Comparative Study of Chemical Coagulation and Electrocoagulation for the Treatment of Real Textile Wastewater: Optimization and Operating Cost Estimation

Integration of sequential electrocoagulation and adsorption for effective removal of colour and total organic carbon in textile effluents and its utilization for seed germination and irrigation

Textile effluent discharge can negatively impact the environment and living organisms due to its potential toxicity, higher percentages of total organic carbon (TOC) contents, and so on. The study investigates the extraordinary performance of the electrocoagulation process (ECP) combined with powdered activated carbon (PAC) as a highly effective and environmental friendly method of treating textile effluents. This scientific work mainly includes the focus on removing toxic components in textile effluents, such as high concentrations of colour and TOC using synthesized PAC derived from coconut shells coupled with the ECP (ECP-PAC). Initially, PAC was characterized by using XRD, Raman, BET, FTIR, and TGA studies. Subsequently, the pilot-scale ECP-PAC batch reactor was constructed with iron (Fe) as an anode and copper (Cu) as a cathode. The pilot-scale ECP-PAC batch reactor has achieved higher treatment efficiency in a shorter reaction time with low energy consumption compared to a stand-alone ECP. Further, the optimum conditions for effective ECP-PAC have been optimized, such as pH 7.5, applied current density (0-50 mA/cm2), reaction time (0-30 min), electrode combinations (Fe-Cu) with electrode distances of 5 cm apart, and an optimum dose of 5 g/L of PAC. Specifically, 98% of the colour and 96% of the TOC contents present in the industrial textile effluent were treated in 15 and 30 min, respectively. In quantitative perspectives, the developed batch reactor has sharply decreased TOC (324.1 mg/L), IC (1410 mg/L) and TC (1019 mg/L) to 13.55 mg/L (96%), 31.49 mg/L (97%), and 48.05 mg/L (95%), respectively, in 30 min demonstrating its sensitivity and selectivity with the utmost care. Moreover, the physicochemical properties of the treated water were convincingly assessed. That is, it remains suitable for the seed germination of mung bean and chlorophyll content study. Thus, the developed methodology could effectively reduce freshwater consumption in the agricultural sector, increase freshwater availability in water-scarce regions, and facilitate the increase of the recharging capacity of groundwater tables.

Innovations in textile wastewater management: a review of zero liquid discharge technology

Zero liquid discharge (ZLD) technology emerges as a transformative solution for sustainable wastewater management in the textile industry, emphasizing water recycling and discharge minimization. This review comprehensively explores ZLD's pivotal role in reshaping wastewater management practices within the textile sector. With a primary focus on water recycling and minimized discharge, the review thoroughly examines the economic and environmental dimensions of ZLD. Additionally, it includes a comparative cost analysis against conventional wastewater treatment methods and offers a comprehensive outlook on the global ZLD market. Presently valued at US $0.71 billion, the market is anticipated to reach US $1.76 billion by 2026, reflecting a robust annual growth rate of 12.6%. Despite ZLD's efficiency in wastewater recovery, environmental challenges, such as heightened greenhouse gas emissions, increased carbon footprint, elevated energy consumption, and chemical usage, are discussed. Methodologies employed in this review involve an extensive analysis of existing literature, empirical data, and case studies on ZLD implementation in the textile industry worldwide. While acknowledging existing adoption barriers, the review underscores ZLD's potential to guide the textile industry toward a more sustainable and environmentally responsible future.

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 15 V, pH = 7, concentration of dye, electrolyte 110 mg/L, 0.2 g/L and time = 15 min. 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.

Continuous electrocoagulation treatment system for partial desalination of tropical brackish peat water in Sarawak coastal peatlands

Sarawak coastal peatlands located on Borneo Island have vast availability of brackish peat water sources especially in some coastal rural areas. However, brackish peat water is currently underutilized as the source for water treatment plants due to excessive salinity levels. As such, this study aims to investigate the salinity reduction in brackish peat water sources for domestic consumption in Sarawak coastal peatlands by utilizing continuous electrocoagulation treatment with aluminium electrodes. Correspondingly, this study analyzes the effects of salinity percentage, electric current, and flow rate on salinity reduction with electrocoagulation treatment. This study has found that the treated salinity levels in brackish peat water with 30 % of salinity percentage meet the Malaysia Class I in National Water Quality Standard. The study has also identified both monolayer and multilayer adsorption that occurs in electrocoagulation treatment as the precursor to salinity reduction. In addition, the presence of in-situ aluminium hydroxide coagulants could adsorb some sodium chloride from brackish peat water with 70 % of salinity percentage at 2503 mg/g of maximum adsorption capacity and 2.65 min^-1 of adsorption rate. This study has also found that electrocoagulation treatment could achieve 91.78 % of maximum salinity reduction efficiency at an optimum electric current of 5 A and flow rate of 1.2 L/min in brackish peat water with 30 % of salinity percentage. This treatment system costs only Ringgit Malaysia (RM) 0.29 or United States Dollars (USD) 0.06 per meter cubic of treated brackish peat water. Overall, this study demonstrates that continuous electrocoagulation treatment could partially desalinate brackish peat water with 30 % of salinity percentage in which the treated salinity levels could be utilized for domestic consumption in Sarawak coastal peatlands at reasonable cost.

Comprehensive understanding of electrochemical treatment systems combined with biological processes for wastewater remediation

The presence of toxic pollutants in wastewater discharge can affect the environment negatively due to presence of the organic and inorganic contaminants. The application of the electrochemical process in wastewater treatment is promising, specifically in treating these harmful pollutants from the aquatic environment. This review focused on recent applications of the electrochemical process for the remediation of such harmful pollutants from aquatic environments. Furthermore, the process conditions that affect the electrochemical process performance are evaluated, and the appropriate treatment processes are suggested according to the presence of organic and inorganic contaminants. Electrocoagulation, electrooxidation, and electro-Fenton applications in wastewater have shown effective performance with high removal rates. The disadvantages of these processes are the formation of toxic intermediate metabolites, high energy consumption, and sludge generation. To overcome such disadvantages combined ecotechnologies can be applied in large-scale wastewater pollutants removal. The combination of electrochemical and biological treatment has gained importance, increased removal performance remarkably, and decreased operational costs. The critical discussion with depth information in this review could be beneficial for wastewater treatment plant operators throughout the world.

Efficient removal of tannins from anaerobically-treated palm oil mill effluent using protein-tannin complexation in conjunction with electrocoagulation

Despite the significant removal of chemical oxygen demand (COD) by anaerobic digestion, anaerobically-treated palm oil mill effluent (POME) still contains tannins and other phenolic compounds, resulting in residual COD and a brownish color. In this study, we investigated the removal of tannins from anaerobically treated POME using protein-tannin complexation in conjunction with electrocoagulation. The amino acid composition of the protein, aqueous pH, and protein: tannin ratios were found to be important parameters affecting the tannin removal efficiency. Pig blood protein was superior to casein protein in removing tannins, possibly because it had aspartic acid as the major amino acid component. At an optimal condition with a pig blood protein: tannin ratio of 0.33 (w/w), a current density of 30 mA/cm², pH 5, and an electrolysis time of 10 min, the removals of tannins, COD, and color were 93%, 96%, and 97%, respectively.

Biochar-mediated removal of pharmaceutical compounds from aqueous matrices via adsorption

Pharmaceutical is one of the noteworthy classes of emerging contaminants. These biologically active compounds pose a range of deleterious impacts on human health and the environment. This is attributed to their refractory behavior, poor biodegradability, and pseudopersistent nature. Their large-scale production by pharmaceutical industries and subsequent widespread utilization in hospitals, community health centers, and veterinary facilities, among others, have significantly increased the occurrence of pharmaceutical residues in various environmental compartments. Several technologies are currently being evaluated to eliminate pharmaceutical compounds (PCs) from aqueous environments. Among them, adsorption appears as the most viable treatment option because of its operational simplicity and low cost. Intensive research and development efforts are, therefore, currently underway to develop inexpensive adsorbents for the effective abatement of PCs. Although numerous adsorbents have been investigated for the removal of PCs in recent years, biochar-based adsorbents have garnered tremendous scientific attention to eliminate PCs from aqueous matrices because of their decent specific surface area, tunable surface chemistry, scalable production, and environmentally benign nature. This review, therefore, attempts to provide an overview of the latest progress in the application of biochar for the removal of PCs from wastewater. Additionally, the fundamental knowledge gaps in the domain knowledge are identified and novel strategic research guidelines are laid out to make further advances in this promising approach towards sustainable development.