生物浸出污泥重金属研究进展

污泥是由污水处理过程中形成的沉淀物,具有含水率高、有机物含量高、重金属含量高等特点,其中重金属污染控制一直是污泥处理处置的难点。生物浸出技术具有耗酸少,运行成本低,重金属去除率高,无二次污染等优点被广泛应用。本文论述了生物浸出技术的浸出菌种,影响因素,研究现状及应用,展望了生物浸出技术研究的重点。     

不同粒径污泥热解制备生物炭及其特性分析

以3种不同粒径污泥为原料,采用固定床反应器在500℃下制备生物炭。考察了3种不同粒径污泥的热解特性及其生物炭中重金属的分布特征,并运用TCLP对污泥及其生物炭的重金属浸出毒性进行了系统研究。结果表明,随着污泥粒径的增大,热解生成的生物炭和热解气产率均有所降低,而焦油产率则逐渐升高;在3种不同粒径污泥热解过程中,重金属除As外主要富集在固体产物生物炭中,相对富集系数均高于90%。随着污泥粒径的增大,污泥中Cu、Zn和Ni的含量增加,而Cr和Pb的含量则减少;虽然3种不同粒径污泥制备的生物炭中重金属的浸出规律不一致,但是污泥热解可以有效抑制重金属的浸出。生物炭中除As和Zn外其他重金属元素的浸出率均低于3.0%。     

污泥掺烧生物质的重金属排放特性研究

针对城市污泥焚烧面临的重金属污染严重等问题,提出了在城市污泥中掺烧生物质解决重金属污染的新方法,并利用5 k W鼓泡流化床进行试验研究,考查城市污泥掺烧生物质过程中重金属的含量和形态分布特性及燃烧飞灰中重金属的浸出毒性。结果表明:城市污泥掺烧生物质使Cd和As的挥发性降低,Pb、Cu和Cr的挥发性增加,对Hg的挥发性影响很小;城市污泥掺烧麦秆对Zn的挥发性影响不大,掺烧棉秆使Zn的挥发性降低;城市污泥掺烧生物质都使飞灰中Pb、As的形态稳定性降低,使Zn的形态稳定性增加,对Cu、Cr的形态稳定性影响较小;污泥掺烧不同生物质对飞灰中重金属浸出量和浸出率的影响不同,棉秆与麦秆相比更有利于降低飞灰中重金属的浸出量和浸出毒性。     

污水污泥页岩烧结制品的重金属固化与水环境浸出稳定性

提高重金属固化程度与浸出稳定性是含重金属污水污泥处置和利用的前提。采用污水污泥并模拟提高其重金属Cr、Cu、Pb的含量,与页岩混合制备烧结砖和陶粒制品,研究重金属在页岩制品高温烧制过程中的固化率以及制品中重金属的水环境浸出稳定性,通过X射线衍射和扫描电子显微镜分析含重金属矿物的赋存形态和页岩制品微观形貌对重金属固化与浸出稳定性影响。与相同条件下焚烧纯污水污泥相比,重金属在页岩制品烧制过程中固化率明显提高,浸出毒性明显降低,重金属在页岩制品中易形成稳定的尖晶石型矿物以及页岩制品所具有的致密微观结构;相比烧结砖,陶粒中重金属固化程度和浸出稳定性更高,因为陶粒在更高温度下有利于尖晶石型矿物和致密结构形成。     

生活污泥焚烧灰的重金属含量及其浸出特征

为了探讨生活污泥焚烧灰中重金属的含量及其浸出特征,收集了广州沥窖污水处理厂的剩余污泥,采用火焰原子吸收光谱法测量重金属含量;应用固体废物浸出毒性的浸出方法(GB5086.2-1997),以不同p H的浸提剂,对污泥中重金属的浸出特性进行了实验研究。结果表明:污泥中Fe的含量最高,达到27378 mg/kg,其次是Mn和Cu,分别为436.5 mg/kg和315.2 mg/kg,Zn、Cr、Pb和Ni的含量较高,依次是721.5、199.2、122.2和110.8 mg/kg,Cd的含量极少,仅有0.33 mg/kg。Cr和Cd金属元素的8小时浸出量分别为62.9 mg/kg、0.96 mg/kg,其余被测的金属元素:Fe、Pb、Cu、Ni、Zn以及Mn,在任何浸提时间下,其浸出量均为0 mg/kg。本实验中重金属在酸性条件下的浸出率明显高于碱性条件下,Cr、Ni和Cd的最佳浸提剂p H值均为2。其中Cu和Zn随浸提剂p H变化的浸出特征不明显。。     

微波-柠檬酸浸出城市污泥中重金属

采用微波辅助柠檬酸浸出城市污泥中的重金属,考察了升温速率、pH值、搅拌时间等对浸出率的影响。结果表明,升温速率为15℃/min,pH值调至3,前搅拌30 min,170 W功率下微波2.3 min,再反应3 h,污泥中Zn、Cu、Ni与Pb的浸出率分别达到了47.84%,11.05%,43.83%,25.59%,较无微波条件下,重金属浸出率平均提升了50.7%,反应时间缩短了8 h。处理后污泥中重金属含量远低于《农用污泥中污染物控制标准》(GB 4284—84)。     

污泥焚烧灰渣中重金属的检测和毒性分析

采用ICP-OES和原子荧光光度计分析了污泥及其焚烧灰渣中重金属的种类和浓度,并对灰渣中重金属的浸出毒性进行分析。结果表明污泥焚烧灰渣中重金属种类多、浓度高,可依据不同重金属的挥发性大小将污泥中重金属划分为极易挥发重金属、易挥发重金属、中等挥发重金属和难挥发重金属四大类,实际污染控制中应重点关注重金属Hg、As、Cd、Pb四种重金属的控制;同时,毒性浸出实验结果表明污泥焚烧之后灰渣中重金属稳定性得到极大提高,可直接进行填埋处理,但做建材使用时仍存在很大的浸出风险。     

固体垃圾与污水污泥混烧中重金属迁移特性的研究

进行了固体垃圾与污水污泥合成样品在管式焚烧炉内的混烧实验,采集样品进行化学成分分析,表征了污水污泥中的重金属在焚烧过程中向飞灰和烟气迁移的特性及对灰渣的毒性影响。结果表明,混烧显著提高了飞灰和底灰中重金属含量,其中Zn表现最明显。毒性测试结果显示,污水污泥的混烧导致了垃圾焚烧飞灰中Zn和Pb的浸出浓度超过中国危险废物浸出的控制标准值。     

污泥中重金属去除的技术

介绍了污泥中重金属存在的形态,综述了污泥中重金属去除的常用的四种技术化学浸出、生物浸出、电分离和超临界流体萃取,重点介绍了化学浸取技术的原理和特点,并对诸项技术的优点以及存在的问题进行了评述。     

电镀污泥中重金属最佳浸出条件的实验研究

研究了电镀污泥中重金属的浸出方法,对几种常用的浸出剂进行对比实验,最终选定硫酸作为浸出荆,并确定最佳漫出工艺条件:污泥细度为100目,每2 g污泥溶解在10 mL、pH值为1.5的硫酸溶液中,常温下振荡1.5 h.在该奈件下,污泥中重金属Cu,Ni,Zn,Cr的浸出率最高,均迭95%以上,为后续回收工艺奠定了较好的基础...     

重金属在城市污水处理中的去除机理

由于重金属的毒性及致癌性,受重金属污染水体备受关注,去除水体中的重金属势在必行。活性污泥作为一种生物吸附剂,在处理低浓度重金属废水应用中前景广泛。以活性污泥为核心的城市污水处理厂在有效去除有机物的同时,对重金属也有一定的去除能力。通过综述城市污水系统中重金属迁变特性的最新研究,分析了活性污泥处理重金属废水的优越性、国内外污水处理厂对重金属的去除效果,推导出活性污泥去除重金属的可能机理,最后展望了城市污水处理厂去除重金属的前景和发展方向。     

活性污泥吸附重金属离子的研究进展

从处理含重金属离子废水的现状出发,简述了活性污泥吸附重金属离子过程中的表面有机络合、离子交换及其它机理;讨论了温度、时间、pH值、污泥种类、预处理、重金属离子浓度等因素对活性污泥吸附重金属离子的影响,并对解吸方式进行了论述;综述了目前国内外有关活性污泥吸附重金属离子的最新研究成果,指明了进一步加强吸附机理和固定化技术以提高活性污泥应用性的研究是今后的方向。     

Soil effects due to sewage sludge application in agriculture

Field trials show that increased nutrients (mainly P) and heavy metals in soil due to agricultural use of sewage sludge have mainly to be expected when sludge is applied in too high amounts. The biological effects of heavy metals on plants are determined by their solubility which is increased by pH decrease and degradation of organic matter. Normally, it should be expected that the microbial activity in soil would increase with the application of organic matter in sewage sludge. But, also negative effects on the microflora by simultaneous enrichment of organic matter or inorganic and organic pollutants were found. The most important deleterious effects on soil microorganisms are the reduction in size of the total biomass, a reduced nitrogen fixing activity and changes in the composition of microbial populations of the soil. At what stage heavy metal toxicity to soil microorganisms or to microbial processes in soil is likely to become evident is unfortunately still uncertain. Again, the soluble fraction of heavy metals (also of organic pollutants) is a determing factor. To minimize the shown environmental risks an adequate sludge management is proposed.     

The multiple binding of heavy metals by digested sludge

The multiple interactions of heavy metals with anaerobically digested sludges and with digested sludge that had been washed with EDTA have been examined by equilibrating the sludge solids with solutions containing mixtures of zinc acetate, lead acetate and chromic chloride. This equilibration has been studied at 20°C and Langmuir and Freundlich isotherms were used to describe the metal binding behaviour of the solids. The rates of adsorption were also measured. This showed that while the rate constants were independent of the added metal concentration for untreated sludge, the binding constant for washed sludge was related to the initial metal concentration. A comparison of the adsorption isotherms suggests that the binding of zinc is different from that of lead and chromium.     

城市污泥中重金属存在形态、去除及稳定化研究进展

城市污水处理厂污泥产生量大,含有丰富的有机质、氮、磷、钾等农作物所需营养物质,但由于受重金属的污染使污泥无法直接农用。本文简述了城市污泥重金属的来源、特点及危害。重点论述了城市污泥中重金属去除和稳定方法,包括化学法（电化学法、化学试剂法）、生物法（微生物法、植物法、低等动物法）、物理法（超临界流体萃取、微波和超声）及联合技术。分析了各种方法处理污泥重金属过程中重金属的形态变化及其对处理效果的影响,对比各种方法的优缺点、影响因素及适用范围。指出污泥中重金属形态分布是影响去除效果的关键因素,污泥中重金属形态分布差异性大,且大部分重金属以稳定或相对稳定的状态存在,导致物理法和生物法去除效率较低,微生物和低等动物处理法相比植物法（备受时空限制）则表现出更好的适应性;电化学法对可氧化、可还原态分布的重金属都能起到较好的转化去除作用,但往往受由污泥向污泥液相中转移过程的控制,电损耗较突出;化学试剂浸提剂是目前效率较高的方法,但强酸环境常导致污泥营养物质流失和酸根离子累积,农用时容易板结而不利于污泥土地利用。因此,以土地利用为前提的条件下,将各种处理技术联合运用以提高污泥重金属去除率有待于进一步研究。     

Pilot plant biosorption in an integrated contact–settling system: application to Cu(II) removal by anaerobically digested sludge

Surplus biological sludge can be used as a low‐cost adsorbent in the removal of heavy metal from wastewater. A three‐zone contact–settling pilot plant was designed and operated to maintain continuous sludge–metal solution contact and subsequent separation of solid–liquid phases, all in the same vessel. Mild agitation was used to ensure good contact between Cu(II) and sludge without impairing solid–liquid separation. Heavy metal removal efficiency was largely unaffected by an increase in the Cu/sludge feed ratio as long as metal binding sites in the sludge remained unsaturated. Maximum metal uptake (75 mg Cu(II) g^?1 of total solids in the sludge) was found for Cu/sludge feed ratios ≥ 90 mg Cu(II) g^?1 of total solids. Pilot plant metal sorption uptake at different operational conditions correlated well with the calculated values from batch equilibrium adsorption isotherms. The amount of Cu(II) adsorbed on sludge influenced the degree of clarification due to the flocculating effect of Cu(II). Under operational conditions, a high degree of heavy metal removal and efficient clarification were achieved. Pilot plant operation at a Cu/sludge feed ratio around 90 mg Cu(II) g^?1 of total solids allowed efficient use of the biosorbent and high heavy metal removal efficiency in addition to a good quality metal‐free effluent in terms of low total suspended solids content. © 2001 Society of Chemical Industry     

农用市政污泥重金属危害的分析及应对措施

一般认为，污泥中重金属对植物和土壤的潜在危害是阻碍污泥资源化特别是阻碍污泥农用的障碍。通过总结国内外研究结果，认为污泥中重金属的危害性与其形态有关，且不同重金属的不同形态对于不同植物和土壤的危害程度也不可一概而论，因此以污泥中重金属总量判断危害程度是不全面的。研究认为，通过对污泥重金属的预处理，以及对污泥施用后的土壤采取必要的修复措施，可进一步降低污泥重金属对环境的危害。     

Impacts of Power Density on Heavy Metal Release During Ultrasonic Sludge Treatment Process

The impact of ultrasonic power density on changes of heavy metals during sludge sonication was inves-tigated. Results showed that ultrasound could release heavy metals from sludge into the supernatant. There existed an effective power density range of 0.8-1.6 W·ml^-1 for the release of the total heavy metal;there was little release below 0.8 W·ml^-1 and too high power density was adverse to the release. Furthermore, sonication showed selective release of heavy metal from sludge to the supernatant;copper, cadmium and lead were not released by sonication, while arsenic and nickel were released easily and their release ratio could reach 40%. The effective energy range for each heavy metal was also different that 0.8-1.2 W·ml^-1 for arsenic, 0.5-1.6 W·ml^-1 for nickel, and 0.8-1.6 W·ml^-1 for mercury and chrome. The differences among heavy metal release during sonication might be explained by the different distribution of chemical fractions of each metal in sludge. Such selectivity could be used to control heavy metal release during sludge treatment.