Study On The Technology Of Resource Utilization Of Rural Domestic Sewage On The Spot

In recent years,the economic level and health awareness of rural residents have increased gradually,resulting in aggravation of water pollution in rural domestic sewage.The amount of water increases every year and rural sewage disposal problem has become increasingly prominent.In order to improve the rural water environment and solve the problem of sewage discharge,this paper takes rural domestic sewage as the research object,and uses natural sedimentation,anaerobic fermentation and aerobic composting as the main means to study the utilization of rural domestic sewage resources on the spot.This paper studied the changes of basic pollution indicators after the natural sedimentation of sewage at first.After 3h of sedimentation,the organic suspended solids naturally settled,which results in a significant drop in the COD of the upper sewage to 93.29mg L.Due to the special bimolecular structure of LAS,the LAS concentration of the liquid surface wastewater increased steeply to 7.68mg/L but still less than 10mg/L,which meeted the irrigation water standards.The organic suspended matter sinks to the lower layer of sewage,and the available materials increase,and the gas production of the biogas increases to 3775mg/L.After the natural sedimentation,the lower layer sewage and the corn stover were mixed and stacked.It was found that the sewage stacking decomposed the large and the complex structure of the straw into small molecules.The anaerobic bacteria can be directly utilized,which shorted the startup time and facilitated the system startup.However,a large amount of organic matter would be consumed,if it stacked for too long time.The available matrix of anaerobic bacteria would be reduced relatively,and the gas production would decrease accordingly.But the effect of sewage stacking on methane contentwass not significant.The optimal stacking time was 8d,the gas production increased by 10.86%,and the peak gas production period was 5d earlier.LAS is the main component of detergents.It was found that the special structure of LAS promoted the dissolution of poorly soluble substances in the fermentation base.The available organic matter which the acid-producing bacteria can use increased,which increased the concentration of SCOD.The acid production efficiency and the volatile acid content increased,and the acid content was positively correlated with the LAS concentration.However,the benzene ring structure of LAS had a certain toxic effect on methanogens.When the concentration of LAS exceeded 15mg/L,the inhibitory effect on methanogens appeared.And the concentration reached 20mg/L,the cumulative gas production and methane production decreased.The promotion of propionic acid and butyric acid by LAS was more significant.And the increase of propionic acid concentration was also the main reason for high concentration of LAS to inhibit gas production.15mg/L is the upper limit of LAS for household biogas digesters.And rural domestic sewage is less than 15mg/L.Therefoue domestic sewage can be discharged into biogas digesters to adjust water content.Compared with the compost mixed with manure or biogas slurry,the contents of N,P and K in the compost of corn stalk and domestic sewage urea solution are not much different.And the total content meeted the organic fertilizer standard.And the use of feces reduced,and the content of heavy metals reduced.The water consumption of sewage increased.The best scheme for straw composting is 2.21 for material ratio（domestic sewage:corn stover）,0.43L·min^-1·kg^-1 for ventilation,and 45.17mm for particle size.