Phyto-assisted synthesis of CuO/industrial waste derived biochar composite for adsorptive removal of doxycycline hydrochloride and recycling of spent biochar as green energy storage device.

The highest exposure of Endocrine disrupting compounds (EDC) into the water bodies as a result of extensive production and application of Covid-19 related drugs is a growing concern now a days. Herein, a novel nanocomposite material was developed by impregnating green synthesized copper oxide nanoparticles on the porous surface of fabric waste derived biochar to eliminate the concerned EDCs along with a sustainable disposal strategy for the spent adsorbent. Morphological characterizations by Field emission scanning electron microscopy confirmed the formation of hierarchical porous structured material. X-ray analysis revealed presence of both amorphous nature of biochar matrix as well as the crystalline nature attributed from monodispersion of copper oxide nanoparticles onto biochar surface. Batch sorption study showed removal of doxycycline hydrochloride (DOX) of >97% after 2 h at pH 7, 30 mg L-1 initial concentration of DOX and 2 g L-1 of adsorbent dose at room temperature after a two-step optimization process. Spectroscopic study and Raman shift suggested that pore filling, strong complexation and electrostatic interactions maximise the adsorption of DOX in the CuO/biochar composite as compared to the pristine biochar. However disposal of spent adsorbent is a crucial aspect for the environment and therefore, a sustainable recycling strategy for DOX loaded adsorbent as electrode material has been proposed for the first time in this study. Maximum specific capacitance value was observed in the range of 221.9-297.3 F g-1 for the DOX loaded nanocomposite at 1 mV s-1 comparable with other reported heteroatom-doped carbonaceous material as electrode. Therefore the excellent adsorption capacity of green synthesized CuO/biochar composite and its recycling after DOX adsorption can be recommended as a sustainable solution for mitigation of pharmaceuticals from wastewater. A detail study on degradation of DOX into eco-friendly products and its cost-effectiveness would be beneficial to suggest appropriate mitigation strategy for such compounds.

Sustainable conversion of textile industry cotton waste into P-dopped biochar for removal of dyes from textile effluent and valorisation of spent biochar into soil conditioner towards circular economy.

Effective immobilization of industrial waste into biochar development could be one of the most promising technologies for solid waste management to achieve circular economy. In this study, post-industrial cotton textile waste (PICTW), a cellulose rich industrial waste, was subjected to slow pyrolysis to develop a surface engineered biochar through phosphoric acid impregnation. Biochar produced at 500 °C designated as PICTWB500 showed a maximum methylene blue number (240 mg g-1) with remarkable specific surface area of 1498 m2 g-1. FESEM, FTIR, XRD and Raman spectra analysis were performed to investigate the surface texture and functionalities developed in the biochar. Adsorption efficiency of the biochar was assessed using drimarene red, blue, violet, and black dyes as model dye pollutants in batch mode at different biochar dose, pH and contact time. The maximum monolayer adsorption capacity was obtained in the range 285-325 mg g-1 for different dyes, determined from Langmuir adsorption model. The kinetic behaviour was more favourable with the pseudo second-order model. The recycling ability of PICTWB500 was proven to be effective up to 6th cycle without compromising its adsorption efficiency significantly. This study demonstrated an excellent adsorption capability of the biochar in dye laden real textile effluent and recycling of spent biochar as a precursor of bio compost. Hence, this study established a dual win strategy for waste utilization in textile industry using a closed loop approach with substantial techno-economic feasibility that may have potential applications.

Performance assessment of the indigenous ceramic UF membrane in bioreactor process for highly polluted tannery wastewater treatment.

The present study evaluates the performance of an indigenously developed ceramic ultrafiltration (UF) membrane in a lab-scale membrane bioreactor (MBR) process to treat real tannery effluent with varying organic loading (1500-6000 mg/L). UF membrane was prepared by the coating of bentonite clay on tubular clay-alumina macroporous support. The membrane surface was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, BET adsorption-desorption, contact angle measurement, and atomic force microscopy. In the side-stream MBR process, sewage sludge from a local sewage treatment plant was used as an activated sludge source with a constant sludge retention time of 30 days. Membrane filtration was performed in cross-flow mode using a single-channel membrane module. Artificial neural network (ANN) modeling tool was used to analyze the influence of various independent input variables, namely, the hydraulic retention time (4-10 h), mixed liquor suspended solid (MLSS) concentration (2-8 g/L), and influent COD concentration (1500-6000 mg/L) on COD removal (%) with feed-forward backpropagation method. Membrane study was done at a transmembrane pressure of 4.3 bar and feed flow rate of 7.5 L/min to observe the flux declination and fouling of the UF membrane with time. Average COD and BOD concentrations obtained in the treated effluent were 147.56 and 31 mg/L, respectively, and chromium concentration was < 0.1 mg/L; thus, treated effluent quality was found to be suitable for industrial recycling purposes apart from the safe environmental discharge. An in-depth study was undertaken to understand the removal mechanism in the MBR process, nature and extent of membrane fouling, changes in the morphology of the UF membrane, surface wettability, and surface topology by detailed surface characterization of the membrane pre- and post-filtration.

Arthrospira sp. mediated bioremediation of gray water in ceramic membrane based photobioreactor: process optimization by response surface methodology.

Direct discharge of raw domestic sewage enriched with nitrogenous and phosphorous compounds into the water bodies causes eutrophication and other environmental hazards with detrimental impacts on public and ecosystem health. The present study focuses on phycoremediation of gray water with Arthrospira sp. using an innovative hydrophobic ceramic membrane-based photobioreactor system integrated with CO2 biofixation and biodiesel production, aiming for green technology development. Surfactant and oil-rich gray water collected from the domestic kitchen was used wherein, chloride, sulfate, and surfactant concentrations were statistically optimized using response surface methodology (RSM), considering maximum microalgal growth rate as a response for the design. Ideal concentrations (mg/L) of working parameters were found to be 7.91 (sulfate), 880.49 (chloride), and 144.02 (surfactant), respectively to achieve optimum growth rate of 0.43 gdwt/L/day. Enhancement of growth rate of targeted microalgae by 150% with suitable CO2 (19.5%) supply and illumination in the photobioreactor affirms its efficient operation. Additionally, harvested microalgal biomass obtained from the process showed a biodiesel content of around 5.33% (dry weight). The microalgal treatment enabled about 96.82, 87.5, and 99.8% reductions in BOD, COD, and TOC, respectively, indicating the potential of the process in pollutant assimilation and recycling of such wastewater along with value-added product generation.

The study elucidated the application of indigenously designed and devised ceramic membranes in an algal photobioreactor for viable production of Arthrospira sp. employing gray water, aided by photosynthetic CO₂ sequestration and microalgal biorefinery. A highly encouraging result was achieved in the microalgal process under optimized culture conditions with >95% removal of organics. It may be stressed here that the process ran effectively without any elaborate arrangement of external aeration, thereby reducing the investment and operating costs to the minimum.

Ceramic membrane-based ultrafiltration combined with adsorption by waste derived biochar for textile effluent treatment and management of spent biochar.

PURPOSE: Effluents produced in the textile industries are important sources of water pollution due to the presence of toxic dyes, auxiliary chemicals, organic substances etc. Recycling of such industrial wastewater is one major aspect of sustainable water management; hence present study is focused on an eco-friendly process development for reclamation of higher loading textile wastewater. METHOD: Industrial effluent samples with varying loading were collected from textile processing units located in and around Kolkata city. Vegetable waste collected from local market was utilized to prepare an efficient biochar for elimination of the recalcitrant dyes. Prior to adsorption, ceramic ultrafiltration (UF) process was used for reduction of the organic loading and other suspended and dissolved components. RESULTS: A remarkably high BET surface area of 1216 m2g-1 and enhanced pore volume of 1.139 cm3g-1 was observed for biochar. The maximum adsorption capacity obtained from the Langmuir isotherm was about 300 mg.g-1. The combined process facilitated >99% removal of dyes and 77-80% removal of chemical oxygen demand (COD) from the various samples of effluent. The treated effluent was found suitable to discharge or reuse in other purposes. About 95% of dye recovery was achieved during biochar regeneration with acetone solution. The dye loaded spent biochar was composted with dry leaves and garden soil as bulking agent. Prepared compost could achieve the recommended parameters with high nutritional value after 45 days. CONCLUSIONS: The overall study showed potential of the proposed process towards treatment of toxic dye loaded textile effluent in an environment friendly and sustainable approach.

Development of graphene oxide/chitosan composite membrane on ceramic support for atrazine remediation by MBR process.

Graphene oxide (GO)-based composite ultrafiltration (UF) membranes were prepared on macroporous ceramic support tubes following a new way. Chitosan was used as an intermediate matrix between the substrate and GO coating. It has hydroxyl and amine groups, which enhances its film forming capacity with hydrophilic GO. This led us to use them as precursors for membrane development. Process efficiency of the prepared UF membrane was assessed in terms of the removal of toxic pesticide atrazine in side-stream membrane bioreactor (MBR) processes. Response surface methodology (RSM) was used to optimize the atrazine biodegradation efficiency. Enhanced atrazine removal of > 95% was obtained in the MBR treatment at the optimized conditions. Hermia's model equations were applied to analyze the mechanism of membrane fouling in the UF-MBR system. The influencing parameters were studied in details and pneumatic backpulsing was applied to minimize fouling in the UF-MBR system by statistical analysis. Mixed liquor suspended solids (MLSS) was found to affect both atrazine biodegradation and membrane fouling; hence, its effect was thoroughly analyzed. The developed process hence proved to be highly proficient in terms of such organic pesticides removal for long-term operations.

Metallic nanoparticle synthesised by biological route: safer candidate for diverse applications.

Biological synthesis of nanoparticles (NPs) involves greater prospect; however, a detailed review is required for ecofriendly, faster and stable NP formulation in large scale for different commercial applications. The present article highlighted recent updates on biological route of single and bimetallic NP synthesis wherein the chemical reducing agents are eliminated and biological entities are utilised to convert metal ions to NPs. Application of the biological reducing agents ranging from bacteria to fungi and even natural plant extracts have emerged as eco-friendly and cost-effective routes for the synthesis of metal nanomaterials. Potential applications of such NPs, a wide range of analytical techniques used for characterisation and factors influencing the synthesis of NPs are focused. Further, elucidation of the mechanisms associated with the NP formation using microorganisms, as well as plant-based materials are analysed which would be helpful for wide range of readers in the field of NP research for future selection and commercial implementation.

Surface Modification of Naturally Available Biomass for Enhancement of Heavy Metal Removal Efficiency, Upscaling Prospects, and Management Aspects of Spent Biosorbents: A Review.

Heavy metal pollution in water emerges as a severe socio-environmental problem originating primarily from the discharge of industrial wastewater. In view of the toxic, non-biodegradable, and persistent nature of most of the heavy metal ions, remediation of such components becomes an absolute necessity. Biosorption is an emerging tool for bioremediation that has gained momentum for employing low-cost biological materials with effective metal binding capacities. Even though biological materials possess excellent metal adsorption abilities, they show poor mechanical strength and low rigidity. Other disadvantages include solid-liquid separation problems, possible biomass swelling, lower efficiency for regeneration or reuse, and frequent development of high pressure drop in the column mode that limits its applications under real conditions. To improve the biosorption efficiency, biomasses need to be modified with a simple technique for selective/multi-metal adsorption. This review is intended to cover discussion on biomass modification for enhanced biosorption efficiency, mechanism studies using various instrumental/analytical techniques, and future direction for research and development including the fate of spent biosorbent. In most of the previously published researches, difficulty of the process in scaling up has not been addressed. The current article outlines the application potential of biosorbents in the development of hybrid technology integrated with membrane processes for water and wastewater treatment in industrial scale.

Exposure of composite tannery effluent on snail, Pila globosa: A comparative assessment of toxic impacts of the untreated and membrane treated effluents.

Effluent from tannery industries can significantly affect the aquatic environment due to the presence of a variety of recalcitrant components. The present study focuses on a comparative assessment of the toxic impacts of an untreated tannery effluent and membrane treated effluents using snail, Pila globosa as an aquatic model. Composite tannery effluent collected from a common effluent treatment plant was selected as the untreated effluent. To investigate the effect of treated effluents on the aquatic organism the effluent was treated by two ways, viz. a single stage microfiltration (MF) using ceramic membrane and a two-step process involving MF followed by reverse osmosis (RO). The whole body tissue, gonad and mantle of P. globosa were subjected to enzyme assays like superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GSH-GPx), glutathione S- transferase (GST), etc. for assessing toxic impact. Changes in the biochemical parameters like protein, carbohydrate and amino acid were observed including histological studies of gonad and mantle tissue upon treatment with tannery effluents. To examine potential DNA damage due to the exposure of the effluent, comet assay was conducted. The study revealed that with an exposure to the untreated effluent, activity of the antioxidant enzymes increased significantly while the protein and carbohydrate content reduced largely in the whole body tissue, gonad as well as mantle tissues of P. globosa. Histological study indicated considerable damage in the gonad and mantle tissues following exposure to the untreated effluent. Comet assay using hemolymph of P. globosa following exposure to tannery effluent, showed significant genotoxicity. Interestingly, compared to the untreated effluent, damaging effect was reduced in molluscs tissues when exposed to MF treated effluent and even lesser when exposed to MF+RO treated effluent. Apart from the reduced activities of oxidative stress enzymes, the protein, amino acid and carbohydrate content of molluscs exposed to both of the treated effluent were found close to that of control. Comet assay revealed no damage in the DNA for MF and MF+RO treated effluent indicating that the membrane based treatment procedure restores environmental condition to control level.

Treatment of cosmetic effluent in different configurations of ceramic UF membrane based bioreactor: Toxicity evaluation of the untreated and treated wastewater using catfish (Heteropneustes fossilis).

Extensive usage of pharmaceutical and personal care products (PPCPs) and their discharge through domestic sewage have been recently recognized as a new generation environmental concern which deserves more scientific attention over the classical environmental pollutants. The major issues of this type of effluent addressed in this study were its colour, triclosan and anionic surfactant (SDS) content. Samples of cosmetic effluent were collected from different beauty treatment salons and spas in and around Kolkata, India and treated in bioreactors containing a bacterial consortium isolated from activated sludge samples collected from a common effluent treatment plant. Members of the consortium were isolated and identified as Klebsiella sp., Pseudomonas sp., Salmonella sp. and Comamonas sp. The biotreated effluent was subjected to ultrafiltration (UF) involving indigenously prepared ceramic membranes in both side-stream and submerged mode. Analysis of the MBR treated effluent revealed 99.22%, 98.56% and 99.74% removal of colour, triclosan and surfactant respectively. Investigation of probable acute and chronic cyto-genotoxic potential of the untreated and treated effluents along with their possible participation in triggering oxidative stress was carried out with Heteropneustes fossilis (Bloch). Comet formation recorded in both liver and gill cells and micronucleus count in peripheral erythrocytes of individuals exposed to untreated effluent increased with duration of exposure and was significantly higher than those treated with UF permeates which in turn neared control levels. Results of this study revealed successful application of the isolated bacterial consortium in MBR process for efficient detoxification of cosmetic effluent thereby conferring the same suitable for discharge and/or reuse.

Anabaena sp. mediated bio-oxidation of arsenite to arsenate in synthetic arsenic (III) solution: Process optimization by response surface methodology.

Blue green algae Anabaena sp. was cultivated in synthetic arsenite solution to investigate its bio-oxidation potential for arsenic species. Response surface methodology (RSM) was employed based on a 3-level full factorial design considering four factors, viz. initial arsenic (III) concentration, algal dose, temperature and time. Bio-oxidation (%) of arsenic (III) was considered as response for the design. The study revealed that about 100% conversion of As (III) to As (V) was obtained for initial As (III) concentration of 2.5-7.5 mg/L at 30 °C for 72 h of exposure using 3 g/L of algal dose signifying a unique bio-oxidation potential of Anabaena sp. The dissolved CO2 (DCO2) and oxygen (DO) concentration in solution was monitored during the process and based on the data, a probable mechanism was proposed wherein algal cell acts like a catalytic membrane surface and expedites the bio-oxidation process. Bioaccumulation of arsenic, as well as, surface adsorption on algal cell was found considerably low. Lipid content of algal biomass grown in arsenite solution was found slightly lower than that of algae grown in synthetic media. Toxicity effects on algal cells due to arsenic exposure were evaluated in terms of comet assay and chlorophyll a content which indicated DNA damage to some extent along with very little decrease in chlorophyll a content. In summary, the present study explored the potential application of Anabaena sp. as an ecofriendly and sustainable option for detoxification of arsenic contaminated natural water with value-added product generation.

Application of isolated bacterial consortium in UMBR for detoxification of textile effluent: comparative analysis of resultant oxidative stress and genotoxicity in catfish (Heteropneustes fossilis) exposed to raw and treated effluents.

A bacterial consortium isolated from activated sludge was identified to be Bacillus sp., Pseudomonas sp., Shigella sp. and E. coli. and was found capable of 98.62 % decolourization of highly toxic textile effluent, when applied in an ultrafiltration (UF) membrane bioreactor (UMBR). Ceramic capillary UF membranes prepared over low cost support proved to be highly efficient in adverse experimental conditions. The UMBR permeate and untreated textile effluent (40 % (v/v)) was then used to treat Heteropneustes fossilis for a comparative assessment of their toxicity. Micronucleus count in peripheral blood erythrocytes and comet assay carried out in liver and gill cells showed significantly lower nuclear and tissue specific DNA damage respectively in organisms exposed to membrane permeate and was further supported by considerably lower oxidative stress response enzyme activities in comparison to raw effluent treated individuals. The results indicate efficient detoxification of textile effluent by the UMBR treatment using the isolated bacterial consortium.

Potential of biosorbent developed from fruit peel of Trewia nudiflora for removal of hexavalent chromium from synthetic and industrial effluent: Analyzing phytotoxicity in germinating Vigna seeds.

Chromium (VI) removal efficiency of a biosorbent prepared from fruit peel of Trewia nudiflora plant was studied. The effect of pH, sorbent dose, initial metal concentration and temperature was studied with synthetic Cr⁺6 solution in batch mode. About 278 mg/g of Cr⁺6 sorption was obtained at 293 K at an optimum pH of 2.0 and biosorbent dose of 0.75 g/L. Equilibrium sorption data with varying initial concentration of Cr⁺6 (22-248 mg/L) at three different temperatures (293-313 K) were analyzed by various isotherms. Biosorption kinetics and thermodynamics were described using standard model equations. Encouraging results were obtained by the application of the biosorptive treatment for removal of Cr⁺6 from wastewater collected from common effluent treatment plant of tannery industry. In addition, C⁺6r desorption behavior was studied on different systems. Biosorbent was characterized by FESEM, FT-IR and XRD, etc. Effect of the biosorptive treatement with respect to the phytotoxicity of Cr⁺6 was analyzed by studying the seed germination behavior and enzyme activity of a pulse seed (Vigna radiata L.). Different concentrations of Cr⁺6 solution in both synthetic medium, as well as, in tannery effluent was employed and the results were compared with that of biosorbent treated medium. The study showed that due to efficient removal of Cr⁺6 from aqueous phase, considerable enhancement of seed germination, as well as, increase in root length was obtained for the biosorbent treated solutions which were close to that of the control values. Significant decrease (P < 0.01) in POD activity was observed in seeds irrigated with biosorbent treated wastewater compared to untreated wastewater. The study showed that the novel biosorbent prepared might be utilized for abatement of heavy metal toxicity, i.e., Cr⁺6 from industrial effluent.

Treatment of textile dyehouse effluent using ceramic membrane based process in combination with chemical pretreatment.

Treatment of highly concentrated dyebath effluent and comparatively dilute composite effluent having mixture of various reactive dyes collected from a cotton fabric dyeing unit was undertaken in the present study. Ceramic microfiltration membrane prepared from a cost effective composition of alumina and clay was used. Prior to microfiltration, a chemical pretreatment was carried out with aluminium sulphate in combination with a polymeric retention aid. An optimum dose of 100 mg/L of aluminium sulphate and 1 ml/L of a commercial flocculant Afilan RAMF was found effective for dye removal (> 98%) from the synthetic solutions of reactive dyes with initial concentration of 150 mg/L in both the single component and two component systems. In the microfiltration study, effect of operating pressure in the permeate flux was observed for both the pretreated and untreated effluents and permeate samples were analyzed for dye concentration, COD, turbidity, TSS, etc. during constant pressure filtration. About 98-99% removal of dyes was obtained in the combined process with COD reduction of 54-64%.