Reaction Mechanism And Engineering Practice Of Alternate-flow United Water Treatment Equipment

Cost-effectively decentralized sewage treatment has become one major problem of the water pollution crisis. Alternate-flow united water treatment equipment developed in this research is a biofilm reactor that composed by a number of circulating flow in Airlift Alternant Loop Complex Bio-filter standard cell in series, which combines biological aerated filter, airlift circulating fluidized bed, baffle reactor and other technology, the unique work principle and technology characteristics. The reactor can appear simultaneously aerobic, anoxic and anaerobic environments as running, truly simultaneous play roles in nitrification and denitrification in a single reactor for domestic wastewater treatment and in addition to carbon and nitrogen removal effectiveness.The main subject of this research includes three parts: First, we will study the fluid dynamics and hydraulic characteristics in Airlift Alternant Loop Complex Bio-filter through the water test equipment; The second part is the pilot sewage test which investigate water quality, hydraulic retention time (HRT) , gas water ratio on the treatment effect of the reactor, also include changes along the way of many factors in each unit of alternate-flow united water treatment equipment, which compares the effect of reactor removal organic and nitrogen under shunt feed water and injector fill mode; And in the last we will discuss the water treatment equipment's actual decontamination ability in the engineering practice of people's hospital sewage treatment.Research results show that air tower gas velocity determines the gas holdup size of the equipment; Gas holdup is proportional to circulating fluid velocity, circulatory driving force, oxygen transfer coefficient, and which is inversely proportional to the liquid circulation time. Liquid circulation velocity and the height of ceramic filter layer is inversely proportional relationship, and influenced greatly. The reactor with flow pattern of completely mixed reactor (CSTR) and plug flow reactor (PFR), decides the integration equipment with good water treatment process performance.Pilot trial operation process found that the reactor has good adaptability on the different water quality, COD and NH₃-N average removal rate is 90%. Comprehensive consideration of the removal efficiency and economic reasons, hydraulic retention time (HRT) is four hours, gas ratio of water is 4:1, which are the ideal reactor operation parameters. Alternate aeration way ensures that in the same reactor aerobic, oxygen can partition running. The integration equipment fold streaming construction make each unit's biomass, COD, NH₃-N, TN along the riser change grads obvious, impact resistant capability is strong, effluent is stable. The design of shunt water efficiently solve the problem of insufficient denitrifying carbon sources, the removal rate of COD is higher than injector fill by 4.9%, total nitrogen removal is higher by 7.4% under the same conditions, which improve facility's carbon nitrogen ability.Engineering practice proved that the alternate-flow united water treatment equipment's adaptability is strong on different water quality, pollutant removal rate is high, stable discharging water, less investment, low operating cost, compact structure, and it can be widely used in sewage treatment of scattered or independent residential areas, hotels, resorts, catering aspects.