【作者】 孟繁宇；

【导师】 赵庆良； 马立；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2014， 博士

【摘要】 城市污水处理厂污泥的大量产生已成为目前亟待解决的环境问题，转变污泥处置思路，寻求合理的污泥资源化途径是当前研究的重点。微生物脱盐电池（Microbial Desalination Cells, MDC）能够在利用污泥中的有机物进行产电的同时淡化盐水，为污泥的能源化资源化利用提供了新的契机。然而，目前对于MDC系统性能的研究尚处于初步阶段，在底物研究中，直接采用城市污水处理厂常规脱水处理后产生的污泥作为阳极底物的报道还很少，而对于产电后剩余阳极污泥的后续资源化也有待进一步深入研究。本文提出了将脱水污泥作为MDC阳极底物进行产电、脱盐的能源化利用方式，以及利用处理后的阳极污泥改良盐碱化土壤的资源化利用方式。为了提高MDC性能和有效避免由于脱盐导致的阳极污泥盐分过量累积，对MDC构型进行了改进，构建了五室微生物脱盐电池（5c-MDC）、五室微生物电容型脱盐电池（5c-MCDC）和七室微生物双脱盐电池（7c-MDDC）三种构型的MDC，并研究它们的产电脱盐性能、阳极污泥中有机物降解、重金属形态转化和植物营养特征变化规律，进而研究了脱水污泥和阳极处理后污泥对盐碱化土壤的改良作用和重金属的潜在生态风险。研究结果表明：以脱水污泥为阳极底物的MDC具有启动快（5~6d），长期运行稳定的优势（200~300d）。三种构型的MDC产电效率相近，且以5c-MDC的产电效率最高，Pmax可达3.178W/m3。脱盐性能方面，5c-MDC的脱盐效率最高，且脱盐效率随着NaCl初始浓度的升高而降低，即61.48±0.10%（2g/L）>52.50±0.26%（10g/L）>48.30±0.61%（35g/L）。5c-MCDC和7c-MDDC均可以有效避免阳极污泥盐分的增加。在污泥降解方面，7c-MDDC的效果最好，运行42d阳极污泥的有机质去除率达到17.71%，200d达到32.7±0.81%，且污泥中速效氮、磷、钾含量的增加最为明显。运行42d阳极污泥浸提液种子发芽指数可达到66.63±3.02%。对5c-MDC与7c-MDDC长期运行性能的研究中发现：随运行时间的延长，阳极污泥的pH值始终维持在6.5~7.5之间，污泥溶解性有机物中腐植酸类荧光峰强度明显增加，重金属形态组成中稳定的残留态比例明显增加，重金属的生物有效性降低明显。以脱水污泥和阳极污泥改良盐碱化土壤的结果表明：两者均可以降低土壤的容重、pH值、碱化度，并增加土壤中有机质、总氮、总磷、速效氮、磷、钾的含量，且阳极污泥的效果要优于脱水污泥。当污泥投加比例超过30%可使土壤容重降低到1g/cm3以下，pH降低1~2个单位，碱化度降低到30%以下，并使得土壤有机质增加2.0~5.9倍，总氮增加1.5~4.6倍，总磷增加1.5~4.5倍，速效氮增加3.7~10.5倍，速效磷增加4.1~19.7倍，速效钾增加1.1~1.8倍；随孵育时间的延长，施用污泥后土壤的容重、pH值、碱化度、有机质、总氮含量持续降低；速效氮、磷、钾含量逐渐增加。种子发芽试验和作物盆栽实验均得到了污泥合理投加比例为30%~50%。经过长期孵育和植物生长后，施用污泥的盐碱化土壤中0.05~1mm微团聚体比例增加，土壤溶解性有机物中溶解性微生物产物、富里酸和腐植酸的荧光强度均有所增加，表明污泥的施用促进了团聚体的形成，增加了土壤中微生物的活性，提高了土壤的腐殖化程度。然而，两种污泥的施入均会增加土壤中重金属的生态风险，在施用初期重金属生物有效性也有所增强，但重金属含量仍明显低于土壤环境质量标准，形态上仍以残留态比例最高。经过长期的孵育，除As外，其余元素生物有效性均有所降低，并向更稳定残留态转化。5种可检测到的重金属和类重金属元素在土壤/小麦和土壤/紫花苜蓿中的富集系数依次是Ni，Zn，B，Cu，Cr，且同种元素在紫花苜蓿中的富集系数大于在小麦种的富集系数。本文提供了一条系统化的脱水污泥综合利用途径，可为MDC的性能优化与功能拓展，以及污泥改良盐碱化土壤的实践提供一定的理论依据。更多还原

【Abstract】 It is imperative to solve the serious environmental problem that the sludge produced by the municipal sewage treatment plants has stacked too much. People need to change the traditional solution program imminently. Therefore, it is paid more attention for the research field that how the sludge can be treated in order to realize the rational and efficient resource utilization. Microbial desalination cells (MDC) can convert the chemical energy in organic of the sludge into the electricity power directly, and the produced electricity power can be used to desaline the seawater in-situ, it can realize the organic remove and sludge stabilization simultaneously. This technology offers a new opportunity to achieve the energy-form and the reutilization in the sludge treatment. At the monment, the studies in MDC system performance are still in preliminary stage. For the available substrate studies, there were few reports that the dewatered sludge, produced in the municipal sewage plant with the normal treatment process, was directly used as an anodic substrate. It is worthy to make further research in the reutilization with the sludge residue after the electrisity generation.It was suggested that the dewatered sludge as the MDC anodic substrate can generate the electricity power, desalt the salt water. And the rest anodic sludge can be continually used as a soil conditioner to improve the saline-alkali soil. In order to improve the MDC property and efficiently, and aviod the desalting-formed exceeding accumulation in the anodic sludge salinity, the MDC construction was modified. The5-Chambers Microbial Desalination Cells (5c-MDC),5-Chambers Microbial Capacitance Desalting Cell (5c-MCDC) and7-Chambers Stacked Microbial Desalination Cells (7c-MDDC) were prepared. The desalination and electricity generation property, organic matter degradation and forms transformation of heavy metal, and plant nutrition characteristic in anodic sludge were studied respectively. The improvement effects of the dewatered sludge and anodic sludge on the saline-alkali soil and the potential ecological risk of heavy metal were also analysed.Through the study in the MDC with the dewatered sludge as an anodic substrate, the result indicated that this system possessed the started rapidly (5~6d) and stabilized in long-term operation (200~300d) characteristics. The electricity efficiencies were almost equal in the3type MDCs, and the highest one (Pmax=3.178W/m3) was achieved by5c-MDC. In the desalination aspect: the5c-MDC was the best in desalination efficiency, and the desalination efficiency decreased with the NaCl initial concentration increased, that was61.48±0.10% (2g/L)>52.50±0.26%(10g/L)>48.30±0.61%(35g/L). Meanwhile, the5c-MCDC and the7c-MDDC both can avoid the salinity accumulation in the anodic sludge. Moreover, the7c-MDDC sludge degradation effect was the best in these three type cells. Specially, in the7c-MDDC, the organic matter removal rate was the highest; the removal rate can get17.71%at the42nd day, and32.7±0.81%at the200th day; an obviously increase can be observed in the available nitrogen, phosphorus and potassium content with time. After42days operation, the seed germination index in the sludge leach liquor can reach66.63±3.02%in7c-MDDC. Under the long-term operation in5c-MDC and7c-MDDC, the results showed that, as the operation times passed, the anodic sludge pH value can be maintained between6.5and7.5, the humic acid fluorescence peaks in sludge dissolved organic matter were enhanced, the heavy metal stable residual state proportion increased, and the heavy metal bio-availability decreased greatly.The results of saline-alkali soil improvement by the dewatered sludge or the anodic sludge indicated that, the dewatered sludge and the anodic sludge both can decrease the soil bulk density, pH value and exchange sodium percent, and increase the soil organic matter, total nitrogen, total phosphorus, available nitrogen, phosphorus and potassium content. Meanwhile, the anodic sludge improvement effect on the saline-alkali soil was much better than the dewatered sludge effect. When the sludge proportion exceed30%, the soil bulk density was below1g/cm3, pH was decreased by1~2, exchange sodium percent was below30%, the soil organic matter, total nitrogen, total phosphorus, available nitrogen, phosphorus and potassium content were increased by2.0~5.9,1.5~4.6,1.5~4.5,3.7~10.5,4.1~19.7,1.1~1.8times, respectively. As the incubating time extension, the sludge-treated soil properties, such as the soil bulk density, pH value, exchange sodium percent, organic matter content and total nitrogen content decreased continually, but the available nitrogen, phosphorus and potassium content gradually increased during the incubating period. Based on the seed germination and crop plants experiment results, the reasonal addition proportion of the dewatered sludge and the anodic sludge were both about30%~50%. After the long incubation and plant growth, the proportion of the0.05~1mm microaggregate could increase in the saline-alkali soil treated by sludge. Through adding sludge in the saline-alkali soil, soluble microorganism product and fulvic acid content in the soil dissolved organic matter increased, the humic acid fluorescence intensity enhanced. All these results indicated that sludge treatment can accelerate the formation of the soil aggregate, increase the microorganism amount and activity in the soil, and improve the soil humification degree. Nevertheless, two kinds of sludge addition can both increase the heavy metal total content in the soil. In the preliminary stage, the heavy metal bio-availabilities can be enhanced partly, but the total heavy metal amount was obviously lower than the soil environmental quality standards, and the residual state proportion was the highest among them. After long-term incubation, except As element, all the other element bio-availabilities decreased, and tended toward the more stable residual state. The enrichment factors of the heavy metal or similar heavy metal, which were detected between soil and wheat or soil and alfalfa, can be ordered like this: Ni, Zn, B, Cu, and Cr. The same element enrichment factor was higher in alfalfa than that in wheat.This study offered a system method to exploit the comprehensive utilization of the dewatered sludge. This work was made some theoretical foundation in MDC performance optimization, function expansion and saline-alkali soil improvement by the sludge.更多还原