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The present study evaluates the Decolorization and pollutant removal efficiency of chemically impregnated coconut shell-activated carbon using textile dye effluent in the filtration system. The coconut shell zinc chloride activated carbon (CSZAC) was used as a filtering media in wastewater treatment due to its wider pore space with better surface area (590.80 m2 g−1) and higher adsorption capacity. The SEM micrograph revealed that the activated carbon had networks of parallel running pores with internal microstructure and more active sites. The designed activated carbon filter system has dimensions of 90 x 60 x 30 cm; the sections included are the holding tank (50 liters capacity), filtration tank and storage tank with the optimized flow rate of 5 x 10−4 m3 min−1. The Color, pH, EC, TDS, TSS, BOD and COD of textile dyeing wastewater were significantly reduced, after the treatment through the CSZAC filtration system. The initial color concentration of textile dye effluent was 7021 HU and after treatment, the color was fully reduced and became colorless. CSZAC treatment reduced the BOD from 600 mg L−1 to 89.7 mg L−1 (80.6 per cent) and COD from 2500 mg L−1 to 205 mg L−1 (90.5 per cent). Therefore, CSZAC can be used as an effective adsorbent material to remove different dye compounds and pollutants from textile wastewater. [ABSTRACT FROM AUTHOR]

Textile and cosmetic industries generate large amounts of dye effluents requiring treatment before discharge. This wastewater contains high levels of reactive dyes, low to none-biodegradable materials and chemical residues. Technically, dye wastewater is characterised by high chemical and biological oxygen demand. Biological, physical and pressure-driven membrane processes have been extensively used in textile wastewater treatment plants. However, these technologies are characterised by process complexity and are often costly. Also, process efficiency is not achieved in cost-effective biochemical and physical treatment processes. Membrane distillation (MD) emerged as a promising technology harnessing challenges faced by pressure-driven membrane processes. To ensure high cost-effectiveness, the MD can be operated by solar energy or low-grade waste heat. Herein, the MD purification of dye wastewater is comprehensively and yet concisely discussed. This involved research advancement in MD processes towards removal of dyes from industrial effluents. Also, challenges faced by this process with a specific focus on fouling are reviewed. Current literature mainly tested MD setups in the laboratory scale suggesting a deep need of further optimization of membrane and module designs in near future, especially for textile wastewater treatment. There is a need to deliver customized high-porosity hydrophobic membrane design with the appropriate thickness and module configuration to reduce concentration and temperature polarization (CP and TP). Also, energy loss should be minimized while increasing dye rejection and permeate flux. Although laboratory experiments remain pivotal in optimizing the MD process for treating dye wastewater, the nature of their time intensity poses a challenge. Given the multitude of parameters involved in MD process optimization, artificial intelligence (AI) methodologies present a promising avenue for assistance. Thus, AI-driven algorithms have the potential to enhance overall process efficiency, cutting down on time, fine-tuning parameters, and driving cost reductions. However, achieving an optimal balance between efficiency enhancements and financial outlays is a complex process. Finally, this paper suggests a research direction for the development of effective synthetic and natural dye removal from industrially discharged wastewater. [Display omitted] • Discharge of dye effluent requires robust and cost-effective treatment processes. • Membrane distillation emerged as a promising tool towards dye remediation. • The current study reviewed research advancement towards environmental dye remediation. • However, fouling and thermal efficiency of MD remain a major challenge. • The reviewed study suggested optimization of membrane and module designs for effective dye remediation. [ABSTRACT FROM AUTHOR]

Graphene oxide can be used to store energy, as electrodes and purify industrial and domestic wastewater as photocatalysts and adsorbents because of its remarkable thermal, electrical, and chemical capabilities. Toward understanding graphene oxide (GO) based nanomaterials considering the background factors, the present review study investigated their characteristics, preparation methods, and characterization processes. The removal of contaminants from wastewater has recently been a focus of attention for materials based on GO. Progress in GO synthesis and surface modification has shown that they can be used to immobilize enzymes. It is possible to immobilize enzymes with varying characteristics on graphene-oxide-based substrates without sacrificing their functioning, thus developing a new environmental remediation platform utilizing nano biocatalysts. GO doping and co-doping with a variety of heterogeneous semiconductor-based metal oxides were included in a brief strategy for boosting GO efficiency. A high band-gap material was also explored as a possibility for immobilization, which shifts the absorption threshold to the visible range and increases photoactivity. For water treatment applications, graphene-based nanomaterials were used in Fenton reactions, photocatalysis, ozonation, photo electrocatalysis, photo-Fenton, and a combination of photon-Fenton and photocatalysis. Nanoparticles made from GO improved the efficiency of composite materials when used for their intended applications. As a result of the analysis, prospects and improvements are clear, especially when it comes to scaling up GO-based wastewater treatment technologies. [Display omitted] • Nano-based graphene oxide (GO) is useful in effective wastewater treatment. • To develop GO to treat wastewater, bottom-up and top-down approaches can be used. • Electro-chemical, mechanical, and surface properties of GO are pollutant traps. • GO plays an important role in adsorption-based water treatment systems. [ABSTRACT FROM AUTHOR]

Abstract: Degradation of Procion Scarlet a reactive dye in dye effluent is investigated by electrochemical and biological oxidation in individual, combined and integrated methods. The main objective of the present work is to reduce the COD and colour of the dye effluent containing Procion Scarlet dye. The influence of various experimental parameters such as COD, colour, power consumption and mass flux were calculated and presented. Microbiological experiments were performed by bacteria which is isolated from textile outlet site soil. From the results, individual electro oxidation process maximum COD removal of about 80% and colour removal of 97.9% was achieved at an optimum current density of about 10.25A/dm2 whereas bio-oxidation process reduced COD and colour removal of about 50% and 42.4% respectively. Integrated process reduced the COD and colour removal of 80% and 96.4% respectively at an optimum current density range of 6.84A/dm2, whereas combined processes showed the COD and colour removal of 90% and 98.5% respectively at an optimized current density of 7.6 and 10.2A/dm2. After post treatment the treated effluent can be reused. [Copyright &y& Elsevier]

Abstract: A complex Remazol dye effluent, comprised of Remazol Brilliant Blue R, Remazol Black, Remazol Violet, Remazol Orange, sodium chloride, sodium carbonate, sodium hydroxide, and acetic acid, was decolorized using polyaniline/extracellular polymeric substance (Pn/EPS) composite. Scanning electron micrograph showed that the surface of the composite was rough with granular appearance, providing a good possibility for dyes adsorption. X-ray diffractogram (XRD) of the composite showed the main reflections of both Pn and EPSs (2θ =6.0, 20.1 and 26.2, 30.4, and 40.8). Experiments were carried out as a function of contact time, pH, and adsorbent dose. Under optimized conditions, the maximum percentage removal was found to be 99.8% for the complex Remazol effluent. The Freundlich isotherm model and pseudo first-order rate expression showed satisfactory fit to the equilibrium biosorption data of Pn/EPS composite. Fourier transform infrared spectroscopy, XRD, and desorption studies confirmed the involvement of aromatic, amino, hydroxyl, and carboxylic groups in dye adsorption. The results indicate that composite is suitable as an adsorbent material for the enhanced removal of dyes from complex Remazol effluent. [Copyright &y& Elsevier]

A simple process, vacuum distillation, was utilized for purification of methyl orange (MO) as dye effluent. The dye effluent characteristic of high chemical oxygen demand (COD) value and high chromaticity is difficult to treat for the industrial wastewater treatment. In our work, the effect of some factors on the distillation efficiency (DE), including pressure, concentration and the surfactant based on the optimal conditions was evaluated. The results showed that the COD removal for 99.57% was obtained when the concentration of MO is 2000 mg l-1 at the pressure of 0.070 MPa. Moreover, the polyacrylamide (cationic) used in initial concentration of 500 mg l-1 show satisfactory removal efficiency in the further test. [ABSTRACT FROM AUTHOR]

Abstract: The high energy cost of an electrochemical method is the fatal drawback that hinders its large scale application in wastewater treatment. The traditional single-chamber electrochemical method used in the waste water treatment mainly focused on anodic oxidation, but hydrogen produced on the cathode and indirect electrochemical treatment involves application of an electrical current to the wastewater containing chloride to convert into chlorine/hypochlorite. The two-compartment electrolytic cell, separated by an anion exchange membrane, has been developed in this work. In the new reactor, indirect oxidation at anode, indirect oxidation by hydrogen peroxide and ultraviolet/hydrogen peroxide (UV/H2O2) at cathode can occur simultaneously. The electrochemically produced hydrogen peroxide at the cathode by reduction of oxygen is affected by passing atmospheric air. Therefore “dual electrochemical oxidation” in one electrochemical reactor was achieved successfully. Compared to a traditional one-cell reactor, this reactor reduces the energy cost approximately by 25–40%, and thus the present work becomes significant in wastewater treatment. Experiments were carried out at different current densities using Ti/RuO2/IrO2 as anode and carbon felt gas diffusion electrode used as a cathode fed with oxygen containing gases to produce hydrogen peroxide. During the various stages of electrolysis, the parameters such as, effect of pH, chemical oxygen demand (COD), colour, energy consumption were monitored. UV–vis spectrometry, Fourier transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC) studies were carried out to assess efficiencies of dye degradation. [Copyright &y& Elsevier]