Experimental analysis and parameter optimization on the reduction of NOx from diesel engine using RSM and ANN Model

Environmental Science and Pollution Research - The major emission sources of NOX are from automobiles, trucks, and various non-road vehicles, power plants, coal fired boilers, cement kilns,...     

Use of Fenton's Reagent as a Disinfectant

Several compositions of Fenton's Reagent and hydrogen peroxide alone were used to disinfect combined sewage samples from a wastewater treatment facility. The presettled samples contained suspended solids (SS) and dissolved organic carbon (DOC) at concentrations of 28 and 290 mg/L, respectively. Disinfection with Fenton's Reagent was carried out at a pH between 5.90 and 6.0 and at a temperature of 25°C. All disinfected samples contained residual oxidants. Under all reaction conditions studied, complete inactivation of E. coli was achieved within one minute of the addition of Fenton's Reagent. Disinfection with hydrogen peroxide alone under similar conditions is incomplete even under much longer contact times. © 2009 Wiley Periodicals, Inc.     

Laboratory studies on the remediation of mercury contaminated soils

Mercury, in contrast to other toxic metals, cycles between the atmosphere, land, and water. During this cycle, it undergoes a series of complex chemical and physical transformations. Because of these transformations, it is found in the environment not only as simple inorganic and organic compounds, but also as complex compounds. As a result, it is difficult to remediate mercury contaminated materials. Laboratory studies were conducted with a mercury contaminated complex waste from an industrial site to evaluate the ability of extractants such as H₂O₂, H₂SO₄ and Na₂S₂O₃ to decontaminate the waste. Up to 87 percent of the total mercury present in the waste was extracted. Mercury was recovered as insoluble mercury sulfide by adding Na₂S solution to the combined filtrates from the H₂O₂ + H₂SO₄ and Na₂S₂O₃ treatment steps. The technique described in this article is capable of recovering mercury in a usable form and can be used as a pretreatment to remediate mercury contaminated waste before laud disposal.     

Seawater intrusion vulnerability in the coastal aquifers of southern India—an appraisal of the GALDIT model,parameters’ sensitivity,and hydrochemical indicators

An appraisal of seawater intrusion into the coastal aquifers is one of the major issues for groundwater resource management. The GALDIT model applies to the analysis of multiple parameters using systematic GIS techniques for mapping and assessment of seawater intrusion vulnerability. It demarcates the mapping of potential vulnerability that shows a higher vulnerability to seawater intrusion in various parts of the coast and the estimated vulnerability index value of 7.50 and 9.64. An area of 33.0 km² spread in the low-lying coastal area comprising estuaries, salt marshes, and saltpans shows the high vulnerability condition with an estimated vulnerability value of 6.42–7.50. An area of 73.20 km² spread over coastal and alluvial plains experiences moderate vulnerability (temporal salinity in the groundwater sources) with an estimated vulnerability index value of 5.46–6.42. Aquifers underlying coastal uplands (hard rock formations) and some parts of accretionary beaches (2.05 km²) are relatively protected fresh groundwater sources, wherein the estimated vulnerability index is 4.55–5.46. The vulnerability mapping of the GALDIT model using hydrochemical analysis of primary groundwater parameters such as TDS, Cl^?, HCO₃, and Cl^?/HCO₃ ratio is validated. Higher concentration of TDS (2637–4162 mg/l) and Cl^? (1268–2347 mg/l) is taken for the areas falling under higher vulnerability to seawater intrusion, especially in the placer mining sites and coastal areas facing erosion. Similarly, the groundwater sources of the low-lying areas including estuaries, salt marshes, saltpans, and backwater were noted to have higher values of Cl^?/HCO₃ with a rationality of 9.87–12.18. Hydrological facies shows the highest concentration of NaCl in the groundwater sources within the proximity of eroded beaches, saltwater bodies, and sand mining areas. A hydrochemical facies evolution (HFE) diagram represents the hydrochemical facies of groundwater elements that shows an intrusion of seawater into the coastal aquifers underlying the very high vulnerable zones. Higher bicarbonate concentration (233–318 mg/l) is noticed in the upland areas and some parts of dunes and accreted beaches, sandy coasts, and uplands. Vulnerability analysis reveals that those areas near saltwater bodies and eroding coasts are prone to lateral and vertical diffusion of saltwater. The geodatabase developed through such modeling studies can help in planning and developing activities for sustainable groundwater resource management in coastal areas.

     

Effects of sample holding time on concentrations of microorganisms in water samples.

This research investigated the effects of extending the holding time of samples for microbial analysis beyond the standard of 24 hours for purposes such as watershed characterization. Experiments were conducted with both sanitary wastewater and stormwater samples. The refrigerated samples (4 degrees C) were held for up to 9 days before being analyzed for two pathogens (Pseudomonas aeruginosa and Staphylococcus aureus) and five indicator organisms (total coliform, fecal coliform, fecal streptococcus, enterococcus, and Escherichia coli) by membrane filtration. The concentrations (as colony-forming units per 100 mL) were normalized by log10(transformation and used in subsequent statistical analysis testing for significant differences. The results suggested that the concentrations of microorganisms in water samples analyzed on days 1 and 2 did not vary significantly in 8 of 13 analyses. The results of a field study concluded that the concentration of fecal coliform did not change significantly between 7 hours holding time and greater than 24 hours holding time for fecal coliform.     

Opportunity to restore irrigation tanks in the Cauvery delta by mining and deepening

Delta region of the Cauvery river in India is well known for paddy cultivation for centuries. Due to increased competition on river water sharing over the past century, availability and reliability of water in this region is dwindling. Changes in management practices, which caused the deterioration of traditional tank (relatively small reservoir) irrigation systems, and the difficulties in reviving them are discussed. Increasing the storage capacity of irrigation tanks for augmenting water availability for irrigation is discussed in detail. Managing the huge cost involved in deepening the heavily silted tanks in a sustainable manner is suggested through allowing mining activities in the tanks. Sample study on the suitability of soil for commercial uses indicates the possibility of mining in the tanks.     

Treatment of MTBE‐Contaminated Waters with Fenton's Reagent

Methyl tertiary‐butyl ether (MTBE) is commonly used as a fuel additive because of its many favorable properties that allow it to improve fuel combustion and reduce resulting concentrations of carbon monoxide and unburnt hydrocarbons. Unfortunately, increased production and use have led to its introduction into the environment. Of particular concern is its introduction into drinking water supplies. Accordingly, research studies have been initiated to investigate the treatment of MTBE‐contaminated soil and groundwater. The summer 2000 issue of Remediation reported the results of an initial study conducted by the authors to evaluate the treatment of MTBE using Fenton's reagent. In this follow‐up study, experiments were conducted to further demonstrate the effectiveness of using Fenton's reagent (H₂O₂:Fe⁺²) to treat MTBE‐contaminated groundwater. The concentration of MTBE was reduced from an initial concentration of 1,300 μg/l (14.77 μ moles) to the regulatory level of 20 μg/l (0.23 μ moles) at a H₂O₂:Fe⁺² molar ratio of 1:1, with ten minutes of contact time and an optimum pH of 5. The by‐products, acetone and tertiary butyl alcohol, which are always present in MTBE in trace amounts, were not removed even after 60 minutes of reaction time. © 2002 Wiley Periodicals, Inc. *     

Control Technologies for Remediation of Contaminated Soil and Waste Deposits at Superf und Lead Battery Recycling Sites

This paper primarily addresses remediation of contaminated soils and waste deposits at defunct lead-acid battery recycling sites (LBRS) via immobilization and separation processes. A defunct LBRS is a facility at which battery breaking, secondary lead smelting, or both operations were performed for the primary purpose of reclaiming lead from spent lead-acid batteries. Metallic lead and lead compounds are generally the principal contaminants of concern in soils and waste deposits (i.e., buried, piled, landfilled waste) at these sites. Other metals (e.g., cadmium, copper, arsenic, antimony, and selenium) are often present at LBRS, but usually at much lower concentrations than lead and often present below hazardous concentrations. This article is primarily based on experience gained from: (1) Superfund site investigation, removal, and remedial actions, and (2) development and demonstration of control technologies under the Superfund Innovative Technology Evaluation (SITE) Program. The primary remedial options for lead contaminated soils and waste deposits include: (1) no action, (2) off-site disposal, (3) containment, (4) immobilization, (5) separation with resource recovery, and (6) separation without resource recovery. In spite of the toxicity of lead at low concentrations, the relative immobility of lead and site-specific risk assessments can still result in the selection of no action or containment remedies. Solidification/stabilization of lead-contaminated soils has been implemented at three Superfund sites and is the selected remedy at several others. Separation technologies (e.g., screening, extraction) are attractive because, if successful, they actually remove the contaminant from the environmental media. Separation technologies also offer the possibility that a valuable product (e.g., lead, plastic, energy) can be recovered, but careful consideration of economic and technical factors are required. Compared to the implementation of containment and solidification I stabilization remedies, separation technologies tend to be relatively novel, complex, and costly.     

Organic micro-pollutant removal in liquid-phase using carbonized silk cotton hull

Phenolic compounds constitute one of the major pollutants in the modern world. Although many physical and chemical treatment technologies for their removal exist, most of them are economically not feasible. The present study was aimed at using silk cotton hull, a potent agricultural waste as an adsobent for removal of 2,4-dichlorophenol (2,4-DCP), which was used as a model phenolic compound. The process parameters were investigated and optimized conditions were determined. The equilibrium time was found to ...     

Effects of the COVID-19 pandemic on the environment,waste management,and energy sectors: a deeper look into the long-term impacts

Environmental Science and Pollution Research - The COVID-19 pandemic not only has caused a global health crisis but also has significant environmental consequences. Although many studies are...