生物沥滤去除城市污泥中重金属的温度控制研究

以桂林城市污泥作为处理介质、单质硫为能量底物、土著硫杆菌为主要的沥滤微生物,对10～40℃下生物沥滤的酸化效果、沥滤微生物活性和去除重金属的效果进行了研究.结果表明,在单质硫的投配量为3 g/L、曝气强度为1.0 L/min的条件下,当温度为10～30℃时,升高温度能明显提高污泥酸化速度和微生物活性.为缩短生物沥滤时间和提高酸化效果,沥滤体系的最佳运行温度范围为20～30℃,其中温度为28.9℃时沥滤微生物的活性最强,此时硫酸根的产率为461.66 mg/(L·d).从达标处理和低能耗运行的工程角度考虑,生物沥滤温度可控制在20℃.5 d后对Cu、Zn、Cd的去除率分别为47.45%、77.07%和80.57%,残余重金属含量均符合污泥农用的相关标准.     

污泥中金属的生物沥滤处理

活性污泥法处理污水后产生大量污泥 ,如何对其加以处理利用引起国内外学者关注。众多研究表明 :污泥农用是实现污泥资源化、解决污泥出路的上策 ,但污泥中常含有较多的重金属 ,若在农田加以施用会导致土壤中重金属积累 ,使农作物遭受污染 ,最后通过食物链进入人体 ,因此污泥在农用前必须去除或降低其重金属含量。 1975年以来 ,国外学者尝试用酸、离子交换、氯化、添加化学试剂等方法均存在成本过高、操作复杂、效果不稳定等系列问题。近年来用生物法沥滤污泥中重金属 ,效果较为明显。1　 生物法沥滤重金属的机理及优点活性污泥中存在Ｔｈｉ…     

污泥生物淋滤过程中Cd及Pb形态变化研究

对太原市污水处理厂的污泥进行了生物淋滤序批实验研究,采用5％接种量和底物浓度4g/L单质硫为工艺参数,采用顺序浸提法测定了生物沥滤中重金属形态之间的转化,通过淋滤前后重金属形态变化分析了其沥滤机制及浸出能力。结果表明,cd是通过间接机制沥出,Pb的沥出主要是由直接机制和间接机制的共同作用完成的。研究结果对预测污泥农用的环境风险有积极意义。     

SBR工艺去除城市污泥中重金属的研究

以桂林市某城市污水处理厂二沉池的生污泥为培养介质、以硫酸亚铁为底物,利用简化的SBR工艺对城市污泥中以氧化亚铁硫杆菌为主的沥滤微生物进行驯化培养,研究了沥滤微生物对城市污泥中重金属的去除效果。结果表明，在底物投配比为10g/L、污泥接种量为30%、室温为25℃的条件下连续曝气运行2 d,对Cu和Zn的去除率达78.3%和77.7%，对Cd的去除率接近99%，沥滤处理后污泥中的残余重金属含量符合污泥农用的国家标准。     

生物沥浸法对常规脱水污泥再深度脱水的效果

为了考察生物沥浸法对常规脱水污泥(指在浓缩污泥中加PAM等高分子絮凝剂并经带式或离心脱水后获得的含水率在80%左右的脱水污泥)进一步深度脱水的效果,将常规脱水污泥用中水稀释成含水率为97%左右的液态污泥后,采用批式运行模式进行生产性生物沥浸法调理(每批次处理污泥为60 m3),然后在不加任何化学絮凝剂的情况下直接用隔膜厢式压滤机进行压滤脱水。结果表明,以浓缩池含水率为97%的浓缩污泥作为对照,在上批次沥浸污泥(接种物)与待处理的液态污泥体积比为1∶1时,生物沥浸过程可在24 h内完成,污泥比阻由沥浸初期的3.56×1012m/kg降低至0.43×1012m/kg。生物沥浸后的污泥通过150 m2的隔膜厢式压滤机,在1.2~1.5 MPa压力下压滤1.5 h,泥饼含水率可稳定地降低到60%以下,外观呈土黄色块状,无臭味。经检测,泥饼有机质和高位热值在生物沥浸处理前后没有降低,且压滤液清澈,无色无味,COD为120~170 mg/L,总氮为40~60 mg/L,总磷在0.5 mg/L以下。可见,常规脱水污泥经稀释后进行生物沥浸法深度脱水处理是完全可行的。     

生物沥滤法对剩余污泥中重金属及养分含量的影响

以城市剩余污泥为材料,通过对硫酸亚铁(FS)、硫酸亚铁铵(FAS)、单质硫(S0)三种底物的单一和复合投加生物沥滤试验,研究不同类型底物对污泥中重金属及养分含量的影响。结果表明,底物为FAS+S0时污泥中重金属溶出效果最佳,此时对污泥中Cu、Zn、Cr和Ni的去除率分别可达86.7%、88.2%、76.2%和65.0%。沥滤结束时,FAS为底物的污泥中TN、TP含量最高,其次为FS,S0为底物时污泥中TN、TP含量最低,FS+S0和FAS+S0为底物时污泥中TN、TP的含量较单独投加S0时有所提高但不明显,说明S0是导致污泥中TN、TP流失的主要因素。     

用生物法去除废水污泥重金属的经济性评价

本文对各种实用的污泥管理办法，包括消化和未消化污泥中金属的生物溶解法及传统的污泥管理方法都进行了经济性的评价。生物溶解法亦称细菌沥滤法，包括石灰中和与土地撒布法，用于未消化污泥比用于消化污泥费用更省。这种办法对于规模在３８．８万ｍ＾３／日的污水厂来说，与未经除污处理的脱水污泥用地撒布法具有同样的竞争力。这两种管理办法大致相同，并且都比所考虑其它方案成本更为低廉。尽管如此，对于一座日处理量为２万ｍ＾     

生物沥浸对城市污泥脱水及其重金属去除的影响

利用沥浸微生物对浓缩污泥与添加聚丙烯酰胺(PAM)的脱水污泥进行生物沥浸处理,同时采用厢式压滤机在0.35 MPa的压力条件下,对生物沥浸前后的污泥进行脱水。结果表明,经过生物沥浸处理,浓缩污泥与稀释后的脱水污泥的CST值可分别降至11.8、14.6 s;沥浸结束后静置24 h,上清液所占比例分别从原来的12.5%、24%升至31%、42%,两种污泥中Zn的溶出率分别为66.65%、59.13%,Cu的溶出率分别为13.31%、23.55%。对浓缩污泥直接进行压滤脱水,泥饼含水率高达75%;加PAM调理后再脱水,泥饼含水率达68%;而经生物沥浸后再脱水,泥饼含水率可降至58%。可见,在相同脱水条件下,生物沥浸法对污泥的调理作用要优于PAM。     

生物沥浸细菌的培养及其对污泥脱水性能的影响

以高碑店污水处理厂的浓缩污泥作为生物沥浸对象进行脱水预处理,研究了生物沥浸细菌的培养及其对污泥脱水性能的影响。将回流污泥上清液分别接种到SM液体培养基和9K液体培养基,通过分离培养、富集获得以氧化硫硫杆菌和氧化亚铁硫杆菌为主的生物酸化细菌,不断转接使培养基pH值降到2以下所需时间由最初的8~10 d缩短到3~4 d,然后共同接种到浓缩污泥中,经强化培养获得生物沥浸的接种物。不同营养物质投加量的沥浸试验发现,当其他条件保持一致时,S投加量为2 g/L的试验组降低体系pH值、提高体系ORP的能力要强于投加量为1 g/L的试验组;在S投加量一定的情况下,Fe SO4·7H2O投加量2 g/L时生物沥浸效果较好。生物沥浸后污泥的脱水性能得到显著改善,经板框脱水可使泥饼含水率降到65%以下。     

一株氧化硫硫杆菌的分离鉴定及其沥滤污泥研究

从山西某煤矿的酸性矿井水中分离得到嗜酸氧化硫硫杆菌Tt-1,对其形态、生理生化特性、16S rDNA基因序列、生长特性及对城市污泥的沥滤效果进行了研究。Tt-1的菌细胞呈短杆状,革兰氏染色为阴性,不产生芽孢,16S rDNA系统学分析证明其为嗜酸氧化硫硫杆菌。菌株Tt-1的最佳生长条件:温度为28℃,pH值为4.0,接种量为10%,S0浓度为10 g/L。菌株Tt-1在污泥浓度为10%、28℃的条件下沥滤15 d,对污泥中Cd、Cr、Cu、Ni、Pb和Zn的最大去除率分别为66.20%、41.35%、91.74%、65.73%、43.86%和93.72%,处理后污泥中的重金属含量可满足污泥农用标准。     

The change in activated sludge surface properties after heavy metals leaching

The change in colloid-chemical properties of natural sludge sol formed as a result of biological treatment of domestic wastewater in the process of heavy metals leaching induced by metabolizing heterotrophic (acidogenic and alkaligenic) chemotrophic biocoenosis was investigated. It was found that bioleaching of heavy metals involving heterotrophs results in hydrophobization of sludge colloids and reduces its negative charge. Heavy metals leaching also results in destabilization of sludge sol, maximum in biological processes. Exopolysaccharides significantly stabilizing sludge sol have a little effect on its stability after heavy metals have been leached.     

复合硫杆菌对污泥重金属生物淋滤机制的影响

对污泥生物淋滤过程中各种重金属元素的形态变化情况进行了测定,借助重金属化学形态转化规律,间接判断污泥重金属生物淋滤的转化机制。试验结果显示,Cu、Ni、Cd的生物淋滤是以直接机制为主的,Zn的生物淋滤过程是以间接机制为主的,Cr、Pb的生物淋滤过程属于混合机制,但其混合机理是有差别的。     

Bioleaching of heavy metals from sludge after biological treatment of municipal effluent

The article has compared the efficiency of removing heavy metals from the sludge after biological treatment of municipal wastewaters in the course of biological leaching involving heterotrophic and chemotrophic microorganisms and chemical leaching. The article also showed advantages of the bioleaching of metals under conditions of acidogenic heterotrophic metabolism. The efficiency of the leaching of heavy metals from the sludge varies 80% (Zn) to 15% (Cr) and corresponds to the following series: Zn > Mn > Cu > Ni > Cd > Pb > Cr.     

Assessment of toxicity reduction after metal removal in bioleached sewage sludge

Sewage sludge can be applied to land to supply and recycle organic matter and nutrients. Trace elements in sludge, however, may accumulate in the soil with repeated sludge applications. Reducing metal content may therefore reduce the adverse effects of sludge application. The objective of this study was to evaluate the efficiency of bioleaching technology in reducing metal content and toxicity as measured by a battery of terrestrial and liquid-phase bioassays. Sludge-soil mixtures simulating the application of sludge to land were tested by means of terrestrial bioassays, barley (Hordeum vulgare L.) seed germination (5 d) and sprout growth (14 d), lettuce (Lactuca sativa) seed germination (5 d), and worm (Eisenia andrei) mortality (14 d). Liquid-phase bioassays, Microtox (Vibrio fischeri, 15 min), lettuce root elongation (L. sativa, 5 d), cladoceran mortality (Daphnia magna, 48 h), and SOS Chromotest (Escherichia coli) were used after elutriation of the sludge. Comparison of the bioassay results (except for D. magna) before and after treatment demonstrated that this bioleaching process reduced both sludge toxicity and metal content. In addition, lower Cu and Zn concentrations found in barley sprouts following treatment supported the assumption that the bioleaching process, by decreasing metal content and bioavailability, reduced sewage sludge toxicity. This study also emphasized the interest of using ecotoxicological bioassays for testing biosolids. In particular, the terrestrial bioassays after simulation of land application and the Microtox test after sludge elutriation proved to be the most appropriate procedures.     

Bioleaching of heavy metals from wastewater sludge by ferrous iron oxidizing bacteria

Experiments on bacterial leaching of heavy metals from aerobically stabilized surplus activated sludge at the Bortnichi aeration plant in Kiev have been conducted with addition of FeSO₄ ? 7H₂O as a stimulant of iron-oxidizing bacteria. The mechanism of heavy metal leaching involving the ferrous iron oxidation by bacteria with subsequent formation of Fe(OH)₃ was confirmed. This process is accompanied by the reduction of pH level of wastewater sludge that results in leaching of heavy metals.     

强化化学淋滤对污泥重金属溶出及磷释放的影响

针对采用传统化学淋滤方法处理污水污泥时重金属溶出率低的问题,设计了两种强化化学淋滤方法的对比试验,通过检测重金属形态分布、污泥有机质及磷释放、污泥含固率,研究了强化化学淋滤对污泥各方面综合性能的影响。结果表明:稀硫酸与氯化铁联合处理(处理方法1)对Cu和Cr的溶出效果不明显,但在加入NaNO₂(处理方法2)后使Cu溶出率由7%提升至82%,Zn溶出率由79%提升至88%;同时,两种强化化学淋滤方法均增加了污泥中有机质和磷的释放,污泥中磷含量由23.2 mg/g分别降至12.3 mg/g和10.7 mg/g;与原污泥相比,强化淋滤后的污泥脱水性也均得到了明显改善,其污泥含固率分别提高了52%和61%。     

生物沥浸改性后污泥基生物炭对Pb^2+和Cd^2+的吸附

为探索利用生物沥浸改性后污泥基生物炭去除废水中Pb^2+和Cd^2+的可行性,以生物沥浸改性后污泥为原料制备生物炭,并测定了该材料的性能和吸附特性。通过单因素试验研究了pH值、生物炭投加量对吸附Pb^2+、Cd^2+性能的影响,并利用吸附动力学和热力学来揭示吸附机制。试验结果表明,经生物沥浸改性后污泥基生物炭的重金属含量降低;吸附Pb^2+和Cd^2+的最佳pH值分别为5、6,最佳生物炭投加量均为2 g/L;其对Pb^2+和Cd^2+的吸附均能较好地符合准二级动力学方程和Langmuir等温线模型,在25、35、45℃三种温度下对Pb^2+、Cd^2+的饱和吸附量分别为30.68、39.95、43.93 mg/g和19.82、28.58、32.29 mg/g,吸附过程均主要以物理吸附为主,且为吸热过程。     

Comparison of dried sludge and sludge ash for phosphorus recovery with acidic and alkaline leaching

Nowadays, the recovery of phosphorus has been in the spotlight due to its importance for food security and depleting sources. In this study, phosphorus recovery from dried sewage sludge and sludge ash by acid and alkaline leaching was evaluated. Optimum extraction time and temperature were determined as two hours and ambient temperature. Results showed the superiority of strong acidic conditions for leaching; 75 ml/g with 0.4N HCl and 25 ml/g with 0.6N HCl were determined as optimum conditions to achieve efficient phosphorus dissolution from sludge ash (94.6%) and dried sludge (91.1%), respectively, with the lower heavy metal concentrations. Lower L/S ratio put forward the dried sludge as a more advantageous resource for phosphorus extraction. Besides, by alkaline leaching of sludge ash and dried sludge, 60.3 and 70.3% phosphorus dissolutions were achieved with 75 ml/g and 1N NaOH; and the leachate was a suitable product for phosphorus precipitation due to its high pH.     

Significance and behaviour of heavy metals in waste water treatment processes II. Sludge treatment and disposal

The literature concerning the significance and behaviour of heavy metals in sewage sludge treatment and following sludge disposal is reviewed. Particular attention is given to metal form during anaerobic digestion and following sludge disposal to agricultural land and to sea, and the influence of metal form on toxicity. It is evident that anaerobic digestion results in a strong association between sludge particulates and heavy metals due to the formation of inorganic precipitates, organo-metallic interactions and by association with the biomass. Toxic inhibition of anaerobic digestion by metals is concluded to be a direct result of the free metal ion concentration and thus mechanisms designed to reduce metal toxicity are based on artificial modification of heavy metal speciation in the digester.Guidelines and legislation designed to limit the application of sludge to agricultural land and the disposal of sludge to sea are reviewed and discussed. Following the application of sludge to agricultural land significant changes occur in heavy metal speciation, which ultimately determine metal availability to plants and potential contamination of groundwaters. Guidelines for application to land currently take limited account of metal form, although the importance of metal speciation is being recognised. Sludge disposal to sea has received relatively little attention with efforts being directed towards monitoring rather than more fundamental research. However, it is apparent that significant heavy metal solubilisation may occur following sludge discharge to the marine environment.It is concluded that sludge disposal to agricultural land and sea, which are increasingly becoming subject to more stringent international pressures, should take account of the ultimate forms of heavy metals in the receiving environment and that a more unified approach should be adopted in the formulation of standards for all forms of sludge disposal.