Aerobic degradation of 2,4,6-TCP content in ECF bleached effluent

Elemental chlorine-free (ECF) bleach effluents from kraft mill are characterised by: a chemical organic demand/biological organic demand (COD/BOD(5)) ratio of 4, chlorophenol content with low chlorine substitution, and toxicity. The effect of increasing the concentration of 2,4,6-trichlorophenol (2,4,6-TCP) content in ECF bleaching sequence effluent on the degradative activity of bacterial communities present in an aerobic system treatment was studied. An aerobic lagoon (AL) was used as a typical secondary treatment of kraft-mill effluent. AL displays a high performance of BOD(5) degradation (up to 90%); however, only 40% of the COD was removed. Simultaneously, the AL system shows a high ability to biodegrade 2,4,6-TCP up to 237 mg/l day. Kinetic parameters of the 2,4,6-TCP biodegradation by aerobic bacteria were determined. The K(s) and K(i) values were 34.3 and 50 mg/l 2,4,6-TCP, respectively. Moreover, the tolerance of aerobic bacteria was observed up to 1.3 g/l 2,4,6-TCP.     

三峡库区消落带下部区域土壤氮磷释放规律模拟实验研究

三峡库区消落带形成后其下部区域（145~155 m）由于长期处于淹没状态,其表层土壤将类似底泥状态,研究选择嘉陵江江底沉积物模拟其在好氧及厌氧淹水条件下N、P向上覆水体的释放规律。结果表明：土壤处于淹水期间,均向上覆水释放N、P,其中好氧状态下上覆水中TN以硝态氮为主,厌氧环境下上覆水中TN以氨氮形式为主;淹水前期,N、P释放速率均较快,随时间增加逐渐减缓,且在厌氧环境下TP释放能力较好氧环境强。好氧淹水中曝气量对上覆水中TN平衡浓度无显著影响,但对氨氮、硝态氮释放过程有影响,从而影响TN浓度变化;底泥状土壤落干过程对N素释放有正影响,对P素释放有负影响;在短暂的落干期间,如果进行农业利用,将增加库区水环境污染和水体富营养化的风险.     

Potential use of solar energy for waste activated sludge treatment

The use of solar energy as a disintegration unit operation for waste activated sludge was tested in a pilot plant. The effect of the treatment process on chemical oxygen demand (COD), total suspended solids (TSS), settling time and filtration index was investigated in single (solar) and sequential processes (solar & biological). Solar oxidation was found to be a good sludge disintegration technology. Available solar photons were utilised to degrade the soluble organic matter and release the cell liquids. The highest COD and TSS removal efficiencies were obtained by the month of June. Sequential process efficiencies were related to accumulate solar photons, aerobic treatment time and operational condition. Sequential process resulted in COD and TSS removal efficiency of 16% and 13%, respectively. Increasing aerobic treatment time and/or mixing the oxidised sludge with fresh sludge improved COD and TSS removal efficiencies to 23% and 27%, respectively. The use of sequential processes improves the settling tendency of sludge by bio-oxidation of the released portions and eliminates protein charge effect on sludge settling.     

Radiosensitivity of subterranean bacteria in the Hungarian Upper Permian Siltstone Formation

The main purpose of this work was to study the radioresistance of subterranean aerobic and anaerobic isolates from the Hungarian Upper Permian Siltstone (Aleurolite) Formation, in order to assess the safety of potential sites of future underground repositories for nuclear waste. A total of 93 isolates were studied. The radiosensitivities of these aerobic and anaerobic bacteria isolates were determined: the D10 values (decimal reducing doses) of the aerobic spore-formers lay in the range 0.80 -2.44 kGy, and those of the anaerobic spore-formers lay in the range 1.86 4.93 kGy. The D10 values of the aerobic and anaerobic vegetative isolates were much lower, in the ranges 0.11 0.57 and 0.22-0.40 kGy. respectively. The variability in bacterial radioresistance indicates the biodiversity at this potential disposal site. These results can affect the construction of a future underground repository, since knowledge of the most resistant microorganism may be of importance as concerns calculation of the time required to inactivate the bacteria surrounding the containers.     

Parameters affecting biological phosphate removal from wastewaters

This paper reviews some of the key wastewater composition parameters, which influence the biological removal of phosphate from wastewaters, such as COD content, volatile fatty acid (VFA) content, cation concentration, phosphorus load, pH and food to microorganism ratio. The discussion also focuses on operational parameters affecting successful nutrient removal in wastewater treatment plants, such as temperature, sludge quality, sludge settlement, dissolved oxygen (DO) concentration, anaerobic P-release and secondary P-release. The aim of this review is to compile an updated document for researchers and operators of biological nutrient removal (BNR) systems. In addition, the article will provide a good foundation for readers with no prior knowledge of the process.     

Mosquito larvae density and pollutant removal in tropical wetland treatment systems in Honduras

Constructed wetlands offer a low-cost wastewater treatment option for tropical developing countries. The vast majority of published treatment wetland research has been conducted in temperate regions. Because the function of treatment wetlands is related to the environmental conditions, more research specific to the tropics should be completed. A six-cell free water surface (FWS) wetland mesocosm was constructed in Santa Rosa de Copán, Honduras that received input from an open-sewer/wastewater-impacted stream. Three cells were planted with Typha domingensis Pers., and three cells were left unplanted. Both planted and unplanted wetlands were constructed with three different surface areas to concurrently study different hydraulic retention times (HRTs) and hydraulic loading rates (HLRs). Results from 6 months of operation showed improved water quality and mosquito larvae populations affected by their specific environment. Five-day biochemical oxygen demand (BOD) removal appeared to be proportional to HRT and HLR, and BOD concentration in the effluent was higher in unplanted cells than in planted cells (P<0.05). BOD removal approached 60% for greater than 3.5 days HRT. Total phosphorus (P) removal and coliform bacteria removal were found to be correlated with pollutant load, and P removal was found to be correlated with HRT but not HLR. A second municipal wastewater FWS treatment wetland in Copán Ruinas, Honduras that had been established for 15 years, was also evaluated. BOD removal in the Copán Ruinas system was determined to be 93% with 2.6 day HRT. These pollutant removal rates are higher than would be expected in temperate regions. Mosquito larvae density was correlated with depth of the wetland. Mosquito larvae densities were higher in cells that were operating below design depth of 0.2 m (P<0.005). Results indicate that it is possible to design FWS wetlands in the tropics for effective BOD removal and reduced mosquito larvae development.     

Assessment of polychlorinated dibenzo-p-dioxins and dibenzofurans in sludges according to the European environmental policy

The amount of sewage sludge generated in Europe is expected to surpass the 10 million tons/year in 2006 as a result of the waste water treatment process according to the Water Policy in European Union. Sewage sludge is what is left behind after water is cleaned in waste treatment plants and is characterized for this high content in nitrogen and phosphorous that could be of great importance in agriculture as fertilizer or soil conditioner. On the other hand, pollutants like metals and organic contaminants are usually removed from water and are accumulated in the sewage sludge, reaching the food chain if their concentrations are not below the safe limits established by the European legislation. The latter issue is of great concern nowadays and in this sense, different works alert against the use of the sewage sludge in agriculture arguing that serious illnesses, even resulting in death as well as adverse environmental impacts are associated to the application of sewage sludge. This work is a continuation of a former comprehensive survey on of priority organic pollutant in sludges for agricultural purposes carried out by our group in Catalonia and this time is focused on the polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), one of the most toxic group of organic compounds listed in the Work Document on Sludge which is the reference tool in this field in Europe and is also included in the Stockholm Convention. Eighty eight samples were collected from the end of 2003 to April 2006 and the concentrations detected were lower than the 100 ng/kg I-TEQ limit recommended by the European legislation (EC, 2000). Thus, sewage sludges generated in Catalonia do not represent a threat to human health if they are used as fertilizers in agriculture.     

Adsorption studies on coir pith for heavy metal removal

Biosorption efficiency of coir pith, a waste product from coir industry, was investigated in this study for the removal of metallic pollutants such as Ni, Cu and Zn from aqueous solutions. The disposal of coir pith is a major problem associated with the coir industries, especially working in the small-scale sector. The present study explores the effectiveness of utilization of coir pith, an accumulating waste, as a biosorbent for heavy metal removal. Batch mode studies were done to evaluate the efficiency of removal of metals under varying adsorption conditions of pH, metal concentration and contact time. Characterization studies of the biosorbent and SEM analysis were done. Kinetic modelling studies were tried using Lagergren pseudo-first-order and second-order models. Equilibrium studies were done using well-known Freundlich, Langmuir and D–R isotherm models. It was found that all isotherms are fitting well indicating the efficiency of coir pith as an adsorbent of heavy metals. The applicability of all the three isotherms to the sorption processes shows that both monolayer adsorption and heterogeneous energetic distribution of active sites on the surface of the adsorbent are possible. Due to the abundance and low cost of these materials, adsorption technologies developed can act as good sustainable options for the future in heavy metal removal from industrial effluents.     

富氧生物膜法修复微污染水源的机理研究

采用弹性立体填料、微孔曝气富氧生物接触氧化法修复上海市受污染的川杨河水,生物填料在进水氨氮浓度2.6～3.1 mg/L和水温20℃～22℃下,7 d自然挂膜培养成功, 氨氮去除率达90%以上。 生化池运行一段时间后,必须根据生物膜厚度和其除污染效率,适时适度冲洗填料和排除池底积泥,以防止好氧生物膜出现厌氧运行状况和影响除污染效果。在川杨河水源水质浊度90～300 NTU、 NH+4-N 0.5～10.0 mg/L、CODMn4.0～10.8 mg/L、污染指数为2～8及生物修复工艺HRT为1.3 h、DO为7.5～10.2 mg/L、g/w为0.5/1的正常运行条件下,观察到膜上的生物相丰富, 微生物种类繁多, 主要是好氧的异养菌和自养菌。生物膜较薄,一般厚度为0.09～0.13 mm,在原水污染物氨氮浓度较低,曝气充足,水中溶解氧浓度高,好氧生物膜传质阻力小、速度快,污染物氨氮的生物降解速率很快,只需较短的水力停留时间,就能达到很高的氨氮去除率。微孔曝气气液传质充分,水中溶解氧充足,膜内无厌氧层存在。好氧生物膜内处于完全的好氧状态,硝化反应比较完全。污染的去除主要是填料上的好氧生物膜在起作用。     

复合垂直流人工湿地氧化还原特征及不同功能区净化作用研究

研究了复合垂直流人工湿地系统氧化还原电位（Eh）的时空变化规律及不同功能区中污染物的净化效果。结果表明：湿地系统下行流池表层、两池底层、上行流池表层Eh的变化范围分别为402～585、-87～-130、308～432 mV，沿水流方向依次形成了好氧A区/缺氧、厌氧区/好氧B区3个功能区。好氧A区是污染物去除的主要区域，BOD₅、COD_Cr、NH⁺_4- N的去除率分别为430%、484%、541%，特别是NH+4 N去除率占总去除率的79%；缺氧、厌氧区主要是进行反硝化反应和有机物的厌氧分解；好氧B区则主要是去除厌氧分解后的有机物以及进一步脱氮。另外，NH+4 N的去除率与系统各功能区Eh呈显著相关关系（〖WTBX〗p〖WTBZ〗＜001），而BOD₅、COD_Cr、NO^-_3-N的去除率与系统各功能区Eh相关性不显著。     

Recent advances in the bioremediation of arsenic-contaminated groundwater

The biological treatment of groundwater is used primarily to remove electron donors from water sources, providing (biologically) stable drinking water, which preclude bacterial regrowth during subsequent water distribution. To the electron donors belong also the dissolved metal cations of ferrous iron and manganese, which are common contaminants found in most (anaerobic) groundwater. The removal of iron and manganese is usually accomplished by the application of chemical oxidation and filtration. However, biological oxidation has recently gained increased importance and application due to the existence of certain advantages, over the conventional physicochemical treatment. The oxidation of iron and manganese is accelerated by the presence of certain indigenous bacteria, the so-called "iron and manganese oxidizing bacteria." In the present paper, selected long-term experimental results will be presented, regarding the bioremediation of natural groundwater, containing elevated concentrations of iron and arsenic. Arsenic is considered as a primary pollutant in drinking water due to its high toxicity. Therefore, its efficient removal from natural waters intended for drinking water is considered of great importance. The application of biological processes for the oxidation and removal of dissolved iron was found to be an efficient treatment technique for the simultaneous removal of arsenic, from initial concentrations between 60 and 80 microg/l to residual (effluent) arsenic concentrations lower than the limit of 10 microg/l. The paper was focused on the removal of As(III) as the most common species in anaerobic groundwater and generally is removed less efficiently than the oxidized form of As(V). To obtain information for the mechanism of As(III) removal, X-ray photoelectron spectroscopy (XPS) analyses were applied and it was found that As(III) was partially oxidized to As(V), which enabled the high arsenic removal efficiency over a treatment period of 10 months.     

太湖主体湖区对梅梁湾藻类影响定量化研究

针对太湖梅梁湾独特的地理位置和富营养化严重的问题,利用太湖水量水质模型和梅梁湾藻类生长模型,在对模型进行了率定、验证的基础下,模拟了在东南风和西北风两种常见风向的条件下,太湖主体湖区对梅梁湾内营养盐浓度和藻类浓度的影响情况,并将其影响定量化。本次模拟较好地反映了太湖主体湖区在两种常见风场的条件下对梅梁湾内水质影响情况。模拟得到以下结果：在不考虑风场和流场的情况下,梅梁湾内部2001年8月藻类平均浓度为43.18 mg/m³,总氮浓度为2.48 mg/L,总磷浓度为0.248 mg/L,只考虑东南风引起流场的情况下,藻类浓度为41.92 mg/m3,总氮浓度为2.07 mg/L,总磷浓度为0.231 mg/L;考虑东南风风场和流场两个因素的情况下,藻类浓度为53.86 mg/m3,总氮浓度为2.06 mg/L,总磷浓度为0.229 mg/L;同期,只考虑西北风风场的情况下,藻类浓度为42.55 mg/m³,总氮浓度为2.19 mg/L,总磷浓度为0.232 mg/L;考虑西北风风场和流场两个因素的情况下,藻类浓度为50.71 mg/m³,总氮浓度为2.17 mg/L,总磷浓度为0.233 mg/L。结果表明,梅梁湾内部的氮、磷等营养盐浓度受到由太湖主体湖区的风场变化引起的湖流扰动的一定影响;太湖主体湖区对梅梁湾内部藻类浓度的影响主要是由藻类漂移引起的,由营养盐浓度改变而引起的藻类浓度变化非常小。     

Simultaneous biological removal of endosulfan (alpha+beta) and nitrates from drinking waters using wheat straw as substrate

Nitrate and endosulfan (alpha+beta) removal was studied in an upflow biological denitrification reactor packed with wheat straw as carbon source and support particles for microorganisms. While almost complete nitrate elimination and between 65% and 70% endosulfan (alpha+beta) elimination occurred when the temperature was higher than 20 degrees C; below that value, nitrate removal efficiency decreased to about 10%. Nitrate, dissolved organic carbon (DOC), and endosulfan (alpha+beta) removal efficiencies decreased considerably at 1500 microg/l endosulfan concentration in the batch experiments. Although a high removal efficiency was observed for endosulfan (alpha+beta) and nitrate in the biological denitrification continuous reactor, the effluent water could not be used for drinking purpose because of the unacceptable levels of endosulfan (alpha+beta), colour and dissolved organic content. During the continuous study, 23.4% of the initial weight of wheat straw was lost and 24 g was consumed per gram of nitrogen removed. The results of the continuous study showed that 21.3% of the endosulfan removal was achieved by adsorption onto the wheat straw and 68.2% of the endosulfan removal occurred by biological activity and the remaining portion was detected in the effluent water.     

Toxicity removal from hard board wastewater

The rapid growth of industry in Egypt in recent years has made industrial pollution an important issue. During the past decade fish production in some canals and lakes have virtually ceased due to the discharge of industrial and agricultural wastewater. The alternatives under study include effluent treatment before discharge to receiving water. Highly polluted wastewater from a hard board mill was treated using the activated sludge process. Factors affecting the efficiency of the treatment were detention time and organic loading rate. The results indicated that BOD and phenol reduction reached 82% and 94% respectively. when the organic loading rate was 0.1 (kg BOD/kg SS). The process proved to be successful in completely eliminating the toxicity effect of the waste on Nile fish (Tilapia nilotica).     

附着生物对富营养化水体氮磷的去除效果

以太湖梅梁湾“863示范工程”水草恢复区原位湖水以及该区渔网围隔上的附着生物为材料，通过室内静态培养试验，研究了附着生物对富营养化湖水的氮、磷去除效果。结果表明，附着生物对水体中的氮有显著的去除效果，半个月内，附着生物对水体中总氮的累积去除率可达60%，在有附着生物的水体中总氮浓度从5 mg/L左右下降到2 mg/L左右；附着生物对水柱中氮的累积去除率和水柱中氮的浓度、附着生物的生物量以及附着生物作用时间密切相关。从培养过程中水体磷的浓度变化来说，培养初期，水体中磷的浓度比较高，附着生物对其有一定的去除作用；培养后期，水柱中磷的浓度比较低，附着生物不但不去除水中的磷，而且还向水柱中释放磷，这可能与附着生物向水体分泌碱性磷酸酶密切相关。     

隔河岩水库水质富营养化状况调查及评价

隔河岩水库位于湖北省境内长江支流清江上，是湖北省重点保护的水源地和旅游胜地。根据1992—2000年间隔河岩水库的水质监测数据，对隔河岩水库的水质现状进行分析发现，隔河岩水库中的总氮浓度、BOD5浓度和CODMn浓度均呈现逐年增加的趋势。此外，还建立了隔河岩水库的富营养化评价标准，用该标准对隔河岩水库的富营养化现状进行评价后得到以下结论：隔河岩水库的总磷、透明度、叶绿素a、CODMn和BOD5这五项指标均处于贫营养状态和贫—中营养状态，只有总氮浓度在各个断面都超过了富营养化标准，这与隔河岩水库库区的农业面源污染较为严重有关。总体来看。隔河岩水库的水质状况良好，库区水质基本属于贫—中营养状态，其营养状态是磷控制型的。     

Metal bioremediation through growing cells

Heavy-metal pollution represents an important environmental problem due to the toxic effects of metals, and their accumulation throughout the food chain leads to serious ecological and health problems. Metal remediation through common physico-chemical techniques is expensive and unsuitable in case of voluminous effluents containing complexing organic matter and low metal contamination. Biotechnological approaches that are designed to cover such niches have, therefore, received great deal of attention in the recent years. Biosorption studies involving low-cost and often dead/pretreated biomass have dominated the literature and, subsequently, extensive reviews focusing on equilibrium and kinetics of metal biosorption have also come up. However, the low binding capacity of biomass for certain recalcitrant metals such as Ni and failure to effectively remove metals from real industrial effluents due to presence of organic or inorganic ligands limit this approach. At times, when pure biosorptive metal removal is not feasible, application of a judicious consortium of growing metal-resistant cells can ensure better removal through a combination of bioprecipitation, biosorption and continuous metabolic uptake of metals after physical adsorption. Such approach may lead to simultaneous removal of toxic metals, organic loads and other inorganic impurities, as well as allow optimization through development of resistant species. However, sensitivity of living cells to extremes of pH or high metal concentration and need to furnish metabolic energy are some of the major constraints of employing growing cells for bioremediation. The efforts to meet such challenges via isolation of metal-resistant bacterial/fungal strains and exploitation of organic wastes as carbon substrates have began. Recent studies show that the strains (bacteria, yeast and fungi) isolated from contaminated sites possess excellent capability of metal scavenging. Some bacterial strains possess high tolerance to various metals and may be potential candidates for their simultaneous removal from wastes. Evidently, the stage has already been set for the application of metal-resistant growing microbial cells for metal harvesting. This review focuses on the applicability of growing bacterial/fungal/algal cells for metal removal and the efforts directed towards cell/process development to make this option technically/economically viable for the comprehensive treatment of metal-rich effluents.     

鄱阳湖沙山植物叶片与土壤C∶N、C∶P沿沙化梯度分布特征

在鄱阳湖多宝沙山沿沙化梯度测定了17种常见植物叶片及土壤有机碳(C)、全氮(N)、全磷(P)含量,以阐明沙山常见植物种与土壤C〖DK〗∶N、C〖DK〗∶P分布特征及对沙化的响应,为沙山植被恢复提供基础数据。结果表明：（1）植物叶片C〖DK〗∶N、C〖DK〗∶P分布范围为185～1273、1698～5071,平均值分别为431、3418;土壤0～10、10～30、30～50 cm层C〖DK〗∶N变化范围分别为98～463、24～465和37～450; 相应土层C〖DK〗∶P范围分别为198～759、30～905和47～765。（2）植物C〖DK〗∶N、C〖DK〗∶P对沙化的响应模式一致,均表现出在重度沙化区数值最小;土壤C〖DK〗∶N随沙化程度增加表现出降低趋势,而C〖DK〗∶P则表现出增加趋势,二者对沙化的响应不一致。（3）植物C〖DK〗∶N、C〖DK〗∶P变化主要取决于叶片的N、P含量;土壤C〖DK〗∶N的变化受控于土壤N含量;C〖DK〗∶P变化则决定于土壤有机C含量     

Comprehensive Analysis of Radioactive and Chemical Contamination of Water Bodies in the Area of Radium-Industry Waste Storage

Genotoxicity and cytotoxicity of water samples from the creeks flowing through the area of radium mining waste storage into the Ukhta River and from this river were assessed using biological tests with Allium schoenoprasum L. Chemical analysis of the samples indicated that concentrations of parent heavy natural radionuclides, ²¹⁰Pb, and ²¹⁰Po do not exceed the allowable level. Of ten heavy metals, only Zn and Mn concentrations exceeded MACs. The results of biological tests provided evidence for the significantly increased genotoxicity of water samples. The mitotic index increased with an increase in the concentration of Zn ions and manifested an inverse dependence on the activity of ²³⁸U. The genotoxic effect linearly depended on Zn concentration. Possible mechanisms responsible for the induction of these biological effects are discussed.     

Redox reaction of iodine in paddy soil investigated by field observation and the I K-Edge XANES fingerprinting method

In order to elucidate the cause for the leaching of iodine in a flooded paddy field, we investigated the transformation of an iodine species affected by the water management of the paddy field. The increased concentration of iodide (I(-)) in soil solution of a flooded paddy field suggested that I(-) was leached from the soil under anaerobic conditions. The post-edge feature of X-ray absorption near-edge structure (XANES) for iodate (IO(3)(-)) spiked to soil totally disappeared after anaerobic incubation of the soils, and I(-) was dissolved in the solution. On the other hand, I(-) in contact with the soil was not likely to be oxidized to IO(3)(-) under aerobic incubation. Iodine was leached out in soil solution as I(-) under anaerobic conditions, whereas part of the iodine species was retained by soil as I(2) or organoiodine both under anaerobic and aerobic conditions.