Treatment of textile wastewater using electrocoagulation, electrochemical peroxidation, and integrated electrochemical peroxidation-nanofiltration processes

This study reports, for the first time, on the assessment of a multistage sequential system composed of coagulation–flocculation with different electro-Fenton-based configurations, followed by neutralization (N), for the treatment of raw textile wastewater heavily contaminated with acid black 194 dye and other pollutants. Electrochemical peroxidation (ECP-N), electro-Fenton (EF-N) and peroxi-coagulation (PC-N) were tested at laboratory scale and compared in terms of their efficiency for the removal of organic matter and color, current efficiency and energetic parameter, operating cost and environmental sustainability using life cycle analysis conducted in large-scale virtual reactors. The three electro-Fenton-based systems complied with current environmental standards (color removal > 87%, COD < 400 mg/L, among others) requiring different electrolysis times: ECP-N (52 min) < PC-N (120 min) < EF-N (160 min); energy consumptions: ECP-N (2.27 kWh/m3) < PC-N (4.28 kWh/m3) < EF-N (33.2 kWh/m3); operational costs: ECP-N (2.63 USD/m3) < EF-N (6.65 USD/m3) < PC-N (6.98 USD/m3); among others. Electricity (for ECP-N and EF-N) and reagents (for ECP-N and PC-N) were found as main environmental hotspots. ECP-N presented the lowest carbon footprint of 10.3 kg CO2-Eq/FU (<PC-N (26.3 kg CO2-Eq/FU) < EF-N (38.0 kg CO2-Eq/FU), had lower incidence in all the impact categories analyzed (ReCiPe-2016 at midpoint level) and can be considered technically, economically and environmentally sustainable for large-scale applications.

The current study covers the textile wastewater (TW) treatment by the electrochemical (EC) method in individual and hybrid modes. The EC experiments have been performed to optimise the operating parameters and current: 1 A, NaCl dose: 1 g/L; solution pH: 7; IED: 1.5 cm and stirrer speed: 1000 RPM have been optimised during the experimental study. Furthermore, the effect of bagasse fly ash (BFA) and bagasse fly ash-based nanoparticles (BFA-NC) adsorbent on the EC process has been studied. By adding 1 g/L of BFA and BFA-NC in the EC process, the % COD removal is increased from 86 to 92 and 97%, respectively. While the treatment time is reduced from 60 to 45 & 30 min, respectively. Overall, INR 74.59, 59.61 and 41.04 per kg COD removal is needed for EC, EC + BFA & EC + BFA-NC, respectively for TW treatment. The sludge/scum can produce 2.37, 3.32 and 3.39 J/mg energy generated EC, EC + BFA & EC + BFA-NC, respectively.

Treatment of the highly polluting and variable textile industry wastewater using aerobic granular sludge (AGS) sequencing batch reactors (SBRs) has been recently suggested. Aiming to develop this technology application, two feeding strategies were compared regarding the capacity of anaerobic-aerobic SBRs to deal with disturbances in the composition of the simulated textile wastewater feed. Both a statically fed, anaerobic-aerobic SBR and an anaerobic plug-flow fed, anaerobic-aerobic SBR could cope with shocks of high azo dye concentration and organic load, the overall chemical oxygen demand and color removal yields being rapidly restored to 80%. Yet, subsequent azo dye metabolite bioconversion was not observed, along the 315-day run. Moreover, switching from a starch-based substrate to acetate in the feed composition deteriorated AGS stability. Overall, the plug-flow fed SBR recovered more rapidly from the imposed disturbances. Further research is needed towards guaranteeing long-term AGS stability during the treatment of textile wastewater.

The use of experimental design for the evaluation of the influence of variables on the H 2O 2/UV treatment of model textile waste water

BackgroundThe textile industry represents a great portion of the global industry due to the increase in population and demand for sustainable products. Tons of textile wastewater contain predominantly synthetic complex organic dyes like direct dyes, processing dyes, reactive dyes, etc., making discharge of colored effluents challenging.Main body of the abstractTextile wastewater treatment is essential to maintain the environmental balance and reduce public health threats. Conventional wastewater treatment methods cannot overcome and decompose these toxic wastes; therefore, numerous modern approaches have been studied and implemented for pollutant degradation to be suitable for environmental disposal. Membranes and photocatalysis have proven their significant effect on the photodegradation of different dyes and the production of pure water for further use in industrial purposes.Short conclusionThis review paper aims to represent a comprehensive review of textile dyeing wastewater treatment by integrating polyvinylidene fluoride (PVDF) and titanium dioxide (TiO2) in a hybrid system named “photocatalytic membrane reactor, PMR”.

Treatment of Pre-treated Textile Wastewater using Moving Bed Bio-film Reactor

Novel pebble bed photocatalytic reactor for solar treatment of textile wastewater

A feasibility study was carried out in the laboratory for the sequential anaerobic/aerobic treatment of textile wastewater. The process units consisted of an anaerobic UASB (upflow anaerobic sludge blanket) reactor and a SCAS (semi-continuous activated sludge) reactor. A contact-sorption layer with GAC (granular activated carbon) was provided at the bottom of the conventional UASB reactor. The raw textile wastewater first passed through the GAC bed and then through the sludge bed. By means of the GAC bed, the top-layer granular sludge was protected from toxicants. Biological regeneration of GAC, which was enhanced via a recycle flow, was demonstrated. The combined GAC-UASB and SCAS treatments allowed a stable performance and a COD (chemical oxygen demand) and colour removal of 98 and 95 %, respectively.

Feasibility of concentrating textile wastewater using a hybrid forward osmosis-membrane distillation (FO-MD) process: Performance and economic evaluation

Treatment of synthetic textile wastewater containing Acid Red 182 by electro-Peroxone process using RSM

Applicability of a new pre-hydrated industrial grade polyaluminium salt for the decolourisation of textile wastewater

This study investigated the water recovery of real textile wastewater by Coagulation/Flocculation (CF) integrated with Direct Contact Membrane Distillation (DCMD). The proof-of-concept tests were studied with synthetic solutions of reactive and disperse black dyes at different concentrations, and real textile wastewater from the discharge machine and the equalization tank. Results showed that CF-DCMD exhibited higher permeate fluxes (up to 40%) than single DCMD and maximum color rejection rates (100%). Moreover, CF-DCMD enabled water reclamation from cotton and polyester dyeing wastewater which was not possible by MD (Membrane Distillation). The integrated system showed excellent chemical oxygen demand removal capacity, total suspended solids, turbidity, conductivity reduction, and removed any signs of toxicity from the tested wastewater. The coagulation/flocculation process prior to the MD reduced the fouling factor for all wastewater, highlighting the equalization tank where a reduction of around 72% was observed, achieving the goal of reducing fouling and increasing the efficiency of the MD. Membrane characterization indicated that CF-DCMD confirmed less fouling of membranes than single DCMD. Thus, this study allows to understand the potential and robustness of the CF-DCMD process in the treatment of textile wastewater and that it is possible to develop alternative technologies to treat complex wastewater effectively.

Wastewater from the textile industry is highly colored and of a complex and variable nature. The substantial amount of dyestuffs used in the dyeing stage of textile manufacturing processes represents an increasing environmental danger due to their refractory nature [1]. The treatment of textile wastewater by conventional methods such as biological and chemical processes or their combination are in common practice but have several drawbacks, e. g. inefficient color removal and/or the formation of toxic by-products [2]. On the other hand, electrochemical oxidation is a very promissory process for refractory pollutants degradation since no chemical reagents are needed and no secondary wastes are formed.In the present study, electrochemical degradation experiments were conducted to degrade a textile dyes namely indigo carmine (IC) and reactive black 5 (RB). A FM01-LC reactor was used to investigate the effect of various operating parameters using a dimensionally stable anode (DSA, Sb2O5-doped Ti/RuO2-ZrO2). The oxidation of IC and RB takes place in the bulk solution with electrolytically generated active chlorine (chlorine, hypochlorite ion and hypochlorous acid). Figure 1 shows the normalized color decay. For the indigo carmine decolorization occurs in 80 min, whereas for the reactive black it takes 2 h. The difference in the time of decolorization is due to the structure of each dye the structure of reactive black 5 is larger than that of indigo carmine.[1] Balcioglu I.A., Arslan I. and Sacan T. Homogenous and heterogenous advances oxidation of two commercial reactive dyes, Environment technology, 22 (2001), pp. 813-822.[2] Rajkumar D., Joo Song B. and Guk Kim J., Electrochemical degradation of Reactive Blue 19 in chloride medium for the treatment of textile dyeing wastewater with identification of intermediate compounds, Dyes and Pigments, 72 (2007), pp. 1-7.

Treatment of textile wastewater using sequential sulfate-reducing anaerobic and sulfide-oxidizing aerobic membrane bioreactors

This study aimed to evaluate the effectiveness of the electro-Fenton process in the treatment of textile wastewater using carbon felt modified with graphene nanoparticles as the cathode and a thin film of platinum as the anode. The primary characteristics of wastewater, including COD, color, BOD5, pH, electrical conductivity (EC), and chlorides, were measured. Factors affecting the efficiency of the electro-Fenton process were studied. The optimum conditions were determined as follows: the inlet airflow of 1 (L/min), pH=2.5, the current intensity of 200 mA, and ferrous ion concentration of 1.5 mM. Based on the results maximum system decolorization and COD removal rates were 94.31% in 120 minutes and 57.47% in 30 minutes of reaction respectively. Dye removal efficiency increases due to graphene particles on the carbon felt and increasing surface area. Also, the application of the platinum electrode and the role of this electrode in anode oxidation causes an increase in the efficiency of dye removal. Because the electro-Fenton process is carried out at acidic pH, it is necessary to conduct pH modification on the final effluent of this process.