Research Of The Puriifcation Effect And Law Of Compound Ecological Treatment Technology For Distributed Domestic Sewage In Hainan Area

The population is numerous, domestic sewage discharge is large in China’s rural areas.Because the capital is in short supply in rural areas, people live more decentralized, centralizdtreatment for domestic sewage was troublesome, most of the domestic sewage was directlydischarged without any treatment. This paper directed at the present economic situation andliving level of countryside, on the basis of previous studies, have studied static test of thesewage purification effect and law of ecological floating bed technology for the domesticsewage in a certain area of HaiNan, numerical simulation test of the three squares purificationtank, reached the following conclusion:（1） Selected rice, water celery, water spinach, FuGuiZhu and white butterfly five kindsof aquatic plants after the preliminary test, in April-July, water temperature24℃³1℃conditions, applied to the ecological floating bed to remove the pollutant of domestic sewagesuch as organic matter, nitrogen and phosphorus, and conduct a comparison test study of theremoval efficiency. The results showed that, in the spring, rice growed most exuberantly, itsdecontamination effect was best,,its average period removal rate to COD_Cr, TN, TP were89.28%,84.89%and94.14%respectively, water spinach was second, water celery was worst.Thus screened out the dominant plant that fit for this season of HaiNan area, it were rice andwater spinach. Conducted a comparison test study of the removal efficiency of the differentseason water fennel floating bed for the pollutants of domestic sewage such as organic matter,nitrogen and phosphorus, showed that the water fennel of floating bed growed fast in winter,its removal ranges on the COD_Cr, TN, TP were75.7⁸7.38%,83.2⁸9.37%and78.66⁹2.31%respectively, the pollutants in water were removed effectively, can apply water fennelfloating bed to remove pollutants in domestic sewage in winter.（2）The influences of the different proportion and different types of filling packing onremoval effect were studied. And the removal effect of ecological floating bed with the ratioof plants to packing for1-0,1:1/2,1:1,1:2for the pollutants of domestic sewage such asorganic matter, nitrogen and phosphorus. Test results: plants: packing=1:1（groove3） its removal effectiveness for COD_Crand NH4+-N in water were the best, average removal ratewas89.67%and97.93%respectively. Plants: packing=1:1/2（groove2） its removaleffectiveness for TN and TP in water were the best, average removal rate was89.05%and91.55%respectively; conducted comparison study of remove effect on COD_Cr、TN、NH₄⁺-N、TP through the different treatments of water fennel+elastic packing, water fennel+softpacking, hyacinth+elastic packing, hyacinth+soft packing and so on, the results showed thatthe water fennel+elastic packing> water fennel+soft packing> hyacinth++elastic packing> hyacinth+soft packing> elastic packing> soft packing. Illustrated that the synergy ofplants and microbes could get good effect on removement of pollutants in water, the removaleffectiveness of elastic packing was better than soft packing, and the removal efficiency ofwater fennel floating bed is superior to the hyacinth floating bed in winter.（3） The effects of the way of the plants cultivation in the floating bed on the removaleffect. The removal effectments of the monoculture of rice, water fennel, white butterfly andthe mixed cropping of rice+water fennel, rice+white butterfly, water fennel+whitebutterfly on the pollutants in water were compared in the experiment. The results indicatedthat: the influence of different plant cultivation structure on the removal ability to organic wasbig, the removal rates of each system for COD_Cr by big to small were respectively rice+whitebutterfly （89.58%）> rice （89.55%）> rice+water fennel （85.13%）> white butterfly （79.38%）> water fennel+white butterfly （76.23%）> water fennel （69.54%）; The removal rates for TN,from big to small were respectively rice+white butterfly （90.72%）> rice （89.46%）>rice+water fennel （83.55%）> white butterfly （82.85%）> water fennel+white butterfly（76.93%）> water fennel （69.06%）; for NH4+-N the removal rates by large to small wererespectively rice+white butterfly （95.67%）> rice （95.46%）> white butterfly （94.28%）> rice+water fennel （90.77%）> water fennel+white butterfly （88.73%）> water fennel （83.93%）,the removal rates for TP by big to small were respectively rice （91.11%）> rice+whitebutterfly （90.21%）> rice+water fennel （85.42%）> white butterfly （81.06%）> water fennel+white butterfly （79.37%）> water fennel （70.82%）. The removal effectment of the mixedcropping was better than that of monoculture on organic matter, nitrogen and phosphorus invarious treatment ways of floating bed.（4） Expounded the commonly used method and theory basis of numerical simulation,on this base, builded three dimensional numerical model of the three case purification groove,using the Renault time average equation turbulent model and just cover assume freesurface simulation method, the ANSYS12.1as the platform, and comparatively studied usingRNG k-e equation for the complex two grooves and processing inner flow state in vadoseregion with porous media, the different import and export pipe height, the good and bad of thepurification groove inner flow state of different model （circular trough, square slot）.The testresult indicated, the vadose regions in the bottom of two grooves were homogeneous, andrelatively conformed to the theoretical value, but turbulent areas were slightly small, whichmakes the inner speed change was bigger than a groove and three grooves, more complex, thecollocation of long tube and short tube was more excellent, round groove was more optimalthan square groove.