污泥水解酸化过程中污染物的释出及其影响因素研究

为了回收利用污泥中的有机物、氮和磷，研究了将厌氧污泥接种到吸附了污染物质的剩余污泥中，对污泥水解酸化的促进以及污泥中微生物所摄取污染物质的释出规律；揭示了厌氧条件下发酵时间、污泥量、pH和热处理对污染物释出的影响。结果表明，接种24 h后污染物被大量释放出来；在发酵时间为24 h条件下，污染物释出量与污泥质量成正比；吸附了污染物的剩余污泥相对含量越高，释磷量越大；污泥厌氧发酵时，碱性条件下有机物和正磷酸盐的释出量大于酸性条件，加碱调高pH可有效促进氨氮的释出；对吸附了污染物的剩余污泥进行短时热处理可有效缩短其厌氧发酵时污染物的释出时间。结果表明，控制污泥厌氧水解发酵条件可以促进污染物的释出，有利于下一步的回收。     

含重金属污泥制砖毒性的浸出

污泥中的重金属是影响污泥处置利用的重要因素,污泥制砖可以有效固结重金属。采用污水厂污泥与页岩按一定配比混合制备烧结砖,通过毒性浸出实验,研究烧结砖对重金属的固化程度以及重金属浸出稳定性,从而评定烧结制砖的安全性。结果表明,在浸出液为中性和酸性条件下,Cu、Cr、As和Pb的浸出浓度基本保持稳定,浸出时间的影响不大,而Zn的初始浸出浓度相对较大,最终逐渐降低;碱性条件下,Cr、Cu和Pb的浸出浓度随时间变化不大,而Zn和As的浸出浓度则在浸提时间内无明显变化规律;但不同p H浸出液下的重金属浸出浓度均远低于国家限值,污泥制砖重金属固化效果好,安全可靠。     

粉煤灰对猪粪堆肥重金属形态及浸出特性的影响

本研究以猪粪为原料,粉煤灰为钝化剂进行好氧堆肥,通过Tessier连续提取法与pH-依赖性浸出实验,研究粉煤灰对堆肥前后重金属形态及不同pH条件下重金属的浸出特性的影响。结果表明,粉煤灰对Zn的钝化效果较Cu更为显著,与原料相比Zn的残渣态增幅为18.97%。堆肥的浸出实验表现出很强的pH依赖性,Cu、Zn和DOM的浸出浓度在中性条件下(pH 6~8)低,在酸性(pH6)和碱性(pH8)环境中高。在pH为3~9的范围内,添加粉煤灰的实验组中Cu和Zn的浸出浓度低于对照组。因此,添加粉煤灰可降低堆肥重金属的浸出风险。     

pH对混合污泥水解酸化的影响

pH对剩余污泥和初沉污泥水解酸化的影响已有报道,但pH对混合污泥水解酸化的影响尚鲜见报道。为此对厌氧环境,(20±1)℃,pH=4～11以及不控制pH条件下混合污泥的水解酸化特征进行了研究。研究发现:对pH调控有利于污泥SCOD的溶出,在较强的碱性条件下污泥溶出的SCOD要大于其他条件下的,特别是pH=10和11条件下污泥溶出的SCOD要远高于其他条件下。碱性环境和酸性环境以及中性环境相比更有利于混合污泥产酸,最佳产酸pH条件为pH=10。在酸性和极端碱性条件下均有利于混合污泥中氨氮和磷的释放。碱性环境利于挥发性悬浮固体(VSS)的去除,但不利于总悬浮固体(TSS)的去除。在不同pH条件下将混合污泥的发酵特征和剩余污泥和初沉污泥发酵特征比较,发现3种污泥水解和产酸均在碱性条件下最好,且在20～22℃的条件下,产酸量均在pH=10的条件下达到最大。     

pH对高铁酸盐氧化剩余污泥的影响

针对高铁酸盐在酸、碱性环境下氧化性和稳定性的不同,采用pH调至1、3、5、7、9、11、13的剩余污泥,投加高铁酸盐溶液进行研究,考察污泥脱水性能(污泥比阻)以及减量化效果,包括破解液性质(氨氮NH_4~+-N、总氮TN、正磷酸盐PO43-、总磷TP、总有机碳TOC、溶解性有机物SCOD、胞外聚合物EPS)和污泥性状(混合液挥发性悬浮固体浓度MLVSS、污泥沉降比SV、污泥体积指数SVI、粒径)。结果表明:pH由低到高,破解液中各类污染物浓度总体呈现出两端高中间低的趋势,高铁酸盐在酸性和碱性条件下的氧化效果均优于中性条件。其中,pH达13时减量化效果最佳,氮素和有机物质溶出最多,然而此时的脱水性能最差;pH为1时破解液中磷素最多,达90.6 mg·L~(-1)。当pH为13,每g污泥(干重)的高铁酸盐投加量为15 mg Fe时,1 g MLVSS的污泥SCOD释放量达1.13 g,TN、SCOD、TOC释放量分别为179.3、3 507.9和1 134.3 mg·L~(-1),在达到污泥减量化效果的同时更有利于破解液的后期资源化回收和处理。     

不同pH控制策略下剩余污泥中NH+4-N、PO3-4-P、COD溶出研究

污水处理厂的剩余污泥中富含氮、磷、COD，在其水解酸化过程中对pH条件进行控制，使污泥中的氮、磷、COD溶出到上清液中并进行回收利用是可行的。在22~25℃的温度条件下,1#反应器中剩余污泥先调节为酸性（pH=3），在实验第8 d氨氮、磷酸盐溶出量最多后调节为碱性（pH=10）；3#反应器中剩余污泥先调节为碱性（pH=10），在实验第8 d COD溶出量最多后调节为酸性(pH=3)； 2#反应器为对照实验，pH不进行调节。结果表明：若要以回收污泥中的氨氮、磷酸盐为主，剩余污泥由碱性（pH=10）调节为酸性（pH=3）优于由酸性（pH=3）调节为碱性（pH=10）；若要回收污泥上清液中的COD为主，剩余污泥由酸性（pH=3）调节为碱性（pH=10）优于由碱性（pH=10）调节为酸性（pH=3）。     

废物水泥窑共处置产品中Cd释放的pH影响

用高温电炉模拟煅烧试验制取水泥熟料后再制作混凝土,参考EA NEN 7375:2004浸出试验,设定5种不同pH的浸取液对混凝土进行长期浸出试验,研究了pH对水泥窑共处置混凝土中Cd释放量以及释放过程的影响.结果表明:(1)pH为2.00、3.50、5.00、7.35和10.00的浸取液中,Cd的累积释放量分别为0.408 0、0.005 8、0.000 7、0.000 4、0.001 2 mg/kg.在酸性条件下,随pH的增大,Cd的累积释放量减小.在碱性条件下,随pH的增大,Cd的累积释放量增大.(2)pH为7.35的浸取液中,Cd累积释放量的释放曲线与斜率为0.5的直线拟合最佳.pH为7.35的浸取液中,混凝土中Cd的释放机制为扩散控制;pH为2.00和5.00的浸取液中,Cd的释放在前期为扩散控制,后期发生了耗竭作用;pH为3.50和10.00条件下,Cd的释放在前期发生了延滞作用,中期为扩散控制,后期发生了耗竭作用.     

生物炭负载Fe3O4对猪粪厌氧消化中重金属Cu、Zn形态的影响

为研究生物炭(BC)负载Fe_3O_4对猪粪厌氧消化中重金属形态的影响,采用化学共沉淀法将Fe~(2+)/Fe~(3+)和水稻秸秆BC复合制备Fe_3O_4/BC复合材料,将其作为钝化剂添加到以猪粪为原料的厌氧消化反应中。通过Tessier连续提取法与pH-依赖性浸出试验,探究BC和Fe_3O_4/BC对重金属形态的影响以及不同pH条件下沼渣中重金属浸出浓度的变化。结果表明,添加Fe_3O_4/BC对Cu和Zn的钝化效果更显著,与空白对照(CK)相比,添加BC和Fe_3O_4/BC后Cu的残渣态质量分数分别增加了-10.46%和52.40%,Zn的残渣态质量分数分别增加了16.82%和42.14%。厌氧消化后沼渣的浸出试验表现出很强的pH依赖性,Cu、Zn浸出曲线呈现出"V形",在中性环境中(pH 6～8)Cu、Zn和溶解性有机质(DOM)的浸出浓度较低,在酸性(pH6)和碱性(pH8)环境中较高。在弱酸弱碱条件下(pH 5～9),添加Fe_3O_4/BC后Cu和Zn的浸出浓度均低于添加BC的试验和CK组。因此,添加Fe_3O_4/BC可有效降低厌氧消化后沼渣中重金属的浸出风险。     

pH值对污泥发酵产酸的影响

利用剩余污泥厌氧发酵产生挥发性脂肪酸,可作为污水脱氮除磷的有机碳源,而pH值是发酵产酸过程中重要的控制参数.研究了不同pH值条件下剩余污泥厌氧发酵产酸过程中各参数变化规律,探索pH值对其过程的影响及其分析.结果表明,碱性条件有利于污泥发酵产酸过程,实验最佳条件是控制反应初始pH值为10.0,仅8d发酵挥发性脂肪酸浓度就达到8.90 mmol/L.此外,污泥在发酵过程中,酸性条件下NH4+-N和PO43--P的释放量均大于碱性条件.     

酸碱联合调节剩余污泥过程中氮、磷和有机质的释放

实现城市污泥的减量化和资源化是污水厂面临的难题之一。通过采用(1)先酸性(pH=3)后碱性(pH=10)、(2)先碱性(pH=10)后酸性(pH=3)的两段控制方式(每段反应8 d),同时做pH不调的对比实验,研究剩余污泥水解酸化过程中氨氮、磷酸盐和溶解性COD(SCOD)、碳水化合物、蛋白质和挥发性脂肪酸(VFAs)等有机质组分的释放。结果表明,酸碱联合调节有利于各组分的释放;氮和磷在酸性条件下的释放量大于碱性,有机质在碱性条件下的释放量大于酸性;采用(2)方式,调为酸性后反应1 d,氨氮的释放量即达到最大(17.28 mg/g TS);采用(1)的调节方式反应7 d,磷酸盐能达到最佳释放量(14.16 mg/g TS);总VFAs的产生受反应时间的影响较大,其余有机质组分在(2)的调节方式下,6 d左右即可达到较大释放量。     

Leaching of heavy metals and alkylphenolic compounds from fresh and dried sewage sludge

Reusing sewage sludge as a soil fertiliser has become a common alternative to disposal. Although this practice has a few benefits, it may contribute to the medium- and long-term contamination of the trophic chain because sewage sludge may contain heavy metals and organic contaminants. As the leaching of contaminants may depend on the sludge pre-treatment, the leaching of heavy metals (Cu, Ni, Pb, Zn and Cr) and alkylphenolic compounds (APCs) (octylphenol (OP), nonylphenol (NP), nonylphenol-mono-ethoxylate (NP₁EO)) was investigated in five fresh and 40 °C dried sewage sludge samples from north-eastern Spain. FT-IR analyses and full-scan GC-MS chromatograms showed that sludge drying changed the nature of organic compounds leading to changes in their solubility. Moreover, sludge drying led to a higher relative contribution of dissolved organic carbon than the particulate organic carbon in the leachates. Leaching of Pb, Zn and Cr was below 5 % in both fresh and dried sludge samples, whereas Cu and Ni leached at rates up to 12 and 43 %, respectively, in some of the dried sludge samples. The leaching yields of OP, NP and NP₁EO ranged from 1.3 to 35 % for fresh samples, but they decreased from 0.8 to 3.4 % in dried samples. The decrease in the leachability of APCs observed in dried sludge samples might be attributed to the fact that these compounds are associated with particulate organic matter, with significantly lower concentration or even absent in dried sludge than in fresh sludge samples. Therefore, it is recommended to dry the sludge before its disposal.     

Characteristics of leachate from pyrolysis residue of sewage sludge

The pyrolysis residue (SP) of sewage sludge (SS) produced at 500 degrees C was subjected to batch and column leaching tests to investigate the release of its organic and inorganic constituents and metals. For comparison, incineration ash (SI) obtained from a SS incinerator was also tested. Pyrolysis and incineration reduced organic matter of SS from 0.78 kg kg(-1)-dry SS to 0.16 and 0.01 kg kg(-1)-dry SS, respectively. Heavy metals remained in SP without being volatilized, although Cd and Pb were transferred into the off-gas during incineration. In the batch leaching test with the leaching liquid-to-solid mass ratio (L/S)=10, the pH of the SS, SP, and SI filtrates was 6.3, 7.9, and 11.0, respectively. The total organic carbon concentrations were in the order SS (877 l mg l(-1))>SP (99 mg l(-1))>SI (26 mg l(-1)). The SP and SI filtrates met the landfill standard for the Cd and Pb concentrations (<0.3 mg l(-1)). In the column tests, although the SP contained more organic matter than that of SI, its carbon discharge into the leachate under aerobic conditions was similar to that of SI under anaerobic conditions. The leaching of heavy metals, such as Cd, Cr, Pb, and Zn, was also suppressed in SP during the active decomposition of organic matter. We demonstrated that pyrolysis reduces the potential release of pollutants from sewage sludge in landfill, making it a promising method of treating sewage sludge before landfilling.     

Effects of sewage sludge biochar on plant metal availability after application to a Mediterranean soil

Pyrolytic conversion of sewage sludge into biochar could be a sustainable management option for Mediterranean agricultural soils. The aim of this work is to evaluate the effects of biochar from sewage sludge pyrolysis on soil properties; heavy metals solubility and bioavailability in a Mediterranean agricultural soil and compared with those of raw sewage sludge. Biochar (B) was prepared by pyrolysis of selected sewage sludge (SL) at 500 °C. The pyrolysis process decreased the plant-available of Cu, Ni, Zn and Pb, the mobile forms of Cu, Ni, Zn, Cd and Pb and also the risk of leaching of Cu, Ni, Zn and Cd. A selected Mediterranean soil was amended with SL and B at two different rates in mass: 4% and 8%. The incubation experiment (200 d) was conducted in order to study carbon mineralization and trace metal solubility and bioavailability of these treatments. Both types of amendments increased soil respiration with respect to the control soil. The increase was lower in the case of B than when SL was directly added. Metals mobility was studied in soil after the incubation and it can be established that the risk of leaching of Cu, Ni and Zn were lower in the soil treated with biochar that in sewage sludge treatment. Biochar amended samples also reduced plant availability of Ni, Zn, Cd and Pb when compared to sewage sludge amended samples.     

污水污泥中重金属污染物的溶出过程研究

污水污泥中污染物尤其是重金属的水体浸出作为重要的二次污染途径备受关注。为了探讨污水污泥中重金属的溶出规律,对上海7个污水处理厂的污水污泥进行了重金属总量分析,并采用水平振荡法对上述污水污泥中重金属进行了溶出动力学研究。结果表明,污水污泥中Cu、Cr和Zn的含量均较高,之后依次是Pb、As、Cd和Hg;污水污泥中重金属溶出动力学过程分为快速反应和慢速反应两个过程,可以用Elovich方程进行模拟;污水污泥中各重金属的溶出负荷差异较大,Cu、Cr和Zn的溶出负荷较大,其他较小,但各重金属相对于污水污泥中重金属总量的溶出百分比差异不大,基本处于10%以下。     

Effects of sewage sludge biochar on plant metal availability after application to a Mediterranean soil

Pyrolytic conversion of sewage sludge into biochar could be a sustainable management option for Mediterranean agricultural soils. The aim of this work is to evaluate the effects of biochar from sewage sludge pyrolysis on soil properties; heavy metals solubility and bioavailability in a Mediterranean agricultural soil and compared with those of raw sewage sludge. Biochar (B) was prepared by pyrolysis of selected sewage sludge (SL) at 500 °C. The pyrolysis process decreased the plant-available of Cu, Ni, Zn and Pb, the mobile forms of Cu, Ni, Zn, Cd and Pb and also the risk of leaching of Cu, Ni, Zn and Cd. A selected Mediterranean soil was amended with SL and B at two different rates in mass: 4% and 8%. The incubation experiment (200 d) was conducted in order to study carbon mineralization and trace metal solubility and bioavailability of these treatments. Both types of amendments increased soil respiration with respect to the control soil. The increase was lower in the case of B than when SL was directly added. Metals mobility was studied in soil after the incubation and it can be established that the risk of leaching of Cu, Ni and Zn were lower in the soil treated with biochar that in sewage sludge treatment. Biochar amended samples also reduced plant availability of Ni, Zn, Cd and Pb when compared to sewage sludge amended samples.     

Soil mobility of sewage sludge-derived dissolved organic matter, copper, nickel and zinc

A soil (sandy loam) column leaching study aimed to determine the extent of mobility and co-mobility of Cu, Ni, Zn and dissolved organic matter (DOM) released from a surface-application (equivalent to 50 t ds ha(-1) of anaerobically-digested sewage sludge. Leaching of DOM through the soil column was found to be almost un-retarded. Decidedly similar behaviour was exhibited by Ni suggesting that it migrated as organic complexes. Whilst Cu was also found to be leached, significant retardation was evident. However, the importance of DOM in promoting the mobility of both Cu and Ni was evidenced by their lack of mobility when added to the soil column as inorganic forms. The presence of DOM did not prevent Zn from becoming completely adsorbed by the soil solid phase. In relation to WHO drinking water guidelines, only Ni concentrations showed potential environmental significance, due to the relatively poor retention of Ni by the sludge solid phase.     

Anion and cation leaching or desorption from activated carbons from municipal sludge and poultry manure as affected by pH.

The conversion of municipal sludge and poultry manure to activated carbon results in a significant ash fraction that contains several different anions and cations. The objectives of this study were to determine whether the select ions are released or leached from virgin carbon into the sorption medium at different pH values. Activated carbon was placed in solutions of pH 1, 5, or 7, and the leaching of six cations (cadmium, chromium, copper, nickel, lead, and zinc) and two anions (arsenate and selenate) was recorded. Considerable quantities of zinc and copper were removed at pH 1 from all carbon sources. However, the amounts leached at pH 5 and 7 were small or undetectable. Our results indicate that leaching or desorption from carbons made from municipal sludge or poultry manure is pH-dependent and occurs readily under highly acidic conditions but minimally under pH conditions typically seen in contaminated water or wastewater.     

污泥活性炭对复合染料的脱色及其重金属浸出毒性

用自制的污泥活性炭处理亚甲基蓝与酸性品红组成的染料废水,研究了pH、吸附时间、温度等因素对复合组分染料废水脱色率的影响,测试分析了污泥活性炭在处理亚甲基蓝与酸性品红复合组分染料废水过程中的重金属浸出毒性。结果表明:与处理单一组分染料废水相比较,处理复合染料废水时pH的影响较为复杂,2种染料在污泥活性炭上存在竞争吸附,但是污泥活性炭对复合组分染料的脱色效果较好。污泥活性炭对复合染料的吸附过程符合Langmuir型吸附。在处理染料废水的过程中,污泥活性炭中的重金属镉、锌及铬会浸出,重金属镉、锌的浸出浓度符合国家标准,但铬的浸出浓度已接近国家标准上限。     

Remediation of metal contaminated soil with mineral-amended composts

This study examined the use of two composts derived from green waste and sewage sludge, amended with minerals (clinoptilolite or bentonite), for the remediation of metal-contaminated brownfield sites to transform them into greenspace. Soils contaminated with high or low levels of metals were mixed with the mineral-enhanced composts at different ratios and assessed by leaching tests, biomass production and metal accumulation of ryegrass (Lolium perenne L.). The results showed that the green waste compost reduced the leaching of Cd and Zn up to 48% whereas the composted sewage sludge doubled the leachate concentration of Zn. However, the same soil amended with composted sewage sludge showed an efficient reduction in plant concentrations of Cd, Cu, Pb or Zn by up to 80%. The results suggest that metal immobilisation and bioavailability are governed by the formation of complexes between the metals and organic matter. The amendment with minerals had only limited effects.     

矿区炼金废渣的固化/稳定化处理

通过对金矿矿区炼金废渣的酸中和能力、净产酸量及浸出毒性实验，测定了废渣的产酸潜力及重金属砷、镉、铅、锌的总量和它们的浸出量。为了合理处置矿区炼金废渣，并为矿区重金属污染土壤的修复提供技术支持，采用石灰、粉煤灰、堆肥化污泥作为添加剂对废渣进行固化/稳定化处理；通过浸出毒性实验对固化/稳定化处理效果进行综合分析，试图寻求一种最佳的稳定剂。结果表明，无论是单独添加石灰、粉煤灰或者堆肥化污泥还是两两组合混合添加，样品浸出液的pH都有升高，As、Cd的浸出浓度都有明显下降，而且两两组合添加比单独添加的固化/稳定化处理效果更好。在两两组合添加中，粉煤灰混合堆肥化污泥的处理效果最好，浸出液的pH值达到7.82，As、Cd的浸出率分别下降72.0%和72.2%。说明粉煤灰混合堆肥化污泥处理炼金废渣效果最佳，同时具有以废治污的资源化生态效能。