The Study Of ABR-compound Constructed Wetland Combination Process On Rural Domestic Wastewater Traeatment

In recent years,most of the urban domestic wastewater has been conducted in the sewage treatment plant.On the contrary,the vast rural areas due to the complexity of terrain,economic downturn,living scatter and the difficulty of collection sewerage and other reasons,lead to corresponding sewage treatment infrastructures are not wholesome,even in the blank zone.If the rural domestic wastewater is untreated and directly get into the nature,the result will bring about a series of serious ecological environment problems,thus solving the problem of wastewater treatment is an urgent need of the reality.But the current mature wastewater treatment technology is not completely suitable for most of the current situation of rural areas.Therefore,this article is based on these characteristics of one-day rural wastewater emission which is small,low pollution load and intermittent discharge,designed the ABR-compound constructed wetland combination process to deal with the rural domestic wastewater.Firstly,through studying performance of adsorption and revomal phosphorus of the five kinds of substrates on anthracite coal,coal cinder,biological ceramsite,sandstone and shale brick slag,in order to master the control factors that affect the adsorption efficiency of the substrate and the related parameters.Secondly,an anaerobic baffle reactor(ABR)and four types vertical flow constructed wetland on shale brick slag(YYZZ),volcanic rock(HSY),biological ceramsite(SWTL)and anthracite(WYM)were constructed.Then,through adjusting the low,medium and high three kinds of water pollutant load and controlling hydraulic retention time(HRT)to study the efficiency of the rural domestic wastewater treatment at the various waste-water treatment unit in hanging film and operation period.Finally,set up the surface flow wetlands(SFW)and subcurrent surface flow wetlands(SSFW)as a secondary process unit of rural domestic wastewater,to treat the wastewater again with deep denitrification and phosphorus removal.The specific experimental results as following:(1)By isothermal adsorption fitting find that Langmuir isothermal adsorption equation is suitable for describing the coal cinder and biological ceramsite,while Freundlich isothermal adsorption equation fitting is more suitable for describing the anthracite,sandstone and shale brick slag.In the five kinds of substrate,the largest amount saturated adsorption is coal cinder in the theory,may reache 1212.34mg/kg,followed by sandstone,anthracite coal and shale brick slag,whatever the biological ceramsite saturated adsorption capacity in the theory is the most small,only be 405mg/kg.The controlling factors,such as initial solution concentration,substrate grade and dosage,solution pH,organic matter types and its concentration,inorganic anion will affect substrate on the adsorption removal effect of nitrogen and phosphorus in wastewater.The ability of Five substrates adsorption phosphorus increases as the initial concentration;the best effect of phosphorus absorption is adopted with 1 mm coal cinder,biological ceramsite,shale brick slag and 5 mm anthracite coal and sandstone;When solid-liquid ratio of the biological ceramsite,shale brick slag,coal cinder,anthracite coal and sandstone is 4g/50 ml,the phosphorus absorption rate increased significantly,respectively reache 96%,95.6%,95.2%,57% and 51%,but if continue to increase the solid-liquid ratio,the corresponding phosphorus absorbed rate has no significantly change;solution pH in the range of 5~10 increasing,the biological ceramsite,sandstone and shale brick slag have no obvious effect on the adsorption of phosphorus removal,but obviously inhibit the adsorption properties of anthracite coal and coal cinder;glucose,humic acid,oxalic acid and citric acid and other organic matters hinder substrate adsorption of phosphorus removal,and with increasing organic concentration,the inhibition effect is more apparently,but as rise the solution concentration of glucose oxalic acid and citric acid has promote the amount of the sandstone substrate to absorb phosphorus,a added increase of 120mg/kg;NO3-and SO42-inorganic anion have certain effects on anthracite coal,coal cinder and sandstone in adsorption of phosphorus,but Cl-,HCO3-and mixing anion have no apparently impacts on the ratio of phosphorus adsorption for five kinds of substrate.(2)CODcr,TN,NH4+-N and TP into ABR of the water respectively reach 137~298mg/L,12.3~33.5 mg/L,33.5~11 mg/L,at Hang membrane period.8mg/L,and 3.8~14mg/L range increment,to 15~20th day hanging film is successful,even if the high load into the water,the ratio of removal respectively is also stable at 36%,10%,24% and 10%;furthermore four types of vertical flow artificial wetland,the content of COD,TN,NH4+-N,TP respectively keep in the range of 71~180mg/L,8~31mg/L,6~16mg/L,4.2~7.8mg/L;in the late of hanging membrane,the COD removal rate of the SWTL and HSY is better,more than 80%,while WYM for TN,NH4+-N removal ratio is good,keeping in the range of 40%~50%,YYZZ has a good effect on the removal rate for TP,around 65%.In regulation research phase,when the HRT of wastewater in the ABR is 8 hours(h)or12h or 24 h,and the water pollutant load is low or medium or high,we can find that the HRT for 12 h and 24 h,the removal rate of COD,TN and TP respectively were 36%,11%,19% and 36%,10%,20%;but the final content of NH4+-N is not reduce instead of increase,the increase rate of 9.5%,8.6% respectively.In addition,with increasing the pollutant load,the removal rate of COD,TN and TP has dropped,the average removal rate being at 30%,11%,19%,but the increase rate of NH4+-N in the range of 13.2%~22%.Whereas the vertical flow artificial wetland of the YYZZ,HSY,SWTL,WYM with pollutant load increase,the corresponding pollutants removal rate fell a lot;even under high pollution load,removal rate of the lowest of four types of wetland systems on COD,TN,NH4+-N,TP also reached 57%,34%,75%,34%.however the content of NO3--N increased significantly,the growth rate of 480%.(3)In period of Hang membrane,SFW and SSFW,two-type system,the content of COD,TN,NH4+-N,NO3--N and TP respectively keep in the range of 98~196 mg/L,8.7~31.7mg/L,4.8~15.7mg/L,15.7~4.8mg/L,2.9~5.6mg/L,while corresponding pollutant removal rate has decreased in the late of hang membrane,but the removal rate is stable accordingly,respectively held at 85%,65%,90%,92% and 75%.At the stage of controlling and regulation,the HRT is 4h,8h and 12 h.when HRT is 8h,the whole average removal rate is 87%,98%,68%,98% and 92% in the two-type constructed wetland on COD,TN,NH4+,NO3-and TP.Besides,when the content of COD,TN,NH4+-N and TP respectively keep at the range of 225~445mg/L,24~37mg/L,8.3~16.2mg/L and 4~8.9mg/L,the pollutants removal rate keep in 80%,80%,81% and 75%;at the same time,the effects on nitrogen removal by denitrification is obvious,the final water quality can reach the town wastewater treatment plant emissions standard(GB18918-2002)level 1 grade B.