Showing papers by "Indumathi M. Nambi published in 2020"

Electro-enhanced adsorptive removal of ciprofloxacin from aqueous solution on graphite felt

Abstract: In this study, enhanced electrosorption removal of ciprofloxacin is investigated using graphite felt electrodes. The effect of operating parameters like pH, applied voltage, electrolyte concentration, and initial concentration on the removal of ciprofloxacin and enhancement in adsorption capacity of graphite felt was studied. The adsorption isotherm and kinetics were studied. Cyclic voltammogram showed no significant redox peaks at the operated experimental conditions. The adsorption capacity was increased from 0.617 mg g−1 at open circuit voltage to 1.915 mg g−1 at 1.0 V and the corresponding pseudo first order kinetic rate constants were increased from 0.069 min−1 to 0.111 min−1. The adsorption capacity and kinetics observed to be high at pH 3.0 and 10.0 compared to pH 7.0. The electrosorption process performance increased with increasing applied voltage (OCV to 1.5 V) and reduced at high electrolyte concentration (0.1–1.0 M Na2SO4). Experimental data was fitted to Langmuir and Freundlich adsorption isotherm models. The electrosorption results proposed that the adsorption rate and adsorptive capacity can be significantly enhanced by electrochemical polarization with the greater affinity derived between the charged ciprofloxacin species and graphite felt. Mechanism of electrosorption removal of ciprofloxacin at different pH is proposed based on the experimental observations.

Investigating Atrazine Concentrations in the Zwischenscholle Aquifer Using MODFLOW with the HYDRUS-1D Package and MT3DMS

Abstract: Simulation models that describe the flow and transport processes of pesticides in soil and groundwater are important tools to analyze how surface pesticide applications influence groundwater quality. The aim of this study is to investigate whether the slow decline and the stable spatial pattern of atrazine concentrations after its ban, which were observed in a long-term monitoring study of pesticide concentrations in the Zwischenscholle aquifer (Germany), could be explained by such model simulations. Model simulations were carried out using MODFLOW model coupled with the HYDRUS-1D package and MT3DMS. The results indicate that the spatial variability in the atrazine application rate and the volume of water entering and leaving the aquifer through lateral boundaries produced variations in the spatial distribution of atrazine in the aquifer. The simulated and observed water table levels and the average annual atrazine concentrations were found to be comparable. The long-term analysis of the simulated impact of atrazine applications in the study area shows that atrazine persisted in groundwater even 20 years after its ban at an average atrazine concentration of 0.035 µg/L. These results corroborate the findings of the previous monitoring studies.

Liquid crystal display electrode-assisted bio-electroperoxone treatment train for the abatement of organic contaminants in a pharmaceutical wastewater

Abstract: Pharmaceutical contaminants present in wastewaters cause severe health hazards among chronically exposed population. Emerging pharmaceutically active contaminants pose a serious challenge to conventional treatment technologies. Employing advanced treatment technologies for the abatement of such contaminants is usually energy-intensive. In this study, a complex pharmaceutical wastewater from a pharmaceutical industry in California, USA, was treated by employing a novel bio-electrochemical treatment train system. Labeled “Bio-electroperoxone,” our proposed system comprises (i) an electrically bound biofilm reactor (EBBR) that accelerates bacterial adhesion for the removal of biodegradable and persistent organics and (ii) an electroperoxone reactor that removes recalcitrant organics with minimal energy uptake. The EBBR comprises a platinum-coated titanium cathode and a conductive nematic liquid crystal display electrode (NLCE) obtained from electronic waste that serves as the anode. Characterization of functional groups, morphology, and elemental mapping of NLCE were carried out to explain mechanisms for rapid biofilm attachment. The concomitant electroperoxone reactor comprises a platinum-coated titanium (Pt-Ti) anode and a reticulated vitreous carbon (RVC) cathode that catalyzes the two-electron reduction of oxygen to form in situ H2O2. The bio-electroperoxone system (i) inactivated 99.99% of the micro-organisms, removed (ii) 92.20% of the color, (iii) 84.72% of the total suspended solids, and (iv) 89% of the total organic carbon (TOC). Possible mechanisms for the degradation of organic contaminants are elucidated. Bio-electroperoxone thus paves the way for an efficient and sustainable approach for the efficient removal of both biodegradable and recalcitrant, persistent organic contaminants from pharmaceutical and possibly other complex wastewaters.

Anthropogenic Impact on Tropical Perennial River in South India: Snapshot of Carbon Dynamics and Bacterial Community Composition

Abstract: Riverine systems play an important role in the global carbon cycle, and they are considered hotspots for bacterial activities such as organic matter decomposition. However, our knowledge about these processes in tropical or subtropical regions is limited. The aim of this study was to investigate anthropogenically induced changes of water quality, the distribution of selected pharmaceuticals, and the effects of pollution on greenhouse gas concentrations and bacterial community composition along the 800 km long Cauvery river, the main river serving as a potable and irrigation water supply in Southern India. We found that in situ measured pCO2 and pCH4 concentrations were supersaturated relative to the atmosphere and ranged from 7.9 to 168.7 μmol L−1, and from 0.01 to 2.76 μmol L−1, respectively. Pharmaceuticals like triclosan, carbamazepine, ibuprofen, naproxen, propylparaben, and diclofenac exceeded warning limits along the Cauvery. Proteobacteria was the major phylum in all samples, ranging between 26.1% and 82.2% relative abundance, and it coincided with the accumulation of nutrients in the flowing water. Results emphasized the impact of industrialization and increased population density on changes in water quality, riverine carbon fluxes, and bacterial community structure.

Antibiotic Resistance and Sanitation in India: Current Situation and Future Perspectives

Abstract: Antimicrobial resistance (AMR) is a global threat as the existing health care may become ineffective. Antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs) considered as emerging contaminants are the three major components of AMR. India is one of the largest consumers of antibiotics with defined daily dose (DDD) of 4,950 per 1,000 population in 2015. By 2030, therapeutic and nontherapeutic use of antibiotics in veterinary animals is projected to increase by 18%. Antibiotics, ARB, and ARGs in the solid and liquid waste generated enter the environment via different pathways. The major sources of antibiotics, ARB, and ARG include domestic, hospital, and pharmaceutical industry wastewater apart from the solid/liquid waste generated from veterinary and food animals. Existing conventional wastewater treatment technologies like activated sludge process (ASP) do not ensure complete removal of antibiotics, ARB, and ARGs from wastewater. Similarly, the sludge generated find its way to agriculture land and eventually spread resistance in the environment. Once introduced in the environment, elimination of these contaminants is difficult. India’s action plan on AMR in 2017 regulates antibiotic use for human and animal and addresses environment AMR spread from all possible sources and containment. In 2020, the Government of India introduced discharge standard for 121 antibiotics in the effluents of bulk drug manufacturing industries, formulation industries, and common effluent treatment plant (CETP) receiving pharmaceutical wastewater.