Experimental Research On Integrated Device Of Household Sewage In Rural Areas

With the economic development, the rate of urban sewage treatment increased year by year, while in the rural areas the lack of sewage treatment facilities due to economic backwardness. The residents of western countryside of China were dispersed for its mountainous and the waste water treatment facilities were relatively lack, so the residents discharged waste water arbitrarily. Besides, it is very expensive to build sewage pipes in these mountainous regions, so it is necessary to develop a household integrated device which will be integrated into the anaerobic treatment and the Bio-filter. We developed an equipment for residents and the treated water can be used for irrigation.This paper mainly studies on the impacts of different hydraulic retention time(HRT) on the treatment efficacy in anaerobic tank and the impacts of different hydraulic loading on the treatment efficacy in Bio-filter. At the same time, we made two same equipment except the different filter materials in the Bio-filter. One was filled with mainly gravels while the other one was crushed bricks.We compared the treatment efficacy of two equipments and finally obtained the optimal running conditions. Results are as follows:(1) We research the impact of HRT on the treatment efficacy in anaerobic tank at the condition that HRT respectively were 48 h, 72 h, 96 h, 120 h and144h.The result showed that the average removal rate of CODcr in the anaerobic tank(gravel) from 41% to 77%, SS average removal rate from 73% to 86% with the HRT increasing; and the changes of anaerobic tank(crushed brick) consistent with anaerobic tank(gravel).(2) the quality of CODcr, NH4+-N, TN, TP and SS of effluent water in mixing tank were close to the quality of influent gray water under above five groups of HRT. The role of mixing tank were mainly dilution and reoxygenation.(3) We research the impact of hydraulic loading on the treatment efficacy in the Bio-filter at the condition that hydraulic loading respectively were 35cm/d, 42cm/d, 52.6cm/d,69.8cm/d and 100.01cm/d. Results showed that the removal efficiency of Bio-filter gradually decreased with the increasing of hydraulic loading.(4) The CODcr removal rate in anaerobic tank(gravel) decreased 10.03% ~ 13.72% in winter(8?~15?) compared to summer(25?~37?) and the changes of CODcr in anaerobic tank(crushed brick) were consistent with and anaerobic tank(gravel). The removal rate of NH4+-N, TN and CODcr in Bio-filter in winter declined obviously while TP, SS declined relatively small.(5) The removal rate of CODcr, NH4+-N, TN, TP, SS was greater in Bio-filter(crushed brick) than the filler material was gravel, especially the TP removal efficiency.(6) The optimal working conditions of integrated process equipment: HRT of anaerobic tank was 144 h, summer(25?~37?)the proportion of black water and in-fluent gray water was 1: 3, the filter material of Bio-filter was crushed bricks and run 25 d when the hydraulic loading was 35cm/d.At these conditions, the average removal rate of CODcr in anaerobic tank was 77%,the average removal rate of CODcr, NH4+-N, TN, TP, SS in ecological filter respectively were 71%, 18%, 19%, 24% and 83%. What's more,CODcr of effluent water was lower than limit of 150mg/L of the standard GB5084-2005 of irrigation water..