Showing papers by "Indumathi M. Nambi published in 2021"
TL;DR: In this article, the catalytic pyrolysis of different types of polyolefin and multilayer packaging based plastic wastes in the presence of commercial zeolite catalyst was studied in the batch pilot scale reactor.
34 citations
TL;DR: In this article, the degradation of total petroleum hydrocarbons (TPH), nC12 to nC23 alkanes and priority pollutants such as polycyclic aromatic hydroCarbons (PAHs) in petroleum-contaminated water using an inexpensive Ti/Sb-SnO2/PbO2 anode.
33 citations
TL;DR: In this article, the performance of microwave pyrolysis for the recovery of oil from furnace oil sludge was evaluated and the characteristics of furnace oil tank bottom sludge such as pH, moisture, viscosity, and volatile hydrocarbon content were determined.
18 citations
TL;DR: In this paper, the authors report human and cow urine pretreatment with simultaneous hydrogen production using a simple redox reaction, which is achieved via in situ formation of aluminium nanoparticles in urine through reduction of aluminum salt using sodium borohydride; the key novelty of the process is the use of Al salt/NaBH4.
8 citations
TL;DR: In this paper, the feasibility of treating diesel contaminated soil excavated from a metro rail construction site in Chennai, Tamil Nadu, India is evaluated, where total petroleum hydrocarbon (TPH) is evaluated.
Abstract: This study will evaluate the feasibility of treating diesel contaminated soil excavated from a metro rail construction site in Chennai, Tamil Nadu, India. Total petroleum hydrocarbon (TPH)...
8 citations
TL;DR: In this article, a comprehensive metagenomics-based approach for global surveillance of antibiotic resistance in sewage, enabling assessment of which antibiotic resistance genes (ARGs) are shared across regions/communities; which ARGs are discriminatory; and factors associated with overall trends including antibiotic concentrations in sewage.
Abstract: Wastewater-based epidemiology (WBE) for disease monitoring is highly promising, but requires consistent methodologies that incorporate predetermined objectives, targets, and metrics. We demonstrate a comprehensive metagenomics-based approach for global surveillance of antibiotic resistance in sewage, enabling assessment of: 1) which antibiotic resistance genes (ARGs) are shared across regions/communities; 2) which ARGs are discriminatory; and 3) factors associated with overall trends including antibiotic concentrations in sewage. Across an internationally-sourced transect of sewage samples collected using a centralized, standardized protocol, ARG relative abundances (16S rRNA gene-normalized) were highest in Hong Kong and India and lowest in Sweden and Switzerland, reflecting national policy, measured antibiotic concentrations, and metal resistance genes. Asian versus European/US resistomes were distinct, with macrolide-lincosamide-streptogramin, phenicol, quinolone, and tetracycline versus multidrug resistance ARGs being discriminatory, respectively. Sales data were not predictive of antibiotics measured in sewage, emphasizing need for direct measurements. The WBE approach defined herein demonstrates multi-site comparability and sensitivity to local/regional factors.
6 citations
TL;DR: In this article, the authors present deterministic and probabilistic human health risk assessment using Monte Carlo simulations on exposure to an Indian river, Kaveri, which has been contaminated by non-steroidal anti-inflammatory drugs (NSAIDs).
Abstract: This study presents deterministic and probabilistic human health risk assessment using Monte Carlo simulations on exposure to an Indian river, Kaveri, which has been contaminated by non-steroidal anti-inflammatory drugs (NSAIDs). The NSAIDs of concern are naproxen, ibuprofen, aspirin, ketoprofen, and diclofenac. We have considered three exposure scenarios (water ingestion, dermal exposure, and fish ingestion) for four different age groups (0-5, 6-10, 11-18, and 19-70 years). Deterministic risk assessment revealed teenagers to be the most sensitive receptors and water ingestion to be the most crucial pathway contributing to maximum health risk (79 to 86%). Based on the results of Monte Carlo simulations, it was found that the probability of exceeding the deterministic mean risks ranged from 17 to 39% for different exposure routes. High end risk estimates such as 95th percentiles and maximum values of HQ for the entire population did not exceed the USEPA allowable risk. This implies that the NSAIDs at the detected concentrations in the Kaveri river may not pose adverse health effects even in the worst-case scenario. Among the five NSAIDs, diclofenac was found to be the major contributor for health risk. Moreover, the concentration of diclofenac was just one order less than the estimated site-specific threshold concentrations. From sensitivity analysis, the most and the least impactful parameters were found to be water ingestion rate and fish ingestion rate respectively.
6 citations
TL;DR: The influence of hydraulic conductivity on the movement of flow and nonreactive solute transport through aquifers was evaluated in this paper, where several different log-normal probability distribution functions bounded within a fixed range were adopted for simulating the heterogeneous spatial distribution of hydraulicconductivity.
Abstract: The influence of hydraulic conductivity on the movement of flow and nonreactive solute transport through aquifers was evaluated. Several different log-normal probability distribution functions bounded within a fixed range were adopted for simulating the heterogeneous spatial distribution of hydraulic conductivity. Programming codes for two-dimensional confined aquifers were developed to solve the groundwater flow and solute transport equations for a hypothetical setup. Well capture zones were delineated using capture fractions and calculated the concentration moments. Results indicated that an increased shape parameter leads to more heterogeneity in the hydraulic conductivity field and significantly enhances the non-uniformity in the flow and solute plume movements. The findings were generalized for the continuous, discrete, and mixed zonal models, simulated with different parameter values, to yield a lower and upper range for the model derivatives. The results also described the influence of the connectedness of hydraulic conductivity fields on groundwater flow and transport, using capture fractions and plume moments as connectivity indicators. Hence, capture fractions and plume moment statistics aided the careful characterization of aquifer conductivity as a reasonable method of ranking flow and transport connectivity in aquifer flow and transport processes.
2 citations
TL;DR: In this article, the effect of various groundwater interferences like chloride, nitrate, sulphate and bicarbonate on the dissolution of mercury from mercury sulphide and elemental mercury was investigated.
Abstract: The study aims to stabilize elemental mercury to mercury sulphide and investigate the effect of various groundwater interferences like chloride, nitrate, sulphate and bicarbonate on the dissolution of mercury from mercury sulphide and elemental mercury. Elemental mercury was stabilized using sodium polysulphide solution in a one-step batch experiment in a period of 96 h. Mercury sulphide was formed as a black fine powder with average particle size of 10–500 nm. Mercury sulphide was tested under different pH conditions and under different concentrations of Cl−, NO3−, SO42−, and HCO3− for dissolution of mercury. At pH ≤ 4 and pH ≥ 12, dissolved mercury concentrations from mercury sulphide were 70.47 μg/L and 41.81 μg/L, respectively. At pH 10, mercury dissolution was the lowest with dissolved mercury as 8 μg/L proving that mild alkaline pH is necessary for stability of mercury. At low concentration of the anions, interfering effects were in the order of NO3− > Cl− > SO42− > HCO3−, whereas under high concentrations, the order was Cl− > NO3− > SO42− > HCO3−. Unlike NO3− and Cl−, SO42− and HCO3− ions were reported to cause potential leaching only if they are present in significantly high concentrations. Nevertheless, mercury sulphide was found to be the preferred chemical state for permanent storage of mercury in the subsurface when compared to elemental mercury.
2 citations
TL;DR: In this article, the influence of four inflow boundary conditions on solute plume migration and compared their concentrations was explored and a numerical model was used to simulate the solute transport for different boundary conditions at the injection well with three different recharge and six hydraulic conductivity scenarios.
Abstract: In this study, an attempt has been made to explore the influence of four inflow boundary conditions on solute plume migration and compared their concentrations. A numerical model was used to simulate the solute transport for different boundary conditions at the injection well with three different recharge and six hydraulic conductivity scenarios. Dirichlet concentration boundary, constant point source, and two Robin boundary conditions were applied to exemplify their effects on the outcomes. Significant variations were visible in the solute concentration profiles and their respective spreading patterns. Results show discrepancies between solutions obtained from the first-type and the third-type inflow boundary conditions for smaller Peclet numbers. The applicability of the M5′ model tree, a tree-based machine learning approach, was investigated and thereby exploited its capability to interpret the plausible functional dependency among the input parameters. The model tree also produced a dominancy structure within the parameter space with its combined classification and regression features. It was concluded that adopting a general boundary condition or generalization of solutions remained highly challenging, given the different input space parameters dictating a hydrogeological model.