【作者】 张晓琦；

【导师】 田禹；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2013， 博士

【摘要】 近年来，基于蠕虫捕食的污泥减量技术引起了广泛的关注。这一技术通过构建污泥捕食者-蠕虫与污泥之间的食物链关系实现污泥量的削减，具有二次污染低和能耗省的优势。然而，目前的多数研究更关注于污泥减量效能，在蠕虫生长、蠕虫捕食对污泥性质的影响方面的研究较为薄弱，蠕虫在捕食污泥过程中的种群稳定性、捕食对污泥中重金属等成分和胞外聚合物等性质的影响尚不明确，以至于无法完善地指导实际应用的开展。本研究将水生寡毛纲蠕虫-霍甫水丝蚓用于捕食污泥，深入研究蠕虫的生长特性和对污泥性质的影响。确定了与蠕虫发育阶段特性相适应的最优环境条件，考察了捕食污泥过程的蠕虫种群生长趋势；解析了典型的重金属在捕食过程中的相分布特征，探讨了污泥中重金属的赋存形式改变和蠕虫生理活性的影响；揭示了蠕虫生物捕食对污泥浓缩脱水性能和微生物活性的影响。蠕虫生长特性和种群特征的研究表明：幼蚓个体是蠕虫发育阶段中环境耐力最高的阶段。在温度25℃、虫体初始密度11~12g-worm/L、以2.8m~3/（m~2·h）的间歇曝气供氧、 pH值6.5、钠盐浓度不高于200mg/L、污泥浓度2000~6000mg/L、SRT≤3d，载体厚度为1cm，自然光照的环境条件下，蠕虫生长和捕食污泥效能最优，获得的平均污泥减量效率为297mg-TSS/L/d。在最优条件下，蠕虫的整体生长发育时间为74.6d。在长期的捕食污泥过程中，蠕虫种群增长速率趋近于1，逐渐接近种群生长的稳定状态。蠕虫生物捕食对污泥组分影响的研究表明：蠕虫捕食对污泥的碳氮成分没有特异选择性，对无机灰分略有累积；对难降解有机物没有明显的吸收作用。在蠕虫捕食过程中，泥相中4.1%的铜、9.7%的锌和4.8%的铅释放到水相中，同时，11.9%的铜、8.2%的锌和10.5%的铅累积在蠕虫体内；捕食后污泥相重金属含量为捕食前的81%以上。蠕虫捕食后污泥中以活跃化学形态存在重金属比例呈不变或降低趋势，捕食对污泥重金属生物利用度影响较弱。蠕虫捕食引起了有机碳和磷的明显释放。蠕虫生物捕食对污泥性质影响的研究表明：蠕虫捕食降低了污泥的SVI值、zeta电位、粘度和结合态胞外聚合物浓度，改善了污泥的凝聚和脱水性能。蠕虫捕食过程通过剥离污泥胶核外部蛋白质结合层，降解污泥可溶性蛋白质物质，促进了污泥调质过程的电中和和压缩双电层作用，提高了污泥的脱水效率。蠕虫对污泥微生物菌群具有随机捕食作用，对污泥的整体微生物群落结构并未造成显著的冲击，捕食后污泥对氨氮和COD污染物具有较好的削减性能。综上，霍甫水丝蚓是用于捕食污泥的较理想的微型动物。其生长特性能够适应长期的生物捕食，带来稳定的污泥减量效率和较低的环境影响。本研究结果为生物捕食污泥减量技术的完善和工艺应用的开展提供了理论参考和数据支持。更多还原

【Abstract】 In the recent years, a novel strategy for sludge reduction through aquaticworms’ predation has attracted significant attention. This technology is achieved onthe basis of a food chain from sludge to worms, and has advantages of lower secondpollution and less energy costs. At present, the majority of related researchesfocused on the performance of sludge reduction whereas few studies paid attentionto the worm growth and the influence of worm predation on sludge characteristics.Relatively little is known about the stability of worm population during sludgepredation and the variation in components and properties of sludge such as heavymetal, extracellular polymeric substances and microbial activity. However, all theseinformation are vital to the practical application of the technology.In the present study, aquatic oligochaeta worm Limnodrilus hoffmeisteri wasused as predator for sludge reduction. The worm growth and the influencemechanism of predation on sludge characteristics were further investigated. Thisobjective was accomplished by confirming the optimal habitat for the worms atdifferent development stages, describing the growth trend of worm populationduring sludge predation; analyzing the heavy metal distribution among sludge,supernatant and worms, discussing the variation in heavy metal speciation and thechange in worm activities; and revealing the effect mechanism of worm predationon sludge settling.The results of growth characteristics of worms showed that newborn wormshad relatively more tolerance to the improper process conditions. The suggestedoptimal process conditions for worm growth and sludge predation included a watertemperature of25°C, an initial worm density in the range of11~12g/L, intermittentaeration with intensity of2.8m~3/（m~2·h）, a pH value of6.5, a NaCl concentrationbelow200mg/L, a sludge concentration in the range of2000~6000mg/L, a SRTwithin3days, a carrier thickness of1cm, and the natural light. Under such optimalconditions, the average sludge predation rate was297mg-TSS/L/d, the duration ofworm life cycle was74.6days, and the asymptotic population growth rate of wormpopulation was approximately1during a period of117days, indicating a stablepopulation size in the sludge predation system.The results of sludge components during worms’ predation showed that theworms had no preference to the carbon or nitrogen in sludge and cannot absorb therefractory organics in their bodies, but had a slight accumulation for inorganiccomponent. More than81%of Cu, Zn and Pb remained in the sludge after predationby the worms, while4.1%,9.7%and4.8%of these metals were released into the liquid, and11.9%，8.2%, and10.5%of that accumulated in worms. The predationdid not increase heavy metal bioavailability in the final sludge as reflected by adecrease or unchanged levels in labile metal, while it caused a release of organiccarbon and phosphorus from solid into supernatant.The results of sludge properties during worms’ predation showed that thepredation decreased the SVI value, the zeta potential, the viscosity, and the amountof bound-EPS of sludge, enhancing the cohesion and hydrophobicity of the sludge.A part of protein bound to sludge flocs were stripped out by worms while thesoluble protein were degradation, both of which helped for the sludge conditioningthrough neutralizing the charge and compressing the double electrode layer,resulting in a higher dehydrated efficiency. The predation of worms onmicroorganisms of sludge was random with low impact on the microbialcommunity structure. The final sludge also exhibited remarkable performance ofammonia nitrogen removal and COD removal.The present study gave a systemic analysis for the process of sludge predationby oligochaeta worm L. hoffmeisteri, and demonstrated that this species is an idealpredator for sludge reduction. The growth characteristics of worms can adapt to thelong-term operation of sludge predation, exhibiting stable sludge reductionefficiency and relatively low effects on predation process and environment. Theresults provide a further understanding for this novel technology for sludgereduction and may help for the development of practical application.更多还原