Effects of suspended particles in the Jinjiang River Estuary on the physiological and biochemical characteristics of Microcystis flos-aquae.

The effects of different concentrations (100, 150, 200, 250 mg/L) and different particle sizes (0-75 μm, 75-120 μm, 120-150 μm, 150-500 μm) on the soluble protein content, superoxide dismutase (SOD) and catalase (CAT) activity, malondialdehyde (MDA) content, chlorophyll a (Chla) content, and photosynthetic parameters of Microcystis flos-aquae were studied, and the mechanism of the effect of suspended particulate matter on the physiology and biochemistry of Microcystis flos-aquae was discussed. The results showed that the soluble protein content of Microcystis flos-aquae did not change noticeably after being stressed by suspended particles of different concentrations/diameters. The SOD activity of Microcystis flos-aquae first increased and then decreased with increasing suspended particulate matter concentrations.

Oxygen micro-nanobubbles for mitigating eutrophication induced sediment pollution in freshwater bodies.

Sediment hypoxia is a growing problem and has negative ecological impacts on the aquatic ecosystem. Hypoxia can disturb the biodiversity and biogeochemical cycles of both phosphorus (P) and nitrogen (N) in water columns and sediments. Anthropogenic eutrophication and internal nutrient release from lakebed sediment accelerate hypoxia to form a dead zone.

Apply MIKE 11 model to study impacts of climate change on water resources and develop adaptation plan in the Mekong Delta, Vietnam: a case of Can Tho city.

Can Tho city in the Mekong Delta is in the top ten areas affected by climate change. Therefore, assessing climate change impacts, social and economic activities require proposed solutions to respond to climate change. This study aims to (i) apply the MIKE 11 model (Hydrodynamic module and Advection-Dispersion module) to simulate the impacts of climate change scenarios on water resources in Can Tho city; (ii) calculate water balance in Can Tho city; and (iii) suggest climate change adaptation plan for sustainable social-economic activities of the city.

Dynamic multivariate analysis for pollution assessment and river habitat conservation in the Vietnamese La Buong watershed.

Analysis of temporal patterns of high-dimensional time-series water quality data is essential for pollution management worldwide. This study has applied dynamic factor analysis (DFA) and cluster analysis (CA) to analyze time-series water quality data monitored at the five stations installed along the La Buong river in Southern Vietnam. Application of the DFA identified two types of temporal patterns, one of the run-off driven parameters (total suspended solid (TSS), turbidity, and iron) and the other of diffuse source pollution.

Variations in the profile distribution and protection mechanisms of organic carbon under long-term fertilization in a Chinese Mollisol.

Long term fertilization may have a significant effect on soil organic carbon (SOC) fractions and profile distribution. However, previous research mostly explored the SOC in the topsoil and provided little or no information about its distribution in deeper layers and various protection mechanisms particularly under long-term fertilization. The present study investigated the contents and profile distribution (0-100 cm) of distinct SOC protection mechanisms in the Mollisol (black soil) of Northeast China after 35 years of mineral and manure application.

Energetic constraints on H2-dependent terminal electron accepting processes in anoxic environments: a review of observations and model approaches.

Microbially mediated terminal electron accepting processes (TEAPs) to a large extent control the fate of redox reactive elements and associated reactions in anoxic soils, sediments, and aquifers. This review focuses on thermodynamic controls and regulation of H2-dependent TEAPs, case studies illustrating this concept, and the quantitative description of thermodynamic controls in modeling. Other electron transfer processes are considered where appropriate.

Effects of pH and hydraulic retention time on hydrogen production versus methanogenesis during anaerobic fermentation of organic household solid waste under extreme-thermophilic temperature (70 degrees C).

Two continuously stirred tank reactors were operated with household solid waste at 70 degrees C, for hydrogen and methane production. The individual effect of hydraulic retention time (HRT as 1, 2, 3, 4, and 6 days) at pH 7 or pH (5, 5.5, 6, 6.

Using tree core samples to monitor natural attenuation and plume distribution after a PCE spill.

The potential of using tree core samples to detect and monitor natural attenuation of perchloroethene (PCE) in groundwater was investigated at a PCE-contaminated site. In the area of the known plume with PCE concentrations between 0.004 and > 40 mg/L, cores were collected from tree trunks at a height of about 1 m above ground surface.

Limited diffusive fluxes of substrate facilitate coexistence of two competing bacterial strains.

Soils are known to support a great bacterial diversity down to the millimeter scale, but the mechanisms by which such a large diversity is sustained are largely unknown. A feature of unsaturated soils is that water usually forms thin, poorly-connected films, which limit solute diffusive fluxes. It has been proposed, but never unambiguously experimentally tested, that a low substrate diffusive flux would impact bacterial diversity, by promoting the coexistence between slow-growing bacteria and their potentially faster-growing competitors.

Release of fluorocarbons from insulation foam in home appliances during shredding.

It is a current practice that refrigerators and freezers in many countries are shredded after the end of useful lives. The shredder residue is deposited in landfills. During the shredding process a significant fraction of blowing agent (BA) in the insulation foam may be released into the atmosphere.

Influence of wastewater characteristics on methane potential in food-processing industry wastewaters.

In this study, we identified the influence of wastewater characteristics on the theoretical and practical methane potential using different food industrial wastewaters as substrates. Ten composite wastewater samples from five industries were investigated. The ultimate practical methane yields (B(o)) were compared to the theoretical methane yields (B(o,th)) in order to evaluate the biodegradability of the tested wastewaters and the influence of their physico-chemical characteristics.

Atmospheric emissions and attenuation of non-methane organic compounds in cover soils at a French landfill.

In addition to methane (CH(4)) and carbon dioxide (CO(2)), landfill gas may contain more than 200 non-methane organic compounds (NMOCs) including C(2+)-alkanes, aromatics, and halogenated hydrocarbons. Although the trace components make up less than 1% v/v of typical landfill gas, they may exert a disproportionate environmental burden. The objective of this work was to study the dynamics of CH(4) and NMOCs in the landfill cover soils overlying two types of gas collection systems: a conventional gas collection system with vertical wells and an innovative horizontal gas collection layer consisting of permeable gravel with a geomembrane above it.

Effects of mixing on methane production during thermophilic anaerobic digestion of manure: lab-scale and pilot-scale studies.

The effect of mixing on anaerobic digestion of manure was evaluated in lab-scale and pilot-scale experiments at 55 degrees C. The effect of continuous (control), minimal (mixing for 10 min prior to extraction/feeding) and intermittent mixing (withholding mixing for 2h prior to extraction/feeding) on methane production was investigated in three lab-scale continuously stirred tank reactors. On comparison to continuous mixing, intermittent and minimal mixing strategies improved methane productions by 1.

Uptake, removal, accumulation, and phytotoxicity of 4-chlorophenol in willow trees.

4-chlorophenol (4-CP) is a well-known hazardous chlorinated compound and a precursor for the synthesis of the herbicide 2,4-dichlorophenoxyacetate. The relation between uptake, accumulation, toxicity, and removal of 4-CP in willow trees (Salix viminalis) was determined. In addition, the feasibility of implementing phytoremediation as a treatment method for 4-CP contamination was investigated.

Uptake, accumulation, phytotoxicity, and removal of 2,4-dichlorophenol in willow trees.

The relation between uptake, accumulation, toxicity and removal of 2,4-dichlorophenol (2,4-DCP) in willow trees (Salix viminalis) and the feasibility of implementing phytoremediation as a treatment method for 2,4-DCP contamination in wastewater and soil were investigated. Willows were exposed to various 2,4-DCP concentrations between 5 and 150 mg/L in hydroponic solution and between 9.1 and 44.

TNT biotransformation: when chemistry confronts mineralization.

Our understanding of the genetics and biochemistry of microbial 2,4,6-trinitrotoluene (TNT) biotransformation has advanced significantly during the past 10 years, and biotreatment technologies have developed. In this review, we summarize this new knowledge. A number of enzyme classes involved in TNT biotransformation include the type I nitroreductases, the old yellow enzyme family, a respiration-associated nitroreductase, and possibly ring hydroxylating dioxygenases.

Effect of temperature and active biogas process on passive separation of digested manure.

The objective of the study was to identify the optimum time interval for effluent removal after temporarily stopping stirring in otherwise continuously stirred tank reactors. Influence of temperature (10 and 55 degrees C) and active biogas process on passive separation of digested manure, where no outside mechanical or chemical action was used, within the reactor was studied in three vertical settling columns (100 cm deep). Variations in solids and microbial distribution at top, middle and bottom layers of column were assessed over a 15 day settling period.

Use of tracer tests to investigate changes in flow and transport properties due to bioclogging of porous media.

Tracer tests were conducted in three laboratory columns to study changes in the hydraulic properties of a porous medium due to bioclogging. About 30 breakthrough curves (BTCs) for each column were obtained. The BTCs were analyzed using analytical equilibrium and dual-porosity models, and estimates of the hydrodynamic dispersion and mass transfer coefficients were obtained by curve fitting.

Towards an internationally harmonized test method for reproductive and developmental effects of endocrine disrupters in marine copepods.

New and updated methods to detect and characterize endocrine disrupting chemicals (EDCs) are urgently needed for the purpose of environmental risk assessment since these substances are often not detected using existing chronic toxicity tests. Numerous reports on the effects of EDCs on crustacean development and reproduction have been published and the development of life-cycle tests with crustaceans has been prioritized within the OECD work program for endocrine disrupter testing and assessment. As a result, Sweden, and Denmark initiated a proposal for development of a full life-cycle test with marine copepods (Acartia tonsa, Nitocra spinipes, Tisbe battagliai, and Amphiascus tenuiremis).

Quantification of potassium permanganate consumption and PCE oxidation in subsurface materials.

A series of laboratory scale batch slurry experiments were conducted in order to establish a data set for oxidant demand by sandy and clayey subsurface materials as well as to identify the reaction kinetic rates of permanganate (MnO(4)(-)) consumption and PCE oxidation as a function of the MnO(4)(-) concentration. The laboratory experiments were carried out with 31 sandy and clayey subsurface sediments from 12 Danish sites. The results show that the consumption of MnO(4)(-) by reaction with the sediment, termed the natural oxidant demand (NOD), is the primary reaction with regards to quantification of MnO(4)(-) consumption.

Degradation of the herbicide dichlobenil and its metabolite BAM in soils and subsurface sediments.

The worldwide used herbicide dichlobenil (2,6-dichlorobenzonitrile) has resulted in widespread presence of its metabolite 2,6-dichlorobenzamide (BAM) in surface water and groundwater. To evaluate the potential for natural attenuation of this BAM pollution in groundwater, we studied the degradation of BAM and dichlobenil in 16 samples of clayey till, unconsolidated sand and limestone, including sediments from both oxidized and reduced conditions. The degradation of dichlobenil occurred primarily in the upper few meters below surface, although dichlobenil was strongly sorbed to these sediments.

The need for bioaugmentation after thermal treatment of a TCE-contaminated aquifer: Laboratory experiments.

A microcosm study was conducted to evaluate the need for bioaugmentation after a thermal treatment to anaerobically dechlorinate trichloroethene (TCE) to ethene. The microcosms were either: heated to 100 degrees C and slowly cooled to simulate thermal remediation while bioaugmenting when the declining temperature reached 10 degrees C; or kept at ambient groundwater temperatures (10 degrees C) and bioaugmented for comparison. Aquifer samples from three sediment locations within a TCE-polluted source zone were investigated in duplicate microcosms.

Effect of temperature and pipe material on biofilm formation and survival of Escherichia coil in used drinking water pipes: a laboratory-based study.

Segments of used drinking water pipes of galvanised steel (GS), cross-linked polyethylene (PEX), copper pipes (Cu) or new medium-density polyethylene (PE) were investigated for the formation of biofilm and survival of E. coli in biofilm and in the water phase. Pipes were filled with water and incubated at 15 degrees C or 35 degrees C under static conditions.

Enhanced biogas recovery by applying post-digestion in large-scale centralized biogas plants.

The main objective of this study was to investigate the degradation efficiency of centralized biogas plants and provide guidance for the design of more efficient digester and post-digestion systems. These centralized biogas plants in Denmark digest manure together with organic waste from the food industry to generate biogas, which is used for electricity and thermal energy. A total of 20 such plants are currently active in Denmark, most of which were included in the investigation.

Thermophilic anaerobic digestion of source-sorted organic fraction of household municipal solid waste: start-up procedure for continuously stirred tank reactor.

Two feeding strategies for start-up of continuously stirred tank reactors (CSTR) treating source-sorted organic fraction of household municipal solid waste (SS-OFMSW) at 55 degrees C were evaluated. Two reactors were started up separately with a limited amount of initial inoculum (i.e.