200t/h Domestic Sewage Treatment Process Design

This study presents a systematic conceptual design of the process that is expected to purify domestic sewage using physical processes associated with biochemical and chemical processes.Based on the main objectives,decision structure,and hierarchical decision suggested for wastewater treatment process design;an integrated physical-biological-chemical treatments conceptual process for the low-cost treatment of domestic sewage is proposed.The process design procedure is carried out in five main steps:(1) sewage treatment process flow sheet identification;(2) sewage treatment fundamentals;(3) design and technological calculations with equipments selection;(4) workshop cost estimation;(5) and the systematic analysis of environmental and fire protection, process safety and health.With the present process,the domestic sewage is subjected to undergo preliminary(coarse materials and grit removals) and primary(primary sedimentation) treatments followed by biological treatment in the biological nutrient removal system (CAAA system);finally the treated wastewater is settled in final settler and then disinfected before being discharged.With the operating design conditions[25℃; preliminary treatment(coarse screen and aerated grit chamber with DT = 5 minutes); primary sedimentation(with DT = 1.8 h) treatment followed by CAAA system (secondary treatment):anaerobic bioreactor with HRT = 1.5 h,anoxic bioreactor with HRT = 1.5 h and SRT = 5 d,aerobic bioreactor with HRT = 3 h and SRT = 5 d],the designed treatment process has a high efficiency.The BOD₅,TSS,nitrogen, phosphorus removal efficiencies attained high treatment levels(95%,95%,80%,and 80%respectively).