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Ambient PM 10 (particulate matter with aerodynamic diameter ≤ 10 µm) samples were collected and characterized from July 2012 to August 2013 with the objective to evaluate the variation in elemental concentration and use the same as markers for source apportionment and health risk assessment for the first time over Bhubaneswar, India. The yearly average mass of PM 10 was 82.28 µg/m 3 , which was ~ 37% higher than the national ambient air quality (NAAQ) standards. Maximum PM 10 concentration was observed during winter season followed by post-monsoon, pre-monsoon, and monsoon months. Acid soluble components in the PM 10 samples were analyzed using ICP-OES (inductive coupled plasma optical emission spectroscopy), and 19 different elements including heavy metals were determined. Enrichment factor analysis attributed the source to either crustal or non-crustal origin. Principal component analysis (PCA) revealed that crustal sources, industrial activities, and vehicular emissions were significant contributors to PM mass. The contribution of total average elemental concentration showed a seasonal variation with the lowest (11.96 µg/m 3 ) and highest (17.77 µg/m 3 ) during monsoon and winter, respectively, which is relatively less significant than the variation in total PM 10 mass that ranged between 48.43 µg/m 3 in monsoon and 138.24 µg/m 3 during the winter season. This observation evidences the predominant contribution of local/regional emission sources to the metallic components in coarse PM 10 mass, which is corroborated by the wind pattern studies carried out using polar plots and a Lagrangian Particle Dispersion Model (LPDM) FLEXPART. Further, carcinogenic and non-carcinogenic health risk assessments of the measured elements that find their way into the human body through different exposure pathways have been calculated using United State Environmental Protection Agency (USEPA) standards. The carcinogenic risk of most of the elements was insignificant. The potential risk assessment study revealed that regular exposure to heavy metals through the ingestion pathway caused detrimental health effects. These effects were observed to be more severe in children in comparison to adults.

The objective of this investigation was to explore the antioxidant and antimicrobial property of bioactive prodigiosin produced from Serratia marcescens using rice bran. The antioxidant potential of prodigiosin was examined by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2′-azino-bis 3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical scavenging method via UV–visible, electron spin resonance spectrum (ESR), cyclic voltammetry and excitation emission spectrum. The antimicrobial activity of prodigiosin was examined against foodborne pathogens. The shelf life extending capacity of prodigiosin was evaluated with meat extract powder (MEP) as a model food material. The DPPH and ABTS radicals were completely scavenged by prodigiosin at the concentration of 10 mg/L. The food spoilage was inhibited by the addition of prodigiosin with MEP and it was compared with conventional preservative. The prodigiosin has prohibited the growth of foodborne pathogens effectively and the shelf life of the food was also extended significantly. The antimicrobial edible preservative developed in this study inhibited the growth of the microbial populations that produced through storage of the MEP and free radical scavenging activity. The results reveal that the bioactive prodigiosin effectively scavenged the free radical and inhibited the bacterial growth in food stuff.

The dyeing process is a very important unit operation in the leather and textile industries; it produces significant amounts of waste effluent containing dyes and poses a substantial threat to the environment. Therefore, degradation of the industrial dye-waste liquid is necessary before its release into the environment. The current is focusing on the reduction of pollutant loads in industrial wastewater through remediating azo and thiazine dyes (synthetic solutions of textile dye consortium). The current research work is focused on the degradation of dye consortium through photo-electro-Fenton (PEF) processes via using dimensionally stable anode (Ti) and graphite cathode. The ideal conditions, which included a pH of 3, 0.1 (g/L) of textile dye consortium, 0.03 (g/L) of iron, 0.2 (g/L) of H 2 O 2 , and a 0.3 mAcm-2 of current density, were achieved to the removal of dye consortium over 40 min. The highest dye removal rate was discovered to be 96%. The transition of azo linkages into N 2 or NH 3 was confirmed by Fourier transforms infra-red spectroscopic analysis. PEF process reduced the 92% of chemical oxygen demand (COD) of textile dye consortium solution, and it meets the kinetics study of the pseudo-first-order. The degradation of dye through the PEF process was evaluated by using the cyclic voltammetric method. The toxicity tests showed that with the treated dye solution, seedlings grew well. Graphical abstract

An alternative and environmentally benign method of disposing the buffing dust, generated from leather industry was carried out in the present investigation. The buffing dust (finished solid waste) was charred in a controlled oxygen atmosphere by coupled pyrolysis and the resultant material was gauged for the application of light weight cement blocks. The results confirmed that, at a flow rate of 1 LPM oxygen supplied for 30 min produced nanostructured fibrous carbon material which was further confirmed through SEM and EDX analyses. Iron nanoparticles were used to inhibit the conversion of trivalent chromium to hexavalent chromium in fibrous carbon before being utilized for making light weight cement block. The addition of iron nanoparticles supplements the mechanical strength by compositional bonding in cement block. The XRD results elucidate that the hexavalent chromium has reduced to trivalent chromium due to the addition of iron nanoparticles in the residue material. The as-prepared light weight cement blocks were fabricated (7 cm × 7 cm × 7 cm) for compression test, simultaneously cement block devoid of iron nanoparticles was prepared as a control. The compressive strength of the light weight cement block comprising of iron nanoparticles (20.7 kN/cm 2 ) was found to be higher than the block without iron nanoparticles (3.82 kN/cm 2 ).

The COVID-19 pandemic resulted in changed emission regimes all over the world. India also imposed complete lockdown on all modes of travel and industrial activities for about 2 months from 25-March-2020 and later unlocked these activities in a phased manner. Here, we study signatures of emissions changes on levels of atmospheric trace gases and aerosols contributing to air pollution over multiple sites in India’s capital Delhi covering various lockdown and unlock phases using satellite data and in-situ observations. The resulting changes in the levels of these species were compared with respect to their average of 2015–2019 to attribute for year to year and seasonal changes. A clear impact of lockdown was observed for AOD, PM, NO 2 , CO, and SO 2 as a result of emission changes, while changed precursor levels led to a change in O 3 chemical regimes impacting its concentrations. A detailed analysis of FLEXPART trajectories revealed increased PM levels over Delhi in north-westerly air masses sourced to Punjab region all the way up to Pakistan. Changes in aerosols and NO 2 were not only restricted to the surface but transcended the total tropospheric column. The maximum decrease in PM, NO 2 , CO, and SO 2 was observed during the month of total lockdown in April. The lockdown impact varied with species e.g., PM 10 and PM 2.5 as well as locations even within the periphery of Delhi. While surface level aerosols and NO 2 showed significant and almost similar changes, AOD showed much lower decrease than tropospheric column NO 2 .

The effectiveness of Fenton oxidation of tannery wastewater was investigated under different operational conditions such as pH, time and dosages of Fenton reagent (H 2 O 2 and FeSO 4 ·7H 2 O). Different mass ratios of Fe 2+ /H 2 O 2 recorded the percentage COD reduction from 54 to 80 % in 4 h at pH 3.5. The batch study has established COD reduction by 82 % with mesoporous activated carbon (MAC 800 ) catalyst and the percentage reduction of COD was 94 % under integrated homo- and hetero-Fenton oxidations of tannery wastewater. Fenton reagent was efficient enough to oxidize most of the organic compounds present in the tannery wastewater. This was confirmed through UV–visible spectroscopy, FT-IR spectroscopy, cyclic voltammetry and NMR spectroscopy.

Purpose of Review This paper reviews recent developments in membrane biosorption and focuses on features and performance of different configurations of membrane biosorption. Biofilm formation, its role, and optimization in biosorption application as well as challenges and strategies for future applications are also discussed. Recent Findings Biosorption has gained increasing attention for wastewater treatment process due to its advantages of high separation efficiency, environmentally friendly, high availability of biomass, and low cost. In addition, biosorbents are reusable since they can be regenerated by employing a wash solution. This also provides the possibility of recovering valuable sorbed components from the concentrated wash solution. It has been demonstrated in several studies that membrane can be used to improve the performance of sorption processes. Membrane biosorption displays interesting features including higher process efficiency and smaller footprint. The membrane enhances contact between the biosorbent and the sorbate (pollutant) resulting in an improved sorption kinetic. Membrane also helps to remove priority pollutant from a wastewater by providing a selective extraction and avoids the mixing between the biosorbent and wastewater. In addition, membrane can improve the contact between gas stream and biosorbent for gas removal from a waste gas stream. It is also possible for supplying bubble-less aeration which improves the biological growth of the biosorbent. Summary Some reported studies show that combined membrane biosorption may allow one to achieve pollutant removal up to three times of the single biosorption process. However, there are several challenges that need to be addressed for membrane biosorption application, including diffusion limitation in membrane and uncontrolled biofilm formation. Therefore, it is imperative to identify membranes with appropriate characteristics as well as biofilm control strategies.

The rice-husk-based mesoporous activated carbon (MAC) used in this study was precarbonized and activated using phosphoric acid. N₂ adsorption/desorption isotherm, X-ray powder diffraction, electron spin resonance, X-ray photoelectron spectroscopy and scanning electron microscopy, transmission electron microscopy, ²⁹Si-NMR spectroscopy, and diffuse reflectance spectroscopy were used to characterize the MAC. The tannery wastewater carrying high total dissolved solids (TDS) discharged from leather industry lacks biodegradability despite the presence of dissolved protein. This paper demonstrates the application of free electron-rich MAC as heterogeneous catalyst along with Fenton reagent for the oxidation of persistence organic compounds in high TDS wastewater. The heterogeneous Fenton oxidation of the pretreated wastewater at optimum pH (3.5), H₂O₂ (4 mmol/L), FeSO₄[Symbol: see text]7H₂O (0.2 mmol/L), and time (4 h) removed chemical oxygen demand, biochemical oxygen demand, total organic carbon and dissolved protein by 86, 91, 83, and 90 %, respectively.

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 (FeSO 4 ·7H 2 O), 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 ΔG, ΔH, and ΔS were calculated for the oxidation processes using Van’t Hoff equation. Furthermore, the degradation of organics was confirmed through FTIR and UV–visible 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–4 h, and H 2 O 2 /FeSO 4 ·7H 2 O in the molar ratio of 2:1.

In this present investigation, physical and chemical characteristics of salt-laden solid waste (SLSW) generated from leather industry during soaking process of raw skins/hides and reverse osmosis reject stream were determined. The disposal of SLSW onto landfill was banned due to the possibility of ground water contamination by leachate, and its treatment process becomes tedious and cost intensive. The detailed characterisation of SLSW was evaluated for the development of effective methods for the treatment and/or disposal of SLSW. In the present study, sodium chloride was recovered to reduce the impact of the disposal of SLSW. The recovery of sodium chloride was achieved by selective precipitation using hydrogen chloride gas as a precipitating agent. The optimum conditions for the precipitation of sodium chloride were concentration of SLSW, 60 % (w/w); HCl gas purging, time 3 min (for a batch volume of 100 mL); pH, 8.0; and temperature, 30–40 °C. The scanning electron microscopy images of SLSW and the recovered sodium chloride were captured to observe the surface morphology. The recovered salt showed purity equivalent to that of standard reference salt. The recovered salt can be reused within leather sector or to the other process industries that meet their specification.