Wastewater Treatment Technologies Research Articles

Efficacy of BPNS/TiO2 in catalyzing the visible-light-driven degradation of BPA

A novel composite material consisting of black phosphorus nanosheets (BPNS) and titanium dioxide (TiO2) for degrading bisphenol A (BPA) under visible light was investigated. Through a series of photocatalytic experiments and characterization techniques, we found that BPNS/TiO2 composite materials exhibit excellent BPA degradation ability under visible light irradiation, are capable of degrading 85 % of BPA, and can degrade up to 88.72 % of BPA in acidic environments. The synergistic effect of the composite, combined with the advantages of BPNS, increases the light absorption capacity of TiO2. The introduction of TiO2 can reduce the photogenerated electron-hole pair recombination ability of the composite material and improve the carrier migration ability of the composite material, making it an efficient and environmentally friendly catalyst for BPA degradation. We identified and characterized intermediate products of BPA degradation using high-performance liquid chromatography–mass spectrometry (HPLC–MS) and other study. This process elucidates the potential degradation pathways. The results of this study provide strong support for addressing BPA pollution in the environment and offer a new scientific foundation for the application of photocatalysis technology in environmental protection and wastewater treatment.

Bacterial networks and enzyme genes in bacterial floccules from hydrolysis and aeration reactors in a dairy wastewater treatment system.

The dairy industry generates substantial wastewater, which is commonly treated using integrated anaerobic hydrolysis and aerated biofilm reactors. However, the bacterial composition and functional differences within the generated floccules remain unclear. In this study, we employed 16S rRNA and metagenomic sequencing to compare bacterial communities and enzyme gene profiles between suspended floccules from the hydrolysis ponds and the aeration ponds. Results revealed that the bacterial phyla Firmicutes, Proteobacteria, and Bacteroidetes dominated the wastewater treatment system and the relative abundance of these bacterial phyla varied in each pond. Additionally, the aeration ponds exhibited higher bacterial operational taxonomic units and enzyme gene abundance. Network analysis demonstrated a more complex bacterial network structure in the hydrolysis ponds compared to the aeration ponds. Furthermore, enzyme gene abundance revealed higher metabolic enzyme genes in the hydrolysis ponds, while signal transduction enzyme genes were more abundant in the aeration ponds. Notably, the top 10 bacterial genera, primarily Hydromonas in the hydrolysis ponds and Ferruginibacter in the aeration ponds, exhibited distinct contributions to signal transduction enzyme genes. Hydromonas dominated the metabolic enzyme genes in both ponds. These findings provide crucial insights for optimizing dairy wastewater treatment technologies.

Towards an electrochemically-based circular economy: Electro-refinery for valorizing phenolic wastewater

This study introduces an innovative approach to wastewater treatment that combines two electrochemical technologies: electrolysis and electrochemical separation facilitated by anionic exchange membranes. This integrated technology converts pollutants into carboxylates, which are valuable intermediates for further electrosynthesis and fuel production. The efficacy of this approach was demonstrated using synthetic wastewater containing phenol as a model pollutant, chosen for its well-documented characteristics that enable comparative analysis with previous studies. The treatment process utilized mixed metal oxides (MMO) anodes with a composition of Ti/(RuO2)0.8(Sb2O4)0.2 and a boron-doped diamond (BDD) anode. The investigation was structured to evaluate each component of the treatment system individually before examining their collective performance. Through a series of case studies, the research not only confirmed the feasibility of this innovative technology but also highlighted the need for further study on the optimization of operational parameters and electrode materials. Comparative analysis revealed that MMO anodes outperformed BDD anodes, achieving maximum carboxylate transport rates of 138.7 mmol m−2h−1. The efficiency of carboxylate separation from the solution where they were generated reached up to 54.6 mmol kWh−1, while the maximum overall production efficiency was 8.77 mmol kWh−1. The study further determined that current density significantly affects both the production rate and the extent of mineralization, identifying optimal densities of 100 mA cm−2 and 30 mA cm−2 for the electrolyzer and electroseparator units, respectively. This work provides valuable insights for the optimization of this promising wastewater treatment technology, with potential applications in various industries.

SEWAGE WATER TREATMENT AND ITS EFFECT ON THE CLEANLINESS OF WATER: A REVIEW FROM ISLAMIC AND SCIENCE PERSPECTIVE

Due to the water combining with feces, sewage water found in the Sewage Treatment Plant (STP) is classified as mutanajjis. However, the wastewater cleaned with current technology in STP has created concerns, particularly among Muslims, over whether it can be classified as muṭlaq water or not. The purpose of this study is to compare the cleaning mechanism from an Islamic perspective with the sewage water treatment technique in Indah Water Konsortium (IWK) Malaysia. Next, to examine the treated sewage water and its impact on the law of ṭahārah in Islam. This study uses a qualitative approach using data collection techniques by document analysis, observations at the Regional Sewage Water Treatment Plant (RSTP) KL-Titiwangsa 2 owned by Indah Water Konsortium (IWK) Malaysia, interviews with Shariah and water experts, and laboratory analysis. The results of the study revealed that the wastewater treatment technology at RSTP Serantau KL-Titiwangsa 2 can change the status of water from mutanajjis to muṭlaq because it meets all the criteria for muṭlaq water set by the fuqaha. Through the results of laboratory analysis, the treated sewage water is categorized in the same category as muṭlaq water. Therefore, the water can be used for ṭahārah purposes. It also sheds light on the aspects of environmental sustainability from an Islamic perspective.

Successful application of photocatalytic recycled TiO2-GO membranes for the removal of trace organic compounds from tertiary effluent

Photocatalytic membranes are a promising technology for water and wastewater treatment. Towards circular economy, extending the lifetime of reverse osmosis (RO) membranes for as long as possible is extremely important, due to the great amount of RO modules discarded every year around the world. Therefore, in the present study, photocatalytic membranes made of recycled post-lifespan RO membrane (polyamide thin-film composite), TiO2 nanoparticles and graphene oxide are used in the treatment tertiary-treated domestic wastewater to remove trace organic compounds (TrOCs). The inclusion of dopamine throughout the surface modification process enhanced the stability of the membranes to be used as long as 10 months of operation. We investigated TrOCs removal by the membrane itself and in combination with UV-C and visible light by LED. The best results were obtained with integrated membrane UV-C system at pH 9, with considerable reductions of diclofenac (92%) and antipyrine (87%). Changes in effluent pH demonstrated an improvement in the attenuation of TrOCs concentration at higher pHs. By modifying membranes with nanocomposites, an increase in membrane hydrophilicity (4° contact angle reduction) was demonstrated. The effect of the lamp position on the light fluence that reaches the membrane was assessed, and greater values were found in the middle of the membrane, providing parameters for process optimization (0.29 ± 0.10 mW cm−2 at the center of the membrane and 0.07 ± 0.03 mW cm−2 at the right and left extremities). Photocatalytic recycled TiO2-GO membranes have shown great performance to remove TrOCs and extend membrane lifespan, as sustainable technology to treat wastewater.

Does stricter sewage treatment targets policy exacerbate the contradiction between effluent water quality improvement and carbon emissions mitigation? An evidence from China

Rapid expansion and upgrading of wastewater treatment facilities globally, driven by stricter wastewater policies, significantly contribute to carbon emissions. China has contributed 30 % of carbon emissions in the world, 1 % of which comes from wastewater treatment, necessitating more understanding of the impact of policies, especially the stringent “10-Point Water Plan” policy. From a micro perspective, this study uses the difference-in-differences method to analyze the impact of wastewater treatment policies on water and carbon issues in China’s 2894 wastewater treatment plants (WWTPs), and delves into the heterogeneity, and mechanisms across various dimensions. The results show that stricter sewage treatment policy decrease effluent concentration of the chemical oxygen demand (COD) by 2.35 %, and also cause a 1.74 % rise in carbon emissions per 10,000 m3 of wastewater treated, intensifying the short-term contradiction, while the contradictions may fall in the long term. It is more significant in southern regions and the cities with lower environmental regulation intensity. Also, there are significant differences in different wastewater treatment technology and scale. Significant improvements in effluent water quality are observed in WWTPs with 100,000 to 200,000 m3/day capacity and those using biofilm treatment technology. Through mechanism analysis, reasonable expansion of urban pipelines and WWTPs, promotion of biofilm treatment technology, reduction of energy consumption, and improvement of pollutant reduction efficiency are feasible paths to improve water quality and reduce carbon emissions. This research provides a perspective on solving water-carbon contradictions in WWTPs, holding critical significance for urban wastewater treatment and carbon emission management.

Electrochemical Wastewater Treatment Technologies Through Life Cycle Assessment: A Review

AbstractElectrochemical wastewater treatment technologies are gaining attraction as sustainable alternatives for industrial and municipal wastewater management. This study conducts a comprehensive life cycle assessment to assess the environmental and economic sustainability of electrochemical methods such as electrocoagulation, electrooxidation, and electroreduction. By analyzing key stages, from raw material extraction to end‐of‐life disposal, the review aims to provide insight into their overall sustainability performance. The study also delves into environmental impact categories and utilization of methods used in quantifying the environmental implications. Moreover, a cost structure analysis and cost‐effectiveness evaluation offer insights into the economic viability of these technologies. Despite facing challenges like high initial costs and regulatory constraints, electrochemical technologies demonstrate competitive advantages in treatment efficiency and energy savings. Collaborative efforts and supportive policy frameworks are deemed crucial for overcoming barriers and fostering the widespread adoption of electrochemical technologies, thereby advancing sustainable wastewater management practices.

Enhanced dye degradation using plasma bubbles for the sustainable environmental remediation

This study proposes a novel and eco-friendly approach for wastewater treatment using plasma jet technology under bubble condition. This method allows for the controlled production of highly reactive hydroxyl radicals (OH•) while minimizing unwanted interactions with nitrogen in the air. The presence of bubbles in liquid significantly boosts the diffusion of OH• within the wastewater, leading to a two-fold increase in degradation rate compared to normal condition. The effectiveness of the treatment was confirmed through ultraviolet-visible spectroscopy, which showed a significant decrease in rhodamine B and methyl orange absorbance peaks. Raman spectroscopy further revealed structural changes in both pollutants, indicating successful degradation. Additionally, plasma characteristics like power, electron temperature, and density were monitored to gain deeper insights into the underlying mechanism. Importantly, the process minimizes the formation of harmful secondary pollutants such as ozone and nitrogen oxides. These pollutants were found under concentration of 0.14 mg m−3 which is below established safety thresholds, adhering to World Health Organization guidelines. This research demonstrates that plasma jet treatment in bubble condition not only enhances the degradation efficiency of pollutants in wastewater but also minimizes the formation of harmful byproducts. This represents a significant breakthrough in developing sustainable wastewater treatment technologies.

Visible-light-driven calcium alginate hydrogel encapsulating BiOBr0.75I0.25 for efficient removal of oxytetracycline from wastewater

Oxytetracycline (OTC), a widely used antibiotic, poses significant environmental risks due to its persistence in ecosystems. This study introduces a visible-light-driven photocatalytic hydrogel system for effectively removing OTC from wastewater. The system employs calcium alginate (CA) hydrogel beads encapsulating a BiOBr0.75I0.25 solid solution, which utilizes the synergistic effects of adsorption and visible-light-driven photocatalysis. The BiOBr0.75I0.25 solid solution photocatalyst was synthesized via a solvothermal method, while CA hydrogel beads encapsulating BiOBr0.75I0.25 were prepared through ionic gelation of sodium alginate with calcium chloride. The novel hydrogel, CA-BiOBr0.75I0.25, demonstrated rapid adsorption, capturing over 50 % of OTC within 30 min and achieving a 90.92 % degradation rate within 60 min under visible light. This performance is associated with the unique petal-like structure of BiOBr0.75I0.25 and the high surface area of the hydrogel, facilitating efficient charge separation and radical generation critical for photocatalytic activity. Additionally, the system showed excellent stability and reusability, maintaining an 83 % removal efficiency after five cycles. These findings highlight the potential of this novel hydrogel as a sustainable solution for advanced wastewater treatment technologies.

Ultrasonic and Electrocoagulation Technologies in Wastewater Treatment and Material Circulation

Due to the emergence of new and persistent pollutants in wastewater, various advanced oxidation processes (AOPs) such as ultrasonic technology and electrocoagulation have been developed and employed for pollutant degradation, removal, and recovery from wastewater. In this study, we investigated the principles, influencing factors, and practical applications of several methods combining ultrasound and electrocoagulation with catalysts and demonstrated the efficiency of each method. Additionally, we analyzed the challenges associated with these ultrasonic methods and electrocoagulation in removing antibiotics and recovering pollutants from aqueous solutions and suggested solutions to these problems. Materials recovered after treatment can be utilized to improve soil quality.

·OH Scavenger Optimized Grounding Electrode Atomization Corona Discharge Technology for Treatment of Coal Mine Acidic Wastewater

Coal mine acid drainage is a type of industrial wastewater generated in the process of coal production and utilization that has a low pH and contains a small amount of organic matter and SO42−, which is harmful to the environment. The ·OH scavenger was used to optimize the grounded electrode atomized corona discharge (GEACD) technology for the treatment of coal mine acidic wastewater. The effects of various factors on the discharge effect were investigated, and the optimal operating scheme for the subsequent test was determined as 35 mm distance between barrel electrodes, 0.6 mm diameter of wire electrodes, and a flow rate of 45 mL/min. The effects of discharge voltage, discharge time, and ·OH scavenger on COD removal rate and pH in coal mine acid drainage were also investigated. The results showed that at the optimum discharge voltage of 12 kV, discharge time of 66 min, and SO42− to ethanol concentration ratio of 1, the COD value decreased from 152.84 mg/L to 43.27 mg/L, and the pH value increased from 5.6 to 6.1.

Navigating Heavy Metal Removal: Insights into Advanced Treatment Technologies for Wastewater: A review.

<p><span lang="EN-US" style="font-size:12.0pt"><span style="background:white"><span style="line-height:107%"><span style="font-family:"Times New Roman",serif"><span style="color:black">This paper provides an overview of heavy metal removal technologies for wastewater treatment, with a focus on adsorption, chemical oxidation, ion exchange, and various coagulation processes. The discussion revolves around wastewater characterization as an essential first step in creating efficient treatment systems. The study examines the uses of different treatment technologies, emphasizing both their benefits and drawbacks. Although flocculation is a rapid and economical procedure, it produces waste and needs further filtration and sedimentation. In addition, natural coagulants are found to be more environmentally friendly than synthetic ones, their effects on water quality may make disinfectants necessary. Despite their low toxicity, stability, and environmental advantages, hybrid coagulants have certain drawbacks that are related to operational variables. Despite its broad applicability and low cost, adsorption faces challenges with regeneration and sludge creation. Although it is acknowledged to have a high metal recovery rate, ion exchange is expensive and requires special maintenance. Chemical oxidation techniques, in particular advanced oxidation processes (AOPs), are useful for eliminating heavy metals and breaking down organic materials. The limitations and difficulties of each approach are discussed in the abstract's conclusion, which highlights the necessity of future study aimed at enhancing treatment efficacy for extremely low quantities of heavy metals. To allay worries about energy usage, the integration of electrochemical processes with renewable energy sources is recommended.</span></span></span></span></span></p>

Preparation of polysulfone-based nanofiber Janus membrane for membrane distillation containing organic pollutants

Membrane distillation is an emerging wastewater treatment technology that harnesses low-grade heat as an energy source and exhibits potential for complete desalination. Nonetheless, two notable challenges hinder the practical application of this technology: membrane wetting and fouling. To counter these challenges, an innovative anti-fouling Janus membrane with asymmetric wettability was developed through electrospinning. The hydrophobic layer was formed using tetraethyl orthosilicate/polysulfone (PSF), and the superhydrophilic layer was created using polyvinylpyrrolidone (PVP)/PSF. A sensitive adhesion probe was used to assess the anti-fouling performance of the Janus membrane against oil. Molecular dynamics simulation suggested that PVP reduced the adsorption tendency of the membrane for humic acid (HA). Under experimental conditions involving saline water with HA and a saline oil–water emulsion, the non-Janus membrane suffered severe fouling, resulting in rapid water permeate flux decline. However, the Janus membrane demonstrated consistent permeate flux (26.84 LMH and 24.92 LMH) and an impressive salt rejection rate (> 99.99%). This study suggests that the Janus membrane, with its high permeate fluxes and remarkable resistance to fouling and wetting, could be an effective solution for wastewater treatment, with considerable potential for future application.

Nationwide evaluation of microplastic properties in municipal wastewater treatment plants in South Korea

Wastewater treatment plants (WWTPs) are considered a significant microplastic discharge source. To evaluate the amount and characteristics of microplastics discharged from WWTPs in South Korea, we selected 22 municipal WWTPs nationally and investigated microplastics at each treatment stage. The mean microplastic removal efficiency by WWTPs was >99%, and most of the microplastics were removed by sedimentation with the second clarifier during wastewater treatment. Consequently, the microplastic removal efficiency of WWTPs did not significantly differ from that of the adopted wastewater treatment technology because a second clarifier was applied in most WWTPs. However, for WWTPs operating a tertiary treatment process, the removal efficiency was enhanced compared with that of WWTPs discharging after a second clarifier. Although the microplastic removal efficiency was high by WWTP, the discharge contribution to the water environment could not be ignored because of the amount of treated wastewater, resulting in an increase of 5.8–270.9 items/m3 of microplastics in the receiving water. The characteristics of microplastics in WWTPs, including their components, shape, and size, were also evaluated. The most detected components included polytetrafluoroethylene and polyester. Most microplastics detected were categorized as fragments and fibers, while other types were hardly detected. The size of more than 70% of the microplastics detected in WWTPs was under 300 μm, implying that the size of microplastics required to control in WWTPs was much smaller than the defined size of microplastics. An evaluation of the correlation between other pollution factors and microplastic abundance did not reveal positive correlations, and microplastic occurrence was not affected by changing seasons, which may need to be evaluated with further studies. Research should also be performed on the effect of influent sources on the level of microplastic abundance and fate of ultrafine plastics in WWTPs.

Wastewater Treatment and Water Reuse Technologies for Sustainable Water Resources: Jordan as a Case Study

Wastewater Treatment and Water Reuse Technologies for Sustainable Water Resources: Jordan as a Case Study

Hydrothermal Carbonization Technology for Wastewater Treatment under the “Dual Carbon” Goals: Current Status, Trends, and Challenges

Hydrothermal carbonization (HTC) technology transforms organic biomass components, such as cellulose and lignin, into valuable carbon materials, gases and inorganic salts through hydrolysis, degradation and polymerization, with significant advantages over traditional methods by reducing energy consumption, lowering pollutant emissions and enhancing carbonization efficiency. In the context of global climate change, HTC plays a critical role in water environment management by addressing industrial, agricultural, and domestic wastewater challenges. The application of HTC extends to wastewater treatment, where hydrochar effectively adsorbs heavy metals, organic compounds, and anions, thereby improving water quality. However, challenges remain, such as optimizing the process for diverse raw materials, managing economic costs, and addressing environmental and social impacts. Future research and policy support are essential for advancing HTC technology. By enhancing reaction mechanisms, developing catalysts, and promoting international cooperation, HTC can significantly contribute towards achieving carbon neutrality goals and fostering sustainable development.

Advancing Wastewater Treatment: A Comparative Study of Photocatalysis, Sonophotolysis, and Sonophotocatalysis for Organics Removal

Clear and sanitarily adequate water scarcity is one of the greatest problems of modern society. Continuous population growth, rising organics concentrations, and common non-efficient wastewater treatment technologies add to the seriousness of this issue. The employment of various advanced oxidation processes (AOPs) in water treatment is becoming more widespread. In this review, the state-of-the-art application of three AOPs is discussed in detail: photocatalysis, sonophotolysis, and sonophotocatalysis. Photocatalysis utilizes semiconductor photocatalysts to degrade organic pollutants under light irradiation. Sonophotolysis combines ultrasound and photolysis to generate reactive radicals, enhancing the degradation of organic pollutants. Sonophotocatalysis synergistically combines ultrasound with photocatalysis, resulting in improved degradation efficiency compared to individual processes. By studying this paper, readers will get an insight into the latest published data regarding the above-mentioned processes from the last 10 years. Different factors are compared and discussed, such as degradation efficiency, reaction kinetics, catalyst type, ultrasound frequency, or water matrix effects on process performance. In addition, the economic aspects of sonophotolysis, photocatalysis, and sonophotocatalysis will be also analyzed and compared to other processes. Also, the future research directions and potential applications of these AOPs in wastewater treatment will be highlighted. This review offers invaluable insights into the selection and optimization of AOPs.

A Sunlight-Driven Self-Cleaning CuCo-MOF Composite Membrane for Highly Efficient Emulsion Separation and Water Purification.

The fouling phenomenon of membranes has hindered the rapid development of separation technology in wastewater treatment. The integration of materials into membranes with both excellent separation performance and self-cleaning properties still pose challenges. Here, a self-assembled composite membrane with solar-driven self-cleaning performance is reported for the treatment of complex oil-water emulsions. The mechanical robustness of the composite membrane is enhanced by the electrostatic attraction between chitosan and metal-organic frameworks (MOF) CuCo-HHTP as well as the crosslinking effect of glutaraldehyde. Molecular dynamics (MD) simulations also revealed the hydrogen bonding interaction between chitosan and CuCo-HHTP. The composite membrane of CuCo-HHTP-5@CS/MPVDF exhibits a high flux ranging from 700.6 to 2350.6 L∙m-2∙h-1∙bar-1 and excellent separation efficiency (>99.0%) for various oil-water emulsions, including crude oil, kerosene, and other light oils. The addition of CuCo-HHTP shows remarkable photothermal effects, thus demonstrating excellent solar-driven self-cleaning capability and antibacterial performance (with an efficiency of ≈100%). Furthermore, CuCo-HHTP-5@CS/MPVDF can activate peroxomonosulfate (PMS) under sunlight, quickly removing oil-fouling and dyes. Density functional theory (DFT) calculations indicate that the bimetallic sites of Cu and Co in CuCo-HHTP effectively promoted the activation of PMS. This study provides distinctive insights into the multifaceted applications of MOFs-derived photothermal anti-fouling composite membranes.

Electrocatalytic degradation of ofloxacin by self-doped copper/carbon cathode materials derived from waste printed circuit boards

Using residual copper metal from waste circuit boards, ordered carbon materials containing copper (PCBs-Cu-800) were synthesized by self-doping for the electrocatalytic degradation of ofloxacin (OFL). Although PCBs-Cu-800 has a smaller specific surface area, its efficiency in degrading OFL was higher than that of carbon materials without copper (PCBs-800), reaching 95.9 % within 2 h. The PCBs-Cu-800 electrode can generate a large amount of H2O2 in the initial stage of degradation, thereby increasing the amount of hydroxyl radicals (·OH) generated and removing OFL. Density functional theory simulations were used to calculate the adsorption energies of O2 on both materials, demonstrating that the self-doped copper model was more prone to O2 adsorption, and elucidating the excellent electrocatalytic performance of PCBs-Cu. The residual copper metal in the raw material is important in the electrocatalytic processes. This study presents an environmentally friendly catalytic material capable of effectively degrading OFL in solution using waste circuit boards and further expands the application scope of advanced electrochemical oxidation technology in wastewater treatment.

Exploring well-defined TiO2 nanotube arrays for enhancing SnO2-Sb-Nd-Pt electrode performance

The short service life and low catalytic activity of electrodes are the major bottlenecks limiting the practical applications of current electrocatalytic oxidation technology in wastewater treatment. In this study, a novel Ti/SnO2-Sb-Nd-Pt electrode loading TiO2 nanotube (TiO2-NTs) array was proposed and prepared. The optimized TiO2 nanotube (TiO2-NTs) arrays provided abundant anchoring sites for SnO2-Sb-Nd-Pt active coating and improved the bonding strength between the Ti matrix and the SnO2-Sb-Nd-Pt active coating as a mediator, as a result, higher electrocatalytic performance and stability. The nitrobenzene (NB) removal and service life were significantly higher in Ti/TiO2-NTs/SnO2-Sb-Nd-Pt (91.08 % and 4381.9 days) when compared to Ti/SnO2-Sb-Nd-Pt (80.61 % and 1151.2 days). In addition, the outstanding electrocatalytic performance of Ti/TiO2-NTs/SnO2-Sb-Nd-Pt with an oxygen evolution potential of 2.03 V and total voltametric charge of 5.88 mC cm−2 makes it a promising candidate for future industrial applications. These findings will lay a solid foundation for broadening the applications of well-defined TiO2-NTs arrays prepared via the two-step anodization.