【作者】 李淑更；

【导师】 周少奇；

【作者基本信息】 华南理工大学 ， 环境工程， 2009， 博士

【摘要】 本文以广州市城市污水处理厂的脱水污泥作为试验对象,在进行泥质分析的基础上,通过盆栽试验考察了植物的生长响应、污泥混配土壤基本性质变化以及污泥混配土壤中N、P和重金属的迁移转化规律,进而分析了脱水污泥土地资源化利用的可行性。研究了在污泥实现非农用资源化的过程中所种植物对污泥中重金属的修复效果,以及植物修复后污泥农用对作物产量和品质的影响。结果表明:脱水污泥的有机质、氮、磷等营养成分较高,具有较高的污泥土地利用潜力;但由于污泥中Zn的含量超标,且Cd、Pb的“活性库”分别为20%和30%,具有一定的生物毒性,因此污泥在农用之前有必要进行适当的处理。结合污泥营养成分高的特点,可先进行非农业的资源化利用,并且在利用中采用植物的修复作用来降低污泥中重金属含量。采用由未受重金属污染的赤红壤与污泥按不同的比例混合配置而成的培养土进行美人蕉、草坪草、酸模叶蓼、牛筋草盆栽试验。结果显示,在一定施用量下,美人蕉可获得良好的生长响应,并随着施用量的增加,每盆的植株数、叶片数、生物量和植株的高度都相应增加;脱水污泥的施用不仅能提高草坪草地上部分的生物量,而且能够促使草坪草的根系更加发达,利于培育状株;牛筋草和酸模叶蓼属于田地内的重要杂草,生命力顽强,能很快适应所生存的环境,能够在全泥的培养基质中生长,污泥的施用能显著提高牛筋草的地上生物量,并能促进其生长。试验过程中还采用叶绿素荧光参数来考证污泥施用对植株的影响,结果表明,尽管植株叶片中重金属含量有所增加,但污泥施用不会对植株产生任何胁迫作用,反而弥补了原始土壤中营养的不足。混配土壤重金属含量分析表明,美人蕉、草坪草、酸模叶蓼对Cd、Ni、Zn的去除效果良好;牛筋草对Cd、Ni、Zn、Cu均具有良好的去除效果,对于Pb和Cr也有一定的去除效果;综合生物量、植物重金属含量和重金属去除率来看,植物修复中污泥施用量宜控制在50%(330 t·hm-2)以内。将美人蕉、草坪草、牛筋草修复后的污泥分别用于种植小白菜、生菜、莴笋,小白菜、生菜、莴笋的种子发芽试验及根伸长试验表明,植物修复后污泥生物毒性较小,可以进行农用。适当的污泥施用量,既能够提高蔬菜的产量,也不会影响其品质,说明植物修复后污泥再进行农用,可以大大降低危害人类健康的风险,脱水污泥的连续利用(非农业利用-农用)可以作为一种有效的污泥处理及资源化的方法。本文还利用土壤环境容量数学模型对污泥土地利用的处理能力进行计算,结果表明施用量为322.2 t·(hm2·a)-1时,不会超过土壤重金属的临界值。同时污泥的利用市场调查也表明在林业及绿化方面污泥的利用前景广阔。更多还原

【Abstract】 The dewatered municipal sludge in Guangzhou municipal wastewater treatment plant was taken as experimental material in the present study. On the basis of analyzing the sludge characteristics, the growth response of different plants, the basic properties changes of compounded soil and transport and transformation of nitrogen, phosphorus and heavy metals in compounded soil were investigated by pot experiment method. And then the possibility of using the dewatered municipal sludge to soil was evaluated. The phytoremediation efficiency of heavy metals by plants during the utilization of sludge for non-agricultural purposes and effects of agricultural use of sludge after phytoremediation on biomass and quality of crops were also studied. The results showed:The contents of organic matter, nitrogen and phosphorus in dewatered sludge were relatively high, which showed that the sludge had the relatively high use potential to soil. However, the concentrations of Zn were higher than the criterion, meanwhile, Cd and Pb existed in active fraction were 20% and 30% respectively, so the sludge must be treated by appropriate method before agricultural utilization. Taking account of the high contents of nutrients, the dewatered sludge could be used for non-agricultural purposes first and during the utilization, phytoremediation could be used to reduce the contents of heavy metals in sludge.The compounded soil mixed by Ferralsols and sludge under different proportion was used to cultivate Canna indica, Turf Grass, Dockleaf Knotweed and Goosegrass Herb in pot experiments. The results showed that the Canna growth pattern exhibited a pronounced positive growth response under the certain application rate and the higher loading rate, the more number of plants, number of leaves and stem length. The application of sludge could not only increase the overground biomass of Turf Grass, but also promote the development of roots. Goosegrass Herb and Dockleaf Knotweed, which could adapt quickly to the environment and belonged to the important weeds in Guangdong, could survive in the sludge, and the sludge application could increase the biomass of Goosegrass Herb and promote its growth.During the experiments, chlorophyll fluorescence parameters were analyzed to test the impacts of sludge on plants. The results showed that sludge did no harm to plant although the heavy metal contents in plant were increased, while under the conditions of barren soil alone, the plants were put into nutrients stress conditions.The analysis of heavy metal contents in compounded soil showed that Canna indica, Turf Grass and Dockleaf Knotweed were effective in removing Cd, Ni and Zn; and Goosegrass Herb was effective in removing Cd, Ni, Zn and Cu, it also had certain removal efficiency with Pb and Cr. Based on biomass, the contents of heavy metals in plants and the removal efficiency of heavy metals, the application rate of sludge should controlled beyond 50% (330 t·hm-2).The compounded soil after phytoremediation by Canna indica, Turf grass and Goosegrass herb were used to plant Brassica Chinensis, Romaine Lettuce and Asparagus Lettuce respectively. Seed germination and root elongation experiments indicated that the biological toxicity of sludge had decreased after phytoremediation and it could be used for agriculture. The appropriate sludge application rate could increase the biomass but couldn’t decrease the quality of these crops, which indicated that healthy risk could be greatly reduced when the sludge was used for agriculture after phytoremediation by plants. The continuous utilization of sludge (non-agricultural use—agricultural use) could be used as an effective method for treatment and application of sludge.The treatment ability of soil was calculated with mathematic model for soil environmental capacity and the results showed that the contents of heavy metals in soil couldn’t exceed the critical value when the application rate of sludge was 322.2 t·(hm2·a)-1. The market investigation of sludge utilization to soil showed that sludge has wide application prospects in respects of using it in forestry and landscaping.更多还原