The Study On The Process Based On ABR Technology For Decentralized Domestic Wastewater In Northwest Villages And Towns

In order to solve free disposal of domestic wastewater of central and northwest villages and towns in China,a process combined the traditional septic tank and anaerobic baffled reactor(ABR)is designed-new ABR septic tank system.In order to enhance its performance and achieve efficient and stable operation,the new ABR septic tank system with 5 compartments was studied in two phases.In the first phase,the start-up and acclimation of the system were studied by gradually decreasing the hydraulic retention time(HRT)or reactor temperature,respectively.And the concentration of pollutants and the characteristics of granular sludge in the different compartments were analyzed.In the second phase,the effects of HRT,temperature and organic load on operating performance of the system was investigated by synchronously regulating the operating conditions.The results are as followings:The first phase,72.69% and 55.93% of COD respectively were achieved on the different condition of start-up.The removal rate of ammonia nitrogen were both less than 10% and the volatility was relatively large,which proves that NH4+-N treatment performance of the system is bad.COD removal rate of each compartments is compared: the 1st compartment > the 2nd compartment > the 4th compartment > the 3rd compartment > the 5th compartment.pH of the system have a positive correlation with the alkalinity and temperature and a negative relation with the VFA.The alkalinity of each compartments was compared as followings: effluent > input water > the 5th compartment > the 4th compartment > the 3rd compartment > the 2nd compartment > the 1st compartment.Sludge sedimentation is relatively well and the proportion of granular sludge is relatively high.Gas production was positively correlated with the temperature.In second phase,the removal rate of COD and SS of the system was high.The average COD concentration of the effluent meets the standard of the farm irrigation water quality(GB 5084-2005).The average concentration of SS was 19.87 mg · L-1,which reached the Grade B of Pollutant Disposal Standard for Urban Wastewater Treatment Plant(GB18981-2002).Removal rate of total nitrogen,ammonia nitrogen and total phosphorus all are relatively low.There often occurs the phenomenon that their removal rate is negative.And each of factors has no significant effect on their removal rate.Acidification of the system is low and there is alkaline environment in the system in the whole.The extension of HRT,the increase of organic load and temperature contribute to the strength of metabolic activities of different anaerobic microbial flora and thus the increase of total gas production.Based on Andrews Equation suspension growth dynamic models on ABR is developed according to the characteristics of the reactor,Moreover,two different ways of model building are studied and their accuracies were compared.The results showed that the reactor as a cascade of CSTR reactors builds a model larger than the simplification of the ABR reactor to a single CSTR reactor to establish a linear model due to the parameter selection and the cumulative error of the compartment model prediction.Finally,the cost-benefit analysis of the equipment shows that the process meets the requirements of applying it in rural areas in the economic aspects.