污泥调理脱水后残余水分存在形态及空间分布

污泥脱水是污泥资源化利用的前提,采用高铁酸钾(K₂FeO₄)和污泥生物炭(脱水污泥在500℃热解制得污泥生物炭,记为BC500)作为调理剂对污泥进行预处理。污泥经3.00 g/L K₂FeO₄和9.00 g/L BC500调理脱水后,泥饼含水率降低至42.33%,较未经调理脱水后泥饼含水率(78.80%)减少36.47百分点。通过低场核磁共振技术(low field nuclear magnetic resonance, LF-NMR)检测脱水泥饼中残留水分的存在形式,并对水分种类进行划分。在K₂FeO₄氧化作用下,水分子与有机物的结合能被削弱,泥饼中残余结合水(0.23～10.72 ms)占比为99.68%～99.81%,毛细管水(70.00～700.00 ms)占比为0.19%～0.32%,原污泥泥饼中强结合水转化为弱结合水、毛细管水、自由水,弱结合水转化为毛细管水或自由水,毛细管水则转化为自由水,而自由水在机械脱水过程中几乎可以完全脱除。根据成像结果...     

电导率对城镇污泥电渗透脱水效果的影响

采用电渗透脱水技术对经机械脱水的城镇污泥泥饼进行深度脱水,考察了使用添加Na2SO4溶液以及使用去离子水清洗的方式改变污泥的电导率对污泥电渗透脱水效果与能耗的影响.结果表明,随着添加的Na2SO4的量的增加,污泥的电导率从1103μS/cm上升至2575μS/cm,电渗透脱水后污泥的最终含水率从51.2%降低至45.7%,脱水效果有所提高,但是由于初始阶段通过污泥泥饼的电流的增加,脱水过程中所需能耗也相应上升23.3%~69.2%.随着对污泥清洗次数的增加, 污泥的电导率从988μS/cm上升至371μS/cm,电渗透脱水后污泥的最终含水率从52.3%增加至53.1%,脱水效果有所下降,但是由于初始阶段通过污泥泥饼的电流的降低,使得所需能耗降低15%~24%.因此,对电导率较低的污泥使用电渗透脱水技术进行深度脱水,可以在保证脱水效果的情况下最大限度地降低能耗.     

交变电场-铁改性生物质强化城市污泥深度脱水

为了实现城市污泥的深度脱水,采用铁改性生物质作为骨架构建体联合交变电场电渗透技术处理污泥,以单因素实验为基础,探究了该联合技术对污泥脱水性能的影响,并通过表面响应法优化了污泥脱水的工艺参数.将玉米秸秆使用浓度为0.03g/mL的FeCl₃溶改性后与污泥混合,当采用不等占空比为4.33:1的交变电场,电压为17.22V/cm,改性生物质投加量为96.81mg/g DS,改性生物质含水率为61.91%,生物质粒径为1.05mm,阴阳极间距为2.10cm时,可以得到含水率为58.21%的脱水污泥,脱水能耗为0.0148kW·h/kg RW (脱除水分).脱水污泥的扫描电镜表征结果显示,铁改性生物质可以在污泥中起到良好的骨架支撑作用,有利于提高污泥的机械强度和可渗透性;热重分析显示,脱水后污泥的上、下层燃烧过程可划分为析出自由水和束缚水阶段,析出和燃烧挥发分阶段、分解无机盐阶段,添加铁改性生物质的脱水污泥有机质含量更高,燃烧得更快.     

炭材料强化污泥电脱水效果及同步燃料化处理

为研究炭材料调理对污泥电脱水性能及泥饼可燃性的影响,使用改性前后的活性炭和石墨对污泥进行预调理,对调理后的污泥进行电脱水实验,深入解析了炭材料调理前后污泥电脱水行为及泥饼可燃性的变化.研究表明：经炭材料调理后的污泥,阴极电脱水速率提升,相较于其他3种炭材料,石墨调理后的阴极电脱水速率提升最为明显,石墨的投加量5% TSS时,阴极平均脱水速率从0.074g/L上升到0.095g/L.炭材料可以提高污泥体系的电导性和污泥絮体的电泳淌度,使得阴极泥饼孔容有上升的趋势,阴极泥饼孔容从未投加炭材料时的0.1147cm³/g增加到AC-0、AC-1、AC-5、石墨的投加量为20% TSS时的0.119、0.122、0.146、0.157cm³/g;此外,炭材料加入后阴阳两极滤液中溶解有机物DOM和蛋白质组分浓度降低,可以缓解滤布堵塞;污泥电脱水过程中经炭材料调理后可以降低脱离每单位水所需要的能耗,未投加炭材料时去除每单位水所需能耗为6.75kW·h/kg_去除水,而当AC-0、AC-1、AC-5、石墨的投加量为20% TSS时,能耗分别降低到5.64、5.22、5.20、5.11kW·h/kg_去除水,且泥饼含水率从未投加炭材料时的58%降低至45%,固炭量增加,提高了泥饼的热值和可持续燃烧时间,当石墨的投加量为20% g/gTSS时,泥饼热值提高了17%.有利于后续焚烧资源化利用.     

玉米秸秆生物炭改善污泥脱水性能

本实验以玉米秸秆为原料,制备了生物炭和AlCl₃改性生物炭,研究了2种生物炭分别调理污泥后的脱水效果,并探讨了污泥脱水性能的改善机理.结果表明,经过2种生物炭调理后,污泥比阻（SRF）、泥饼含水率（MC）、污泥沉降体积指数（SV₃₀）、毛细抽吸时间（CST）均下降,污泥净产率（Y_N）升高,说明污泥脱水性能得到了改善,且AlCl₃改性生物炭对污泥脱水性能的改善效果明显优于生物炭.当AlCl₃（溶液浓度3mol/L）改性生物炭的用量为3g/L时,调理后的污泥SRF,MC,SV₃₀,CST分别降低至1.3×10¹²m/kg,81.9%,78.6%,35s,Y_N增加至17.8kg/（m²·h）.分析原因：一方面,经过生物炭调理后,泥饼中会形成一定的骨架结构,使得污泥中的水和EPS能够更容易地释放;另一方面,经过AlCl₃改性后,改性生物炭携带的正电荷（Al³⁺）能够与污泥颗粒所带的负电荷发生电中和作用,使得污泥颗粒更容易聚集,从而提高污泥的脱水效果.     

基于半焦的城市污泥调质与机械压滤脱水

采用污泥调质和机械压滤脱水的实验方法,研究了半焦添加量和压榨压力对基于半焦的城市污泥调质与机械压滤脱水泥饼含水率的影响。结果表明:在相同的实验条件下,城市污泥机械压滤脱水泥饼含水率随着半焦添加量的增加、压榨压力的增大而降低,当半焦添加量为4 g/100 mL污泥（含水95%）,压榨压力为1.6 MPa时,压滤泥饼的含水率由现有的80%左右降至32.19%;基于半焦的城市污泥调质与机械压滤脱水的半工业试验验证了上述结论的正确性,同时发现压滤泥饼的热值由原污泥的7.82 MJ/kg提高到15.29 MJ/kg,可直接代替煤炭燃烧发电。半焦调质城市污泥+机械压滤脱水能实现城市污泥的高效能源化利用,对节约资源,保护环境有重要意义。     

堆存污泥深度脱水及其干化泥饼焚烧特性研究

堆存污泥的深度脱水及后续处置一直是制约污泥填埋场发展的难题.焚烧是实现填埋场堆存污泥最大量减容的有效途径,而高效的深度脱水过程却是污泥焚烧处置的必要前提.以抽滤曲线、毛细吸水时间（CST）和泥饼含水率为评价指标探究了聚合氯化铝（PAC）-生石灰-秸秆粉末组合调理剂对堆存污泥深度脱水的效果,并分析了各因素的影响强弱关系和经济成本;此外,通过热重试验建立TG-DTG曲线,分析脱水后干化泥饼的焚烧特性.结果表明:聚合氯化铝（PAC）-生石灰-秸秆粉末组合调理剂中各成分对城市堆存污泥CST削减的影响大小表现为PAC>生石灰>秸秆粉末,PAC和生石灰主要通过吸附架桥或压缩双电子层作用促进结合水向自由水的转变,而秸秆对压滤过程中构建骨架结构起到重要作用;当PAC、生石灰和秸秆粉末添加量（干基比）分别为35%、20%、29%时,堆存污泥的泥饼含水率和CST均达到最优,分别为56.3%和47.9 s,且组合配方经济成本优势显著;脱水干化后的泥饼点燃温度相较原状污泥有所提高,秸秆粉末的添加保障了泥饼在焚烧过程中的可持续性燃烧,泥饼燃烧过程中最大燃烧失重速率（T_m）达到3.828%/min.研究显示,PAC-生石灰-秸秆粉末组合调理剂通过改变堆存污泥的化学性能和压滤性能增强了污泥深度脱水的效果,同时改善了干化泥饼的燃烧行为,对堆存污泥的减量化及焚烧处置具有重要意义.      

高压脉冲电解-压滤联合实现城市污泥深度脱水

设计了一种新型的聚丙烯/不锈钢绝缘复合电极及装置,采用高压脉冲电解-压滤联合处理城市污水厂离心污泥深度脱水,考察了脉冲电场强度、机械压力和处理时间对污泥脱水性能指标-比阻(SRF)和滤饼含水率的影响,并测定处理前后滤液中COD、胞外聚合物(EPS)和重金属离子的含量。结果表明:以7. 5 k V/cm电场强度,50 k Pa机械压力联合处理污泥15 min,污泥比阻由10. 8×10~(12)m/kg降低至4. 47×10~(12)m/kg,泥饼含水率由85. 60%降低至57. 83%;污泥滤出液蛋白质、多糖、SCOD浓度增大为原来的290. 2%、350. 1%、1070. 4%。高压脉冲电解-压滤法可有效破解污泥EPS并降低污泥含水率。     

超声-生物沥浸-氧化钙联合超高压压滤系统实现市政污泥深度脱水及其泥饼的毒性评估

本研究采用超声-生物沥浸-氧化钙调理联合超高压压滤系统对市政污泥进行深度脱水试验,探讨了其调理过程对污泥脱水效率的影响,并对调理后的脱水污泥的重金属含量及植物毒性进行评估.结果表明,经超声-生物沥浸-氧化钙调理后,比阻（SRF）去除率和结合水去除率分别达到90.12%和72.21%.经预调理联合超高压压滤系统处理后,泥饼含水率降低至49.94%,泥饼中Cr 、Cu、Cd、 Zn、As 和Pb的去除率分别为42.41%、36.50%、30.92%、27.97%、25.94%、22.11%,白菜发芽指数大于80%.通过分析污泥理化性质及滤液有机物含量,阐明该联合技术的作用机理.首先,超声预处理后,污泥结构被破坏,造成污泥粒径d_0.5减小、zeta电位上升,污泥中多糖和蛋白质被释放,从而改善脱水性能,促进污泥中重金属释放,植物毒性降低;经超声-生物沥浸调理后,污泥粒径d_0.5进一步减小、zeta电位趋近于中性,滤液中酪氨酸/色氨酸类氨基酸类有机物和酪氨酸/色氨酸类蛋白有机物被降解且疏水性的腐殖酸和富里酸类有机物含量升高,污泥脱水性能进一步提高,泥饼重金属含量进一步下降,但植物毒性反而加强;最后添加氧化钙后,污泥颗粒被重新絮凝,形成刚性骨架,增加了污泥的可压缩性能,在高压压滤过程释放出更多有机物,最终实现了污泥深度脱水,重金属总量减少,植物毒性显著降低.此外,经济分析表明该联合工艺具有一定潜在推广应用价值.     

污泥电脱水过程重金属迁移规律研究

以市政污泥和添加外源重金属的污泥为对象,研究了污泥中重金属(As、Cd、Cr、Cu、Mn、Ni、Pb和Zn)及常见金属元素(Fe、Ca、Al和Na)在电脱水过程中的迁移规律。在特定电脱水条件下,分别考察了2种污泥的脱水效果和脱水速率,解析了电脱水过程中重金属的迁移程度及迁移速度。结果表明,电脱水可以有效降低污泥中的水分,市政污泥和添加外源重金属污泥的含水率分别由84.2%和82.3%降至54.7%和52.6%。电脱水后,重金属基本保留在泥饼中。市政污泥中重金属保留在泥饼中的比例高达88.1%~96.7%,添加外源重金属污泥则为90.2%~95.4%。常见金属保留在泥饼中的比例为82.3%~94.1%,仅有Na大部分迁移至滤液,脱水后其保留在泥饼中的比例为17.6%。该研究还发现重金属从污泥至滤液的迁移程度主要取决于其物理存在形态,而重金属的迁移速度则主要取决于其化学形态。     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.