石灰干化污泥对土壤重金属稳定化处理的效果

以采自湖南省嘉禾县重金属复合污染土壤为研究对象,采用城市污水处理石灰干化污泥作为稳定剂,对污染土壤进行稳定化处理,并采用TCLP和BCR连续提取法对稳定化效果进行分析和评价。研究结果表明,单独使用石灰干化污泥,TCLP浸出浓度随着干化污泥质量分数的增加而显著减少,干化污泥的质量分数为40%时,稳定化率最大为Zn-98.92%、Cd-99.06%、Pb-96.84%;但是干化污泥的高pH值导致稳定后土壤中As的浸出增加。为了恢复植物生长功能,经过亚铁盐和磷酸调节pH后,石灰干化污泥稳定过的土壤pH有效降低,同时亚铁盐和磷酸有利于促进Pb和Zn的稳定效果;但是对Cd的稳定有负面影响;另外,亚铁盐的加入同时可以减少As的浸出浓度。经处理后土壤中重金属形态由不稳定态转为稳定态,使重金属的浸出浓度明显降低,减少了土壤重金属的浸出毒性。该研究结果表明,石灰干化污泥可以作为资源回收利用,应用于重金属污染土壤的修复中,并能改善稳定后土壤适宜植物生长的理化性质。     

不同有机质含量进泥的污泥干化芦苇床运行效能

污泥干化芦苇床是将人工湿地和污泥干化床进行有机结合,形成的一种新型污泥处理系统。系统运行时,周期性地将污泥布向湿地表面,水经填料层向下渗滤,并经由底部排水管流出;污泥中的固体物质被截留在填料层上面,通过蒸发蒸腾作用进一步脱水。通过系统地考察不同有机质含量剩余污泥在污泥干化芦苇床中的稳定化效果,总结并对比分析了污泥干化芦苇床对不同原泥的矿化程度、氮磷等营养物质的去除、微污染有机物的降解以及温室气体排放等。经过2年的布泥期和1年的稳定期,污泥有机质得到有效处理,高、低有机质含量污泥的稳定化程度分别达到54.50%和58.20%,满足GB 18918-2002中稳定化污泥标准的要求,同时高于GB 8712-1987(10%)的城镇垃圾农用控制标准要求。污泥氮磷含量仍然处于较高水平,可作为植物性营养元素;其中高、低有机质含量污泥中氮的含量分别从7.10%降到3.10%和从2.52%降到0.98%。微污染有机物如多环芳烃得到有效去除,高、低有机质含量污泥中多环芳烃分别去除了67.28%和32.64%,其中湿地植物芦苇起到了积极作用;监测结果表明,污泥干化芦苇床会释放一定量的温室气体,其中CO_2释放量为16.5~65.2 g·(m~2·d)~(-1),CH_4释放量为0.43~1.95 g·(m~2·d)~(-1),用CO_2来衡量CH_4的全球变暖趋势,污泥干化芦苇床CO_2释放量为15.02 g·(m~2·d)~(-1)。     

污泥热干化过程中重金属Pb、Cu、Zn的形态转化及稳定特性

基于不同干化工艺条件下,对城市脱水污泥在不同的温度下进行干化预处理研究,对干化后污泥中重金属的量及不同形态进行定量分析,研究污泥干化过程前后影响污泥中重金属含量及形态变化的条件因子。结果表明,污泥中不同重金属的含量差异较大,在不同工艺温度干化作用下,不同重金属形态含量发生了明显的变化,且不同重金属在干化过程中各形态含量变化差异较大。污泥在高温干化作用下,可使一部分重金属的交换态、可还原态和可氧化态向残渣态转化。高温对污泥中重金属形态有较好的稳定作用。研究结果对城市污泥热处理过程中重金属的污染迁移及控制有重要指导意义。     

人工湿地宽叶香蒲对重金属的累积与机理

宽叶香蒲(Typha latifolia L.)对环境胁迫具有较强的耐性。为了解宽叶香蒲对重金属的富集能力与耐性机理,通过野外调研,采集韶关凡口铅锌矿废水处理人工湿地中的宽叶香蒲与相应土壤样品,测定了土壤、植物的重金属总量与叶片亚细胞中重金属含量,分析了植物重金属含量与土壤重金属含量的相关性,并估算了宽叶香蒲地上部对重金属的提取量。土壤p H值在6.83~7.70之间,宽叶香蒲能有效降低土壤中的Cd、Pb、Zn、Cu和Mn的含量,对重金属的吸收主要受土壤重金属含量的影响,Pb和Cd的富集系数平均在0.5以上;除Fe外,叶片重金属主要分布在细胞壁和胞基质中。结果表明,宽叶香蒲是多种重金属的耐性植物,根系对重金属的富集与选择性向上运输、叶片细胞壁和胞基质对过量重金属的阻隔与结合作用是宽叶香蒲耐受重金属的重要机理。     

高盐工业废水人工湿地处理中植物的筛选

通过人工湿地中试实验,考察了芦苇、睡莲、水葱、狭叶香蒲和宽叶香蒲水生植物单元对经生化处理的石油和精细化工工业区的工业废水中盐含量较高、氮磷营养盐含量较低和化学需氧量(COD)含量较高的废水中污染物的去除情况,研究了在植物不同生长阶段系统中COD的去除同盐度之间的关系,探讨了盐度差异对植物生长状况的影响,为确定人工湿地适合的进水盐度,达到有效去除高含盐量工业废水中有机污染物提供依据。结果表明,芦苇、睡莲和狭叶香蒲3种植物单元内高含盐量工业废水中污染物的净化效果较水葱和宽叶香蒲单元的净化效果好:前3种植物单元内COD、生化需氧量(BOD)和总磷(TP)的去除率大约在38%、55%和62%左右,而水葱和宽叶香蒲2种植物单元内COD、BOD和TP的去除率大约在30%、36%和52%左右;系统中各个单元内总氮(TN)去除率都在85%以上。在植物的不同生长阶段,人工湿地系统中氯离子浓度与COD浓度之间的相关性存在差异:植物生长初期,系统中氯离子浓度与系统中COD浓度之间无显著相关性,而在植物生长旺期和末期,两者则成正相关关系。因此,需根据植物的生长阶段调整人工湿地的进水盐度。     

人工湿地挺水植物脱氮效果研究

为了比较不同季节人工湿地挺水植物的脱氮效果,以菖蒲(Acorus calamus)、香蒲(Typha angustifolia)和芦苇(Phragmites australis)3种挺水植物为材料构建潜流型人工湿地,在春夏、夏秋两季间歇式均匀布水条件下,通过测定污水中pH及溶解氧(DO)、氨氮、硝态氮、总氮浓度,分析不同季节挺水植物的脱氮效果。结果表明:出水DO浓度在春夏季表现为对照(CK)湿地菖蒲湿地香蒲湿地芦苇湿地,在夏秋季表现为CK湿地菖蒲湿地芦苇湿地香蒲湿地;人工湿地出水pH均呈弱碱性,种有挺水植物的人工湿地在春夏季和夏秋季的pH分别为7.33~8.09、6.81~7.59;在春夏季,芦苇湿地的总氮去除率最高;在夏秋季,香蒲湿地的总氮去除率最高。     

Fenton氧化联合人工湿地处理污泥中的重金属

针对单独应用Fenton氧化技术处理污泥的不足以及人工湿地在处理污水污泥方面的优势,以污水处理厂污泥浓缩池中含重金属污泥为对象,研究其依次经过Fenton氧化和人工湿地处理后重金属的去除效果及形态变化,以及污泥pH、TN和TP的变化情况。结果表明,Fenton氧化提高了污泥重金属的生物有效性,并促进了人工湿地对重金属的去除。Fenton氧化污泥经人工湿地处理后,Cu、Zn、Ni和Mn的去除率分别为67.2%、79.7%、37.0%和17.0%,与对照相比重金属的平均去除率提高了27.5%。经人工湿地处理后Fenton氧化污泥和原污泥重金属的生物有效性均降低。Fenton氧化污泥pH为4.4~4.6,经人工湿地处理后为6.2~7.1。人工湿地对Fenton氧化污泥和原污泥中TN的影响较小,而对TP表现出较高的去除率,2系统TP的去除率分别为51.1%和45.5%。     

小城镇污水处理厂污泥土壤化植物床的运行

随着我国污水处理率不断提高,污泥产量快速增加,污泥的资源化利用问题日益突出。针对这一问题,采用污泥土壤化植物床技术处理小城镇污水厂污泥。通过一个小试装置和4个中试单元,对植物床处理过程中的污泥泥质以及滤液水质变化进行了分析,研究比较了甜象草床、芦苇床、香蒲床对污泥的处理效果。研究表明,污泥土壤化植物床对投加到其中的污泥会产生一系列复杂作用,有助于污泥脱水和稳定化,同时能有效地对污泥渗滤液进行截流净化。     

金矿区高浓度砷污染土壤的稳定化处理

以粉煤灰、干化污泥、粉碎花生壳、硫酸亚铁(Fe_2SO_4)和磷酸二氢钾(KH_2PO_4)为稳定剂对矿区高浓度As污染土壤进行处理,通过土壤理化性质、重金属形态和浸出浓度变化等综合评估稳定剂对高浓度砷污染土壤的稳定化处理效果。结果表明,添加稳定剂可以提高土壤pH值、有机质含量和阳离子交换量。粉煤灰、干化污泥、粉碎花生壳、硫酸亚铁对土壤中的As有较好的稳定化作用,其中硫酸亚铁对土壤中As的稳定效果最好。同时添加10%粉煤灰、10%干化污泥和1%硫酸亚铁后,土壤中可交换态As、碳酸盐结合态As、铁锰氧化物结合态As、有机结合态As含量显著降低,降幅分别为62.3%、55.2%、29.6%、58.2%,残渣态As含量增加8.1%。添加粉煤灰、干化污泥、硫酸亚铁能显著降低土壤中As的浸出浓度,而添加KH_2PO_4会使土壤中As浸出浓度增加,移动性增强。当同时添加10%粉煤灰、10%干化污泥、1%粉碎花生壳和1%硫酸亚铁后,As浸出浓度最低(0.93 mg·L~(-1)),稳定效果最好,稳定化效率达到了74.8%。土壤中As的浸出浓度与可交换态As和碳酸盐结合态As呈显著正相关,与残渣态As呈显著负相关,可交换态As、碳酸盐结合态As和残渣态-As含量是影响土壤中As浸出浓度变化的主要因素。     

人工湿地植物对重金属铅的抗性

随着含铅废水污染引起的生态安全问题日益加重,以及处理要求的日益严格,含铅废水的处理已成为目前研究和工程实践的重点。由于植物修复技术操作管理方便,成本低廉,处理效率高和选择性强等优点,植物修复已成为处理含铅废水的较有潜力的和行之有效的优化技术。实验参照水体重金属污染现状,模拟设置不同铅浓度的水体,通过盆栽水培实验及实验室分析测试,分别研究了重金属铅对芦苇、香蒲、鸭跖草这3种植物生长的影响、分析各种植物对铅的抗性的表现及重金属在植物体内的积累和分布,为人工湿地植物的选择提供科学依据。     

Use of halophytes in pilot-scale horizontal flow constructed wetland treating domestic wastewater

Recent findings encourage the use of halophytes in constructed wetlands for domestic wastewater treatment due to their special physiological characteristics as the ability to accumulate heavy metals and salts in their tissues makes them ideal candidates for constructed wetland vegetation. In this particular study, we investigated the application of halophytic plants in a horizontal flow constructed wetland for domestic wastewater treatment purposes. The pilot plant which was situated in Crete (Greece) was planted with a polyculture of halophytes (Tamarix parviflora, Juncus acutus, Sarcocornia perrenis, and Limoniastrum monopetalum). The system’s performance was monitored for a period of 11 months during which it received primary treated wastewater from the local wastewater treatment plant. Results show that halophytes developed successfully in the constructed wetland and achieved organic matter and pathogen removal efficiencies comparable to those reported for reeds in previous works (63% and 1.6 log units, respectively). In addition, boron concentration in the effluent was reduced by 40% in comparison with the influent. Salinity as expressed by electrical conductivity did not change during the treatment, indicating that the accumulation of salts in the leaves is not able to overcome electrical conductivity increasing due to evapotranspiration. The results indicate an improvement in the treatment of domestic wastewater via the use of halophyte-planted CWs.     

Growth of Phragmites australis (Cav.) Trin ex. Steudel in mine water treatment wetlands: effects of metal and nutrient uptake

The abandoned mine of Shilbottle Colliery, Northumberland, UK is an example of acidic spoil heap discharge that contains elevated levels of many metals. Aerobic wetlands planted with the common reed, Phragmites australis, were constructed at the site to treat surface runoff from the spoil heap. The presence of a perched water table within the spoil heap resulted in the lower wetlands receiving acidic metal contaminated water from within the spoil heap while the upper wetland receives alkaline, uncontaminated surface runoff from the revegetated spoil. This unique situation enabled the comparison of metal uptake and growth of plants used in treatment schemes in two cognate wetlands. Results indicated a significant difference in plant growth between the two wetlands in terms of shoot height and seed production. Analyses of metal and nutrient concentrations within plant tissues provided the basis for three hypotheses to explain these differences: (i) the toxic effects of high levels of metals in shoot tissues, (ii) the inhibition of Ca (an essential nutrient) uptake by the presence of metals and H+ ions, and (iii) low concentrations of bioavailable nitrogen sources resulting in nitrogen deficiency. This has important implications for the engineering of constructed wetlands in terms of the potential success of plant establishment and vegetation development.     

稳定表流湿地中污泥的形成及除污效果

探讨了温度、植物及不同湿地流态对稳定表流人工湿地中污泥的形成和组成的影响,并考察了湿地在污泥形成过程中的除污效果。结果表明,温度对VSS的影响较大,植物在污泥形成过程中对污泥量没有明显影响,但可以改变污泥组成,湿地流态对污泥形成和组成均有影响,湿地中污泥的含量为0.4～0.6 g/L;种植有风车草的推流挡板湿地(池5)总体效果相对较好;各稳定表流湿地出水水质基本达到《城镇污水处理厂污染物排放标准》(GB18918-2002)二级标准,污泥形成后TN和NH3-N的去除率均有提高。     

污泥干化芦苇床中的渗滤液水质变化特征

对3个中试规模的高有机质剩余污泥干化床中污泥渗滤液水质变化特征进行了为期2年的实验研究。Ⅰ单元作为对照床,未种植植物;Ⅱ单元和Ⅲ单元种植芦苇。Ⅰ单元和Ⅱ单元底部充填炉渣,通过穿孔PVC通风管与大气相连通,目的是通过床体填料空隙提供氧气。3个干化床按照如下周期运行:进泥大约半小时,闲置1周,污泥负荷平均为41.3kg TSS/(m2·a)。实验结果表明,污泥干化芦苇床去除污泥渗滤液中的有机物较传统干化床更有效,通风结构有利于有机物的降解;3个床体的污泥渗滤液总磷浓度均高于进泥,但两个芦苇床渗滤液总磷浓度较低,可能的原因是较传统干化床多了植物吸收作用。根据实验数据分析,3个床体中都发生了氨化、硝化和反硝化作用,单元Ⅲ获得了最高的总氮去除率30.38%,Ⅱ单元和Ⅰ单元获得的总氮去除率分别为25.47%和20.59%。高有机质剩余污泥渗滤液仍含有较高的污染物浓度,需回流至污水处理单元进行进一步处理。     

水平潜流人工湿地处理太原市城市再生水的运行效能

以山西省太原市某污水厂的高氮低碳尾水为研究对象，开展基于3床并联的水平潜流人工湿地处理尾水的中试研究。研究结果表明，该人工湿地系统启动2个月进入稳定运行期；稳定运行期3个床体的出水水质除TN外其余指标均满足《地表水环境质量标准》（GB3838—2002）中Ⅳ类水体标准，TN指标满足《城镇污水处理厂污染物排放标准》（GB18918．2002）中一级A标准，该湿地系统出水可直接用于补充景观用水；稳定运行期3床的植物与基质的配置更适合处理同类尾水，3个床体对各污染物的去除效果均为3床〉2床〉1床；本系统中填料对污染物处理效果的影响大于植物对污染物处理效果的影响，最优填料顺序依次为沸石、砾石和钢渣，最适植物栽种顺序为芦苇、香蒲、美人蕉、黄菖蒲和芦苇。     

Stabilization of heavy metals in municipal sewage sludge by freeze–thaw treatment with a blend of diatomite,FeSO4, and Ca(OH)2

In this work, the effects of diatomite with 15% FeSO₄?7H₂O and 7.5% Ca(OH)₂ on sludge stabilization were investigated using batch leaching tests. The influence of cell rupture caused by freezing and thawing on stabilization was also evaluated. The results indicated that the optimal diatomite percentage was 2%. Cell rupture by freezing and thawing reduced heavy metal leachability, followed by cell death and decrease of organic groups. The concentration of heavy metals in sludge leachate increased after cell rupture, indicating that the heavy metal leachability was reduced after freezing and thawings. Moreover, the stabilization effects were generally improved after freezing and thawing. As compared with the stabilization of the original sludge, the unstable fractions decreased and the residual fractions of the heavy metals increased in the stabilized sludge after cell rupture.

Implications: This study developed a method to stabilize heavy metals in municipal sewage sludge. Diatomite combined with FeSO₄·7H₂O and Ca(OH)₂ improved the treatment of sewage sludge contaminated by heavy metals. Cell lysis by freeze–thaw treatment reduced the risk of leaching heavy metals caused by cell death and decreased major organic groups in the sludge.     

Reed beds receiving industrial sludge containing nitroaromatic compounds

Goal, Scope and Background Sweden has prohibited the deposition of organic waste since January, 2005. Since 1 million tons of sludge is produced every year in Sweden and the capacity for incineration does not fill the demands, other methods of sludge management have to be introduced to a larger degree. One common method in the USA and parts of Europe is the use of wetlands to treat wastewater and sewage sludge. The capacity of reed beds to affect the toxicity of a complex mixture of nitroaromatics in sludge, however, is not fully elucidated. In this study, an industrial sludge containing explosives and pharmaceutical residues was therefore treated in artificial reed beds and the change in toxicity was studied. Nitroaromatic compounds, which are the main ingredients of many pharmaceuticals and explosives, are well known to cause cytotoxicity and genotoxicity. Recently performed studies have also showed that embryos of zebrafish (Danio rerio) are sensitive to nitroaromatic compounds. Therefore, we tested the sludge passing through constructed wetlands in order to detect any changes in levels of embryotoxicity, genotoxicity and dioxin-like activity (AhR-agonists). We also compared unplanted and planted systems in order to examine the impact of the root system on the fate of the toxicants. Methods An industrial sludge containing a complex mixture of nitroaromatics was added daily to small-scale constructed wetlands (vertical flow), both unplanted and planted with Phragmites australis. Sludge with an average dry weight of 1.25%, was added with an average hydraulic loading rate of 1.2 L/day. Outgoing water was collected daily and stored at −20°C. The artificial wetland sediment was Soxhlet extracted, followed by clean-up with multi-layer silica, or extracted by ultrasonic treatment, yielding one organic extract and one water extract of the same sample. Genotoxicity of the extracts was measured according to the ISO protocol for the umu-C genotoxicity assay (ISO/TC 147/SC 5/WG9 N8), using Salmonella typhimurium TA1535/pSK1002 as test organism. Embryotoxicity and teratogenicity were studied using the fish egg assay with zebrafish (Danio rerio) and the dioxin-like activity was measured using the DR-CALUX assay. Chemical analyses of nitroaromatic compounds were performed using Solid Phase Micro Extraction (SPME) and GC-MS. Results Organic extracts of the bed material showed toxic potential in all three toxicity tests after two years of sludge loading. There was a difference between the planted and the unplanted beds, where the toxicity of organic extracts overall was higher in the bed material from the planted beds. The higher toxicity of the planted beds could have been caused by the higher levels of total carbon in the planted beds, which binds organic toxicants, and by enrichment caused by lower volumes of outgoing water from the planted beds. Discussion Developmental disorders were observed in zebrafish exposed directly in contact to bed material from unplanted beds, but not in fish exposed to bed material from planted beds. Hatching rates were slightly lower in zebrafish exposed to outgoing water from unplanted beds than in embryos exposed to outgoing water from planted beds. Genotoxicity in the outgoing water was below detection limit for both planted and unplanted beds. Most of the added toxicants via the sludge were unaccounted for in the outgoing water, suggesting that the beds had toxicant removal potential, although the mechanisms behind this remain unknown. Conclusions During the experimental period, the beds received a sludge volume (dry weight) of around three times their own volume. In spite of this, the toxicity in the bed material was lower than in the sludge. Thus, the beds were probably able to actually decrease the toxicity of the added, sludge-associated toxicants. When testing the acetone extracts of the bed material, the planted bed showed a higher toxicity than the unplanted beds in all three toxicity tests. The toxicity of water extracts from the unplanted beds, detected by the fish egg assay, were higher than the water extracts from the planted beds. No genotoxicity was detected in outgoing water from either planted or unplanted beds. All this together indicates that the planted reed beds retained semi-lipophilic acetone-soluble toxic compounds from the sludge better than the unplanted beds, which tended to leak out more of the water soluble toxic compounds in the outgoing water. The compounds identified by SPME/GC in the outgoing water were not in sufficient concentrations to have caused induction in the genotoxicity test. Recommendations and Perspectives This study has pointed out the benefits of using constructed wetlands receiving an industrial sludge containing a complex mixture of nitroaromatics to reduce toxicity in the outgoing water. The water from planted, constructed wetlands could therefore be directed to a recipient without further cleaning. The bed material should be investigated over a longer period of time in order to evaluate potential accumulation and leakage prior to proper usage or storage. The plants should be investigated in order to examine uptake and possible release when the plant biomass is degraded. This article has been developed on the basis of a presentation given at the Annual meeting of SETAC Europe German Language Branch 2004 in Aachen. ESS-Submission Editor: Dr. Ludek Blaha (blaha@recetox.muni.cz)     

潜流人工湿地对微污染河水的净化效果

为了探讨潜流人工湿地对微污染河水的净化效果,在野外条件下构建潜流人工湿地,分析了湿地中pH、氧化还原电位(ORP)和DO的进出水变化,考察了湿地中污染物的净化效果,探讨了温度对湿地净化效果的影响。各湿地进、出水DO浓度相差不大;除美人蕉湿地外,其余湿地出水pH较进水变化较小;植物湿地出水ORP较进水均有所增大。植物湿地对污染物的去除效果均优于空白湿地,且随着气温的升高,NH4+-N、TN和CODMn的去除率逐渐增加,去除率分别可达90%、50%和20%。TP去除率却未随温度发生明显变化,始终波动在30%～60%之间。相关性分析结果表明湿地中NH4+-N和TN的去除率与温度相关,较低的有机物浓度造成CODMn的去除率与温度相关性差,由于湿地对磷的去除主要以颗粒态磷(PP)为主,TP的去除与温度不相关。     

Performance of hybrid vertical up- and downflow subsurface flow constructed wetlands in treating synthetic high-strength wastewater

The performance and temporal variation of hybrid vertical-subsurface flow constructed wetlands (VFCWs) in response to two-stage combinations of vertical upflow (VUF) and vertical downflow (VDF) were analyzed in this research. The results of high carbon (C) treatment and high nitrogen (N) treatment were similar. The Lythrum salicaria treatment showed higher removal efficiency than CWs planted with Acorus calamus. Under high C- and N-loading treatments, the optimum two-stage combination was VDF-VUF VFCWs planted with A. calamus. Furthermore, the highest nutrient removal efficiencies were achieved in late summer (July and August) and early autumn (September). The chemical oxygen demand and total nitrogen removal efficiencies were significantly affected (P?<?0.05) by season, system, and wetland plant.     

水培翅碱蓬对重金属吸收的研究

由于人类活动以及工业化的迅速发展,滩涂湿地正在遭受前所未有的污染和破坏,其中重金属污染是主要污染问题之一。生物修复技术是近年发展起来的新型环境污染治理方法,它在去除污染的同时还具有较高的环保价值,因此受到人们的广泛关注。以中国北方滩涂湿地的优势种植物翅碱蓬(Suaeda heteroptera kitag)为研究对象,通过测定翅碱蓬体内重金属的含量,分别探讨了翅碱蓬对单一Cu、Zn、Pb、Cd及Cu和Zn、Pb和Cd混合重金属的吸收规律、翅碱蓬不同部位对Cu的积累特性。实验结果表明,翅碱蓬对Cu、Zn、Pb、Cd的最大吸收速率分别为31、101、34、62mg/(kg.d);Cu的存在,促进了翅碱蓬对Zn的吸收,翅碱蓬各部位对Cu的积累量大小为根>茎>叶。