Study On Eco-pond & Wetland Coupled System Deal With Surface Water In Chongming Of Shanghai

This research comed from the major scientific and technological project of Shanghai Science and Technology Commission," The evolution of the law of the domain of water environment and water quality improvement technology research in Chongming Island,"(Number:06DZ12307),and received a Ph.D.thesis Innovation Project funding(Number:113-06-0019027) of Donghua University.River water of Qian Wei village,Chongming as the object of study,carried out the eco-pond& wetland coupled system of its purification and mechanism performance,process experiments. Main research contents:(1) Establish small pilot plant of ecological pond-vertical-flow wetland and ecological pond- horizontal flow wetlands for water purification performance study.(2) Study the hydraulic loading,dissolved oxygen and temperature on the pollutant removal ability of pollutants along the way influence and change.(2) From the matrix,higher plants,lower plants research nitrogen and phosphorus in center river water in the system of migration and transformation rules. (3) Establish pilot projects to look at the whole system pollutants removal performance from the main unit of eco-fiber pond,subsurface flow constructed wetlands and pollutants-type removal mechanism,the contribution of the whole system,nutrients transport in the law.(4) Fit of pollutants in non-plant systems, duckweed system,hornwort system removing dynamics model and Study parameter. (5) Evaluate environmental efficiency,ecological benefits,economic and social benefits of Systems and research way to improve system capability of removing contaminants.Major innovations points:(1) Deepening research on characterization of high turbidity of surface water in Qian Wei village of Chongming for nitrogen and phosphorus pollution control the suspended solids retention,use of plant roots and ceramic The adsorption of ammonia-nitrogen retention role of the water do further processing.These two system TP removal rates was form 19%to 54%and 14%to 45%respectively,and the pond -vertical-flow system for TP removal slightly higher than the pond- the level of flow system.Filling of wetlands on the existence of a dynamic balance of total phosphorus removal,4～6 hours decreased the rate of desorption,6h after the desorption of phosphate ceramic volume rendering rise slowly,0.2mg/L precipitation and adsorption to achieve dynamic balance.Pond- vertical subsurface flow constructed wetland system CODcr removal better than pond- the level of subsurface flow constructed wetland system.The removal rate of Eco-pond was up to 28%,it was the main removal CODcr unit.(5)The contribution of nitrogen removal in system was followed by microbial metabolism(nitrification,denitrification and microbial uptake),matrix adsorption,the aboveground biomass of wetland plants to absorb,Tong absorbed within the algae. The contribution of phosphorus removal in system was followed by substrate adsorption,absorption of the aboveground biomass of plants,pond algae absorbed within.Ceramic adsorption was the most important wetlands in the form of phosphorus,plants also played an important role.(6) Limestone and ceramic adsorbed nitrogen,and the two kinds of substrate with the concentration of pollutants,adsorption capacity has also been increased,but the growth rate to a certain extent there was a downward trend in total nitrogen concentration in the adsorption capacity of limestone 21.5 mg/L under the conditions to achieve maximum value,with the total nitrogen concentration increases,adsorption basically remained stable.For the total nitrogen adsorption capacity,adsorption capacity of better than ceramic limestone,in the total nitrogen concentration of 19mg /L under the conditions to reach adsorption equilibrium,the adsorption capacity of limestone 0.089mg/g,while the adsorption capacity of ceramsite 0.228mg/g,about 2.56 times the adsorption capacity of limestone.Select ceramic as a filler more conducive to the removal of total nitrogen.(7)Limestone and ceramic had a good role in adsorption of phosphorus,ceramic limestone stronger than the role of adsorption of phosphorus.In the 1.8mg/L total phosphorus effluent to reach equilibrium,the adsorption capacity of limestone for the TP to 0.1mg/g,the adsorption capacity of ceramic 0.15mg/g,about 1.5 times the adsorption capacity of limestone.With the increase in pollutant concentration,two kinds of substrate adsorption capacity has increased,but the ceramic to increase faster, containing 0.6mg/L of total phosphorus in wastewater,to achieve equilibrium,while the adsorption capacity of limestone 0.24mg/g,the adsorption capacity of ceramic 0.38mg/g,the adsorption capacity of limestone is about 1.6 times.For the adsorption of phosphorus,the matrix should choose ceramic better.Under the same conditions, ceramic limestone on the phosphorus sorption capacity of more than 1.5 times,total nitrogen adsorption capacity of more than 2.5 times,and the ceramic porous,large surface area and ease of microbial attachment to form a biofilm.But taken together, limestone and access to convenient,and the use of limestone increased the anaerobic layer thickness is conducive to the removal of nitrogen and other pollutants,while limestone can adjust the pH value of water,so that micro-organisms living environment more stability is conducive to microbial growth,so use of the bottom of ceramic,the middle layer of limestone.(8) The transfer of plants to the amount of N and P showed a positive correlation with plant capacity,and device type,and little to do with acreage.N and P uptake by plants changed little,very little absorption through the harvest can not be greatly improved devices,nitrogen and phosphorus removal efficiency,but should take appropriate harvesting of plants to remove corruption and the way to deal with wetland plants.(9) Study the role of algae on the absorption of nitrogen.Basically,the influent TN concentration of 1.6mg/L or so,the effluent concentrations maintained at 1.2mg/L, while the removal rate has gradually changed with time low,down 35%from the start of the last remaining at around 20%and rely on algae for the absorption of nitrogenwas no able to meet the processing requirements.TP influent concentration in 0.12-0.17mg/L,within the scope of wandering,the effluent was also maintained at 0.07-0.11mg/L,between the treatment effect was not very satisfactory.Simple use of algae for the absorption of nitrogen and phosphorus to deal with the water,the effect was not satisfactory.Role in nitrogen removal,with the extension of time to deal with effects of a gradual decline;while in the role of phosphorus removal,the removal rate was very unstable,the effluent total phosphorus concentration changed dramatically with the water,and then taking into account the phosphorus in water The content and the relationship between turbidity and suspended solids in the sedimentation experiment,thus reflecting the effects of algae to phosphorus removalwas also not obvious.(10) Establish a pilot engineering system,CODcr,TN,TP,turbidity,the average removal rates in high-efficiency ecological fiber Pool/ Subsurface Flow Constructed wetlands were 48.4%,45.3%,65.38%and 94.89%.The final effluent indicators had reached or close to design requirements,to meet the water needs of the rural landscape.System mainly depend on microbial metabolism of organic pollutants, nitrogen removal mainly depend on microbial nitrification and denitrification, phosphorus removal,mainly through substrate adsorption precipitation,turbidity, mainly through natural sedimentation,eco-fiber membrane and filler surface adsorption and biofilm removed.(11) Covering the surface of ceramic filler average particle size of 20 cm in the 3～5 cm of gravel,mainly limestone,in a sense to the anaerobic layer thickness of 20cm, the extension of the anaerobic layer of hydraulic retention time there were more layers of organic material was consumed in the anaerobic degradation of the same quality of soil organic matter anaerobic microbial production capacity is far less than the aerobic microorganisms;the size of gravel surface after the adsorption of larger reduction in the surface sludge was not easy deposition;limestone also improves the bottom of the anaerobic microbial fermentation of the formation of acid acidic water,as the surface of aerobic micro-organisms to create better environmental conditions conducive to the removal of CODcr.(12) Pre-eco-fiber pond could effectively remove suspended pollutants,improving water Chongming high turbidity of surface water conditions.To reduce the load on the wetlands to resolve the current widespread obstruction of the wetlands. Pre-oxidation pond and artificial grass was used self-developed polyester elastic filler by Dong Hwa University,from flexible wire,center pieces and central rope, composed of spandex for the adhesion of biofilm,fillers suspended in water,the vertical elastic filler suspension,water of suspended particles after the collision speed and flexibility of filler decreases,thus settling to the bottom of the oxidation pond, and subsurface flow constructed wetland in comparison,you can set the mud tubes, which was eco-fiber pond as the suspended solids removal unit main irreplaceable advantages,(13) NH₃-N,TP,PO₄^3- P,CODcr removal in No plant,Lemna minor,Ceratophyllum demersum system were line with a reaction kinetics.Processing capacity as follows: Ceratophyllum demersum systems,duckweed system,no plant system.NH3-N removal rate of No plants,Lemna minor,Ceratophyllum demersum system coefficients were 0.0372d^-1,0.1071d^-1 and 0.1534d^-1,TP removal rate coefficient were 0.0061d^-1,0.0097d^-1,and 0.0234d^-1,PO₄^3- P removal rate coefficient were 0.0036d^-1, 0.0108d^-1 and 0.0364d^-1,CODcr removal rate coefficient were 0.0046 d^-1,0.064 d^-1 and 0.074d^-1.(14) Research and development of wastewater treatment technology on this project not only had high practical value,but also had obvious environmental benefits,social benefits and economic benefits.