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1.
Wastewater treatment with bioelectrical generation is an attractive feature with microbial fuel cells. The chitosan/biodegradable copolymer proton exchange membrane was used to assess its performance with brewery wastewater in a dual chambered microbial fuel cell. The biodegradable copolymer was made by thermal condensation of malic acid and citric acid in 3:1 ratio and then blended with chitosan to form a membrane via solution casting and solvent evaporation techniques. The performance of the chitosan/biodegradable copolymer membrane was evaluated in bioelectricity production with brewery effluent as an anolyte in a carbon electrode microbial fuel cell. Additionally, the competence of the prepared blend proton exchange membrane is compared with the commercial Nafion 117 membrane and Agar salt bridge in separate microbial fuel cell units with the same effluent and electrodes. At neutral pH, the effect of adding metabolites such as glucose and acetate to the anolyte was also investigated. The maximum current density and power density generated with chitosan/biodegradable copolymer membrane was 111.94 mA m?2 and 3022.39 mW m?2, respectively, whereas the Nafion 117 membrane had a maximum current density of 120.23 mA m?2 and power density of 3486.73 mW m?2.  相似文献   

2.
A denitrifying biocathode in a microbial fuel cell was developed to investigate the replacement of the costly Pt-coated abiotic cathodes for electricity generation. The denitrifying biocathode was sandwiched between the dual-anode systems. The study investigated the performance for simultaneous treatment of wastewater on the anode, biological denitrification on the cathode and the potential recovery of electrical energy. Autotrophic biofilms performed denitrification on the cathode using supplied electrons by the biodegradation of organics on the anode. Graphite granules were used as electrodes for biofilm attachment, and nafion membranes were used as separators between electrodes. The system achieved a volumetric power of 7 ± 0.4 W m?3 net cathodic compartment (NCC) with the simultaneous removal of 229.5 ± 18 mg L?1 COD on anode and 88.9 g m?3 NCC day?1 nitrogen on cathode, respectively. The columbic efficiency for cathodic and anodic reactions was 98.9 ± 0.57 and 23.54 ± 0.87 %, respectively. This is a combined study for domestic wastewater treatment and biological denitrification in a compact MFC reactor. Further optimization of the system is desired to improve its performance and applicability.  相似文献   

3.
The role of endogenous redox mediators has considerable importance in electron shuttling reactions and associated performance of microbial fuel cell. Single-chamber microbial fuel cell-II with dual air-cathode assembly (area = 18.84 cm2) supported highest bacterial (Pseudomonas aeruginosa) density (6.7 × 109) and active biomass [4.4 ± 0.3 mg cm?2 (carbon content = 0.48 ± 0.1 mg cm?2)] on anode thereby resulting in maximum production of redox metabolite, 5-methyl 1, hydroxy phenazine (301 ppm) and voltage (595 ± 5 mV) than similar cells with relatively less surface area of cathode. It was further revealed that 5-methyl 1, hydroxy phenazine production was positively correlated with chemical oxygen demand removal rate (77 ± 2.5%) and power generation (66.6 ± 2.2 mW cm?2) efficiency of single-chamber microbial fuel cell-II. Maximum power density of 258 ± 4.5 mW cm?2 was generated when reactor was supplemented with 2 ml crude extract of 5-methyl 1, hydroxy phenazine metabolite, whereas power output was about 229 ± 2.5 mW cm?2 when reactor was bio-stimulated with 1 ml pure extract of 5-methyl 1, hydroxy phenazine. With this concentration, the electrochemical response of mixed culture biofilm (sediment) was enhanced by 99.3%. However, further increase in concentration of endogenous mediator proved to be limiting on reactor performance. Pyrosequencing and phylogenetic analysis on the basis of partial 16S rRNA sequences demonstrated both culturable and unculturable bacterial species in anodic biofilm and relative abundance of family Pseudomonadaceae was found to be maximum, i.e., 61.7% followed by Rhodocyclaceae 19.2%, Xanthomonadaceae 6.3% and Opitutaceae 3.18%.  相似文献   

4.
Nowadays, natural resources are under increasing stress which fosters wastewater reuse planning and emphasizes on the decentralized wastewater treatment. Vermifiltration has been described as a viable alternative to treat domestic and urban wastewater, but few studies have focused on the impact of different filter packings on vermifiltration performance. This study evaluates the effect of vermicompost and sawdust in a single-stage vermifilter (VF) for urban wastewater treatment. After an acclimation period of 45 days, urban wastewater from a combined sewage collection system was applied continuously for 24 h. Earthworm stock density was of 20 g L?1, HRT of 6 h, HLR of 0.89 m3 m?2 day?1 and OLR of 7.38 g BOD5 day?1. System performance was assessed by the removal efficiencies of BOD5, COD, TSS, NH4 +, TN and TP, and fecal coliforms and helminth eggs elimination. Vermicompost (VE) and sawdust (SE) were tested, using an earthworm abundance of 20 g L?1. Treatment efficiencies were 91.3% for BOD5, 87.6% for COD, 98.4% for TSS and 76.5% for NH4 + in VE, and 90.5% for BOD5, 79.7% for COD, 98.4% for TSS and 63.4% for NH4 + in SE. Earthworms contributed to reduce NH4 + and TN removal and to increase NO3 ? concentration. No treatment was able to eliminate fecal coliforms down to guidelines values for wastewater irrigation as helminth eggs were completely eliminated. Single-stage vermifiltration system using both filter packings is inconsistent and cannot meet EU guideline values for discharge in sensitive water bodies and WHO guidelines for irrigation with treated wastewater.  相似文献   

5.
The potential of the autoclaved Tunisian landfill leachate treatment using microalgae (Chlorella sp.) cultivation was investigated in this study. Landfill leachate was collected from Borj Chakir landfill, Tunisia. A full factorial experimental design 22 was proposed to study the effects of the incubation time and leachate ratio factors on the organic matter removal expressed in chemical oxygen demand (COD) and ammoniacal nitrogen (NH4─N) and on the biological response of Chlorella sp. expressed by the cell density and chlorophyll content. All experiments were batch runs at ambient temperature (25 ± 2 °C). The Chlorella sp. biomass and chlorophyll a concentrations of 1.2 and 5.32 mg L?1, respectively, were obtained with 10% leachate spike ratio. The obtained results showed that up to 90% of the ammoniacal nitrogen in landfill leachate was removed in 10% leachate ratio spiked medium with a residual concentration of 40 mg L?1. The maximum COD removal rate reached 60% within 13 days of incubation time indicating that microalgae consortium was quite effective for treating landfill leachate organic contaminants. Furthermore, with the 10% leachate ratio spiked medium, the maximum lipid productivity was 4.74 mg L?1 d?1. The present study provides valuable information for potential adaptation of microalgae culture and its contribution for the treatment of Tunisian landfill leachate.  相似文献   

6.
The current work deals with efficient removal of acetaminophen (AC) from hospital wastewater using electro-Fenton (EF) process. The degradation yield of 99.5% was obtained under optimal experimental conditions, namely 5.75 mg L?1 initial AC concentration, 2.75 pH solution, 3-cm inter-electrode distance, 100 mg L?1 KCl electrolyte, 122.5 µL L?1 H2O2, 8 mA cm?2 current density at equilibrium time of 8 min. Analysis of variance (ANOVA) suggested that the effect of mentioned operating parameters was statistically significant on the AC removal. The low probability amount of P value (P < 0.0001), the Fisher’s F-value of 65.91, and correlation coefficient of the model (R2 = 0.9545) revealed a satisfactory correlation between the experimental and the predicted values of AC removal. The predicted removal efficiency of 99.4% was in satisfactory agreement with the obtained experimental removal efficiency of 98.7%. The AC degradation during the EF followed a first-order kinetic model with rate constants (Kapp) of 0.6718 min?1. Using the ordinary radical scavengers revealed that main mechanism of AC degradation controlled by the hydroxyl free radicals produced throughout the EF process. The excess amount of iron (II) scavenged the active radicals and diminished the concentration of ·OH available to react with AC. The optimum molar ratio of H2O2 to Fe2+ was found to be 2.5. The developed EF process as a promising technique applied for treatment of real samples.  相似文献   

7.
The removal of colour and organic compounds from vinasses derived from the wine distillery industry was studied using boron-doped diamond-based electrodes and dimensionally stable anodes. The maximum reduction of organic compounds and colour was attained with the use of boron-doped diamond-based electrode after 10 h of operation at a current density of 6.6 mA cm?2. The current efficiency obtained was about 90% with a specific energy consumption (measured in terms of removal of chemical oxygen demand) of 17 kWh kg?1 COD removed. The dimensionally stable anodes were capable of removing 6–47% of the organic material and reached 60% decolourisation but with a lower current efficiency (between 85 and 10%) and much higher specific energy consumption values. The anaerobic digestion of vinasse after 1 h of treatment using boron-doped diamond-based electrode showed an effective mineralisation of the organic matter contained in the sample leading to an increase in methane production during anaerobic digestion.  相似文献   

8.
The long-term sustainability of an anaerobic ammonium oxidation (anammox) process in a moving bed biofilm reactor (MBBR) treating highly concentrated (mean of 740 mg NH4 +-N L?1) wastewater was demonstrated by 1600 days of efficient operation. A high maximum total nitrogen removal rate (TNRR) of 1.5 g N m?2 d?1 was achieved at the low temperature of 20 °C. For nitrogen removal recovery in cases of nitrite inhibition, anammox intermediate nitric oxide (NO) was tested in batch experiments as an N-removal accelerating agent. The effect of the addition of various NO dosages (8–72 mg NO-N L?1) was studied under inhibitory nitrite concentrations (>100 mg NO2 ?-N L?1) for anammox bacteria. Optimal maintained NO concentration was 58 mg NO-N L?1 and brought about the highest biofilm-specific anammox activity (SAA). Compared to a blank test, the minimum concentration of added NO of 40 mg NO-N L?1 showed a statistically significant (p < 0.05) accelerating effect on SAA. No inhibition of SAA by NO was observed, although at NO concentrations exceeding 72 mg NO-N L?1, the acceleratory effect upon SAA was decreased by 8%. Changes in the bacterial consortia involved in nitrogen conversion were determined concurrently for the different nitrogen removal rates and operational conditions. Quantities of Planctomycetales clone P4 strains, which are the closest (99% similarity) relative to Candidatus Brocadia fulgida, increased from 1 × 103 to 1 × 106 anammox gene copies per g total suspended solids during reactor operation days 568–1600, which was determined by quantitative polymerase chain reaction. During the operation of the MBBR, the abundance of ammonium-oxidizing bacteria (AOB) increased proportionally (up to 30%). The abundance of nitrite-oxidizing bacteria (NOB) did not increase (remaining below 10%) during days 232–860. AOB became predominant over NOBs owing to the inhibition of free ammonia spiking on NOBs.  相似文献   

9.
The co-treatment of landfill leachate (LFL) with municipal wastewater (MWW) using shortcut sequencing batch reactor combined with coagulation–settling process (SBR + CS) was investigated. Four ratios of LFL to MWW volume (v/v) were used during experiments including the ratios 1:9, 2:8, 3:7 and 5:5. The average quality of the LFL was chemical oxygen demand (COD) of 20,800 mg L?1 and NH4-N of 2,645 mg L?1. The SBR-treating LFL in six series where mixing aeration and settling phases were varied from 4 to 14 h was combined with coagulation (FeCl3, Al2(SO4)3) with an interval of 2 h. It was found that ratio (1:9) of leachate to MWW under aeration and mixing phase of 4 h with settling time of 1.5 h exhibited the highest ability to remove both COD and NH 4 + -N, 99% and 85%, respectively. The short-time sequential batch reactor was tested for the treatment of raw LFL, and only 47% and 23% removal of COD and NH 4 + -N, respectively, could be achieved.  相似文献   

10.
An electrochemical advanced oxidation process employing a boron-doped diamond anode for the treatment of synthetic waters and secondary effluents of wastewater treatment plants (WWTP) was studied. The efficiency and formation of transformation products (TPs) for this treatment process were investigated at different current densities for bisphenol A (BPA) spiked to synthetic water and WWTP effluents. A complete removal of the parent compound was achieved in WWTP effluents. Higher applied current densities resulted in faster removal. At the same time, a correlation between the applied current density and the ozone concentration measured in the bulk solution was revealed. Hence, the observed transformation of BPA is likely due to the generation of reactive oxygen species such as hydroxyl radicals and ozone. Based on a suspected target screening approach, four known TPs and two unreported (new) TPs were identified by LC–MS analysis. These results suggest a transformation pathway following three steps: hydroxylation of the aromatic ring, followed by oxidation of the isopropylidene bridge and finally a ring opening and formation of organic acids and other small molecules. The presence of chloride ions in WWTP effluents can result in the generation of excessive concentrations of chlorate and perchlorate during electrochemical oxidation. Applying a current density of 208 mA cm?2, a complete elimination of BPA was achievable after 15 min (Q/V = 430 mA h L?1); however, the oxidation resulted in concentrations of chlorate and perchlorate of 2.85 and 5.65 mg L?1, respectively. These values were directly dependent on the exposure time and desired degree of BPA removal.  相似文献   

11.
The state of Punjab—a part of the Indus basin of the Indian subcontinent has an excellent net work of irrigation facilities. However, due to intensive cultivation it is facing a major problem with respect to quality of groundwater for irrigation. In the present investigation, geo-referenced groundwater samples were analysed to map water quality using geographical information system. Electrical conductivity varied from 0.418 to 5.754 dS m?1 with an average of 1.365 dS m?1. The carbonate ranged between 0 and 120 mg L?1, whereas bicarbonate ranged from 5 to 1,000 mg L?1. Chloride varied from 7 to 2,347 mg L?1. Calcium plus magnesium ranged from 12 to 1,216 mg L?1 with a mean value of 169 mg L?1. Sodium adsorption ratio ranged between 0.0 and 34.78 with an average of 2.66 meq L?1/2. Residual sodium carbonate varied from 0 to 21.30 meq L?1 with a standard deviation of 2.24. The Geographic Information System (GIS)-based mapping indicated that water in suitable category spatially covered 45.7 % of the state which is located mostly in the sub-mountain (Siwalik Hills), north-eastern undulating and piedmont and alluvial plain agro-eco-subregions. Marginally suitable groundwater spatially covered 46.1 % in the central alluvial plain and south-western alluvial plain agro-eco-subregions. Unsuitable groundwater covered 8.2 % of the state, mostly in the erstwhile sodic soils areas in the central alluvial plain and south-western alluvial plain agro-eco-subregions. GIS-based maps are effective in identifying hot spots which need immediate attention and call for strategic planning for sustainable management.  相似文献   

12.
A simple spectrophotometric method for determination of hydrogen sulfide in wastewater and hot spring samples was developed. The method is based on the reaction between hydrogen sulfide and sodium 1,2-naphthoquinone-4-sulfonate (NQS). The effect of various experimental factors on the reaction between hydrogen sulfide and NQS was investigated and optimized using central composite design. The optimal values of the factors were 5.00 × 10?4 mol L?1 for concentration of NQS and 1.00 × 10?2 mol L?1 for concentration of hydrochloric acid. The wavelength of the maximum absorption of the reaction product was 320 nm. Constructed calibration curve for hydrogen sulfide determination was linear in the range of 0.5–20.0 mg L?1 with the detection limit of 0.16 mg L?1. The method was free from interferences. Percent relative errors below 2 % were obtained for determination of hydrogen sulfide in environmental samples.  相似文献   

13.
The present paper undertakes a study of the physico-chemical properties and toxic heavy metals content in the untreated and treated pharmaceutical effluents in order to evaluate the working efficiency of industrial effluent treatment plants. The treatment efficiency achieved for various parameters was conductivity (79.94%), alkalinity (93.91%), hardness (87.70%), chloride (89.24%), cyanide (79.66%), phosphate (99.19%), total dissolved solids (85.89%), total suspended solids (96.87%), salinity (52.41%), dissolved oxygen (27.32%), biochemical oxygen demand (83.39%) and chemical oxygen demand (72.21%). The removal efficiency achieved for different heavy metals was Cu2+ (79.66%), Ni2+ (69.22%), Cr6+ (80.15%), Pb2+ (72.14%), Fe3+ (92.59%) and Zn2+ (90.61%). The level of biochemical oxygen demand (64 mg L?1) in the treated effluents was above the limit of 30.0 mg L?1, chemical oxygen demand level (208 mg L?1) was close to a limit of 250 mg L?1, while average Pb2+ concentration (0.10 mg L?1) was on the borderline of maximum permissible limit of 0.10 mg L?1 set by Central Pollution Control Board for safe discharge of industrial effluent in inland surface water. The average concentration of cyanide (0.01 mg L?1) in the treated industrial effluent of our study is of great concern to the fisheries of freshwater ecosystem in which the effluents finally get discharged. Based on the results of the present study, it is concluded that the pollution level in the discharged pharmaceutical effluent is of the great concern requiring proper treatment and regular scientific monitoring so as to protect the environmental degradation of water resources and facilitate the propagation of the aquatic life.  相似文献   

14.
Enhancing of the efficient tissue culture protocol for somatic embryos would facilitate the engineered breeding plants program. In this report, we describe the reproducible protocol of Malaysian rice (Oryza sativa L.) cultivar MR219 through somatic embryogenesis. Effect of a wide spectrum of exogenesis materials was assessed in three phases, namely callogenesis, proliferation and regeneration. Initially, rice seeds were subjected under various auxin treatments. Secondly, the effect of different concentrations of 2,4-D on callus induction was evaluated. In the next step, the efficiency of different explants was identified. Subsequently, the effects of different auxins, cytokinins, l-proline, casein hydrolysate and potassium metasilicate concentrations on the callus proliferation and regeneration were considered. For the callogenesis phase, 2 mg L?1of 2,4-D and roots were chosen as the best auxin and explant. In the callus proliferation stage, the highest efficiency was observed at week eight in the MS media supplemented with 2 mg L?1 of 2,4-D, 2 mg L?1 of kinetin, 50 mg L?1 of l-proline, 100 mg L?1 of casein hydrolysate and 30 mg L?1 of potassium metasilicate. In the last phase of the research, the MS media added with 3 mg L?1 of kinetin, 30 mg L?1of potassium metasilicate and 2 mg L?1 of NAA were selected. Meanwhile, to promote the roots of regenerated explants, 0.4 mg L?1 of IBA has shown potential as an appropriate activator.  相似文献   

15.
El Bey river, which drains 60% of the pollutant load of several urban cities in the northeast of Tunisia, provides a good example of the transfer of organic and metallic pollutants that result from industrial and urban activity, and can be used to show how these charges are transported and discharged into the Gulf of Tunis. Persistent organic pollutants (PAH and PCB) in dissolved, particulate matter, bed sediments, and three wastewater effluents in El Bey watershed were analyzed. PAH (∑14PAHs) concentration ranged from 0.248 to 9.955 mg L?1 and from 0.836 to 28.539 mg L?1 in dissolved and particulate fraction respectively. The particulate/dissolved partition coefficient value (Kd) was less than one which confirmed the affinity of PAH to be adsorbed. In sediment, the high-molecular weight PAHs were found principally with percentage between 50 and 100% witch present 239.99 to 5362.19 μg kg?1, which is relatively higher in comparison with other estuaries river. Contrary to PAH patterns, PCB were bound to dissolve fraction. Kd (PCB) value (Kd?>?1) reflected this affinity which is related to environment energy. The spatial distribution and profile of analyzed organic pollutants confirmed the direct impact of wastewater effluent on the organic pollution level in three compartment of El Bey watershed and his profiles suggested different transport patterns.  相似文献   

16.
Changes in water chemistry along the High Arctic fluvial–lacustrine system located in Wedel Jarlsberg Land in the SW Spitsbergen (Svalbard) were investigated during the summer season of 2010 and 2011. The newly formed river–lake system consists of three lakes connected with the Brattegg River. The first bathymetric measurements of these lakes were made by the authors in 2010. The Brattegg River catchment represents a partly glaciered Arctic water system. The studied lakes are characterized by low mineralization and temperature of water. The value of the electrolytic conductivity (EC) ranges from 30.2 to 50.5 μS cm?1 and the temperature of surface water from 1.5 to 7.8 °C. The temperature increase takes place downstream starting from Upper Lake to the outflow from Myrktjørna Lake. The waters of lakes have higher temperatures than the stream. The predominant ions are HCO3 ? (up to 16.5 mg L?1), Cl? (6.66–8.53 mg L?1), Ca2+ (2.40–4.45 mg L?1) and Na+ (2.65–3.36 mg L?1). The highest values of ammonium and DOC found in the lowest Myrktjørna Lake seem to be related to the presence of aquatic organisms and also birds. From the group of 10 analyzed microelements, increased concentrations of aluminum, up to almost 500 μg L?1, are present in the lakes’ water. Water isotopic composition ranges for δ18O and δ2H, from ?10.6 to ?10.9‰ and from ?70.8 to ?72.3‰, respectively. The vertical zonality of lake waters is manifested in a decrease in the temperature and increase in EC and chemical elements concentrations.  相似文献   

17.
The Choptank River, Chesapeake Bay’s largest eastern-shore tributary, is experiencing increasing nutrient loading and eutrophication. Productivity in the Choptank is predominantly nitrogen-limited, and most nitrogen inputs occur via discharge of high-nitrate groundwater into the river system’s surface waters. However, spatial patterns in the magnitude and quality of groundwater discharge are not well understood. In this study, we surveyed the activity of 222Rn, a natural groundwater tracer, in the Choptank’s main tidal channel, the large tidal tributary Tuckahoe Creek, smaller tidal and non-tidal tributaries around the basin, and groundwater discharging into those tributaries, measuring nitrate and salinity concurrently. 222Rn activities were <100 Bq m?3 in the main tidal channel and 100–700 Bq m?3 in the upper Choptank River and Tuckahoe Creek, while the median Rn activities of fresh tributaries and discharging groundwater were 1,000 and 7,000 Bq m?3, respectively. Nitrate-N concentrations were <0.01 mg L?1 throughout most of the tidal channel, 1.5–3 mg L?1 in the upper reaches, up to 13 mg L?1 in tributary samples, and up to 19.6 mg L?1 in groundwater. Nitrate concentrations in tributary surface water were correlated with Rn activity in three of five sub-watersheds, indicating a groundwater nitrate source. 222Rn and salinity mass balances indicated that Rn-enriched groundwater discharges directly into the Choptank’s tidal waters and suggested that it consists of a mixture of fresh groundwater and brackish re-circulated estuarine water. Further sampling is necessary to constrain the Rn activity and nitrate concentration of discharging groundwater and quantify direct discharge and associated nitrogen inputs.  相似文献   

18.
A nutrient mass balance for the tidal freshwater segment of the James River was used to assess sources of nutrients supporting phytoplankton production and the importance of the tidal freshwater zone in mitigating nutrient transport to marine waters. Monthly mass balances for 2007–2010 were based on riverine inputs, local point sources (including sewer overflow events), ungauged inputs, riverine outputs, and tidal exchange. The tidal freshwater James River received exceptionally high areal loads (446 mg TN m?2 day?1 and 55 mg TP m?2 day?1) compared to other estuaries in the region and elsewhere. P inputs were principally from riverine sources (84 %) whereas point sources contributed appreciably (54 %) to high N loads. Despite high loading rates and short water residence time, areal mass retention was high (143 mg TN m?2 day?1 and 33 mg TP m?2 day?1). Retention of particulate fractions occurred during high discharge, whereas dissolved inorganic fractions were retained during low discharge when chlorophyll-a concentrations were high. On an annualized basis, P was retained more effectively (59 %) than N (32 %). P was retained by abiotic mechanisms via trapping of particulate forms, whereas N was retained through biological assimilation of dissolved inorganic forms. Results from a limited suite of stable isotope determinations suggest that DIN from point sources was preferentially retained. Combined inputs from diffuse and point sources accounted for only 20 % and 36 % (respectively) of estimated algal N and P demand, indicating that internal nutrient recycling was important to sustaining high rates of phytoplankton production in the tidal freshwater zone.  相似文献   

19.
A pilot-scale study was conducted to characterize the performance of molasses' release from a well-type barrier system harboring solidifying molasses named slowly released molasses (SRM) as a reactive medium to promote indigenous denitrifying activity. A SRM rod was made by mixing molasses with paraffin wax, cellulose, and silica sands in a cylindrical mold. Two SRM systems harboring 30 and 60 SRM rods, referred to as Systems A and B, respectively, were constructed in a large flow tank (L × W × D = 8 m × 4 m × 2 m) filled with natural sands. These two systems continuously delivered molasses with groundwater flow over 96 days, with decreasing molasses' concentrations ranging from 763 to 95 and 1,150 to 183 mg L?1 as chemical oxygen demand values (COD) for Systems A and B, respectively. From simulation results with an aid of the upscaled mass transfer function (MTF) model, the molasses' mass flux was slowly decreased with time, exhibiting 57, 11, and 3 mg COD day?1 in 10, 100, and 365 days in System A, and 138, 25, and 6 mg COD day?1 in System B, respectively; 90, 70, and 50 % of total molasses' mass remained after 12, 63, and 267 days in System A and 12, 65, and 291 days in System B, respectively. This study demonstrates that SRM system can provide a remedial alternative for long-term in situ treatment of nitrate-contaminated groundwater.  相似文献   

20.
Diazinon is a widely applied agricultural pesticide whose effect importantly on the environment and the possible contamination of surface waters has led to increased interest in toxicological studies. Crayfish, as an ecologically important benthic macroinvertebrate, seems to be an appropriate model organism for such assessments. Acute toxicity tests were carried out on three crayfish age groups: young-of-the-year (total length = 25.0 ± 4.9 mm), juvenile (total length = 56.5 ± 3.8 mm) and adult (total length = 83.5 ± 5.7 mm). Young-of-the-year crayfish were found to be the most sensitive to diazinon (96 h LC50 = 0.15 mg L?1), followed by juvenile crayfish (96 h LC50 = 0.27 mg L?1), and adults (96 h LC50 = 0.51 mg L?1). Crayfish were highly sensitive to diazinon. A delayed effect of Diazinon 60EC on adults was detected (144 h LC50 = 0.44 mg L?1) suggests functional damage from the use of sublethal concentrations.  相似文献   

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