Remediation of textile effluents by membrane based treatment techniques: a state of the art review

Starch hydrolysates, their impurities and the role of membrane-based technologies as a promising sustainable purification method at industrial scale

Starch hydrolysates are syrups obtained through the hydrolysis of starch with a defined carbohydrate composition and concentration. Annual harvest conditions and the availability of raw materials, such as corn, wheat, rice, potato, and certain plant roots, influence their quality. High-quality starch hydrolysate products serve numerous applications, including ingredients in food, textiles, paper, cosmetics, bioplastics, pharmaceuticals and construction. However, impurities such as colour molecules, characteristic flavours, salts, and proteins encountered in the solution along the starch processing steps can compromise product quality. With increasing emphasis on organic and sustainable production, starch hydrolysates must meet higher health and environmental standards. This review provides a comprehensive overview of starch hydrolysates production and purification. It explores the chemical processes leading to the formation of impurities and their impact on the final product composition and specific characteristics. Downstream processing methods for recovery, purification, and concentration are also investigated, comparing traditional techniques with emerging membrane-based technologies. Membrane technologies offer a potential solution for purifying plant-based starch hydrolysates efficiently and sustainably by enhancing purification while reducing energy consumption and waste generation. They operate at lower temperatures, avoiding phase transitions, extra heating, chemicals, and solvent exchanges. Although membrane technologies are widely used in various food industries, minimal research exist on their applications in starch hydrolysate processing, with limited experimental validation available. Addressing this gap, this review compiles established applications and discusses challenges hindering industrial adoption-including membrane fouling, the selection of appropriate membranes, the operational lifespan, and replacement costs,- while also identifying areas requiring further experimental research and development.

Valorization of agitated thin film dryer (ATFD)-mixed-salt from textile wastewater for its application in leather manufacturing - a sustainable approach

The textile industry uses sodium chloride and sodium sulphate during the dyeing process to improve the fixation of dyes on fabrics. After wastewater treatment, the reject stream is dried resulting in mixed salts as solid wastes that are not reused. The leather industry also uses a vast quantity of salt for temporary preservation of skins/hides and as swelling-suppressing agent during the pickling (acidification) process. Thus, an attempt was made to utilize the mixed salt obtained from the textile industry to replace sodium chloride in leather processing. It was found that a 40% w/w offer of ATFD salt was able to preserve the skins for 3 months, which was on par with the preservation carried out using a similar quantity of sodium chloride in conventional preservation process. Likewise, for the pickling process, an offer of 10% w/w ATFD salt provided sufficient deswelling action when compared to conventionally used sodium chloride. However, the residual colour of the mixed salts affected the quality of the leather obtained. To overcome this, an electro-oxidation treatment was carried out to obtain decolourized salts. The COD measurements showed that the 1% solution of ATFD-3 salt reduced from 471 ± 25 to 88 ± 16 ppm. A similar trend was also seen in BOD reduction from 80 ± 12 to 18 ± 10 ppm. These results confirmed that the colour removal could be due to the degradation of the organic contaminants present in the ATFD salt. Thus, the treated ATFD salt can be reused for leather processing without affecting leather quality, thus promoting the concept of circular economy.

Ultra-Fast Removal of CBB from Wastewater by Imidazolium Ionic Liquids-Modified Nano-Silica

The efficient removal of dyes is of significant importance for environmental purification and human health. In this study, a novel material (Si-MPTS-IL) has been synthesized by the immobilization of imidazole ionic liquids (ILs) onto nano-silica using the radiation grafting technique. The adsorption performance of Si-MPTS-IL for Coomassie Brilliant Blue (CBB) removal is studied by a series of static adsorption experiments. It is found that Si-MPTS-IL has ultra-fast adsorption kinetics, reaching equilibrium within 2 min. The adsorption process for CBB conforms to the Langmuir model. In addition, Si-MPTS-IL exhibits a negligible impact on the adsorption efficiency of CBB with the increase in salt concentration. After six cycles of adsorption-desorption, the adsorption efficiency of Si-MPTS-IL remained above 80%, indicating excellent regenerative properties and a promising candidate for the treatment of wastewater containing CBB. A study of the mechanism indicates that the CBB capture by Si-MPTS-IL can be attributed to the synergistic effects of electrostatic interactions and pore filling.

Membrane process and adsorption on pine nut shell for removal of dye from synthetic wastewater

Purification methods such as membrane technology and adsorption have been studied for the purification of textile effluents. This article aimed to evaluate the membrane separation process and adsorption on pine nut shell, separately and sequentially, for reactive dye blue 5G removal from a synthetic effluent. The membrane separation process was carried out in a front filtration module using polymeric membranes. The maximum dye retention was 35.9% using a regenerated cellulose membrane, with agitation and a pressure of 0.5 bar. The permeate flux was fully restored after cleaning the membrane. In the adsorption using pine nut shell, the best results were at pH 2, 50°C, and 50 ppm, with 85% dye removal. The Freundlich isotherm showed the best fit to the data, as did the pseudo-second-order kinetic model. The thermodynamic parameters indicated that the adsorption is of the physical type, with the process being endothermic and spontaneous. In the combined process, the permeate from the membrane separation process was subjected to adsorption on pine nut shell, achieving a removal rate of 98.7 for the initial concentration of 50 ppm. Therefore, this work shows the potential of pine nut shell as an adsorbent, not only to purify textile effluents but also to add value to a waste product, indicating that the combination of membrane technology and adsorption on pine nut shell could be an alternative for the treatment of textile effluents containing the reactive dye 5G blue.

Nanomodified bamboo (Phyllostachys aurea) biomass: its adsorbent features in the removal of dyes from water under high salinity conditions

The effluent generated by textile industries is among the most polluting to the environment. Dyes such as methylene blue (MB) and indigo blue (IB) are used in cotton dyeing. This work proposes to evaluate the potential of in natura (BIN) and nanomodified (BNP) bamboo (Phyllostachys aurea) biomass as biosorbents for the removal of MB and IB dyes in an aqueous medium under high salinity conditions. These materials were characterized by Fourier transform infrared (FTIR) and X-ray (XRD) spectroscopies and scanning electron microscopy (SEM) to investigate their morphology and interaction with the dyes and the nanoparticles. The FTIR spectra revealed the existence of hydroxyl and carbonyl groups, ethers, phenols, and aromatic compounds, indicating the presence of a lignocellulosic structure. XRD and SEM analyses confirmed the effectiveness of the nanocomposite synthesis process. The dyes were quantified by ultraviolet-visible spectroscopy (UV/Vis). The material's pH at the point of zero charge (pHPZC) was 5.52 (BIN) and 4.84 (BNP), and the best IB and MB sorption pH were 3.0 and 9.0 for BNP, respectively, employing 30 min of contact time. The material sorption capacity (Qexp) was assessed using batch procedures, in which 100-1000 mg/L dye concentrations were tested with a 0.5 g/L adsorbent dose. The dye's Qexp for BIN and BNP was 25.41 ± 0.58 and 23.42 ± 0.07 mg/g (MB) and 84.26 ± 1.1 and 130.81 ± 0.20 mg/g (IB), respectively. The kinetic model that best fit BNP experimental data was the pseudo-2nd-order with r2 = 0.99868 (MB) and r2 = 0.99873 (IB), and Freundlich, D-R, and Temkin isotherms best fit the dye sorption data. The bamboo nanomodification facilitates the biosorbent removal from the medium after sorption, enabling large-scale studies and industrial applications-the investigated materials provided promising adsorption features for removing contaminant dyes in saline water.

Springtail-inspired omniphobic slippery membrane with nano-concave re-entrant structures for membrane distillation

Omniphobic membranes, due to their exceptional properties, have drawn significant attention for overcoming the bottleneck in membrane distillation (MD) technology. This study demonstrates an innovative method for fabricating an omniphobic membrane that is simple and facile compared to other methods such as wet/dry etching and photolithography. The surface morphology of springtails was imitated using electrospraying technique to coat a polyvinylidene fluoride substrate with concave-shaped polystyrene beads that were successfully developed by controlling the electrical traction (voltage) and air resistance (humidity). Then, the lipid coating of springtail surfaces was mimicked by dip-coating the membrane in a low-toxicity short-chain perfluoropolyether lubricant. The concave structure's tiny air pockets increased membrane hydrophobicity significantly, indicated by the fact that the first round of water bouncing took only 16.3 ms. Finally, in MD treatment of seawater containing 1.0 mM sodium dodecyl sulfate, the optimized omniphobic membrane maintained a stable 99.9% salt rejection rate.

Microplastics and dye removal from textile wastewater using MIL-53 (Fe) metal-organic framework-based ultrafiltration membranes

Microplastics (MPs) and other organic matters in textile wastewater have posed a formidable challenge for treatment processes, particularly in the primary stages such as ultrafiltration (UF). UF plays a crucial role in preventing the entry of pollutants into subsequent treatment steps. However, the performance efficiency of UF membranes is compromised by the potential fouling of membrane pores by MPs, dyes and other organic pollutants such as bovine serum albumin (BSA). This study focuses on enhancing UF membrane performance, specifically its antifouling properties, through the development of high-performance membranes using MIL-53(Fe) metal-organic framework (MOF) particles (noted as MIL-53 here). Various concentrations of the MIL-53 (0.05, 0.1, 0.2, and 0.5 wt%) were integrated into the membrane structure through phase inversion process. Streaming zeta potential results confirmed the negatively charged surface of the membranes and their high hydrophilicity was validated through contact angle analysis. FTIR, SEM, EDS, and XRD confirmed the presence of MIL-53 particles on the surface of membranes. The developed membranes were tested for 24 h to assess their antifouling properties, with a subsequent 30-min hydraulic flush to measure their flux recovery ratios. Methylene Blue (MB) dye was used as a cationic dye present in textile wastewater to evaluate the efficiency of the developed membranes in dye removal and the synergistic effects of dye rejection in the presence of organic matters (i.e., MPs and BSA). Since previous studies have not fully addressed the combination of dyes and organic matter, this study thoroughly investigated the effect of particle-type foulants (MPs) and their interactions with dye (MB), as well as water soluble protein-type foulants (BSA) and their interaction with MB. The results indicated that the developed membranes exhibited higher MB rejection when the dye was present with either MP or BSA, along with improved antifouling properties. The optimised UF membrane integrated with 0.1 wt% MIL-53 demonstrated nearly 96% BSA rejection and around 86% MB rejection in the mixed foulant case (BSA-MB). The modified membrane exhibited a substantial increase in water flux from 176 L m-2.h-1 to 327 L m-2.h-1. The findings of this research show the potential of iron-based MOFs in improving the performance of UF membranes and provide a platform for future studies on significant areas such as long-term stability studies and testing with other pollutants found in textile wastewater.

Textile effluent treatment by reductive process using commercial steel wool followed by oxidative process

Textile industries stand out as one of the main polluters of water resources, generating large amounts of liquid effluents with variable composition and intense coloration. The objective of this work is the integration of the reductive process using commercial steel wool, combined with oxidative processes, in the treatment of textile effluent. The effect of the variables of the reductive process were studied using a 32 factorial design. After 30 minutes, the reductive process allowed a reduction of 68% COD, 46% TOC, 62% true color and 72% of total phenols, but showed an increase in color apparent and turbidity, due to the iron species formed by the oxidation of steel wool during the process. With the combined process using sunlight, the reduction was 73% COD, 50% TOC, 97% phenols, 93% true color and 48% apparent color. With artificial light, the reduction was 94% COD, 63% TOC, 95% phenols, 98% true color and 65% apparent color. The evaluation of the acute toxicity against Daphnia magna indicated that after the proposed treatments, the effluent did not present toxicity or the toxicity was reduced. It is concluded that the combined process can be considered an efficient alternative for the treatment of textile effluent.

A review on the application of biochar as an innovative and sustainable biocarrier material in moving bed biofilm reactors for dye removal from environmental matrices

Dye decolorization through biological treatment techniques has been gaining momentum as it is based on suspended and attached growth biomass in both batch and continuous modes. Hence, this review focused on the contribution of moving bed biofilm reactors (MBBR) in dye removal. MBBR have been demonstrated to be an excellent technology for pollution extraction, load shock resistance, and equipment size and energy consumption reduction. The review went further to highlight different biocarrier materials for biofilm development this review identified biochar as an innovative and environmentally friendly material produced through the application of different kinds of reusable or recyclable wastes and biowastes. Biochar as a carbonized waste biomass could be a better competitor and environmentally friendly substitute to activated carbon given its lower mass costs. Biochar can be easily produced particularly in rural locations where there is an abundance of biomass-based trash. Given that circular bioeconomy lowers dependency on natural resources by turning organic wastes into an array of useful products, biochar empowers the creation of competitive goods. Thus, biochar was identified as a novel, cost-effective, and long-term management strategy since it brings about several essential benefits, including food security, climate change mitigation, biodiversity preservation, and sustainability improvement. This review concludes that integrating two treatment methods could greatly lead to better color, organic matter, and nutrients removal than a single biological MBBR treatment process.

Graphene oxide intercalated Alk-MXene adsorbents for efficient removal of Malachite green and Congo red from aqueous solutions

Currently, adsorbents with high adsorption performance for eliminating pollutants from discharged wastewater have received many researchers' attention. To this aim, a novel AMXGO absorbent was fabricated by intercalating graphene oxide (GO) into alkalized MXene (Alk-MXene) layer which exhibited high efficacy for the removal of cationic Malachite Green (MG) and anionic Congo Red (CR). Analysis of FTIR, XRD, SEM and TG presented that AMXGO absorbent have a typical three-dimensional layer by layer structure and abundant oxygen-containing groups and its thermal stability was remarkably improved. BET results elucidated that AMXGO1 adsorbent has larger specific surface area and pore volume (16.686 m2 g-1, 0.04733 cm3 g-1) as compared to Alk-MXene (4.729 m2 g-1, 0.02522 cm3 g-1). A dependence of adsorption performance on mass ratio between Alk-MXene and GO, initial dye concentration, contact time, temperature and pH was revealed. Maximum adsorption capacity of MG (1111.6 mg/g) and CR (1133.7 mg/g) were particularly found for AMXGO1 absorbent with a mass ratio of 3:1 and its removal for both dyes were higher than 92%. The adsorption process of AMXGO1 adsorbent for both MG and CR complies with pseudo-second-order kinetic model and Freundlich isotherm model. In addition, adsorption mechanism was explored that synergism effects as electrostatic attraction, π-π conjugates, intercalation adsorption and pore filling were the main driving force for the high adsorption performance of dye. Therefore, AMXGO adsorbent has a potential application prospect in the purification of dye wastewater.

Rapid catalytic reduction of environmentally toxic azo dye pollutant by Prussian blue analogue nanocatalyst

The release of toxic azo dyes pollutants in the environment from different industries represents a public health concern and a serious environmental problem. Therefore, the conversion of hazardous methyl orange (MO) azo dye to environmentally benign products is a critical demand. In this work, an eco-friendly Prussian blue analogue (PBA) was synthesized and its catalytic activity toward the reduction of MO was investigated. The PBA copper(ii) hexacyanocobaltate(III) (Cu3[Co(CN)6]2) was synthesized by a facile inexpensive chemical coprecipitation method without using hazardous solvents. The nanocatalyst was characterized using XPS, Raman, FTIR spectroscopy, and XRD. The chemical reduction of MO using NaBH4 and the PBA as nanocatalyst was monitored by UV-VIS spectroscopy. Toxic MO was completely reduced in 105 s with a rate constant (k) 0.0386 s-1 using only 10 μg of the PBA nanocatalyst. Besides the powerful catalytic activity, the nanocatalyst also showed excellent stability and recyclability for ten consecutive cycles, with no significant decrease in the catalytic performance. Therefore, the proposed PBA is a promising, stable, cost-effective, and eco-friendly nanocatalyst for the rapid elimination of hazardous azo dyes.

Intermolecular interactions in mixed dye systems and the effects on dye wastewater treatment processes

Dye wastewater discharge is a critical concern across textiles, paper, cosmetics, and other industries. This study explores the impact of dye-dye interactions on chemical coagulation and ultrafiltration process. Using basic and reactive dyes, representing cationic and anionic compounds, the intricate interplay between these dyes was examined through spectroscopic analysis. Remarkably, interactions between dyes of opposite charges exhibited significant effects on both techniques. Electrostatic attractions played a key role. Positive coagulant hydrolysates selectively attracted negative dyes, while negatively charged membranes effectively captured positive dyes. Combining dyes with opposite charges resulted in enhanced removal efficiency, addressing challenging dyes collectively. This discovery offers a novel approach to improving dye removal, utilizing opposite-charged dye mixtures can tackle stubborn dyes unmanageable by conventional methods.

Biological treatment processes for saline organic wastewater and related inhibition mechanisms and facilitation techniques: A comprehensive review

Owing to its profound pollution-inducing properties and resistance to biodegradation, saline organic wastewater (SOW) has unavoidably emerged as a predominant focal point within the wastewater treatment domain. Substantial quantities of SOW are discharged by diverse industries encompassing food processing, pharmaceuticals, leather manufacturing, petrochemicals, and textiles. Within this review, the inhibitory repercussions of elevated salinity upon biological water treatment systems are subject to methodical scrutiny spanning from sludge characteristics, microbial consortia to the physiological functionality of microorganisms have been investigated. This exposition elucidates the application of both anaerobic and aerobic biological technologies for SOW treatment, which noting that conventional bioreactors can effectually treat SOW through microbial adaptation, and elaborating that cultivation of salt-tolerant bacteria and the design of advanced bioreactors represents a promising avenue for SOW treatment. Furthermore, the mechanisms underpinning microbial acclimatization to hypersaline milieus and the methodologies aimed at amplifying the efficacy of biological SOW treatment are delved into, which point out that microorganism exhibit salt tolerance via extracellular polymeric substance accumulation or by facilitating the influx of osmolarity-regulating agents into the bacterial matrix. Finally, the projections for future inquiry are proffered, encompassing the proliferation and deployment of high salt-tolerant strains, as well as the development of techniques enhancing the salt tolerance of microflora engaged in wastewater treatment.

Rapid adsorptive removal of eosin yellow and methyl orange using zeolite Y

In this study, zeolite Y was synthesised using a novel method. The heat generated from the reaction of H2SO4 with metakaolin was used as a heat source instead of applying external heat for the dealuminated process. The synthesised zeolite Y produced was analysed by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier-infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS) and Brunauer-Emmett-Teller (BET). Zeolite Y synthesis was mesoporous because of its pore diameter (30.53 nm), as shown in the BET results. Surface area and pore size decrease after adsorption due to dye deposition on the adsorbent's surface. FTIR has bonds like O-H, C-H, -CH3, and -COOH responsible for adsorption. The maximum adsorption capacity of eosin yellow (EY) and methyl orange (MO) on to zeolite Y by the Langmuir isotherm was 52.91 mg/g and 20.62 mg/g respectively, at pH 2.5 and 8 for EY and MO dye. The batch adsorption studies were conducted, and the influence of different parameters (i.e., adsorbent dose, adsorption time, initial dye concentration, pH and temperature) was investigated. Experimental data were analysed by two linear model equations (Langmuir and Freundlich isotherms), and it was found that the Langmuir isotherm model best describes the adsorption data for methyl orange and Freundlich isotherm for eosin yellow, respectively. Adsorption rate constants were determined using linear pseudo-first-order and pseudo-second-order. The results showed that MO and EY dye adsorption onto zeolite Y followed a pseudo-second-order kinetic model. Thermodynamic studies show that adsorption was an exothermic reaction (enthalpy < 0) and feasible ([Formula: see text]) at various temperatures under investigation.

Preparation of 1,8-dichloroanthraquinone/graphene oxide/poly (vinylidene fluoride) (1,8-AQ/GO/PVDF) mediator membrane and its application to catalyzing biodegradation of azo dyes

Anthraquinone is a redox mediator that can effectively catalyze the degradation of azo dyes by promoting the electron transfer. In this study, a mediator membrane with poly (vinylidene fluoride) (PVDF) as the membrane support and 1,8-dichloroanthraquinone (1,8-AQ) and graphene oxide (GO) as the additives was prepared and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), atomic force microscopy (AFM) and water contact angle. The introduction of GO increases the pure water flux of the membrane to 258.56±12.93 L/(m2·h). Its catalytic performances for the biodegradation of azo dyes were evaluated. Under the optimized conditions, the 1,8-AQ/GO/PVDF composite membrane is able to improve the dye degradation efficiency 2.2 times for reactive red X-3B and 1.1 times for acid red B, as compared with PVDF membrane. In addition, the mediator membrane maintains stable and high catalytic efficiency in the cyclic test and over 90 % dye degradation efficiency is still obtained after 5 cycles of decolorization. These results suggest the great application potentials of the 1,8-AQ/GO/PVDF membrane in the dye wastewater treatment.

Effect of basic and basic/acid modifications on the surface of PVDF membranes for the insertion of TiO2 and its use in environmental applications

Supporting titanium oxide (TiO2) on polymeric membrane surfaces is a strategy to increase the photocatalytic activity of this material as well as to modify membrane surface with antifouling properties or to develop hybrid processes of water treatment. The chemical characteristics of the polymeric membrane surfaces are a determining factor in the correct impregnation of TiO2 particles. In this work, the titanium oxide was immobilized on polyvinylidene fluoride (PVDF) membrane surface by direct impregnation during the synthesis of the inorganic particles by sol-gel route. The PVDF membranes were previously modified by treatments based on an alkaline attack followed by acid treatment. The final TiO2-modified membranes were characterized by infrared and Raman spectroscopy, as well as by scanning electron microscopy. In addition, the changes on the surface characteristics were determined by contact angle measurements. Finally, the membranes were tested on the photocatalytic degradation of methyl orange (MO). The results obtained indicate that the basic/acid pretreatment allows the generation of active sites in the membrane and that when carrying out the synthesis of TiO2 on the membrane, it can be anchored stably on its surface and through the pores. The microscopies indicate that the structure of the membrane is not compromised by the pretreatment. The amount of TiO2 deposited on the membrane was of 0.1580 ± 0.01773 mg TiO2/cm2 membrane. With this amount of TiO2, a degradation percentage of 98.2% is achieved after 450 min; when the membrane is used for a second cycle, a degradation percentage of 82.0% is obtained, which remains constant for 3 subsequent cycles. This method, which uses the PVDF membrane as a support for TiO2 particles, represents a low-cost and easy-to-prepare insertion procedure, with good degradation percentages, which means that the membrane can be used for subsequent studies in filtration systems in the treatment of effluents from the textile industry.

Pineapple wastewater as co-substrate in treating real alkaline, non-biodegradable textile wastewater using biogranulation technology

This study was to develop biogranules using a sequencing batch reactor (SBR) and to evaluate the effect of pineapple wastewater (PW) as a co-substrate for treating real textile wastewater (RTW). The biogranular system cycle was 24 h (2 stages of phase), with an anaerobic phase (17.8 h) followed by an aerobic phase (5.8 h) for every stage of the phase. The concentration of pineapple wastewater was the main factor studied in influencing COD and color removal efficiency. Pineapple wastewater with different concentrations (7, 5, 4, 3, and 0% v/v) makes a total volume of 3 L and causes the OLRs to vary from 2.90 to 0.23 kg COD/m3day. The system achieved 55% of average color removal and 88% of average COD removal at 7%v/v PW concentration during treatment. With the addition of PW, the removal increased significantly. The experiment on the treatment of RTW without any added nutrients proved the importance of co-substrate in dye degradation.

A novel cationic covalent organic framework as adsorbent for simultaneous removal of methyl orange and hexavalent chromium

The simultaneous removal of toxic, carcinogenic organic dyes and metal ions from water by one material offers significant advantages when fast, facile, and robust water purification is required. Ionic covalent organic frameworks (ICOFs) have the combined properties of COFs and ion exchange resins and are expected to achieve simultaneous capture of heavy metal ions and organic dyes from water. Herein, a novel guanidinium-based ICOF was synthesized using a solvothermal method. Benefitting from the cationic character, porosity and nanoscale pore size of ICOFs, the adsorbent exhibited high simultaneous adsorption capacities of 290 mg g-1 and 158 mg g-1 for methyl orange (MO) and Cr(vi), respectively, and retained more than 90% adsorption capacity after six adsorption-desorption cycles. In addition, based on dual control of size-exclusion and charge-selection, precisely selective adsorption is achieved towards diverse mixed anionic and cationic pollutants. This strategy offers a practical solution for COFs to confront environmental pollution issues.

Osmotic cleaning of typical inorganic and organic foulants on reverse osmosis membrane for textile printing and dyeing wastewater treatment

Reverse osmosis (RO) is one of the most fundamental membrane technology because it has higher salt rejections, which suffers from the issue of membrane fouling, as the membrane is inevitably exposed to foulants during the filtration process. For different fouling mechanisms of RO membrane, physical and chemical cleaning are widely used in the control of RO membrane fouling. The present study investigated the performance and water flux recovery using osmotic cleaning to clean the typical inorganic and organic foulants on RO membrane for textile printing and dyeing wastewater treatment. The effects of operation conditions (i.e., the concentration of cleaning solution, the filtrating time and cleaning time, and the flow rate of cleaning solution) on relative water flux recovery were examined. The results show that a highly water flux recovery (98.3% for cleaning of inorganic fouling and 99.6% for cleaning of organic fouling) was achieved under optimal operation of the concentration and flow rate of cleaning solution and the filtrating and cleaning time. Moreover, the experiment of repeated "filtrating-cleaning" cycles indicated that the osmotic cleaning has highly performance of recoverability of water flux (over 95.0%) can be extended in a relatively long time. The experimental results and changes on SEM and AFM images of RO membrane confirmed the successful development and application of osmotic cleaning for inorganic and organic fouling of RO membrane.

Selective separation of dye/salt mixture using diatomite-based sandwich-like membrane

A novel nanofiltration membrane was developed by entrapping a layer of modified diatomaceous earth between two layers of electrospun polysulfone (E-PSf) nanofibers. The diatomaceous earth particles and the fabricated membrane were characterized using FTIR, SEM, EDS, zeta potential, and water contact angle techniques. The static adsorption and dynamic separation of pristine E-PSF and sandwich-like membranes for methylene blue (MB) with/without salt were investigated under different operating conditions. The Langmuir model suited the MB adsorption isotherm data with a linear regression correlation coefficient (R²) >0.9955. As pH increased, both flux and MB rejection of the sandwich-like membrane improved by up to 183.8 LMH and 99.7%, respectively, when operated under gravity. The water flux of the sandwich-like membrane was sharply increased by increasing the pressure up to 19,518.2 LMH at 4.0 bar. However, this came at the expense of MB rejection (10.93%) and reduced its practical impact. At a high salt concentration, the sandwich-like membrane also indicated remarkable dye/salt separation with a higher permeation of salt (<0.2% NaCl rejection) and MB rejection (>99%). The performance of the regenerated diatomaceous material and membrane was maintained during five cycles of operation compared to that of the original ones.

Organic solvent-free constructing of stable zeolitic imidazolate framework functional layer enhanced by halloysite nanotubes and polyvinyl alcohol on polyvinylidene fluoride hollow fiber membranes for treating dyeing wastewater

In this study, zeolitic imidazolate framework (ZIF-8)/polyvinylidene fluoride (PVDF) loose nanofiltration (NF) hollow fiber membranes were fabricated by constructing ZIF-8 functional layer on the PVDF supporting membranes based on the vacuum-assisted assembly process. The ZIF-8 synthesis was completed in a water system, and the synthesized ZIF-8 suspension was directly added to polyvinyl alcohol (PVA) and halloysite nanotubes (HNTs) aqueous solution system without drying to prepare the casting solution, which could solve the agglomeration and poor dispersion problem of ZIF-8 particles. In addition, the embedded HNTs and the loaded PVA among the ZIF-8 layer could improve the bonding strength between the ZIF-8 layer and the supporting membranes. After constructing ZIF-8 functional layer, the pore size of supporting membranes decreased from more than 300 nm to several nanometers. Furthermore, the water contact angle reduced from 91.1° to 54.2°. Applied to treat dye wastewater, the prepared ZIF-8/PVDF membranes maintained high dye rejection (˃99.0 %) for Congo red (CR), but low salt rejection for NaCl (about 2 %). In addition, the flux could reach 21.6 L m^-2h^-1 after continuous filtration 360 min, exhibiting a potential for treating the dye/salt wastewater. In particular, there were no organic solvents used in the work, which provided a promising idea for solvent-free fabrication of loose NF membranes.

A critical review on graphene oxide membrane for industrial wastewater treatment

An important way to promote the environmental industry's goal of carbon reduction is to promote the recycling of resources. Membrane separation technology has unique advantages in resource recovery and advanced treatment of industrial wastewater. However, the great promise of traditional organic membrane is hampered by challenges associated with organic solvent tolerance, lack of oxidation resistance, and serious membrane fouling control. Moreover, the high concentrations of organic matter and inorganic salts in the membrane filtration concentrate also hinder the wider application of the membrane separation technology. The emerging cost-effective graphene oxide (GO)-based membrane with excellent resistance to organic solvents and oxidants, more hydrophilicity, lower membrane fouling, better separation performance has been expected to contribute more in industrial wastewater treatment. Herein, we provide comprehensive insights into the preparation and characteristic of GO membranes, as well as current research status and problems related to its future application in industrial wastewater treatment. Finally, concluding remarks and future perspectives have been deduced and recommended for the GO membrane separation technology application for industrial wastewater treatment, which leads to realizing sustainable wastewater recycling and a nearly "zero discharge" water treatment process.

ZIF-67 blended PVDF membrane for improved Congo red removal and antifouling properties: A correlation establishment between morphological features and ultra-filtration parameters

Dye effluents from various sectors have constantly imperilled the environment and ecosystem. Nano-composite membrane technology incorporating metal-organic frameworks (MOFs) has shown tremendous potential for toxic pollutant remediation. This study details the impact of ZIF-67 MOF nanoparticles on the structural properties of polyvinylidene fluoride (PVDF) ultrafiltration membrane during the non-solvent induced phase separation (NIPS) process. In order to outline the properties that determine the performance parameters in a MOF-modified mixed matrix membrane, the corresponding changes in mean pore size (MPS), surface porosity, solvent viscosity, and hydrophilicity have been discussed with appropriate surface characterization analysis. The suitability of ZIF-67 as filler nanoparticles were established based on polymer compatibility, dispersibility, and water stability studies. The ZIF-67 incorporated PVDF mixed matrix membranes (MMM) showed 99.5% CR dye removal with 2.6 times DI water permeability than the neat. The flux recovery ratio (FRR) improved by 1.9 times and the membranes were found suitable for up to 5 filtration cycles. Based on the overall results, a correlation analysis between the MMM surface properties and membrane performance parameters were established to determine the key performance parameters. It was observed that in comparison to MPS, surface porosity was more correlated to J_d/J_w (r = 0.96) and FRR (r = 0.95).

Aleppo pine seeds (Pinus halepensis Mill.) as a promising novel green coagulant for the removal of Congo red dye: Optimization via machine learning algorithm

Consideration is now being given to the use of metal coagulants to remove turbidity from drinking water and wastewater. Concerns about the long-term impact of non-biodegradable sludge on human health and the potential contamination of aquatic systems are gaining popularity. Recently, alternative biocoagulants have been suggested to address these concerns. In this study, using a 1 M sodium chloride (NaCl) solution, the active coagulating agent was extracted from Pinus halepensis Mill. Seed, and used for the first time to remove Congo red dye, the influence of numerous factors on dye removal was evaluated in order to make comparisons with conventional coagulants. The application of biocoagulant was shown to be very successful, with coagulant dosages ranging from 3 to 12 mL L^-1 achieving up to 80% dye removal and yielding 28 mL L^-1 of sludge. It was also found that biocoagulant is extremely pH sensitive with an optimum operating pH of 3. Ferric chloride, on the other hand, achieved similar removal rate with higher sludge production (46 mL L^-1) under the same conditions. A Fourier Transform Infrared Spectroscopy and proximate composition analysis were undertaken to determine qualitatively the potential active coagulant ingredient in the seeds and suggested the involvement of proteins in the coagulation-flocculation mechanism. The evaluation criteria of the Support vector machine_Gray wolf optimizer model in terms of statistical coefficients and errors reveals quite interesting results and demonstrates the performance of the model, with statistical coefficients close to 1 (R = 0.9998, R² = 0.9995 and R² adj = 0.9995) and minimal statistical errors (RMSE = 0.5813, MSE = 0.3379, EPM = 0 0.9808, ESP = 0.9677 and MAE = 0.2382). The study findings demonstrate that Pinus halepensis Mill. Seed extract might be a novel, environmentally friendly, and easily available coagulant for water and wastewater treatment.

Next-generation ultrafiltration membranes: A review of material design, properties, recent progress, and challenges

Membrane technology utilizing ultrafiltration (UF) processes has emerged as the most widely used and cost-effective simple process in many industrial applications. The industries like textiles and petroleum refining are promptly required membrane based UF processes to alleviate the potential environmental threat caused by the generation of various wastewater. At the same time, major limitations such as material selection as well as fouling behavior challenge the overall performance of UF membranes, particularly in wastewater treatment. Therefore, a complete discussion on material design with structural property relation and separation performance of UF membranes is always exciting. This state-of-the-art review has exclusively focused on the development of UF membranes, the material design, properties, progress in separation processes, and critical challenges. So far, most of the review articles have examined the UF membrane processes through a selected track of paving typical materials and their limited applications. In contrast, in this review, we have exclusively aimed at comprehensive research from material selection and fabrication methods to all the possible applications of UF membranes, giving more attention and theoretical understanding to the complete development of high-performance UF systems. We have discussed the methodical engineering behind the development of UF membranes regardless of their materials and fabrication mechanisms. Identifying the utility of UF membrane systems in various applications, as well as their mode of separation processes, has been well discussed. Overall, the current review conveys the knowledge of the present-day significance of UF membranes together with their future prospective opportunities whilst overcoming known difficulties in many potential applications.

Photocatalytic degradation of dyes by novel electrospun nanofibers: A review

Textile industry is a significant contributor of wastewater, which contains pollutants including dye and other chemical substances. The release of thousands of tons of dye used in textile processing and finishing into natural streams and aquatic bodies present dire harm to the environment. In response to environmental concerns, a number of research have been done using low-cost technology to produce absorbents that can remove dyes from water bodies. Distinct techniques such as adsorption, enzymatic and photocatalytic degradation, etc. have been employed to remove dyes. In the last few decades, photocatalysis, a simple and green strategy, has emerged as the most valuable and recent principle that deals with wastewater treatment, using uniquely fabricated nanomaterials. Among them, rapid and versatile electrospinning methods have been used for the construction of a large surface area, hierarchical and reusable nanofibers for environmental remediation. As a flexible and fast fabrication method, reviewing the use of electrospun photocatalytic nanofibers, influential parameters in electrospinning and their effectiveness in the generation of oxidizing agents are a promising platform for the fabrication of novel nanomaterials in photocatalytic degradation of dyes. This review discusses techniques for dye removal, electrospun nanofibers, their fabrication and application in photocatalysis; mechanism of photocatalytic degradation, and challenges and suggested remedies for electrospun nanofibers in photocatalysis.

Investigation of functional performance of treatment systems for textile wastewater in selected textile industries in Tanzania

Textile industrialization is an integral part of the economic growth in Tanzania. However, the corresponding wastewater from textile treatment processes consists of dyes and auxiliaries associated with acute toxicological impacts. This necessitates an investigation of the functional performance of the industrial treatment systems used before effluent discharge. The study primarily accesses the catalog of industrial dyes and the functionality of the treatment system at Arusha, Morogoro and Dar es Salaam vis-à-vis the effluent physicochemical properties. The analytical study reveals disperse (42%), vat (34%) and reactive (26%) as the most used industrial dyes. The physicochemical properties of the quantified wastewater reveal a significant amount of and phosphorus which was consequent to the high turbidity, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) apart from the color at the different sampling points. Although the treatability of the wastewater was 90% efficient using an activated carbon system (237.33 ± 0.67 mg/L). Similarly, the use of aerated constructed wetlands shows efficiency in the remediation of the recalcitrant having a value of 12.13 ± 0.89^b mg/L (90%) and 13.22 ± 0.15^a mg/L (94%). Thereafter, needful recommendations were suggested based on the physicochemical properties of the textile wastewater and to improve the functionality of the treatment systems in the respective industries.

Adsorption performance and mechanism of cationic and anionic dyes by KOH activated biochar derived from medical waste pyrolysis

The massive generation of medical waste (MW) results in a series of environmental, social, and ecological problems. Pyrolysis is one such approach that has attracted more attention because of the production of value-added products with lesser environmental risk. In this study, the activated biochar (ABC600) was obtained from MW pyrolysis and activated with KOH. The adsorption mechanism of activated biochar on cationic (methylene blue) and anionic (reactive yellow) dyes were studied. The physicochemical characterization of biochar showed that increasing pyrolysis temperature and KOH activation resulted in increased surface area, a rough surface with a clear porous structure, and sufficient functional groups. MB and RYD-145 adsorption on ABC600 was more consistent with Langmuir isotherm (R² ≥ 0.996) and pseudo-second-order kinetics (R² ≥ 0.998), indicating chemisorption with monolayer characteristics. The Langmuir model fitting demonstrated that MB and RYD-145 had maximum uptake capacities of 922.2 and 343.4 mg⋅g^-1. The thermodynamics study of both dyes showed a positive change in enthalpy (ΔH°) and entropy (ΔS°), revealing the endothermic adsorption behavior and randomness in dye molecule arrangement on activated-biochar/solution surface. The activated biochar has excellent adsorption potential for cationic and anionic dyes; hence, it can be considered an economical and efficient adsorbent.

Molecular response of Anoxybacillus sp. PDR2 under azo dye stress: An integrated analysis of proteomics and metabolomics

Treating azo dye wastewater using thermophilic bacteria is considered a more efficient bioremediation strategy. In this study, a thermophilic bacterial strain, Anoxybacillus sp. PDR2, was regarded as the research target. This strain was characterized at different stages of azo dye degradation by using TMT quantitative proteomic and non-targeted metabolome technology. A total of 165 differentially expressed proteins (DEPs) and 439 differentially metabolites (DMs) were detected in comparisons between bacteria with and without azo dye. It was found that Anoxybacillus sp. PDR2 can degrade azo dye Direct Black G (DBG) through extracellular electron transfer with glucose serving as electron donors. Most proteins related to carbohydrate metabolism, including acetoacetate synthase, and malate synthase G, were overexpressed to provide energy. The bacterium can also self-synthesize riboflavin as a redox mediator of in vitro electron transport. These results lay a theoretical basis for industrial bioremediation of azo dye wastewater.

Decolorization of safranin using Fissidens species and its ecotoxicological assessments: An in vitro and in silico approach

Decolorization of safranin was investigated using Fissidens species in a batch system under optimized conditions. The decolorization efficiency was improved by optimizing the conditions such as initial pH (3-9), temperature (25-45 °C), initial dye concentration (10-50 mg/L), biosorbent dosage (100-500 mg/L) and contact time (1-6 days). Maximum decolorization (95%) was recorded at initial pH of 6 with dye concentration of 20 mg/L, biosorbent dosage of 200 mg/L at 30 °C and contact time of 2 days. Desorption studies revealed 0.1 N NaOH as the best desorbing agent with 92% recovery on third day. Experimental data well fitted to Langmuir isotherm and Pseudo-second order kinetic model. The negative values of ΔG^o and positive value of ΔS^o and ΔH^o indicates that the reaction is spontaneous, favorable and endothermic. The biosorbent - dye interactions were confirmed using UV-Vis, FT-IR, XRD and FE-SEM with EDX studies. The detoxified nature of the dye degraded metabolites was confirmed by the significant growth of green gram. The color fastness and color strength of the fabrics dyed using Fissidens species treated dye solution were compared with the tap water dyed fabrics which indicated the reuse potential of treated water in textile sector. The decolorization efficiency was further confirmed through in silico approach, where safranin well docked with the active sites of Photosystem II protein D1 of the Fissidens species. Thus, the present study proves that Fissidens species is a promising biosorbent for safranin decolorization and will lay a platform for the control and management of environmental pollution.

Preparation and performance of acrylic acid grafted PES ultrafiltration membrane via plasma surface activation

A modified PES ultrafiltration membrane with excellent separation and antifouling properties was obtained after modification by remote Ar–NH3 plasma-induced acrylic acid (AA) grafting. Hydrophilic properties were characterised using water contact angle measurements. The morphology was analysed using SEM and BET measurements. Changes in the surface functional groups were determined using XPS and ATR-FTIR. The separation and antifouling properties were evaluated through a bovine serum albumin (BSA) separation experiment. The results revealed that the surface structure of the modified membrane was not destroyed, that amino groups were introduced on the surface of the PES membrane, and that AA was successfully grafted. The water contact angle decreased from 67° in the original membrane to 5 ± 0.63° in the modified membrane. The water flux increased from 30 to 93.6 L/(m2·h). The rejection rate of BSA increased from 61.5 to 93.8%, and the flux recovery rate increased from 60.0 to 92.3%.

Effect of Textile Wastewater Secondary Effluent on UF Membrane Characteristics

The influence of textile wastewater (TWW) secondary effluent on ultrafiltration (UF) membrane characteristics was investigated. TWW treated with a membrane bioreactor was subjected to four commercial UF membranes (2, 3, 5, and 10 kDa). Both the pristine membranes and the membranes after TWW secondary effluent treatment were characterized. Surface roughness, microscopic analysis of the membrane surface and cross-section, zeta potential, contact angle, membrane composition, and membrane flux were compared. After treatment of secondary effluent, the zeta potential decreased for 5 and 10 kDa membranes, while the contact angle and surface roughness increased for all investigated membranes. In addition, a fouling layer formed on all membranes, and new interactions with pollutants and membranes were confirmed. Membranes with larger pores (5 and 10 kDa) showed a greater decrease in permeate flux during treatment. Detailed analysis showed variations in membrane characteristics after TWW secondary effluent treatment, indicating the stability of the membranes used.

Integrated physical-biological treatment system for batik industry wastewater: A review on process selection

Batik is well known as one of the unique identifiers of the Southeast Asian region. Several countries that still preserve the batik heritage are Malaysia, Indonesia, China and India. The Batik industry holds a significant place in Malaysia's craft-based industry. In Malaysia, batik motifs and patterns are mostly hand-drawn and painted directly on fabric, therefore, each one is unique. The players in the Batik industry are mostly small businesses and cottage industries, particularly in the states of Kelantan, Terengganu, Pahang, Sabah and Sarawak. However, their market growth and contribution are not synchronized with the treatment system. The wastewater generated by this industry rarely meets standard effluent requirements and regulations, thus worrying the authorities. Batik wastewater is categorized as one of the highly polluted wastewaters. The toxicity of pollutants from batik may reduce environmental quality and pose a risk to human health. Batik wastewater needs extensive treatment, since no complete and appropriate treatment has been applied for so many years in specific batik industries. This paper reviews the batik industry in Malaysia, its wastewater generation and the available current treatment practices. It discusses integrated treatments of coagulation-flocculation and phytoremediation technology as a batik wastewater treatment process with potential utility in the batik industry. This review may become part of the guidance for the entire batik industry, especially in Malaysia.

Study and evaluation of the characteristics of saline wastewater (brine) produced by desalination and industrial plants

Desalination and industrial plants all around the world generate large amounts of saline wastewater (brine). The discharge of brine from facilities poses a severe environmental threat, while at the same time, the opportunity to recover resources is being lost as discharged brine is rich in valuable metals that could be recovered as salts/minerals. To this aim, this study presents and analyzes for the first time the characteristics of different brine effluents (from industries such as desalination, oil and gas production, petrochemical, aquaculture, pharmaceutical, textile) to prevent environmental pollution and to recover valuable resources (i.e., salts, minerals, metals, chemicals) enabling the concept of waste-to-resource (circular water economy model). The results revealed that the common salinity values in brine effluents range from 0.5 to 150 g/L, while the only exception is the produced water from the oil and gas industry (up to 400 g/L). Brine effluents from all sectors contain sodium, chloride, calcium, and potassium ions in high concentrations, while the production of common salts such as NaCl, CaCl₂, and MgCl₂ from brine can be economically profitable. Besides common ions, precious metals such as lithium, rubidium, and cesium are present in low concentrations (<25 mg/L); however, their extraction from brine effluents can be significantly profitable due to their very high sale price. The treatment and valorization of brine can be implemented by the hybridization of membrane-based, chemical, biological, and thermal-based technologies/processes in minimal and zero liquid discharge (MLD/ZLD) systems.

Modification of polyethersulfone membranes by Polyethyleneimine (PEI) grafted Silica nanoparticles and their application for textile wastewater treatment

In the current work, a novel nanocomposite membrane for wastewater treatment applications has been synthesized. A hydrophilic nature nanoadditive comprised grafting polyethylenimine (PEI) molecules onto the surfaces of silica nanoparticles (SiO₂ NPs) was synthesized then entrapped within a polyethersulfone polymeric matrix at disparate ratios via the classical phase inversion technique. A series of experimental tools were employed to probe the influence of SiO₂-PEI on the surface topography and morphological changes, hydrophilicity, porosity, surface chemistry as well as permeation and dyes retention characteristics of the new nanocomposite. Upon increasing the nanoadditives content (up to 0.7 wt. % SiO₂- PEI), clear cross-sectional changes were depicted along with a noticeable decline in the water contact angle by 29.7%. Performance evaluation measurements against synthetic dye solutions were disclosed explicit enhancement in both; retention and permeation characteristics of the nanocomposite membranes. Besides, prolonged permeation test has maintained high flux stability against real textile wastewater; implying better resistance and self-cleaning characteristics have been achieved.

Role of Plasmid in Pesticide Degradation and Metal Tolerance in Two Plant Growth-Promoting Rhizobacteria Bacillus cereus (NCIM 5557) and Bacillus safensis (NCIM 5558)

Disha A (Bacillus cereus) and Disha B (Bacillus safensis) were isolated from pesticide-infested agricultural field and showed tolerance against pesticides, heavy metals, and antibiotics. The isolates exhibited PGPR activities in vitro as well as in field conditions in lentil (Lens culinaris) and cow pea (Vigna unguiculata). Both the Bacillus species could not be grown in mineral salt medium but efficiently grown in the media supplemented with pesticide (imidacloprid/carbendazim) demonstrating the utilization of pesticide as carbon/nitrogen source. The HPLC studies exhibited the pesticide (imidacloprid/carbendazim) degradation by both the bacteria. B. safensis showed better degradation of carbendazim (88.93%) and imidacloprid (82.48%) than that of B. cereus 78.07% and 49.12%, respectively. The bacterial isolates showed high concentration of heavy metal tolerance viz. lead, molybdenum, cadmium, copper, cobalt, and zinc, except mercury. Both the bacteria possessed single plasmid. The plasmid-cured isolates of B. cereus did not tolerate any pesticide, whereas that of B. safensis tolerated all the pesticides, like wild strains. The plasmid curing experiments did not affect the heavy metal tolerance ability of both the bacteria indicating the genomic nature of heavy metal tolerance genes, whereas pesticide resistance genes are plasmid-dependent in B. cereus but genomic in B. safensis.

Low-pressure highly permeable polyester loose nanofiltration membranes tailored by natural carbohydrates for effective dye/salt fractionation

With the continuous pressure of water contamination caused by textile industry, loose nanofiltration (LNF) membranes prepared by green materials with an extraordinary water permeability are highly desirable for the recovery and purification of dyes and salts. In this work, low-pressure LNF membranes with ultrahigh permeability were fabricated via one-step interfacial polymerization (IP), in which inexpensive natural carbohydrate-derived sugars with large size and low reactivity were utilized as aqueous monomers to design selective layer. A systematic characterization by chemical analysis and optical microscopy demonstrated that the formed polyester film features not only loosen the structure, but also results in a hydrophilic and negatively charged surface. The optimized sucrose-based membrane (Su0.6/TMC0.1) with an excellent water permeability of 52.4 LMH bar^-1 was found to have a high rejection of dyes and a high transmission of salts. In addition, the sugar-based membrane manifested an excellent anti-fouling performance and long-term stability. Furthermore, the non-optimized Gl0.6/TMC0.1 and Ra0.6/TMC0.1 membranes also shown a high water permeability, while maintaining a competitive dye/salt separation performance, which confirmed the universal applicability of the membrane design principle. Therefore, the proposed new strategy for preparing next-generation LNF membranes can contribute towards the textile wastewater treatment.

Treatment of Textile Wastewater Using Advanced Oxidation Processes—A Critical Review

Textile manufacturing is a multi-stage operation process that produces significant amounts of highly toxic wastewater. Given the size of the global textile market and its environmental impact, the development of effective, economical, and easy-to handle alternative treatment technologies for textile wastewater is of significant interest. Based on the analysis of peer-reviewed publications over the last two decades, this paper provides a comprehensive review of advanced oxidation processes (AOPs) on textile wastewater treatment, including their performances, mechanisms, advantages, disadvantages, influencing factors, and electrical energy per order (EEO) requirements. Fenton-based AOPs show the lowest median EEO value of 0.98 kWh m−3 order−1, followed by photochemical (3.20 kWh m−3 order−1), ozonation (3.34 kWh m−3 order−1), electrochemical (29.5 kWh m−3 order−1), photocatalysis (91 kWh m−3 order−1), and ultrasound (971.45 kWh m−3 order−1). The Fenton process can treat textile effluent at the lowest possible cost due to the minimal energy input and low reagent cost, while Ultrasound-based AOPs show the lowest electrical efficiency due to the high energy consumption. Further, to explore the applicability of these methods, available results from a full-scale implementation of the enhanced Fenton technology at a textile mill wastewater treatment plant (WWTP) are discussed. The WWTP operates at an estimated cost of CNY ¥1.62 m−3 (USD $0.23 m−3) with effluent meeting the China Grade I-A pollutant discharge standard for municipal WWTPs, indicating that the enhanced Fenton technology is efficient and cost-effective in industrial treatment for textile effluent.