Study On The Influence Of Sewage Sludge And Aged Refuse On The Biological Effect And Enviromental Effect

As the world population increasing quickly and the economy growing fast, thenatural resources in the world are being consumed swiftly, The problem of environmentalpollution has become increasing serious.In recent years, many municipal plants forsewage treatment have been built, which effectively alleviate the pollution of waterenvironment caused by disposing of municipal sewage and industrial waste water.At thesame time, a number of landfills have been built to fill the municipal solid wastes.Sincethe construction of new landfills is becoming more and more difficult, it is feasible toexcavate and utilize the aged refuse in landfills, by which it is possible to greatly enlargethe landfill capacity and extend the service.period of the landfill,Since the naturalresources in china is so seriously short, the research on resources recycle is even moreimportant than ever.Due to the large amount of nutrition elements such as nitrogen, phosphorus andpotassium, utilization of sewage sludge and aged refuse is becomes an important topic incuurent research. However, the excess of nitrogen,phosphorus and heavy metals insewage sludge and aged refuse is the critical factor that limits,the utilization of sewagesludge and aged refuse in soil.Many studies focused on decreasing and reducing thepoisonous effect of these materias in sewage sludge and aged refuse, but the featursystem, economy and feasibility still cannot meet the practical demands o By studying onthe equilibrium and transfer of nitrogen, phosphorus in soil-plant ecosystem, and theirenvironmental effects, this dissertation aims to find awide lapplication of sludge compostand aged refuse to green area, which may support the theory and practical guide for thegarden utilization of sewage sludge.This research investigated the performance of potted experiment and leachingexperiment of ryegrass using the dewatered sewage sludge from Shanghai ChenQiaowater Quality Purifying Factory and aged refuse Which has about 10 years filled formShanghai Laogang landfill o Using W,L,WL serice and several mix rates of the Shanghailocal soils With the quick compost sludge and aged refuse.The potted experiment demonstrated that there exists dose-effect relationshipbetween sludge compost and aged refuse application rate and plant biomass.With theapplication of sludge compost and aged refuse, the biomass of turfgrass increases Sludgecompost and aged refuse brought into play action in slow-release fertilization.In addition,sludge compost and aged refuse improve the total and effective nutrient contents of N,P and K in soil.But the content of heavy metals and organisms have the negative impact onburgeon when the sludge compost increased to 20%, Thus, twenty percentage isrecommended as the maximum application rate. Aged refuse also is this, so aged refusedosage should control below 50%.A simulated column experiment was performed to analyze the effects of nitrogen andphosphorus from living sewage sludge of municipal and aged refuse movement on theunderground water, and on the removal of nitrogen and phosphorus by aged refuse. Theresult shows that the pH value tends to become low, but the total nitrogen and EC valueincrease apparently when the sewage sludge and aged refuse are used in soils.In addition,the nitrate increases significantly so as to pollute the underground water, whilephosphorus changes little and has scarcely chance to pollute the underground water. It haslittle effect on removal of nitrogen by using aged refuse but has some impact on removalof phosphorus from leachates, which, however, increases the nitrogen content in theleachates.Therefore, attention should be paid to the pollution by nitrogen especially nitratewhen the aged refuse is utilized to replace soils. The paper studied of heavy metals inaged refuse and sludge compost which mix with sludge through soil columnexperiment.The pollution comprehensive index method is used to analyze the effects ofheavy metal migration on underground water. The result shows that different heavymetals will pose potential danger to underground water at different stages of leachate sothe supervision should be conducted according to separate stages. [As], [Cr], [Co], [Cu]and [Mn] should be supervised at early stage of leachate; [Ni] and [Pb] at middle stage ofleachate: [Fe] at later stage of leachate: The assessment by pollution comprehensive indexmethod shows the key factor to pollute underground water in aged refuse and its mix withsludge during leachate are [Mn] and [Fe].By balance analysis of soil-environmental ecosystem in pot experiment and leachingexperiment after application of sludge compost and aged refuse showed that N,P andheavy metals in mixed soil.It could be concluded from effect balance that the optimalapplication rate of sludge compost is 5-10% and aged refuse is 50% for gardening.