| South Area Wastewater Treatment Plant of DAQING city occupy6.6hectareground and serves for160thousand people, its handling capacity is sixty thousand tonper day. The main process of Plant is biological aerated filter and biologicaldenitrification filter adopted widely internationally, the pretreatment process used is acoagulation sedimentation craft with baffle reaction tank and inclined plate settlingtank, the treated wastewater quality accords with the GB18918-2002named《Discharge standard of pollutants for municipal wastewater treatment plant》,thirtythousand tons effluent is discharged to western main canal of DAQING directly whichis treated above the B of primary standard of GB18918-2002, another thirty thousandtons effluent as sight water is discharged to BILI Lake which is treated above the A ofprimary standard of GB18918-2002. The hydraulic detention time of coagulationreaction tank is much longer than the designed value for the actual treatmentwastewater yield is far lower than the designed wastewater yield, the gridding boardlaid in the coagulation reaction tank is often jammed for the improper gridding boardarrangement, these problem leads to the lower flocculation efficiency, so the SS valueof coagulation sedimentation craft effluent is too high to treated efficiently by the nextprocess-biological aerated filter, this problems becomes extra serious during May andJune for the50-60%wastewater flow rate increasing together with the deterioration ofwastewater quality showed in the much fluctuation of COD and BOD value, thisimpact load to the coagulation sedimentation and the next biological aerated filtercertainly leads to the unqualified water discharge out of the Plant.The key problem existing in the coagulation sedimentation tank craft of thewastewater treatment plant is drew based on the wastewater treatment craft and it’sdesigned and running parameters analysis, techniques reconstruction is put forwardand actualized, the plan includes the new coagulant screening program-the griddingboard rearrangement and structure alteration of the coagulation reaction tank-the innercoagulation reaction efficiency evaluation of coagulation reaction tank-sludgedischarging optimizing.Iron trichloride and polymeric aluminum ferric chloride coagulation effect iscomparative studied evaluated by the SS,COD and TP removal efficiency for thewastewater, the SS and COD removal efficiency of polymeric aluminum ferricchloride is far beyond the ones of iron trichloride with the84.7%～91.7%SS removal efficiency and77.2%～86.8%COD removal efficiency under the40～140mg/Lcoagulant dosage, the TP removal efficiency have not difference between the twocoagulants and is affected mainly by it’s dosage, polymeric aluminum ferric chlorideis choose as the coagulant and it’s optimized dosage is ascertained as80～120mg/L.Based on the actual operating state, the No3coagulation reaction tank is alteredincluding the structure simple change, the gridding board rearrangement and it’sstructure and quantity adjusting, these reforms obviously solves the gridding boardjamming problems.Techniques reconstruction result on the four kinds of coagulant addition wayconcerned with the No3coagulation reaction tank is done, the original coagulantaddition equipment addition way is proper when the dosage is80-100mg/L, theposition of the20min hydraulic detention time in the coagulation reaction tank isproper addition point when the dosage is120mg/L.The inner coagulation sedimentation efficiency and it’s trend of No3coagulationreaction tank is evaluated by contrast with No4coagulation reaction tank, the datagotten is useful for the future wastewater plant auto operation.The discharged way and frequency of sludge and it’s detailed operation step isdrew up and optimized.The above No3coagulation reaction tank techniques reconstruction bring aboutdistinct lower SS value which is100mg/L from the original181mg/L with thecorresponding SS removal efficiency increasing from51.6%to69.5%which isbeneficial for the plant operation. |
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