Ecological Restoration To Micro-polluted Water And Material Study In Qianwei Village Of Chongming Island

The projects come form the Shanghai Science and Technology Commission that "Water resource protection and water ecological restoration technology and demonstration of Chongming Island". Item No.:05dz 12009.The Qianwei village which is famous as one of the "One of the five hundred best ecological villages in the world" is Shanghai's ecological base in Chongming County. Its green radiation functions have become increasingly prominent, and with the growing number of tourists increased, the biggest landscape lake--The Center Lake, has shown the characteristic of bad carrying capacity by pollution with increasingly serious problem, the water quality is worse and worse.Based on this case, we put forward the technology of oxidation pond/constructed wetland treatment system to control the pollution of The Center Lake. This technology was applied very little in domestic and abroad, as a new attempt, we had nearly a year of small-scale test studies and master of the maintenance and management measures of oxidation pond/constructed wetland system. At the same time, study the treatment effect and characteristic of micro-polluted lake water by complex ecological system in specific climate and soil conditions of Chongming, analyze effect of temperature, influent concentration, and hydraulic load factors on the removal of contamination, all of these afford absolutely necessarily experience for working order of medium-sized test project.Test results showed that HRT for three days, the system has high removal rate toward micro-polluted water and no significant influence toward removal effect if extend HRT. Think over the treatment effect of The Center Lake by four different flow patterns that subsurface flow constructed wetland, undercurrent constructed wetland, oxidation pond/subsurface flow constructed wetland and oxidation pond/undercurrent constructed wetland:CODCr removal of 10% to 50%, turbidity place the rate at 35% to 90%, the concentration of TN removal rate of 35% to 55%, NH4+-N concentration in the removal of 38% to 44.2%, NO3--N concentrations removal rate of 25% to 37%, TP concentration of the removal of 56% to 81%, the concentration of TDP removal rate of 30% to 44%. The results showed that four processing units have not very different to removal effect of test items, and account for four treatment system can play an effective role to pollution control of The Center Lake water and provide help for designed of medium-sized test project.The ceramic used in small-scale test system made by river sediment ourselves, the move has better effect to reduce pollution and increase social economic benefit, and opened up a new ways toward river sediment processing, disposal and reutilization.The main chemical composition, particle size distribution, mineral component and heavy metals in river sediment has been analyzed; the results indicate that the main chemical compositions are similar to the clay raw materials, which provide possibility of reutilization river sediment. River sediment contains heavy metals and lixivium concentration higher, but analysis of the results of Cu2+, Zn2+, Pb2+, Cd2+, Cr6+, Hg+ showed that sediment samples is not reaching the level of hazard waste.Consideration of chemical composition of the raw materials, to determine the river sediment, sewage sludge, Guangxi Baini and water glass are chosen to be the raw materials of ceramic. Orthogonal Test Preparation of sediment ceramic optimum conditions and formulas, that the river sediment:sewage sludge:Guangxi Baini:water glass=100:20:15:6, sintering temperature of 1140 centigrade, the heat preservation time of 9 minutes. The test to determine optimum conditions for the prepared ceramic that its surface of 3.67m2/g, packing density is 710kg/m3, the apparent density of 1517kg/m3,53% porosity, high strength 3MPa washed over. Comparable with the same kind of products, the sediment ceramic have some strongpoint of a large surface area, low packing density and high porosity. The sediment ceramic is better bio-film carrier and strong adsorption capability toward organic matter and NH4+-N.By reference the experience gained and lessons learned from small-scale test system, in accordance with conservation and efficient principles, water treatment of The Center Lake used oxidation pond/constructed wetland complex processing system, the structure rebuild by tropical fish breeding ponds of Qianwei village lie north of The Center Lake. Adopt subsurface flow combined with undercurrent construction way, plan to be through the land purification ecological system of micro-polluted water to realize purification and resources of decentralized micro-polluted water, and for adopt land treatment system building "Ecological Chongming" play an demonstration.Oxidation pond/constructed wetland system since February 2006 run until March 2008 running more than two years, the system for the removal of turbidity of 70%～94%, the CODCr removal rate of 20%～47.6%, the TP removal rate of 50%～90%, the TN average removal rate of 21.2%, the effluent turbidity 8NTU within, CODCr 20～36mg/L and the TP at 0.10mg/L within (reach surface water classⅡlevel), TN content of 0.98～1.641mg/L and above effluent index have close to the classⅢof State except TN. Because microorganism need long-term training that its long generation cycle, for example nitrobacteria. And the system operations in winter, temperature limit microbial growth and activity worse, with the further stabilization operations, the best operating conditions of exploration, operating parameter control, the effluent water quality can be further improved.The five innovations bring out in thesis:1) The first time take the ecosystem fiber as "artificial water grass" to apply pretreatment of constructed wetland;2) Constructed wetland and oxidation pond combine together is a new complex ecosystem and the oxidation pond system as pretreatment system of constructed wetland. By experiment mensurate of small-scale test system and medium-sized test project toward The Center Lake, analyze effect of temperature, influent concentration, and hydraulic load factors on the removal of contamination;3) The first time that makes light quality ceramic by river sediment and applies to circulation economy research of riverway ecological repair in constructed wetland;Make use of river sediment polluted in The Center Lake before experiment base in Qianwei village, Chongming County. The river sediment pollution by living sewage and fishery breed aquatics waste water, so the organic matter content is higher, making use of its organic matter as vesicant and applied it with ecological fibre in undercurrent constructed wetland can get rid of NH4+-N and CODCr, clean the water and curry out the purpose of "with dirty cure dirty".4) Study the influence of water current that use of ceramic in constructed wetland for the first time;Study the variety of water current that use of ceramic in constructed wetland.5) Zero energy water circle drive system and mulriple constructed wetland river water cleanse system an integration a technique.Adopt windmill as power to realize the step up of polluted water. The windmill can provide enough power in order to provide ample oxygen for the biology contact oxygenation. To realize the reasonable layout of water area ecology, the delamination of acuiculture fish and accrete of fish and hydrophyte.