Estimating Potential E. coli Sources in a Watershed Using Spatially Explicit Modeling Techniques1

Riebschleager, K.J., R. Karthikeyan, R. Srinivasan, and K. McKee, 2012. Estimating Potential E. coli Sources in a Watershed Using Spatially Explicit Modeling Techniques. Journal of the American Water Resources Association (JAWRA) 48(4): 745‐761. DOI: 10.1111/j.1752‐1688.2012.00649.x Abstract: The Spatially Explicit Load Enrichment Calculation Tool (SELECT) was automated to characterize waste and the associated pathogens from various sources within a mixed land use watershed. Potential Escherichia coli loads in Lake Granbury watershed were estimated using spatially variable governing factors, such as land use, soil condition, and distance to streams. A new approach for characterizing E. coli loads resulting from malfunctioning on‐site wastewater treatment systems (OWTSs) was incorporated into SELECT along with the Pollutant Connectivity Factor (PCF) module. The PCF component was applied to identify areas contributing E. coli loads during runoff events by incorporating the influence of potential E. coli loading, runoff potential, and travel distance to waterbodies. Simulation results indicated livestock and wildlife are potential E. coli contributing sources in the watershed. The areas in which these sources are potentially contributing are not currently monitored for E. coli. The bacterial water quality violations seen around Lake Granbury are most likely the result of malfunctioning OWTSs and pet wastes. SELECT results demonstrate the need to evaluate each contributing source separately to effectively allocate site specific best management practices (BMPs) utilizing stakeholder inputs. It also serves as a powerful screening tool for determining areas where detailed investigation is merited.     

The effect of cerium oxide additive on the performance and emission characteristics of a CI engine operated with rice bran biodiesel and its blends

In this study, the rice bran oil (RBO) has been converted into methyl ester with an aid of transesterification reaction. Chemically, transesterification means conversion of triglyceride molecule or a complex fatty acid into alcohol and ester by removing the glycerin and neutralizing the free fatty acids. The B20 blend samples [80% diesel + 20% biodiesel] were prepared for each methyl ester obtained from RBO and then the cerium oxide (CeO₂) nanoparticles were added to the each B20 blend samples at a dosage of 50 ppm and 100 ppm with an aid of ultrasonicator. Moreover, in the absence of any engine modifications, the performance and emission characteristics of those blend samples have been investigated from the experimentally measured values such as density, viscosity, cloud point, pour point, and calorific value while the engine performance was also analyzed through the parameters like exhaust gas temperature (EGT), brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), exhaust emission of carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx). The experimental results reveal that the use of CeO₂ blended biodiesel in diesel engine has exhibited good improvement in performance characteristic and reduction in exhaust emissions.     

Heterocatalytic Fenton oxidation process for the treatment of tannery effluent: kinetic and thermodynamic studies

Background, aim, scope

Treatment of wastewater has become significant with the declining water resources. The presence of recalcitrant organics is the major issue in meeting the pollution control board norms in India. The theme of the present investigation was on partial or complete removal of pollutants or their transformation into less toxic and more biodegradable products by heterogeneous Fenton oxidation process using mesoporous activated carbon (MAC) as the catalyst.

Materials and methods

Ferrous sulfate (FeSO₄·7H₂O), sulfuric acid (36?N, specific gravity 1.81, 98% purity), hydrogen peroxide (50% v/v) and all other chemicals used in this study were of analytical grade (Merck). Two reactors, each of height 50?cm and diameter 6?cm, were fabricated with PVC while one reactor was packed with MAC of mass 150?g and other without MAC served as control.

Results and discussion

The oxidation process was presented with kinetic and thermodynamic constants for the removal of COD, BOD, and TOC from the wastewater. The activation energy (Ea) for homogeneous and heterogeneous Fenton oxidation processes were 44.79 and 25.89?kJ/mol, respectively. The thermodynamic parameters ??G, ??H, and ??S were calculated for the oxidation processes using Van??t Hoff equation. Furthermore, the degradation of organics was confirmed through FTIR and UV?Cvisible spectroscopy, and cyclic voltammetry.

Conclusions

The heterocatalytic Fenton oxidation process efficiently increased the biodegradability index (BOD/COD) of the tannery effluent. The optimized conditions for the heterocatalytic Fenton oxidation of organics in tannery effluent were pH 3.5, reaction time?C4?h, and H₂O₂/FeSO₄·7H₂O in the molar ratio of 2:1.     

Nanoporous activated carbon fluidized bed catalytic oxidations of aqueous o, p and m-cresols: kinetic and thermodynamic studies

Nanoporous activated carbon prepared from rice husk through precarbonisation at 400 °C and phosphoric acid activation at 800 °C was used as fluidized bed in Fenton oxidation of the o, p and m-cresols in aqueous solution. The efficiencies of homogeneous Fenton oxidation, fluidized Fenton oxidation and aerobic biological oxidation systems for the removal of o, p and m-cresols in aqueous solution have been compared. The kinetic constants and the thermodynamic parameters for the homogeneous Fenton, heterogeneous Fenton and aerobic biological oxidations of o, p and m-cresols in synthetic wastewater were determined. The degradation of cresols in synthetic wastewater was confirmed using FT-IR, ¹H-NMR and UV–visible spectroscopy.     

Heterogeneous Fenton oxidation of dissolved organics in salt-laden wastewater from leather industry without sludge production

This is the first report on the heterogeneous oxidation of dissolved organics in wastewater with little consumption of Fenton’s reagent and without sludge production. The salt-laden wastewater discharged from leather industry has poor biodegradability due to the presence of high total dissolved solids. This wastewater is evaporated in solar evaporation pans. The evaporated residue faces disposal problem due to high concentration of organic and inorganic salts. The present study demonstrates the preparation, characterization and application of mesoporous activated carbon matrix along with Fenton’s reagent for the removal of dissolved organics in wastewater. Free electron-rich mesoporous activated carbon matrices (MAC₇₀₀, MAC₈₀₀ and MAC₉₀₀) were prepared and characterized for surface area, C, H, N, ash content, free electron density and energy gap value. Results show that heterogeneous catalytic oxidation of dissolved organics in the wastewater decreased biochemical oxygen demand, chemical oxygen demand, total organic carbon and dissolved protein, respectively, by 74, 69, 61 and 80% at optimum pH (3.5), H₂O₂ (7.5 mmol/l), FeSO₄.7H₂O (0.3 mmol/l) and MAC₈₀₀ (10 g/l).     

Mechanism of Anti-rotavirus Synergistic Activity by Epigallocatechin Gallate and a Proanthocyanidin-Containing Nutraceutical

Epigallocatechin gallate (EGCG) of green tea and the nutraceutical CystiCran^®-40 (containing 40% proanthocyanidins) of the cranberry plant have been associated with antiviral activity. The purpose of this work was to determine the mechanism of antiviral synergy between each compound. Coliphage T4II (phage T4) and the rotavirus strain SA-11(RTV) were used as model virus systems. Individual and combined flavonoids structural and molecular weight analyses were performed by NMR and HPCL/MS, respectively. A suboptimal concentration of EGCG or C-40 alone or in combination reduced phage infectivity by ≤10%. Similarly, EGCG (30 µg/ml) and C-40 (25 µg/ml), respectively, reduced RTV titers by 3 and 13%. However, RTV titers were reduced by 32% (p < .05) with both flavonoids used in combination. RTV was not recognized in host cells by electron microscopy 24-h post-inoculation. NMR and HPLC/MS findings revealed significant structural and potential changes in molecular weight of the flavonoids in complex.     

Causes of heavy metal contamination in groundwater of Tuticorin industrial block,Tamil Nadu,India

Environmental Science and Pollution Research - Groundwater is the major freshwater resource in urban and rural areas of India that provides potable water. The quality evaluation of existing...     

Reject management from a Mechanical Biological Treatment plant in Bangkok, Thailand

The potential reuse of rejects from upstream and downstream process of Mechanical-Biological-Treatment (MBT) plant for the production refuse derived fuel (RDF) was investigated in the present study. Since, the rejects were characterized with the high calorific values of approximately 21 kJ/kg for upstream process and 29.5 kJ/kg for downstream process, both can be considered for RDF production. Further, heavy metal contents were also not exceeding the European standards for using it as RDF is additional benefit. But, RDF production from upstream process rejects showed maximum energy supply of 3.20 × 10⁶ MJ/d with less ash (11.8%), chlorine (0.6%) and sulfur (0.2%) contents than the downstream process rejects. Among the three potential RDF users surveyed, the cement industries showed positive interest to burn RDF in their cement kiln with the energy supply cost of <2.1 USD/GJ. Few technical, economical and safety barriers were also identified with the RDF end users and potential suggestions were discussed for thriving RDF market in Thailand.     

Performance of bioreactor landfill with waste mined from a dumpsite

Emissions from landfills via leachate and gas are influenced by state and stability of the organic matter in the solid waste and the environmental conditions within the landfill. This paper describes a modified, ecologically sound waste treatment technique, where municipal solid waste is anaerobically treated in a lysimeter-scale landfill bioreactor with leachate recirculation to enhance organic degradation. The results demonstrate a substantial decrease in organic matter (BOD 99%, COD 88% and TOC 81%) and a clear decrease in nutrient concentrations especially ammonia (85%) over a period of 1 year with leachate recirculation.     

Treatment of simulated Reactive Yellow 22 (azo) dye effluents using Spirogyra species

The potential of commonly available green algae belonging to Spirogyra species was investigated as viable biomaterials for biological treatment of simulated synthetic azo dye (Reactive Yellow 22) effluents. The results obtained from the batch experiments revealed the ability of the algal species in removing the dye colour and was dependent both on the dye concentration and algal biomass. Maximum dye colour removal was observed on the third day for all the system conditions. Monitoring of ORP values helped to understand the overlying biochemical mechanism of algal-dye system. Based upon the results, the dye-algal treatment mechanism was attributed to biosorption (sorption of dye molecules over the surface of algal cells), bioconversion (diffusion of dye molecules into the algal cells and subsequent conversion) and biocoagulation (coagulation of dye molecules present in the aqueous phase onto the biopolymers released as metabolic intermediates during metabolic conversion of dye and subsequent settlement).