Study On The Technology And Integrated Treating Equipment For Decentralized Wastewater Ecological Trertment Of Courtyard-type

It has become one of the primary problem of the current environment pollution that the total is more, the water quality fluctuation is large and highly centralized management is difficult of the decentralized wastewater. Due to the collection system is constructed difficultly and the lack of the treatment technology model that according with processing requirements, the current studies on decentralized wastewater treatment technology is not yet mature, lack of relevant standards and norms, and supporting device is more rare. Therefore, the study is based on constructing biological-ecological coupling treatment technology, through regulating load distribution between the pretreatment part and the core processing part to optimize the process parameters of the whole system, then developing an integration device of the courtyard decentralized wastewater treatment which the Subsurface Wastewater Infiltration System(SWIS) is the core part, and the device has the advantages of low energy consumption and unattended. The specific research contents and conclusions are as follows:Firstly, the biological-ecological coupling process is determined by comparison of process and technology screening, the coupling process which SWIS is the core part and hydrolysis acidification(HA) is the pretreatment part. The distribution of pollution load is the key connected factor of the coupling process, it has many merits as no(micro) energy consumption, stable water quality and so forth, laying a solid foundation for developing integration device based on the process subsequently.On the basis, the main parameters and controllable range of HA pretreatment process are determined by the simulation experiment in the start and stable phase, the stirring speed is 10~20r·min-1, 2h<HRT<4h; Then the impact resistance of HA is investigated under the condition of water load fluctuations, the results show that the stable operation of the HA is less affected by the load fluctuation.Study on the cut threshold of the major pollution indicators show that the SS reduction rate is more than 91%, the CODcrreduction rate is 42%-65%, the NH4+-Nreduction rate is more than 43.8% and the TN reduction rate is more than 36.4% under the condition of conventional water quality, when reaching the above standard, it can meet the requirements of the core treatment process SWIS influent water quality; The SS and CODcrare sensitive to the response of the operation parameters change, can be used as indicators that can guarantee influent water quality of SWIS, HRT and stirring speed of the suitable technological parameters ranges respectively are 3h~3.5h and 15~20r·min-1; The removal rate of the NH4+-N and TN can not reach the ideal threshold in HA unit, which can be adopted measures to cut by adding carbon source in the SWIS anaerobic zone(adding raw sewage: raw sewage is 1:3).And then, the HA and SWIS are coupled together with pollution load distribution for the principle, through theoretical calculation and experimental verification of the method, determining the scope of the theoretical load distribution rate that CODcr pollution load distribution between the HA and SWIS is 0.4~0.6. By using the quadratic regression orthogonal experiment to optimize the operation parameters of coupled process, the dry-wet ratio, hydraulic loading(HL), hydraulic retention time(HRT), and stirring speed are the main experimental factors, and the removal rates of CODcr,NH4+-N,TN and TP are the evaluation index. The results show that the sequence of the influence facrors in the CODcr, NH4+-N, TN and TP removal efficiency is different, for CODcr: DO>dry-wet ratio>HL>HRT;for NH4+-N: HRT>DO>HL>dry-wet ratio; for TN:HRT>DO>HL>dry-wet ratio; for TP: HL>DO>HRT>dry-wet ratio.Under the optimal working conditions which dry-wet ratio is 1.6, HL is 0.15m3·m-2·d-1, HRT is 2.5h, stirring speed is 15r·min-1,the removal rates of CODcr, NH4+-N, TN and TP are 92%, 78.6%, 65.0% and 92.7%, respectively, the effluent satisfy the landscape water reuse standard(GB/T18921-2002) and the first B level(GB18918-2002).Finally, based on the above research results, designed and researched on the integration device that is named i-SWIS in HA-SWIS, the device has the characteristics of compact structure, low investment, no(micro) energy consumption, high efficiency, no person on duty, etc, and its investment of less than 5000 yuan, tons of water treatment cost is only 0.27 yuan. The device is suitable for the areas where the pip network is not matching, it provides a new choice for decentralized wastewater treatment technology in China.