【作者】 和苗苗；

【导师】 田光明；

【作者基本信息】 浙江大学 ， 环境工程， 2009， 博士

【摘要】 随着社会生产力与人们生活水平的提高，固体废弃物所带来的环境问题日益严重。在目前的处理途径中，将城乡有机固体废弃物堆肥化后土地利用，是解决固废问题最具经济、社会和环境效益的方法之一。但是，有机固体废弃物中不易降解的重金属以及显著高于土壤背景值的营养成分，会给土壤健康、植物生长甚至地下水环境带来非常大的风险。本论文以污水厂剩余污泥与禽畜粪便为研究对象，通过中试试验，探讨了堆肥过程对有机固废中重金属形态分布及植物毒性的影响机理；通过实验室模拟，获得了土壤中C、N、微生物数量与种群等参数对牛粪堆肥土地利用的短期响应动态模型，阐明了污泥堆肥施用对土壤-植物系统的影响机制，并探究了土壤重金属在施用污泥堆肥后的活化机制与空间迁移规律。研究结果为全面了解有机物料对土壤生态系统的影响，实现有机固体废弃物的资源化提供理论依据与技术指导。主要结论有：1、污泥与猪粪中重金属Cu、Zn、Pb的总量及其活性在堆肥的中温期与高温期显著降低；同时，通过种子发芽试验发现污泥及猪粪对青菜（Brassica Chinensis）与黑麦草（Loliumperenne L．）的植物毒性随堆肥的进行显著降低，表明施用腐熟的堆肥可降低土地利用的风险。在用重金属有效性形态之和（交换态+碳酸盐结合态+铁锰氧化态+有机结合态，EXCH+CAR+FeMnOX+OMB）回归青菜与黑麦草发芽指数（GI）的方程中，只有污泥堆肥中的Cu和猪粪堆肥中的Pb与青菜及黑麦草的GI线性相关。但是，在回归方程中加入pH、有机质（OM）以及溶解性有机碳（DOC）等参数后，回归相关系数R显著提高，说明将重金属形态与堆肥过程中关键理化性质结合来评估堆肥的植物毒性，能建立更有价值的评价模型。2、土壤中Copiotrophic菌数量、微生物活性以及种群多样性在施用牛粪堆肥后都呈波动变化，并通过傅立叶分析检测出显著的简谐振动波。土壤中pH值、DOC含量、NH₄⁺-N与NO₃^--N等化学性质只在施用堆肥后一周内有显著的波动变化，并与土壤Copiotrophic菌数量、微生物活性及种群数显著相关。土传病菌P. ultimum致病性的AUDPC（area underdisease process curve）在添加牛粪堆肥后短期内呈简谐振动模型变化，且与Copiotrophic菌数量的变化有相同的简谐振动频率与周期。这些参数在传统耕作土壤中的波动幅度均大于常年有机化管理的土壤，说明传统耕作土壤生态系统对施用堆肥的响应更强烈，有机化管理的土壤生态系统更稳定、更健康。3、土地投放量比较低的污泥或污泥堆肥可明显提高青菜的株高及产量，而黑麦草的株高与生物量随堆肥添加量的增加而增加。添加污泥或堆肥增加了植物体内Cu和Zn的含量，通过连续提取法发现，植物中重金属含量与其在土壤中EXCH及CAR形态的变化量有较好的相关关系，且相关系数随植株栽培时间的增加而增加，说明有机固废堆肥中Cu、Zn的毒性随土地利用时间而增强。同时，植物吸收重金属的量还与FeMnOX与OMB的变化量显著相关，说明植物可能间接影响了土壤中重金属的形态分布。就青菜与黑麦草的生长情况及其吸收重金属的含量而言，施用堆肥更为适宜，且最佳添加量分别控制在20％与60％以内。4、60cm土柱模拟试验结果表明：表施与混施污泥堆肥30天后，土壤pH值在施用深度以下5～10cm的变化最显著，且有机质也有总体向下迂移的趋势。表面施用堆肥使表层土壤中（0～10cm）Cu、Zn、Pb的溶出量在短期内均显著增加，而在下层土壤剖面中逐渐累积。混合施用堆肥的处理中，0～20cm层Cu、Zn、Pb的溶出量均在施用堆肥后第5天达到最高，在30～50cm,层土壤中，重金属也在10天内达到最大溶出量，将对地下水质量造成一定威胁。土壤Cu和Zn的淋溶量均与DOC呈对数线性拟合关系，而土壤溶液中Pb的含量与DOC呈线性相关，这说明在重金属的溶出过程中DOC起到很重要的作用，特别是在土壤中重金属含量较高的情况下。土壤中EXCH、CAR、FeMnOX及OMB形态重金属的变化与其溶出量显著相关，特别是以EXCH与FeMnOX形态存在的Cu、Zn、Pb含量的变化均与其溶出量呈显著负相关关系。5、利用以FeSO₄为底物的氧化亚铁硫杆菌（T.fe）对污泥进行生物沥滤去除重金属。Zn的去除率在第2天就达到95％，而Cu的沥滤启动较慢，在第4天才有了37％的去除率，这主要是由于Zn在pH值3．0～4．0时就有很高的去除率，而Cu在pH＜3．0时才能得到较好的去除。由于污泥长时间处于酸性环境，氮、磷、钾及有机质等营养物质有一定流失。在堆肥过程中添加粉煤灰（FA）、石灰（LM）及磷矿粉（PR）等钝化剂，使Cu、Zn、Pb总量的降低幅度显著增大。FA和LM降低了Cu、Zn、Pb较活泼形态所占的比例：而PR虽然降低了Pb的活性但不利于Cu和Zn的固定。种子发芽试验表明，PR处理中的污泥堆肥显著提高青菜与黑麦草的发芽率及根的生长，而添加石灰的堆肥对青菜种子的发芽与黑麦草根的生长有抑制作用，这可能是由于Ca含量及pH值均较高时不适宜种子的发芽。更多还原

【Abstract】 The development of our society and public living standard brings a large number of solidwastes, which pose the serious problems and challenges to our environment. Reusing organic solidwastes to agricultural land after composting may take the most considerably economic andenvironmental benefits. However, the presence of heavy metals and much higher contents ofnutrients bring potential risks on soil healthy, plant growth, and even underground water. Thisresearch investigated the effects of composting on heavy metal distributions and phytotoxicity oforganic solid wastes. Using pot experiments, we studied the evolutions of soil carbon, nitrogen,microbial population and diversity in short-term after addition of manure compost, and assessedthe impacts of sludge compost and sewage sludge on soil-plant system. Moreover, the activationof heavy metals and their downward movements in the compost-amended soil were investigatedby soil column experiment.Aerobic composting of sewage sludge （SS） and swine manure （SM） showed that, bothsystems decreased the total amounts and mobility of Cu, Zn and Pb, especially during thethermophilc and mesophilic phases. Furthermore, the germination rate （RSG）, root growth （RRG）and germination index （GI） of pakchoi （Brassica Chinensis L.） and ryegrass （Lolium perenne L.）increased during the composting process, indicating that phytotoxicity of sewage sludge and swinemanure diminished with composting age. Linear regression analysis demonstrated that GI, whichrepresented phytotoxic behavior to the plants, could be poorly predicted by the sum of mobilemetal fractions （exchangeable +carbonate +reducible iron and manganese+ organic matter bound,EXCH+CAR+FeMnOX+OMB）, i.e., Cu （EXCH+CAR+FeMnOX+OMB） in SS, Pb （EXCH+CAR+FeMnOX+OMB） in SM. However, the inclusion of other physicochemical parameters （pH,OM and DOC） could enhance the linear regression significances （R）, suggesting that thetransformenation of heavy metal speciation and phytotoxicity of organic solid wastes duringaerobic composting was rather strongly dependent on multiple components than a single element.The pot experiments revealed that the population of Copiotrophic bacteria （colony-formingunits, CFUs）, microbial activity and diversities fluctuated over time, and be demonstrated byHarmonics analysis in remarkable wave-like patterns with significant harmonics afterincorporations of cattle manure compost into soils. However, the pH, DOC, NH₄⁺-N and NO₃^--N only oscillated within the first week after addition of compost, and correlated with microbialpopulations and activities. The Pythium ultimum （soil-borne pathogen） damping-off, which wasmeasured by AUDPC （area under disease process curve）, oscillated with significant harmonicsand similar periods to Copiotrophic CFUs after nutrient impulses. Moreover, the soil fromconventionally managed farm had the larger amplitude in fluctuations of microbial and chemicalparameters than organically managed farm after addition of compost, indicating that the responsesof conventional soil system were much stronger and organic soil ecosystem was steadier andhealthier.Lower addition rates of sewage sludge or composted sludge could significantly increase theheight and yield of pakchoi, and the growth of ryegrass enhanced with addition rates. Landapplication of sewage sludge or compost also increased the Cu and Zn concentrations in plants.Plant uptake of Cu and Zn significantly correlated with variations of their EXCH and CARfractions in the soil, and the coefficients increased with time. This revealed that organic wastesmight represent stronger impacts on the plants in long-term land application. Based on growth andmetal uptake of pakchoi and ryegrass, sludge compost posed less harm to plants and its optimumland application rate should be control within 20% and 60%, respectively.60cm long soil column experiment showed that, the most significant variations of soil pHappeared in 5～10cm soil profiles below compost application. Organic matter also had thedownward movements. Surface application （SA） of sludge compost significantly increasedconcentrations of Cu, Zn and Pb in upper soil leachate （0～10cm） in short-term, and accumulatedin the deeper soil sections. In the mixed applied treatment （MA）, Cu, Zn and Pb in soil solutionsof 0～20cm sections reached the maximum on day 5 after addition of sludge compost, and metalcontents in the lower soil solutions （30～50cm） peaked on day 10. The results indicated thatcompost with high metal contents would bring risks on the underground water. Cu and Zn contentsin soil leachate were in logarithmic correlations with DOC contents, and Pb linearly related toDOC, indicating DOC played an important role on activation of heavy metals, especially under thesoil with high metal conditions. The mobile fractions of heavy metals, namely EXCH, CAR,FeMnOX, and OMB, also influenced their leaching concentrations. Especially the EXCH andFeMnOX of Cu, Zn and Pb were negtively correlated with their contents in soil solution.The bioleaching with Thiobacillus ferrooxidans （T.fe） was used for decreasing concentrations of heavy metals in sewage sludge. The removal rate of Zn reached 97.8% after 2 days. Theefficiency of Cu removing was 37% on the 4^th day and increasing persistently. For Zn, the removalrates were high when pH3.0～4.0, and when pH＜3.0 the removal rate of Cu was better. However,the losses of nutrition （TN, TP, TK and organic materials） were serious under the acidenvironment. The passivating agents fly ash （FA）, lime （LM） and phosphorus rock （PR） were usedin the composting process to reduce the mobility of heavy metals. Three passivating agents couldsignificantly decrease total Cu, Zn and Pb in sludge. FA and LM reduced the percentages ofmobile fractions in Cu, Zn and Pb. However, PR could not work on immobility of Cu and Zn. Theresults from seed germination test showed that, the addition of phosphorus rock to sludgecornposting could significantly enhance seed germination rate and root growth, but lime-sludgecompost affected germination of pakchoi seeds and root growth of ryegrass. The coexistence ofhigh concentrations of Ca and high pH value might be not benefit for seed germination.更多还原