The Demonstration Of Upgrading And Reconstructing Technical Plan For Hongqiao Sewage Treatment Plant In Urumqi

According to the requirements of"Urumqi water pollution prevention and control""13th Five-Year"plan（2016-2020）,the newly-built,expanded or reconstructed sewage treatment plant should implement the national Class A emission standard,realize the regeneration and reuse of water,and reduce the pressure of water supply,in order to build an ecological garden city,Urumqi.At present,Hongqiao Sewage Treatment Plant（Hongqiao WWTP）implements GB5084-2005.However,this standard is no longer able to meet current requirements,and needs to be upgraded.Hongqiao WWTP was built in 2002,and had a scale of3×10⁴ m³/d,and A section of AB process was adopted.Based on investigation of original process about Hongqiao WWTP,this study combines the quality of influent water,demonstrates the best technological solution for upgrading,and completes the design of this WWTP with the actual conditions of it.Mainly draw the following conclusions:（1）The original process of the Hongqiao WWTP has only been completed A section of AB process.The discharge water doesn’t meet secondary emission standards,with a low degree of treatment.There is no nitrogen and phosphorus removal function,the impact load capacity is poor,and the operation is extremely unstable.In addition,the equipment is running for a long time and seriously aged,resulting in high maintenance costs and energy consumption.（2）Due to the small size of plant area,the upgrading and reconstructing plan should not only make full use of existing structures,but also have features of small size,low investment,economy,safety and reliability.BOD₅/TN=2.58,meaning that the ratio is lower and lacks carbon source.The average temperature is relatively low in winter,and the BOD₅/TN ratio will affect nitrification and denitrification rate in the biochemical system when inlet water temperature is low.（3）Through comprehensive analysis,the technical plan for upgrading and reconstructing has been determined.Firstly,retain the original pretreatment unit structure,replace the original pretreatment equipment,and transform the original A-stage aeration tank into primary sedimentation tank;Secondly,a new semi-subterranean multi-stage multi-level AO（AMAO）biochemical pool was built in the biochemical treatment unit.The multi-point water distribution method improves nitrification and denitrification capacity of low-carbon source water quality,and solves problem of ammonia nitrogen removal in the effluent.As a new high efficiency fiber beam filter unit is built,the high efficiency retention of fiber filter material can effectively reduce the concentration of SS and TP.The disinfection process adopts ultraviolet disinfection technology to sterilize.The reclaimed water was reused to disinfect sodium hypochlorite twice in order to ensure the requirement of residual chlorine in the water quality standard.The newly-built bio-deodorization unit adopts biological method to collect and dispose the malodorous gas produced by the pre-treatment and sludge treatment unit in a concentrated way,and then discharge it at high altitude after reaching the standard.The remaining sludge is condensed and dehydrated directly by centrifuge,and the water content is reduced to less than 80%,which is transported to the landfill site for landfill.After the upgrading and reconstructing,water discharged from the Hongqiao WWTP needs to meet the Class A emission standard of GB18918-2002.