treatment plant .
This design uses CASS (cyclic activated sludge system) processing technology.The process is the sequencing batch reactor (SBR) of anti-straight along the length of the pool is divided into two parts, the front of the selected area, also known as biological pre-reaction zone, the rear of the main reaction zone, then install to the Department ofmovements Decanter device, CASS in continuous water - water cycle of intermittent operation mode, set aeration - precipitation - water in one.The process is an aerobic / anoxic / anaerobic process alternately running, with some nitrogen and phosphorus removal, waste water flow to push run, but the reaction Region was completely mixed in the form of running in order to achieve simultaneous nitrification and denitrificationand biological phosphorus removal.For the average urban sawage,CASS process does not require a high degree of pretreantment,simply set the caorse grid and the grit chamber,without the primary sedimentation tank and secondary setting tank,do not need a huge sludge recycle system(in CASS reactor within about 2O% of the sludge return).
The CASS project design two pools, each pool CASS has located three separate reaction cell, each processing cycle of 4 hours, after water, aeration, sedimentation Decanter four stages to achieve the purpose of continuous water.The treated wastewater effluent quality required to meet the requirements of the local environmental protection departments: CODcr ≤ 60mg / l, BOD5≤ 20mg / l, TN ≤ 15mg / l, TP ≤ 3mg / l, NH4-N ≤ 10mg / l.
The aeration system consists of the construction supply blower, first announced by the microporous membrane aeration gas, there is uniform aeration, high efficiency air superiority.
The design of sludge treatment options remaninging under the cass reactor sludge characteristics of a high phosphorus content of sludge by pretreatment, mechanical dewatering, the final incineration.
Keywords: CASS process ;Wastewater Treatment Plant Preliminary Design ; Nitrogen and phosphorus removal