Color Removal Efficiency Research Articles

Magnetic coagulant derived from Cassia fistula seed for real textile wastewater treatment: A pilot-scale study

Cassia fistula (C. fistula) seed-derived coagulants have demonstrated substantial potential for treating dye-based wastewater. Such coagulants exhibit notable coagulating-flocculating activity and are environmentally friendly. However, recovering these natural coagulants from aqueous media poses challenges. In this study, we introduce a novel plant-derived magnetic coagulant that is a combination of C. fistula seed gum with magnetic spinel ferrite. This research includes a pilot-scale study to simulate full-scale textile wastewater treatment using this composite. Material characterisations revealed that spherical CoFe2O4 particles could be effectively coated with the active coagulant, C. fistula gum. The saturation magnetisation of the composite, measured at 54.11 emu/g, facilitates its convenient separation from aqueous solutions using an external magnetic field. Bench-scale studies showed that initial pH and coagulant dosage substantially affect the removal efficiency of colour and chemical oxygen demand (COD). In the pilot-scale study, the C. fistula–CoFe2O4 composite demonstrated promising coagulant properties. It achieved a colour removal percentage of 94.0 % with a volume of 30 L and a coagulant dosage of 12.3 g L− 1. Using this coagulation–flocculation process as a primary treatment step, possibly followed by biological or membrane methods, can help meet Vietnamese environmental standards.

Comparing efficacy of anodic and cathodic chambers in a low-cost algae-assisted microbial fuel cell for textile wastewater remediation

Remediation of industrial textile effluent using both the anodic and cathodic chambers of an algae-assisted microbial fuel cell (AMFC) is demonstrated and evaluated in this study. A low-cost AMFC is developed using clayware as the anode compartment housed inside a plastic bucket which acts as the cathode chamber. A comparative analysis of textile wastewater (TWW) treatment in both chambers is presented. Four treatment configurations were considered, namely T1 (only cathode supplied with TWW), T2 (both cathode and anode supplied with TWW), T3 (only anode supplied with TWW) and the control AMFC (no TWW was added in any compartment). It was observed that the bacterial populations in the anodic compartment were more adapted towards TWW than the microalgae in the cathodic chamber. The color removal efficiency by the anode and cathode chamber was respectively 89.55% and 40.53%. The COD removal was 94% and 48% from the anodic and cathodic chambers respectively. The T3 AMFC with effluent being supplied only to the anode chamber exhibited the highest power and current density of 2.1 W/m3 and 8 A/m3. The proposed system was able to degrade dyes from real textile wastewater and simultaneously generate bioelectricity and algal biomass.

Aluminum Waste as Electrode for Home Textile Industry Wastewater Treatment using Batch Electrocoagulation Process: Studies on Operating Parameters

The manufacture of the Sasirangan home textile industry involves coloring and dyeing processes using synthetic dyes in large quantities. These contaminants of dyes and organic materials would cause high color and chemical oxygen demand (COD) contaminants values. This study aims to characterize the wastewater of batik-modified Sasirangan and determine the effect of current density and length of operating time on color removal and reduction of COD in Sasirangan home textile industry wastewater through the batch electrocoagulation process. The method used in this research is an electric current flowing in the same direction to the Sasirangan home textile industry wastewater in a reactor with dimensions of 310 180 240 mm3. The electrode used is aluminum alloy type 1100. The aluminum/aluminum (Al/Al) electrode is used in this electrocoagulation (EC) process, then connected to a direct current (DC) power supply. The experiment was carried out at room temperature using an electrode distance of 2 cm with variations in the time of the electrocoagulation process for 15–120 minutes. The experiment was repeated for variations in pH (4–9) with a current density of 3.5–5.5 mA/cm2. Furthermore, an analysis of the color removal and the decrease in the concentration of COD was carried out. The results showed that the contaminant content in Sasirangan home textile industry wastewater decreased significantly, whereas the optimal conditions for the EC reaction were determined using color and COD removal efficiency parameters. The decrease in color and COD concentrations occurred at a current density of 5.5 mA/cm2 with a pH of 4 for 120 minutes, around 1110 PtCo and 90.4 mg/L of COD, respectively

Study on COD and color removal efficiency in textile dyeing wastewater by iron electro-coagulation technology combined with persulfate

Electrocoagulation (EC) is an attractive method for treating many types of wastewater due to its advantages. The purpose of this study is to investigate the effect of persulfate addition on the efficiency of textile wastewater treatment through the removal percentage of COD and color parameters. Persulfate is proven to significantly enhance the rate and efficiency of pollutant removal in textile wastewater. The removal percentage of COD could reach 91.33 ± 1.23% and 97.99% ± 0.52% was the highest removal percentage of the color parameter at the optimal reaction parameters. The effluent concentration meets the standards according to Vietnam national technical regulation on textile industry wastewater. By using persulfate, the COD and color removal efficiency increased by 17.53 ± 2.69% and 8.81 ± 0.91%, respectively, compared to the single electrocoagulation process. The amount of sludge generated in the system is 0.542 ± 0.0357 kg/m3, significantly reduced compared to the flocculation process of 0.875 ± 0.0295 kg/m3.

In-situ anion-exchange construction of Z-scheme Ag3PO4/AgI, derived AgCl/Ag3PO4/AgI and Ag2CO3/Ag3PO4/AgI composites with multiple redox energy bands and charge transfer pathways for efficient absorption and sonocatalytic properties

Z-scheme Ag3PO4/AgI composites were synthesized by facile in-situ anion-exchange method at room temperature (RT). All the catalysts have excellent affinity to dyes and adsorb larger than 70 % of Methyl blue. The fastest adsorption equilibrium of Ag3PO4 (qe: 25.9278 mg/g) with low specific surface area (SSA: 4.6624 m2/g) can be rapidly attained for 6 min. The best color removal efficiency (RE) for Methyl blue over all the composites can rapidly increase to 100 % within 45 min. Meanwhile, the highest RE for RhB over S3 is 98.9 % for 60 min, and corresponding rate constant (k) is 0.07018 min−1. After adding NaCl or Na2CO3 into sonocatalysis, because of the formation of novel ternary AgCl/Ag3PO4/AgI and Ag2CO3/Ag3PO4/AgI during sonocatalytic process, the best REs for RhB over S3 composite increase from 89.8 % (no scavenger) to 98.2 % (1.2 mM NaCl), or to 97.6 % (1.8 mM Na2CO3) for 30 min, respectively, and the REs for Methyl blue over S3 are about 100 % for 10 min. From single Ag3PO4 to binary Ag3PO4/AgI, and to ternary Ag2CO3/Ag3PO4/AgI or AgCl/Ag3PO4/AgI, REs are significantly enhanced. New redox energy bands and charge transfer channels lead to efficiently spatial charge separation and further activation of hole (h+), superoxide anions (·O2−), hydroxyl radicals (·OH). Additionally, the relation among oxygen vacancies (Ov), Zeta potential and RE was discussed in detail. Density functional theory (DFT) calculations were used to make clear charge transfer and sonocatalytic mechanism. The evaluation of used samples, adsorption kinetics and modes, diverse degradation pathways and sonocatalytic mechanisms were also discussed in detail. The work provides a novel in-situ strategy for real-time control of catalytic performance by rapidly forming new phase during catalysis at RT. Furthermore, the strategy obviously facilitates real-time development of rare more than ternary composites for enhanced catalytic performance.

Heavy metals removal from industrial wastewater using date seeds powder and aluminum chloride-based hybrid natural/chemical coagulation

High levels of heavy metals in industrial wastewater pose a significant environmental concern due to their toxicity to living organisms and ecosystems. Traditional techniques that use chemical coagulants to eliminate heavy metals from industrial wastewater have proven effective. However, the use of chemical coagulants produces sludge that is highly toxic and requires careful management. On the other hand, natural coagulants offer a cost-effective and sustainable alternative that is safer to handle, locally available, and potentially useful for resource recovery. These benefits make natural coagulants a promising substitute for chemical coagulants. This study aimed to investigate the performance of combining Date stone powder (DSP) and aluminum chloride (AlCl3), to remove heavy metals from industrial wastewater efficiently. Through an optimization process of DSP/AlCl3 dosage and pH, the study sought to determine the optimal conditions for heavy metal removal. The main findings indicate that a DSP/AlCl3 dosage of 7:1 (g/g) was the most effective coagulant dosage, resulting in high removal efficiencies for COD (88.56%), color (89.56%), TSS (99.00%), NH3-N (92.50%), Mn (94.10%), Fe (95.47%), Zn (93.57%), Al (88.42%), and Ni (93.3%) at pH 8. Interestingly, the results of pH optimization showed that no pH modification was necessary, as it already achieved high removal efficiencies for COD (84.57%), color (88.94%), TSS (99.00%), NH3-N (92.25%), Mn (92.66%), Fe (90.57%), Zn (95.59%), Al (99.00%), and Ni (93.33%). This study demonstrates that the hybrid DSP/AlCl3 coagulation method can be an effective and sustainable solution for removing heavy metals from industrial wastewater. However, further research is necessary to assess its scalability and potential limitations.

Modification of Agro-wastes Reinforced onto the PET Fabric for Decolorisation of Palm Oil Mill Effluent

The abundance of agricultural wastes from various industrialized processes has become one of the significant contributors to water pollution, particularly in the color of effluents from industrial-based palm oil mills. Inventively, this research focused on three different agro-wastes: pineapple leaves (PL), rice straw (RS), and empty fruit bunch (EFB) reinforced onto PET fabric composite and its decolorization performances by using palm oil mill final effluent discharged (POME-FED). The calcinated agro wastes/polyvinylidene fluoride (PVDF) reinforced onto the polyethylene terephthalate (PET) fabrics were prepared by using the dip-coating technique and characterized via Scanning Electron Microscopy (SEM-EDS), spectroscopy (FTIR-ATR), turbidity and color of POME-FED. It was found that the calcinated PL/PVDF/Fabric displayed the best performance in the turbidity and decolorization by 12.02 NTU, 760 ADMI, and ~60% color removal efficiency as compared with raw POME-FED (~1800 ADMI). Nevertheless, the decolorization efficiencies of RS/PVDF/Fabric and EFB/PVDF/Fabric had increased by ~37 % and ~49 %, respectively. It shows that the formation of a reinforcing layer on the PET fabric surface has improved the transparency of POME-FED. The SEM micrographs and the change of peaks at regions 1650 cm-1, 1450 cm-1, 1210 cm-1, and 990 cm-1 in composites' spectroscopies demonstrate the different patterns of these calcinated samples are various patterns that impart the strength of the composite fabric surface functionality and hydrophobicity. The reduction of the color value of effluent showed the hydrophobicity of the integrated palm oil waste coated with PET, which enables to trap of the particles in the effluent, thus this composite has potential use in the filtration of water treatment.

A Fenton-based approach at neutral and un-conditioned pH for recalcitrant COD removal in tannery wastewater: Experimental test and sludge characterization

The combination of raw animal skin manufacturing processes involves the use of large amounts of chemicals, resulting in the generation of complex and highly polluted tannery wastewater. In this context, the high concentration of chloride in tannery wastewater represents a crucial bottleneck. Indeed, sodium chloride, commonly used in tannery industry to prevent skin rot, increases the concentration of chlorides up to 50 %. At the same time, most of the advanced oxidation processes usually employed in tannery wastewater treatment to remove recalcitrant COD involve the use of conditioning agents, thus increasing the overall concentration of chlorides in the treated effluent. The aim of this study was to evaluate the electrochemical peroxidation process (ECP) efficiency in the treatment of tannery wastewater without changing pH, to improve Fenton technology by avoiding the use of chemicals. The influence of different electric currents on COD and color removal was investigated. The characterization of the produced sludge was conducted through FTIR, SEM and XRD analysis, exploring the morphology and composition of precipitate, depending on the applied current. Although an electrical current of 750 mA yields the highest COD and color removal efficiency (69.7 % and 97.8 %, respectively), 500 mA can be considered the best compromise because of energy consumptions. Iron oxides and hydroxides were generated during the ECP process, playing the role of coagulants through the absorption of organic and inorganic contaminants. The consumption of energy increased as a function of time and applied current; however, cost analysis showed that the electrodes contributed the most to the total cost of the process. In authors' knowledge, the application of ECP process as a tertiary treatment for the removal of recalcitrant COD in tannery wastewater represents a novelty in the literature and the results obtained can be considered as the basis for scaling up the process in future research.

Actas Pink-2B dye removal in biochar nanocomposites augmented vertical flow constructed wetland (VF-CWs)

Industries generate hazardous dye wastewater, posing significant threats to public health and the environment. Removing dyes before discharge is crucial. The ongoing study primarily focused on synthesizing, applying, and understanding the mechanism of green nano-biochar composites. These composites, including zinc oxide/biochar, copper oxide/biochar, magnesium oxide/biochar, and manganese oxide/biochar, are designed to effectively remove Actas Pink-2B (Direct Red-31) in conjunction with constructed wetlands. Constructed wetland maintained pH 6.0–7.9. At the 10th week, the copper oxide/biochar treatment demonstrated the highest removal efficiency of total suspended solids (72%), dissolved oxygen (7.2 mg/L), and total dissolved solids (79.90%), followed by other biochar composites. The maximum removal efficiency for chemical oxygen demand (COD) and color was observed at a retention time of 60 days. The electrical conductivity also followed the same order, with a decrease observed up to the 8th week before becoming constant. A comprehensive statistical analysis was conducted, encompassing various techniques including variance analysis, regression analysis, correlation analysis, and principal component analysis. The rate of color and COD removal followed a second-order and first-order kinetics, respectively. A significant negative relationship was observed between dissolved oxygen and COD. The study indicates that employing biochar composites in constructed wetlands improves textile dye removal efficiency.

Multivariate optimization of organic matter and color removal from textile dyeing industry wastewater by ultraviolet-activated oxidants

This study investigated the efficiency of ultraviolet (UV) activation of the oxidants that are used in advanced oxidation processes in textile dyeing industry wastewater treatment with high concentrations of refractory organic matter and strong color. The effect of peroxymonosulfate (PMS), peroxydisulfate (PS), hydrogen peroxide (HP), percarbonate (PC), and chlorine as oxidants in UV-based processes was first evaluated. The two processes with the greatest removal efficiency were determined as UV/PS and UV/PMS. Then the operating parameters for UV/PS and UV/PMS were optimized by the Box-Behnken Design (BBD). Process parameters for both processes were oxidant dosage, initial pH, and reaction time whereas system responses were chemical oxygen demand (COD), UV254, and color removal efficiency. Under optimum conditions in the UV/PS process (pH 5.54, PS dosage 24.4 mM, and reaction time 117 min), COD, UV254, and color removal efficiency were 83.21 %, 92.14 %, and 93.87 %, respectively. Under optimum conditions in the UV/PMS process (pH 5.83, PMS dosage 23.1 mM, and reaction time 120 min), COD, UV254, and color removal efficiency were 66.89 %, 78.45 %, and 96.89 %, respectively. The R2 of all the models that applied for the system responses of both processes was nearly one and the adj R2 values were very near to the R2 values. These findings showed that the BBD is efficient, suitable, and significant in modeling the removal of pollutants in textile dyeing industry wastewater by UV/PS and UV/PMS processes. Electrical Energy per Order (EE/O) calculations for UV/PS and UV/PMS processes were 101 and 167 kWh/m3 for optimum conditions, respectively. The results showed that both UV/PS and UV/PMS processes are effective; however, the UV/PS process is more economical and effective concerning pollutant removal efficiency and EE/O calculations.

REMOVAL OF DIRECT BLUE DYE IN TEXTILEWASTEWATER EFFLUENT BY ELECTROCOAGULATION

Removal of direct blue dye by electrocoagulation method has been investigated using aluminum electrode in a bench-scale electrochemical system. Current density, NaCl concentration, electrocoagulation time, and dye concentration has been studied as effecting parameters in color removal efficiency. Increasing of current density will increase the color removal efficiency and energy consumption as well. While increasing NaCl concentration increase the color removal efficiency but it decrease energy consumption. High dye concentration is needed for extra electrocaogolation time to reach the same efficiency that obtained with low dye concentration .With current applied 0.35 amps. and NaCl concentration of 2 g/l more than 93% efficiency achieved in 14 min. of electrocaogolation time.

THE EFFECT OF IMMOBILIZED ENZYME ON TEXTILE WASTEWATER

Textile wastewater has a complex composition characterized by high dye content and chemical oxygen demand. Therefore, textile wastewaters have serious environmental impacts, such as aesthetic degradation, and carcinogenic properties. Treatment and the recovery of textile wastewater are important due to their high volume and toxicity. The effects of peroxidase enzyme immobilized on magnetic chitosan-clay beads of synthetic textile wastewater were investigated in a batch reactor. System performance was determined by chemical oxygen demand (COD) and color. The batch reactor was operated in three different pH (5, 7, 10), temperatures (25, 35, 45 °C), and reaction times (0-5-10-20-30 min.) with synthetic textile wastewater. As a result, COD and color removal efficiencies were determined as 44% and 56%, respectively, corresponding effluent concentrations are 1442 mg/L, 450 Pt-Co. The results of this study show that using the enzyme immobilization process is an effective method to remove color and COD concentration from textile wastewater.

Selection of White-Rot Fungi for Decolorization of Palm Oil Mill Effluent and Evaluation of Biodegradation and Biosorption Processes

Ten species of white-rot fungi were evaluated for their ability to decolorization of palm oil mill effluent. The highest decolorization efficiency was found with Trametes elegans (PP17-06), followed by Ganoderma sp.2 (PW17-06) and Ganoderma sp.2 (PW17-177), respectively. T. elegans was further evaluated for the long-term performance of decolorization for 24 d. The optimal retention time for the decolorization was 8 d, with a color removal efficiency of 47.7%. Beyond 18 d of incubation, decolorization efficiency was reduced due to the autolysis of enzymes. During the biodegradation process, manganese peroxidase enzyme activities reached a maximum of 36.03 U.L−1. However, no significant laccase and lignin peroxidase activities were observed. T. elegans was also assessed for decolorization performance through biosorption on mycelial biomass. The synthesis of the enzyme was prevented by exposing the mycelium to HgCl2. Within an optimal contact time of 2 d, decolorization efficiency reached 12.5% with ADMI reduction from 4259.0 (±20.1) ADMI to 3727 (±104.04) ADMI. Results indicate that the adsorption capacity was reached at this time, and no significant color removal can be achieved by biomass. Results obtained in this study showed the potential of T. elegans in decolorizing palm oil mill effluent.

Electrocoagulation (EC) treatment of model wastewater containing Rhodamine B

The colour removal of synthetic Rhodamine B (RhB) wastewater by using the electrocoagulation (EC) process in batch mode utilizing commercially available iron plates as electrodes was investigated. The colour removal (%) was calculated for the EC process by taking into account the effects of several factors such as pHi, current density, RhB concentration and temperature. When NaCl was utilized as the electrolyte for EC, the efficiency of colour removal was enhanced. At the optimal experimental conditions (pHi 7.0, 100 A/m2, 50 ppm RhB concentration, 30 minutes, 30 oC and 0.075 M NaCl concentration), the colour removal (%) was 87.27 %. The negative values of ΔH° and ΔS° and ΔG° indicate that the adsorption process was spontaneous in nature and unfavorable at higher temperatures. The electrical energy consumption was assessed to be 2.44 KWh/m3. Characterization of the sludge was also carried out.

Treatment of wet coffee processing wastewater using a pulsed-electrocoagulation process: optimization using response surface technique

In this study, the removal efficiency of chemical oxygen demand (COD), color, turbidity, phosphate, and nitrate from wet coffee processing wastewater by pulsed-electrocoagulation process (PECP) was examined with various factors such as pH: 3–11, reaction time: 15–75 min, current: 0.150–0.750 Amp, and electrolyte concentration: 0.25–1.25 g/L. Several operational parameters for the treatment of wet coffee processing wastewater utilizing the PECP have been optimized through the application of the surface response design technique, which is based on the central composite design. A quadratic model helped estimate the percentage removal of COD, color, turbidity, phosphate, and nitrate with power consumption under various situations. It also evaluated the significance and their interaction with independent variables using analysis of variance (ANOVA). Through the use of statistical and mathematical techniques, optimum conditions were determined in order to remove the maximum pollutant and nutrient while using the minimum of power. The results showed that the removal of COD—98.50%, color—99.50%, turbidity—99.00%, phosphate—99%, and nitrate—98.83%, with a power consumption of 0.971 kWh m−3 were achieved at pH-7, NaCl dose of 0.75 g/L, electrolysis duration of 45 min, and current of 0.45 Amp. Therefore, under the different operating conditions, the PECP demonstrated to be a successful technique for pollutant removal from wastewater and industrial effluent.

An Optimization Study of Advanced Fenton Oxidation Methods (UV/Fenton–MW/Fenton) for Treatment of Real Epoxy Paint Wastewater

The use of various advanced oxidation methods in the treatment of wastewater has become the subject of many studies published in recent years. In particular, it is exceedingly significant to compare these treatment methods for industrial wastewater to reduce environmental effects and optimize plant operations and economics. The present study is the first to deal with the treatability of real epoxy paint wastewater (EPW) using MW- and UV-assisted Fenton processes within an optimization framework. A three-factor, three-level Box–Behnken experimental design combined with response surface methodology (RSM) was conducted for maximizing the chemical oxygen demand (COD) and color removal efficiencies of ultraviolet (UV)/Fenton and microwave (MW)/Fenton processes in the treatment of the real epoxy paint wastewater (EPW, initial COD = 4600 ± 90 mg/L, initial color = 114 ± 4 Pt-Co), based on 15 different experimental runs. Three independent variables (reaction time ranging from 20 to 60 min (UV) and from 5 to 15 min (MW), power ranging from 20 to 40 W (UV) and from 300 to 600 W (MW), and H2O2/Fe2+ ratio ranging from 0.2 to 0.6 (for both UV and MW)) were consecutively coded as A, B, and C at three levels (−1, 0, and 1), and four second-order polynomial regression equations were then derived to estimate the responses (COD and color removals) of two distinct systems. The significance of the independent model components and their interrelations were appraised by means of a variance analysis with 99% confidence limits (α = 0.01). The standardized differences of the independent variables and the consistency between the actual and predicted values were also investigated by preparing normal probability residual plots and experiment-model plots for all processes. The optimal operating conditions were attained by solving the quadratic regression models and analyzing the surface and contour plots. UV/Fenton and MW/Fenton processes, which constitute combined Fenton processes, were performed using advanced oxidation methods, while Fenton processes were utilized as the standard method for wastewater treatment. When UV/Fenton and MW/Fenton processes were applied separately, the COD removal efficiencies were determined to be 96.4% and 95.3%, respectively. For the color parameter, the removal efficiencies after the application of both processes were found to exceed 97.5%. While these efficiencies were achieved in 1 h with a 38 W UV unit, they were achieved in 15 min with a MW power of 570 W. According to the RSM-based regression analysis results, the R2 values for both processes were greater than 0.97 and p values were less than 0.003.

Dynamic Adsorption of a Cationic Dye onto Wool Fibers as Column-Filling Media: Response Surface Optimization and Fixed-Bed Adsorption Modeling.

This study reports a simple and low-cost method for water purification using recyclable natural fibers (coarse wool fibers) as column-filling media for adsorption in the dynamic mode. As an instance of a dissolved organic pollutant, a cationic dye (basic blue 9, BB9) was assayed. According to the Langmuir isotherm (recorded at 300 K), the calculated maximum adsorption capacity of the fibrous material was found to be 24.86 mg/g for the retention of BB9. Response surface methodology (RSM) was employed for the design of experiments and the model-based optimization of the adsorption process performed in the dynamic regime (fixed-bed column). The optimal conditions provided by RSM indicated an adsorbent column height of H = 13.5 cm and a feed flow rate of Fv = 3 mL/min; these operating parameters ensured a color removal efficiency of 92.56% after 240 min of contact time. The recorded breakthrough curve under the optimal conditions was further interpolated using five quantitative mathematical models (Adams-Bohart, Thomas, Yoon-Nelson, Yan, and Clark) to assess the dynamic behaviors in the fixed-bed column. The best goodness-of-fit was achieved for the Thomas and Yoon-Nelson models. Thus, the coarse wool fibers used in a fixed bed demonstrated a relevant efficiency in the removal of cationic organic pollutants from contaminated water.

Degradation of residual dyes in actual textile wastewater using UV/H<sub>2</sub>O<sub>2</sub>: Evaluation of the impact of operating variables through multi-layer perceptron analysis

UV/H<sub>2</sub>O<sub>2</sub> is a commonly used advanced oxidation process for removing non-biodegradable organic compounds. However, additional efforts are needed to understand the relative significance of operational factors during the UV/H<sub>2</sub>O<sub>2</sub>. Here, we investigated the effect and specific contribution of crucial factors such as H<sub>2</sub>O<sub>2</sub> concentration, UV intensity, and reaction time on the color and total organic carbon (TOC) removal efficiency in textile wastewater using the one-factor-at-a-time method and multi-layer perceptron (MLP) analysis. The results showed that color removal was enhanced with high H<sub>2</sub>O<sub>2</sub> concentration, high UV intensity, and long reaction time. Overall, more than 99% removal of color was achieved by the UV/H<sub>2</sub>O<sub>2</sub>, utilizing the following parameters: H<sub>2</sub>O<sub>2</sub> concentration of 5 mM, UV intensity of 26.6 W/m<sup>2</sup>, and reaction time of 180 min. On the other hand, the removal of TOC was increased by high H<sub>2</sub>O<sub>2</sub> concentration and long reaction time, but not by high UV intensity. In the MLP analysis, the H<sub>2</sub>O<sub>2</sub> concentration was identified as the primary factor affecting both color and TOC removal, accounting for 43% and 50% reduction of the color and TOC, respectively. Overall, this study helps to understand the relative importance of the most critical operating factors in treating actual textile wastewater by the UV/H<sub>2</sub>O<sub>2</sub>.

Electrocoagulation using Ti/Ti for the remediation and reuse of aqueous Dispersive Blue-79.

The entire ecology is contaminated by the synthetic dyes that are widely utilised in the textile industries. They can be handled using a variety of technologies, but an eco-friendly method called electrocoagulation has been used to prevent additional contamination. Textile wastewater containing disperse dyes are successfully treated in Electrocoagulation (EC) utilizing Al, Fe, and Stainless Steel (SS), but it is not cost effective, also the treated water contains certain mg/L of the metals used, along with dye components, which obstructs the reuse of the same. The effects of initial pH, applied voltage, dye concentration, supporting electrolyte, and treatment time on the colour removal efficiency (CRE) and consumption of energy were examined in EC process followed by activated charcoal filtration (hybrid process) with a monopolar Ti/Ti electrode on the remediation of aqueous solution of Dispersive Blue-79 (dye 3G). The maximum CREobtained was 99.4%, chemical oxygen demand (COD) 93%, and biological oxygen demand (BOD) 85%, under the following optimized operating conditions, applied voltage 15V, pH = 7, concentration of dye, electrolyte 110mg/L, 0.2g/L and time = 15min. The overall operating cost for the treatment of aqueous dye 3G was 0.455US/m3. The mechanism of EC was studied using XPS analysis in the sludge obtained. For the purpose of the reuse, FTIR, AAS, and ICP-OES analysis were done and compared with the aqueous dye 3G, after EC and hybrid process to ensure the maximum removal of the degraded dye components and metal. ICP-OES results showed that there were no traces of metal in the treated aqueous dye 3G using this method. Throughout the study, the experimental outcomes indicated that the hybrid process upgraded the quality of the treated aqueous dye 3G.

Feasibility of UVA photocatalytic post-treatment of molasses wastewater: Effects on melanoidins removal, mineralization and oxidation of ammoniacal-nitrogen

The brown color of molasses wastewater is due to the presence of melanoidins which are toxic to human health and environment. In this study, combination of coagulation-flocculation process with UVA-photocatalytic degradation of raw and diluted molasses wastewater in the presence of zinc oxide (ZnO) and titanium dioxide (TiO2) as photocatalyst was investigated. The effect of various operating parameters, such as light irradiation, aeration, catalyst dosage and pH of molasses wastewater on the photocatalytic degradation process was examined. The pre-treated diluted molasses wastewater (2 DF) showed greater performance compared to pre-treated raw for both photocatalysts due to high penetration of light into the wastewater. The formation of •OH enhanced color intensity reduction rate of pre-treated raw and 2 DF molasses wastewater in the presence of light irradiation and aeration. The color removal efficiency of pre-treated raw and 2 DF molasses wastewater was better in alkaline medium (pH 10) when ZnO used as photocatalyst, meanwhile it achieved higher removal efficiency in acidic medium (pH 4) when TiO2 was used as photocatalyst. The mineralization and oxidation of ammoniacal-nitrogen of molasses wastewater showed enhanced performance in photocatalytic treatment.