Denitrification characteristics of reject water in upflow biofiltration

Two types of bench-scale experiments using upflow biofilm reactors packed with granular floating polystyrene (GFP) or polyurethane foam cubes (PFC), were used to investigate the denitrification of reject water. A high denitrification rate was achieved in both upflow biofilm reactors since the highly concentrated volatile fatty acids in reject water served as effective hydrogen donors for denitrification. Of the two biofiltrations, the denitrification rate using GFP was 3.5 kg⁻¹ N m⁻³ per day, and higher than that using PFC. The amount of total attached biomass and solid capture capacity were also greater in GFP than in PFC. Moreover, the backwashing of the GFP packed column was optimized with air and water agitation. Of the processes investigated in this study, upflow biofiltration using GFP was the most acceptable process for reject water treatment based on treatability and operation.     

Isolation and characterization of a manganese‐oxidizing bacterium from a biofiltration system for the treatment of borehole water in KwaZulu‐Natal (South Africa)

Using minimal salts medium containing vitamins and pyruvate (MSVP) plus added manganese sulfate, a manganese (II) oxidizing bacterial strain was isolated from water samples of a biofiltration system treating borehole water in KwaZulu‐Natal, South Africa. The nonmotile Gram‐negative and oxidase‐negative isolate was subsequently characterized microbiologically. Based on its morphological and physiological characteristics and on the analysis of its 16S rRNA gene sequence, the isolate was assigned to the genus Acinetobacter. Growth of the isolated strain in MSVP with added manganese sulfate gave rise to a drop in pH and a concomitant increase in oxidation–reduction potential, which was absent in controls, thus indicating manganese oxidation. The ability of Acinetobacter sp. strain LB1 to oxidize Mn (II) was further verified using the leucoberbelin blue dye assay as well as by energy dispersive X‐ray analysis of crystals formed in the medium. In addition, a biofilm assay indicated that this isolate can attach to solid surfaces such as a biofilter matrix, thus confirming its potential for biotechnological applications in the area of water purification.     

A pretreatment method for the determination of nitrate in brackish water and seawater based on the hydrazinium reduction technique

The hydrazinium reduction technique has so far been inapplicable to the determination of nitrate in brackish water and seawater due to interference from magnesium ions. We developed a pretreatment method for brackish water and seawater samples for the determination of nitrate based on the hydrazinium reduction technique. Magnesium ions in water samples were converted to a precipitate of a complex with oxine (8-quinolinol) at pH 9.5, and then the precipitate was centrifuged at 3000 rpm for 20 min. The extra oxine in the resulting sample (the supernatant liquid), which inhibits the reduction of nitrate to nitrite, was removed using a Sep-Pak C18 cartridge. Thus we achieved the preparation of a magnesium-free water sample. Using the hydrazinium reduction technique with the proposed pretreatment method, nitrate in brackish water and seawater as well as fresh water was quantitatively determined with high accuracy. Received: July 21, 1999 / Accepted: September 26, 1999     

The effect of long-term nitrate treatment on SRB activity,corrosion rate and bacterial community composition in offshore water injection systems

Biogenic production of hydrogen sulphide (H₂S) is a problem for the oil industry as it leads to corrosion and reservoir souring. Continuous injection of a low nitrate concentration (0.25–0.33 mM) replaced glutaraldehyde as corrosion and souring control at the Veslefrikk and Gullfaks oil field (North Sea) in 1999. The response to nitrate treatment was a rapid reduction in number and activity of sulphate-reducing bacteria (SRB) in the water injection system biofilm at both fields. The present long-term study shows that SRB activity has remained low at ≤0.3 and ≤0.9 μg H₂S/cm²/day at Veslefrikk and Gullfaks respectively, during the 7–8 years with continuous nitrate injection. At Veslefrikk, 16S rRNA gene based community analysis by PCR–DGGE showed that bacteria affiliated to nitrate-reducing sulphide-oxidizing Sulfurimonas (NR–SOB) formed major populations at the injection well head throughout the treatment period. Downstream of deaerator the presence of Sulfurimonas like bacteria was less pronounced, and were no longer observed 40 months into the treatment period. The biofilm community during nitrate treatment was highly diverse and relative stable for long periods of time. At the Gullfaks field, a reduction in corrosion of up to 40% was observed after switch to nitrate treatment. The present study show that nitrate injection may provide a stable long-term inhibition of SRB in sea water injection systems, and that corrosion may be significantly reduced when compared to traditional biocide treatment.     

Analysis of phosphorus retention in free-water surface treatment wetlands

Wetlands have become the focus of numerous research and restoration efforts due to their ability to assimilate phosphorus and nitrogen from urban wastewater and stormwater runoff. Long-term data collected at Boney Marsh, Florida, USA, and the USEPA wetland database were analyzed to develop a simple tool that can be used to predict and optimize phosphorus retention in wetland treatment systems. Wetland properties such as water loading rate, water depth, P-loading rate, and water retention time were examined for their influence on phosphorus retention. The relationship between wetland properties and phosphorus removal efficiency was reduced to a simple quantitative diagram, 'The Phosphorus Removal Efficiency Diagram. The proposed diagram provides a simple management tool that predicts expected treatment range using controllable hydrologic conditions.The author uses the editors suggestion for abbreviation.     

土地利用类型对渭河流域关中段地表水硝酸盐污染的影响

地表水硝酸盐(NO~-_3)污染会造成水生态环境损害,引起水生态系统发生退化。通过溯源研究能够及时发现隐患和危害的源头,对保障水生态环境安全具有重要的意义。本研究选取渭河流域关中段13个子流域为研究对象,运用同位素方法结合水化学研究土地利用类型与地表水NO~-_3含量的关系,准确识别NO~-_3的主要污染来源。研究结果表明,整个流域NO~-_3含量范围为4.2—150.1 mg/L,平均含量38.2 mg/L。约有35.3%的样品NO~-_3含量超过《地表水环境质量标准》(GB 3838—2002)中硝酸盐的含量。渭河干流污染较支流严重,南岸支流较北岸支流污染严重。渭河干流、支流的源头及上游区域NO~-_3浓度普遍较低,说明受人类活动影响较小,沿着河流流向,NO~-_3浓度逐渐升高。耕地和城乡/工矿/居民用地面积与地表水NO~-_3浓度呈显著正相关(P0.05),相关系数分别为0.627和0.830。而草地和林地与NO~-_3浓度呈显著负相关(P0.05),相关系数分别为-0.775和-0.695。流域内,NO~-_3污染来源主要为动物排泄物及生活污水和工业废水的排放。农业活动中化肥的施用也是NO~-_3升高的一个重要原因。根据流域污染溯源结果,建议规范建设用地,加强污水排放和畜禽粪便的管理,同时提高化肥的使用效率,以达到减少水生态环境损害的目的。     

Reuse of effluent water from a municipal wastewater treatment plant in microalgae cultivation for biofuel production

This study assessed the usability of effluent water discharged from a secondary municipal wastewater treatment plant for mass cultivation of microalgae for biofuel production. It was observed that bacteria and protozoa in the effluent water exerted a negative impact on the growth of Chlorella sp. 227. To reduce the effect, filtration or UV-radiation were applied on the effluent water as pre-treatment methods. Of all the pretreatment options tested, the filtration (by 0.2 μm) resulted in the highest biomass and lipid productivity. To be comparable with the growth in the autoclaved effluent water, the filtration with a proper pore size filter (less than 0.45 μm) or UV-B radiation of a proper dose (over 1620 mJ cm⁻²) are proposed. These findings led us to conclude that the utilization can be realized only when bacteria and other microorganisms are greatly reduced or eliminated from the effluent prior to its use.     

Constructed wetlands for waste water treatment: the use of laterite in the bed medium in phosphorus and heavy metal removal

In Northern Ireland, phosphorus enrichment of lakes due to agriculture is a significant problem. Heavy metal exports from landfill sites, often located on water-logged land, are also of concern. Locally available laterite, a low grade bauxite which is rich in iron and aluminium, is used in acid solution with subsequent precipitation to remove phosphorus and heavy metals at several sewage treatment works. Constructed wetlands offer an attractive alternative to conventional waste water treatment in certain circumstances but removal of phosphorus is strongly dependent on the bed medium. Calcium-, iron- and aluminium-rich solid media are recommended. A brief introduction to the use and cost-effectiveness of constructed wetlands (CWs) in treating a range of effluents is given. This study, using both laboratory tests and pilot-scale constructed wetlands, reports the effectiveness of granular laterite in removing phosphorus and heavy metals from landfill leachate. Initial laboratory studies have shown that laterite is capable of 99% removal of phosphorus from solution. A pilot-scale experimental CW containing laterite achieved 96% removal of phosphorus. This removal is much greater than that reported in other systems. Initial removals of aluminium and iron by pilot-scale CWs have been up to 85% and 98% respectively. Percolating columns of laterite reduced Cd, Cr and Pb to undetectable concentrations. Possible application of this low cost, low technology, visually unobtrusive yet efficient system to rural areas with dispersed point sources of pollution is discussed.     

湿地法处理生活污水对仙桃湿地地表水微生物群落结构的影响

【背景】随着中小城市经济的高速发展和人们生活水平的提高,生活污水排放量也日益增大,致使水源水质污染呈恶化趋势。【目的】了解湿地法处理生活污水对湿地地表水微生物群落多样性变化的影响。【方法】对人工湿地(仙桃)参照点(-2 000)、200、400、600、3 000、5 000 m水平方向6点地表水进行理化检测,再通过高通量测序对微生物群落结构进行解析,并探讨微生物群落结构变化与生活污水的污染效应。【结果】当湿地法处理的生活污水到达5 000 m时,化学需氧量、氨态氮、总氮和总磷均达《城镇污水处理厂污染物排放标准》一级标准,且理化指标之间均呈极显著正相关。样品在门水平上的优势物种分别为变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)、蓝藻门(Cyanobacteria)、疣微菌门(Verrucomicrobia)、厚壁菌门(Firmicutes)、酸杆菌门(Acidobacteria)和绿弯菌门(Chloroflexi)。变形菌门(Proteobacteria)可用来作为排放生活污水污染物的指示性微生物,放线菌门(Actinobacteria)、蓝藻门(Cyanobacteria)、疣微菌门(Verrucomicrobia)和绿弯菌门(Chloroflexi)可用来作为排放生活污水净化的指示性微生物。【结论】首次比较分析了湿地法处理仙桃生活污水地表水环境中微生物群落多样性变化的情况,可使人们从微生物层面更加明确地了解人工湿地运作机理及地表水环境的污染情况。     

Biocatalytic properties of cell surface display laccase for degradation of emerging contaminant acetaminophen in water reclamation

The surface display laccase (SDL) biocatalyst, where the enzyme laccase is displayed on the surface of biological cells through synthetic biology, provides a new opportunity to develop sustainable technologies for removal of emerging contaminants from wastewater. This study vigorously characterized biocatalytic properties of the SDL in comparison to free laccase in removing emerging contaminant acetaminophen (APAP), with the aim to understand the effect of surface display on enzyme functionality and identify the strategy to overcome the potential limitation. The SDL could effectively remove APAP. Adding redox mediators substantially improved the removal efficiency. The Michaelis–Menten kinetic analysis showed that the redox mediator 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonate could overcome the limitation of APAP accessing the active site of laccase in the SDL biocatalyst. The APAP removal rate catalyzed by the SDL in real secondary wastewater effluent was higher than that in acetate buffer; comprehensive enzyme kinetic analysis provided clear evidence that there were redox mediating compounds in the wastewater. Analysis of transformation products revealed that surface display did not change laccase functionality in terms of APAP transformation mechanism. In addition, the SDL retained 88% of the initial activity after six repeated APAP biotransformation reactions. Results from this study provide a scientific basis for developing and implementing SDL as an innovative biocatalytic material for contaminant treatment applications.     

Identification and phylogeny of eukaryotic 18S rDNA phylotypes detected in chlorinated finished drinking water samples from three Parisian surface water treatment plants

Aims:  We performed a preliminary assessment of the eukaryotic 18S rDNA diversity present in finished drinking water samples from three different surface water treatment plants supplying water to the city of Paris (France).
Methods and Results:  A molecular analysis was performed on a sample from each site based on sequencing of PCR amplified and cloned 18S ribosomal RNA genes. Overall, the 18S rDNA sequences combined from all samples could be affiliated to the Amoebozoa (20·8% of the phylotypes), Ciliophora (25%), Metazoa (33·3%), Fungi (8·3%), Cercozoa (4·2%) and unclassified eukaryotes (8·3%) groups.
Conclusions:  The 18S rDNA sequences affiliated to the Amoebozoa, Ciliophora and Metazoa lineages were found to be the most abundant phylotypes observed in the drinking water samples. Phylotypes found to be present in two, or all three, samples (41·7% of the total) may represent groups with members adapted to drinking water treatment plant (DWTP) ecosystem conditions.
Significance and Impact of the Study:  This study shows that finished drinking water can contain 18S rDNA sequences representing a variety of eukaryotic taxa. Further research is needed to better characterize the eukaryotic biodiversity of DWTPs and the effects of the finished drinking water diversity on the downstream water distribution network.     

Recombinant protein expression of Moringa oleifera lectin in methylotrophic yeast as active coagulant for sustainable high turbid water treatment

The natural coagulant Moringa oleifera lectin (MoL) as cationic protein is a promising candidate in coagulation process of water treatment plant. Introducing the gene encoding MoL into a host, Pichia pastoris, to secrete soluble recombinant protein is assessed in this study. Initial screening using PCR confirmed the insertion of MoL gene, and SDS-PAGE analysis detected the MoL protein at 8 kDa. Cultured optimization showed the highest MoL protein at 520 mg/L was observed at 28 °C for 144 h of culturing by induction in 1% methanol. Approximately, 0.40 mg/mL of recombinant MoL protein showed 95 ± 2% turbidity removal of 1% kaolin suspension. In 0.1% kaolin suspension, the concentration of MoL at 10 μg/mL exhibits the highest turbidity reduction at 68 ± 1%. Thus, recombinant MoL protein from P. pastoris is an effective coagulant for water treatment.     

Comparison of two filtration-elution procedures to improve the standard methods ISO 10705-1 & 2 for bacteriophage detection in groundwater, surface water and finished water samples

Aim: To select a reliable method for bacteriophage concentration prior detection by culture from surface water, groundwater and drinking water to enhance the sensitivity of the standard methods ISO 10705‐1 & 2. Methods and Results: Artificially contaminated (groundwater and drinking water) and naturally contaminated (surface water) 1‐litre samples were processed for bacteriophages detection. The spiked samples were inoculated with about 150 PFU of F‐specific RNA bacteriophages and somatic coliphages using wastewater. Bacteriophage detection in the water samples was achieved using the standard method without and with a concentration step (electropositive Anodisc membrane or a pretreated electronegative Micro Filtration membrane, MF). For artificially contaminated matrices (drinking and ground waters), recovery rates using the concentration step were superior to 70% whilst analyses without concentration step mainly led to false negative results. Besides, the MF membrane presented higher performances compared with the Anodisc membrane. Conclusion: The concentration of a large volume of water (up to one litre) on a filter membrane avoids false negative results obtained by direct analysis as it allows detecting low number of bacteriophages in water samples. Significance and Impact of the Study: The addition of concentration step before applying the standard method could be useful to enhance the reliability of bacteriophages monitoring in water samples as bio‐indicators to highlight faecal pollution.     

两类水质综合评价方法的特点及其在河流水环境管理中的作用

河流水质恶化已成为严峻的环境问题,针对河流开展水质综合评价对河流水环境管理具有重要意义。依据不同的评价目标,选择合理的综合评价的评估标准成为河流水质评价中重要的问题之一。通过基于期望值和阈值的水质健康综合评估法(ETI)和水质质量指数(WQI)两种水质综合评价方法对"引滦入津"工程重要水源地伊逊河水质进行评价,结果显示:1)伊逊河水质ETI评估结果为良好等级,WQI评估结果为一般等级;2)伊逊河采样点水质在ETI评价中分布于4个等级,WQI仅分布于2个等级;3)伊逊河自上游至下游水质显著降低,特别是ETI评估中由优秀等级转变为差等级;4)ETI和WQI评估结果显示极显著相关性(R=0.951,P0.01);5)通过逐步多元回归,ETI评估结果的主导因子是DO、EC、SS、BOD_5和TP(P0.05),WQI评估结果的主导因子是DO、SS、BOD_5、TP、TN和NH_3-N(P0.05)。进一步分析表明伊逊河水质恶化与其流域内土地利用情况密切相关。在河流水环境管理中,ETI作为一种水质相对值评估方法,能更好体现流域内水质差异的区分度,便于管理者迅速定位流域内亟需治理的河流或河段,同时能够根据河流自身特征制定管理目标,可作为河流管理绩效评估的有效手段;而WQI作为一种水质绝对值评估方法,更适用于河流水质时间变化评估,对河流经长期治理后的管理效果评价起到重要作用。     

A direct immunoassay for detecting diatoms in groundwater as an indicator of the direct influence of surface water

Groundwater under the direct influence of surface water (GWUDISW) is of concern in communities where growing public demand on groundwater resources has resulted in increased withdrawals and hydraulic stress near surface water bodies. Under these conditions, contaminants such as methyl-tert butyl ether (MTBE) and biological materials have been detected in domestic wells. Other contaminants and pathogens associated with surface water are not routinely tested for in groundwater-supplied systems. To address the need for methods to easily identify potentially vulnerable supplies, a direct immunoassay for the quantitative detection of diatoms in raw water samples was developed as a measure of surface water influence on groundwater. Cell wall preparations from Nitzschia palea Kützing, a freshwater diatom found throughout North America, were used to produce a polyclonal antibody that was applied in a direct enzyme-linked immunosorbent assay (ELISA) developed to detect the presence of N. palea cell wall components. The direct immunoassay allows detection at 500 cells L⁻¹, a level similar to diatom concentrations observed in samples of groundwater collected near the test site. This investigation was the first attempt to utilize an ELISA as an indicator of surface water influence on groundwater. Further research is needed to develop more specific diatom-based monoclonal antibodies, determine cross-reactivity, and optimize sample processing and ELISA procedures for development of a standardized method.     

Effects of hydrologic changes on aboveground production and surface water chemistry in two boreal peatlands in Alberta: Implications for global warming

Aboveground net primary production (NPP) and surface water chemistryvariables were monitored in a lacustrine sedge fen and a bog for four years.There were no significant differences in precipitation, mean growing seasonannual temperature, and number of growing degree days from 1991 to 1994. Themean annual water levels in the lacustrine sedge fen differed significantly,whereas they were similar in the bog during these four years. We measured 15surface water variables in the lacustrine sedge fen and the bog, and foundthat only two correlated significantly with water level fluctuations. In thelacustrine sedge fen, calcium correlated positively (r²= 0.56) and nitrate correlated negatively (r² =0.20) with water levels. In the bog, potassium correlated positively(r² = 0.88) and total dissolved phosphorus correlatednegatively (r² = 0.62) with water levels. The remainingchemical variables showed no significant correlations with water levelfluctuations. Net primary production of the different vegetation strataappeared to respond to different environmental variables. In the lacustrinesedge fen, graminoid production was explained to a significant degree bywater levels (r² = 0.53), whereas shrub production wasexplained to a significant degree by surface water chemistry variables, suchas nitrate (r² = 0.74) and total phosphorus(r² = 0.22). In the bog, temperature was the onlyvariable that explained moss production to a significant degree(r² = 0.71), whereas ammonium explained graminoidproduction (r² = 0.66) and soluble reactive phosphorusexplained shrub production to significant degrees (r² =0.71). There are few direct data on the impact of climatic warming in borealwetlands, although paleoecological and 2×CO₂ model datahave provided some indications of past and possibly future changes invegetation composition, respectively. Our results suggest that thelacustrine sedge fen may succeed to a bog dominated by Sphagnum spp. andPicea mariana, whereas the bog may succeed to an upland-type forestecosystem. This revised version was published online in July 2006 with corrections to the Cover Date.     

Methodology for the implementation of monitoring plans with different spatial and temporal scales of plant protection products residues in water bodies based on site-specific environmental pressures assessments

Abstract

The awareness of plant protection products residues causing problems in water bodies is increasing more and more. A lot of effort is being made by countries in investigating the situation of diffuse pesticide pollution. This article illustrates a new methodology developed for the implementation of monitoring plans for plant protection products residues in rivers, lakes and groundwater, at river basin scale, based on an operational workflow which, by integrating different databases, let to evaluate site-specific environmental pressures affecting the definition of the related monitoring networks. It follows that sampling and analytical activities, carried out in the monitoring network nodes, not only are functional to water bodies ecological and chemical quality status assessment but are able to highlight possible compromises of environmental balance in agro-ecosystems, deriving from plant protection products use, through the application of environmental modeling able to bring out evolutive trends. This information would allow the Administrators to take increasingly effective initiatives both in the field of controls and authorizations for particular substances, in the light of the negative effects shown, and in the field of spatial planning, being able to dispose of the necessary knowledge in order to take safeguard measures before a certain evolutionary process of degradation becomes irreversible.     

水位波动对洞庭湖越冬小天鹅家域的影响

洞庭湖是小天鹅在我国的重要越冬地之一,为探讨洞庭湖水位变动对越冬小天鹅活动的影响,本研究于2014-2015年利用卫星跟踪技术对洞庭湖自然保护区18只越冬小天鹅活动轨迹进行跟踪,采用最小凸多边形（MCP）和核心密度估计（KDE）方法估算了越冬中、后期不同水位条件下小天鹅的家域。同时,基于MODIS遥感数据提取洞庭湖水体面积、计算水体淹没时间指数（STI）,进而开展了水位与家域关系、栖息地选择模式等方面的分析和探讨。结果表明：水位对小天鹅家域起制约作用,随着水位上升小天鹅家域范围会明显减小;越冬期间小天鹅喜好在空间相邻的浅水和草地综合性区域活动,食物资源分布和可获得性是小天鹅活动区发生改变的主要原因。