Pollutants Leaching Rules Of Solid Waste And It's Impact On The Water Of Songtao Reservoir In Hainan Province

Songtao reservoir locates in a minority area in the midwest of Hainan province. It is the biggest reservoir in Hainan, with the catchment area of 1496km2 and the total reservoir capacity of 3.345 billion m3. After a long term monitoring, it indicates that the water quality of Songtao reservoir is mainly kept on the standard II of surface water. However, there is some pollution in local region as well as an expanding of water pollution. All these mentioned above are making serious threats to the water quality of drinking water source. With the economic development in the reservoir, the MSW (Municipal Solid Waste) has already become one of the main pollutants that influenced the water quality safety. Attention should be attracted in such situation.By field survey and typical sample analysis, MSW in towns and farms implements the centralization of collecting-transporting-dumping. At the same time, the MSW dumping sites are not so normative that the pollutants influence the ambience, which is engendered by MSW incineration. The MSW of country is not centralized collected or transported but discarded and dumped in the villages randomly, while some is carried by the rainfall runoff. The MSW outputs of towns, farms and countries in the reservoir are 0.74 kg·d-1, 0.61 kg·d-1 and 0.16 kg·d-1. The dumping MSW outputs are 5548t, 2495t and 2700t, totally 10743t. The organic components of MSW in towns, farms and countries are 75.61%, 64.24% and 82.28%. The average recycle rate in the reservoir is 10.15% and a low recycle rate in remote districts and counties with inconvenient transportation.The physical-chemical analysis in lab indicates that the content of TN, TP and TK in MSW of the reservoir basically satisfies the National MSW Control Standard for Agriculture whereas the content of Pb and Cd in MSW of towns and Cd in MSW of farms are a bit higher than the standard. Moreover, the contents of As, Hg, Cr, Cd and Pb are all below the leaching toxicity identification evaluation and no harmful and toxic solid waste in the MSW of such reservoir.Part of MSW enters the waters by surface runoff. And then the pollutants release directly into the water after leaching. When the dumped MSW rushes by rainfall, the pollutants enter into the underground and surface waters. According to the distributional characteristics of MSW in such reservoir, the static leaching experiment of typical MSW and dynamic leaching experiment of MSW are carried through. The result of static leaching experiment indicates that temperature plays a key role to the temperature variety of leaching liquid and also influences the leaching velocity a little in the water-changing experiment scheme. Furthermore, liquid to solid ratio has a significant influence to the pH of leachate and leaching rules of pollutants, while pH is of significance to the leaching rules. In the no-water-changing experiment, temperature has just a bit influence of leaching rules and no influence to pH of the leachate. pH and liquid to solid ratio have a remarkable influence to the leaching rules.As to the result of theory and experimental data, we deduct the leaching rule model of MSW pollutants when dipping. Due to the leaching velocity equation of pollutants, the leaching velocities in the water-changing experiment of CODcr, BOD5, TP, NH3-N and TN are 882.24, 325.88, 14.95, 16.20 and 40.78 mg·kg-1·d-1 separately. While in the no-water-changing experiment, the velocities are 320.39, 242.21, 2.26, 40.02 and 39.75 mg·kg-1·d-1.The dynamic leaching experiment indicates that the MSW thickness has no significant influence to the pH of landfill leachate and leaching rules of pollutants. In the continuous tricking water experiment, the thickness plays a key role to the leachate pH but no influence to leaching rules. Compared with two experiment schemes, the same thickness and different leaching scheme influence pH of leachate while not significantly influence the leaching rules. At the same time, leachate pH and leaching rules of pollutants have no remarkable differences.As to the result of theory and experimental data, we deduct the leaching rule model of MSW pollutants when dumping. Due to the leaching velocity equation of pollutants, the average leaching velocities in the dynamic leaching experiment of CODcr, BOD5, TP, NH3-N and TN are 208.77, 42.44, 5.43, 14.08 and 75.71mg/kg.d separately. Compared with the static leaching experiment and dynamic leaching experiment, leaching rules of CODcr, BOD5, TP and TN are a totally different while NH3-N is not so.Based on the hydrologic conditions of Songtao Reservoir, we forecast the influence to water quality by the MSW in Baisha County. One dimension water quality model is used while all the degradation coefficients are the middling value in this process. And the difference method is used with no consideration of the nutriment exchange in the bed mud. We find that the model can reflect the pollutant variety in water practically and the most significant pollutants of water quality is COD.MSW in Danzhou region is mainly the dispersive countryside garbage that Dellen model is taking into forecast for N and P elements. The results indicate that the concentrations of TN and TP would reach 0.00006 mg·L-1,0.00003 mg·L-1 by the influence of MSW. Due to the eutrophication status assessment index, the reservoir will be from oligotrophication to mesotrophication by the influence of TP from MSW, which the significant source of P in the reservoir.Due to the infrastructure, economic conditions, terrain, solid waste situation and disposal technique practice of solid waste, the study indicates prevention and control methods of pollution in the reservoir, such as cleaning up the stocking solid waste around the reservoir, establishing a scientific and accomplished collecting and transporting system as well as integrated disposal methods of solid waste.