Department of Civil Engineering

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Subject: search.filters.subject.Nitrate

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    Influence of landscape patterns on nitrate and particulate organic nitrogen inputs to urban stormwater runoff
    (Elsevier, 2023-12) Goonetilleke, Ashantha
    This study investigated the effect of the landscape pattern of permeable/impermeable patches on NO3−-N and particulate organic nitrogen (PON) concentrations during stormwater runoff transport and their source contributions. Six landscape pattern indices, namely, mean proximity index (MPI), largest patch index (LPI), mean shape index (MSI), landscape shape index (LSI), connect index (CONNECT), and splitting index (SPLIT), were selected to reflect the fragmentation, complexity, and connectivity of permeable patches in urban catchments. The results show that lower fragmentation, higher complexity, and greater connectivity can reduce NO3−-N concentrations in road runoff and drainage flow (i.e., the flow in the stormwater drainage network), as well as PON concentrations in road runoff. Further, the above landscape pattern is effective for mitigating the contributions of NO3--N and PON from road runoff. Low impact development (LID) can be incorporated with the landscape pattern of permeable/impermeable patches to mitigate nitrogen pollution in urban stormwater at the catchment scale by optimizing the spatial arrangement.
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    Chlorine mediated indirect electro-oxidation of ammonia using non-active PbO2 anode: Influencing parameters and mechanism identification
    (Elsevier, 2020-09) Mandal, Pubali
    Removal of ammonia-nitrogen from wastewater has gained considerable attention in recent years to reduce the critical problems arising in the water bodies receiving ammonia containing wastewater. Eutrophication and formation of odors due to wastewater discharging, the formation of undesirable by-products during the disinfection process can be significantly reduced using various treatment technologies. Although biological processes are mainly implemented to reduce ammonia-nitrogen concentration, several studies demonstrated electro-oxidation process as a potential alternative for ammonia-nitrogen removal. Among the non-active anodes, the majorly studied anode for chlorine mediated ammonia oxidation is boron-doped diamond anode. In this study, a non-active but comparatively low-cost graphite/PbO2 anode has been proposed for removing ammonia-nitrogen from wastewater. The study describes the effects of three influencing factors; current intensity, initial Cl− and NH3-N concentration on the oxidation efficiency of ammonia using graphite/PbO2 anode. The ammonia removal efficiency was found to be dependent on all the three parameters selected. The NH3-N removal efficiency of 96.5 ± 0.4% was achieved after 120 min of electro-oxidation of 100 mg L−1 NH3-N and 900 mg L−1Cl− containing solution at a current intensity of 0.3 A. Nitrate ion, and nitrogen gas were found as the stable end-products of the ammonia removal process. The formation of desirable end-product, N2, increased from 11.6% to 28.9% with increase in Cl− concentration from 300 to 1500 mg L−1. The steady-state concentrations of chloramine indicate formation of chloramine as an intermediate step of ammonia-nitrogen removal. The total chloramine concentration was <2.5% of the initial nitrogen content throughout the reaction.
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    Role of inorganic anions on the performance of landfill leachate treatment by electrochemical oxidation using graphite/PbO2 electrode
    (Elsevier, 2020-02) Mandal, Pubali
    The influences of sulfate, chloride, nitrate, and bicarbonate ions on the electrochemical treatment performances of landfill leachate have been investigated. The concentrations of SO42−, Cl−, NO3− ions, and bicarbonate alkalinity of landfill leachate were 252 mg L-1, 1244 ± 22.3 mg L-1, 12 mg L-1, and 1750 ± 40.8 mg L-1 as CaCO3 without any external salt addition. The concentrations of anions were analyzed after 2 h of electrochemical oxidation to understand any conversion of externally added anions. Chemical oxygen demand (COD), dissolved organic carbon (DOC), and ammonia-nitrogen removal efficiencies after 2 h of electrolysis were 35.1 ± 2.3 %, 25.6 ± 2.9 %, and 97.6 ± 0.7 % respectively. Although no effect was observed for COD and DOC removal, increasing sulfate ion adversely affected NH3-N removal efficiency; the removal percentage decreased to 87.7 ± 0.5 % for 6082 mg L-1 of SO42− containing leachate. Addition of chloride improved the overall system performance. Obtained COD and DOC removal efficiencies were 67.2 ± 1.5 % and 55.8 ± 2.1 % for Cl− concentration of 4361 mg L-1 in leachate. Very low NH3-N removal (60 ± 2.1 %) for 1483 mg L-1 of nitrate containing leachate was obtained in this study due to the regeneration of ammonia by cathodic reduction of nitrate. Nitrate formation was observed as part of reactions for ammonia removal; for instance, the nitrate concentration increased from 12 mg L-1 to 39.3 ± 4 mg L-1 after electrolysis. For the leachate treatment containing 6000 mg L-1 of externally added HCO3−, the COD and DOC removal efficiencies decreased to 19.6 ± 0.6 % and 17.8 ± 1.1 %, but the more adverse effect was observed for NH3-N removal efficiency which was only 7.4 ± 1.8 %.
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    Sustainable Bio-Adsorbent for Treatment of Nitrate, Fluoride and TDS in Groundwater
    (IJRPAC, 2019-06) Gupta, Rajiv; Singhal, Anupam
    The quality of groundwater and surface water bodies have been analyzed globally and showed that 23% of primary drinking water sources have more than permissible limits of pollutants’ concentration. A major part of the world suffers from high concentrations of Nitrate, Fluoride and total dissolved solids (TDS) in drinking water. Therefore, the present work focuses on the treatment of these three parameters. There are many processes available to remove and reduce the higher concentration of the aforesaid pollutants in water with advantages and disadvantages. One of the main disadvantages of these processes is the sustainability and availability of treating materials. In this regard, the work explores different agricultural materials (nine to be exact) for reduction of Fluoride, Nitrate and TDS in water. It is found that most of the materials have the potential to reduce either of one contaminant. However, only potato gel has shown potential in reduction of all three contaminants', i.e. Fluoride, Nitrate and TDS, concentration. The Isotherm plots indicate that Nitrate and TDS biosorption mechanism follows the Langmuir Isotherm while Fluoride biosorption follows the Freundlich Isotherm. Optimization is carried out, using batch and continuous study, in terms of time and mass of adsorbent against the concentration of the contaminant. Adsorption column tests indicate the reduction of 89%, 92% and 86% in the concentration of Fluoride, Nitrate and TDS respectively by potato gel.