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Showing papers in "Journal of water process engineering in 2021"


Journal ArticleDOI
TL;DR: In this article, a review of the potential of low-cost microalgae-based integrated biorefinery for wastewater treatments and resource recovery is presented. But, the main aim of the review is to provide the knowledge about the potential for low-low-cost integrated biOthis articleinery.
Abstract: Extensive and improper utilization of water from industrial, municipal, and agricultural activities generate 380 trillion L/y of wastewater worldwide. Wastewaters from different sources contain enormous amounts of nutrients such as carbon, nitrogen, and phosphorus. Thus, the recovery of these nutrients via appropriate sustainable process becomes a necessity. Among various processes microalgae-based technologies has attracted considerable attention and its strategies for sustainable and low-cost treatment of wastewater has allowed removal of over 70% nutrient loads from the wastewater. After the treatment of wastewater, the harvested microalgae biomass contains value-added biomolecules which can used for bioenergy production and nanoparticle synthesis. At present, high operational costs represent a major limitation for the development of microalgae-based biorefineries. Thus, the main aim of the review is to provide the knowledge about the potential of low-cost microalgae-based integrated biorefinery for wastewater treatments and resource recovery. Also, this review provides the insight of microalgae biomass-based bioenergy products, nanoparticles synthesis their application within the concept of circular bioeconomy. Furthermore, this review also provides information on different established industries which used microalgae for wastewater treatment.

146 citations


Journal ArticleDOI
TL;DR: In this article, a review discusses and investigates antibiotics and antibiotic-resistant bacteria removal and inactivation with their associated genes through photocatalysis technique as an efficient and ecofriendly advanced oxidation process (AOP).
Abstract: To deal with the contamination of the water environment, which represents an arena for microorganisms and antibiotics, a photocatalytic process has been proposed due to its high efficiency and non-toxicity. This review discusses and investigates antibiotics and antibiotic-resistant bacteria (ARB) removal and inactivation with their associated genes through photocatalysis technique as an efficient and ecofriendly advanced oxidation process (AOP) photocatalysis. The paper summarizes recent studies that dealt with both pollutants and their process parameters, optimal operating conditions, used semiconductor photocatalysts and their corresponding removal efficiency. Thus, it suggests that photocatalysis can offer impressive treatment efficiencies for both organic and microbial pollutants simultaneously. The review also states that both antibiotics and bacteria have a destroying effect against each other, where antibiotics have antimicrobial activity and bacteria have microbial degradation. This phenomenon creates a hybrid system for each pollutant (photocatalysis-bacteria, photocatalysis-antibiotic, bacteria-antibiotic), which accelerates the purification and disinfection of the polluted water caused by pathogens and hazardous pollutants using green and safe technology. Moreover, the reaction mechanism was detailed in order to define the role of reactive oxygen species (ROS). Likewise, photocatalysis coupling with other AOP techniques in this context was discussed to achieve more promising results. The main contribution of this review is to explain the relationship between antibiotics, microbial contaminants and photocatalysis. It also introduces a new area of study and concludes with an outlook on future research topics, such as viral disinfection.

142 citations


Journal ArticleDOI
TL;DR: In this paper, the advantages and disadvantages of single AOP, AOP combined with nanocatalsyts, and other technologies for the treatment of textile dye wastewater and pharmaceutical residual wastewater, and several critical mechanisms of the degradation of pollutants were summarized and analyzed.
Abstract: With the rapid development of industrialization and globalization in recent years, an increasing amount of textile dye wastewater and pharmaceutical wastewater has been discharged into the environment. Current wastewater treatment technology has difficulty meeting all the practical requirements of harmless wastewater discharge, and therefore, the exploration and development of new technologies to treat various types of wastewater is urgently needed. Advanced oxidation processes (AOPs) have the advantages of strong oxidation ability, complete decomposition of organic pollutants, and no secondary pollution, and scientists have found that the introduction of nanocatalysts with good performance into AOPs can achieve excellent treatment effects. Numerous studies have shown that the introduction of catalysts to AOPs can greatly improve the treatment effect. These results demonstrate that AOPs may be an efficient approach for the large-scale treatment of wastewater, however, there are very few systematic reviews that address the treatment of textile dye wastewater and pharmaceutical residue wastewater by AOPs. This study provides a unique focus on the advantages and disadvantages of single AOPs, AOPs combined with nanocatalsyts, and other technologies for the treatment of textile dye wastewater and pharmaceutical residual wastewater, and several critical mechanisms of the degradation of pollutants have been summarized and analyzed. Finally, the challenges and prospects of AOPs in wastewater treatment are summarized. This study provides a useful theoretical foundation and practical guidance for scientists in the fields of environmental science, environmental engineering, and environmental health.

133 citations


Journal ArticleDOI
TL;DR: In this article, the authors present the recent advances in activated carbon preparation and modification for heavy metal removal from water and discuss different fabrication techniques and the mechanisms of heavy metal adsorption.
Abstract: The contamination of water with heavy metals is a global issue. Its water solubility and non-degradability nature convert it into a potential threat to human health as well as flora and fauna. Several methods have been applied for heavy metal removal from water using a different mechanism, which differs in specification and removal efficacy. Activated carbon has recently attracted the attention of wastewater treatment industries because of its significantly high adsorption capacity against heavy metals. The large surface area, suitable surface functional groups, and appropriate pore diameter make activated carbon a potential adsorbent. Significant advances have been recently reported to modify the activated carbon using physical, chemical, organic, and inorganic loading techniques to improve the adsorption performance of activated carbon. This review presents the recent advances in activated carbon preparation and modification for heavy metal removal from water. Different fabrication techniques and the mechanisms of heavy metal adsorption are also discussed in detail.

111 citations


Journal ArticleDOI
TL;DR: In this article, the authors provide an overview of the most widely studied coagulants, such as coagulation aids, dual-coagulant aids, and alternative methods for removing NOM.
Abstract: Natural organic matter (NOM) represents a range of soluble and insoluble material which can have considerable impact on drinking water quality. In addition to creating problems with taste, odour, clarification, and colour, removal of NOM is problematic because it can initiate the formation of disinfection by-products, which can adversely affect human health. Numerous technologies and methods have been employed to remove NOM in water treatment, with the most common processes involving the use of coagulants and similar technologies. This paper provides an overview of the most widely studied coagulants, coagulant aids, dual coagulants, and alternative coagulants. The paper also investigates the effects of operating parameters such as temperature, coagulant dose, pH, use of inorganic salts, inorganic polymeric coagulants, and organic polyelectrolytes in terms of charge neutralisation, polymer adsorption, and polymer bridging. Finally, emerging technologies and the use of novel coagulants are investigated.

86 citations


Journal ArticleDOI
TL;DR: In this paper, the authors provide an overview of the efficiencies of the ball-milled biochar-nanoparticle composite, which improves the physicochemical properties of biochar and biochar nano-particle composite.
Abstract: The ball-milling of carbon-based materials with nanoparticles is currently emerging as a promising cost-effective alternative method of producing nanocomposites with great surface characteristics. Biochar-based nanocomposites are effective in the adsorption of heavy metals, dyes and emerging organic contaminants in water and wastewater because of the combined benefits of biochar and nanoparticles. Contaminants of emerging concern are increasingly being detected in the environment and there is, therefore, an urgent need to develop nanotechnology-based multifunctional and highly efficient processes that can remove a wide range of these chemicalsmost of which are persistent and may bioaccumulate. To date, not many reviews are available on the use of the ball-milling method for engineering biochar-based nanocomposites. Ball milling (solid-state synthesis) is a process extensively used in industry to synthesize nanomaterials. Ball milling process produces small particle size as small as 10 microns, coupled with the advantages of continuous operation. Thus, this review article aims to provide an overview of the efficiencies of the ball-milled biochar-nanoparticle composite. Ball milling approach improves the physicochemical properties of biochar and biochar–nanoparticle composite such as total and micropore surface of biochar which in turns enhance their sorption abilities. Different adsorption mechanisms of biochar and modified biochar have been reported, which include physisorption, chemisorption, ion-exchange, pore-filling, hydrophobic effects and π-π electron donor-acceptor (π-π EDA) interactions.

84 citations


Journal ArticleDOI
TL;DR: In this article, a review paper critically analyzed the application of microalgae for the remediation of diverse types of pollutants commonly present in the environment through different mechanisms, such as biosorption, bioaccumulation and biodegradation.
Abstract: Environmental pollution is increasing day by day due to anthropogenic activities and different types of toxic contaminants such as heavy metals, chemicals, dyes, pesticides etc enter the environment from different sources such as municipal, industries and agricultural. Among wastewater treatment techniques, bioremediation is one of promising techniques, which utilize the inherent biological mechanism of plant and microorganism for the remediation of diverse pollutants. Microalgae have been applied to mitigate the toxic and recalcitrant pollutants in the effluents. Microalgae have the capacity to remove different types of contaminants through different methods such as biosorption, bioaccumulation and biodegradation. It has been observed that microalgae can remove the pollutants originated from the domestic effluents, agricultural runoffs, textile, leather, pharmaceutical and electroplating industries etc. Additionally, the microalgae have the ability to mitigate the carbon dioxide in their growth process and utilize the micronutrients in the effluents. This review paper critically analysed the application of microalgae for the remediation of diverse types of pollutants commonly present in the environment through different mechanisms.

81 citations


Journal ArticleDOI
TL;DR: In this paper, a review article focusing on the usage of modified plant-based adsorbents for the efficient removal of heavy metals and dyes from wastewater has been presented, in which various methods of activation and modification like physical, chemical and composite formation with components such as polymers, carbon nanotube (CNT), graphene, layered double hydroxides (LDHs) and metal oxides are discussed in depth Generally, these modifications of plant based adorbents resulted in significant enhancement of adsorption capacity Apart from this, the effect of various parameters such as
Abstract: Currently, sequestration of contaminants like heavy metals and dyes from wastewater has been widely studied by researchers using modified plant-based adsorbents in order to purify water for domestic as well as industrial purposes Although, there are various promising techniques for the removal of pollutants from wastewater but adsorption technique is considered an ideal alternative to other expensive methods This review article focuses on the usage of modified plant-based adsorbents for the efficient removal of heavy metals and dyes Various methods of activation and modification like physical, chemical and composite formation with components such as polymers, carbon nanotube (CNT), graphene, layered double hydroxides (LDHs) and metal oxides are discussed in depth Generally, these modifications of plant-based adsorbents resulted in significant enhancement of adsorption capacity Apart from this, the effect of various parameters such as adsorbent dosage, initial contaminant concentration, pH, temperature and contact time on the adsorption efficiency have also been reviewed The regeneration of used adsorbent prevented the generation of solid waste The reading of this review will be highly beneficial for researchers working on utilization of modified plant-based adsorbents for wastewater treatment

78 citations


Journal ArticleDOI
TL;DR: In this article, a comprehensive review of the performance of photolysis, photocatalysis, ozonation, Fenton process, anodic oxidation, sonolysis and wet air oxidation for the effective degradation of a wide range of trace organic contaminants (TrOCs) is presented.
Abstract: The persistent nature and low biodegradability of a large number of trace organic contaminants (TrOCs) reduce effectiveness of their removal by conventional wastewater treatments. In this context, advanced oxidation processes (AOPs), such as photolysis, photocatalysis, ozonation, Fenton process, anodic oxidation, sonolysis and wet air oxidation, have been studied extensively for the effective degradation of the wide range of TrOCs. All AOPs produce reactive oxygen species (HO2●, O2●−), especially hydroxyl radicals that unselectively attack contaminants and oxidise them. Factors affecting the degradation rates of TrOCs by different AOPs include the concentration and nature of the TrOCs, bulk wastewater characteristics, dose of chemicals or catalysts used, and other reaction parameters. This review critically analyses the overview of already established AOPs, the effect of the structure of TrOCs based on different functional groups such as electron donating groups (EDGs) and electron withdrawing groups (EWGs) on their degradation by each AOP. The overall degradation rates based on data collected from a comprehensive literature review show that ozonation achieves effective degradation for a broad range of TrOCs, but it can lead to the production of toxic degradation by-products. By comparison, photocatalysis shows moderate to high degradation rate for TrOCs. Photolysis and Fenton processes show TrOC-specific suitability. This review also demonstrates that optimum doses of chemicals/catalysts are required for each AOP. This is because excessive concentrations of catalysts or other chemicals (e.g., H2O2: iron dose in Fenton process) may result in low TrOC degradation. Degradation of individual TrOCs can result in a number of degradation by-product that varies in nature. Different AOP has different reaction mechanisms that also affect the number and nature of by-product formation during TrOC degradation.

78 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present and discuss trends and scientific developments about recovery of value-added products from dye industry effluent with emphasis on nanotechnological approaches and microbial electrochemical technologies (METs).
Abstract: Increased population and industrialization generate a large number of organic pollutants that create problems on the planet earth. The level of freshwater is reducing which has pushed the society to reuse/recycle wastewater. Eco-friendly and economically sound treatment of industrial wastewater has attracted global attention and hence is a thrust area of research. Organic compounds rich wastewater can be used to generate bioenergy and value-added products from the resource recovery point of view. Wastewater treatment(s) can be used to trap energy from industrial effluents in form of biofuel, bioenergy and biogas. Recovered products can be used in various ways such as recovered nutrients for (bio)fertilizer production and algal biomass for bioplastic production. Microbial electrochemical technology is a promising approach for resource recovery. This review article aims to present and discuss trends and scientific developments about recovery of value-added products from dye industry effluent. It also provides state-of-art technical information about technologies for remediation of pollutants from dye industry effluent with emphasis on nanotechnological approaches and microbial electrochemical technologies (METs). It narrates literature on classification and properties of dyes, effects of dye pollutants on environment and human health and factors affecting degradation of dyes. Generation of bioenergy and recovery of valuables from dye industrial wastewater along with challenges and perspectives of this research area have been covered.

75 citations


Journal ArticleDOI
TL;DR: In this article, the decolorization and degradation of dyes by various microbes, acting as biological tools against azo dyes, is discussed, and the azo dye degradation mechanism and factors affecting the degradations.
Abstract: Water pollution, mainly occurring from manufacturing industries, has been a serious environmental issue in the contemporary world. Dyeing processes produce a massive amount of dye-contaminated effluent; it is a major culprit for water and soil pollution in developing and underdeveloped countries. The azo dye released from industries poses a severe environmental menace by contaminating the aquatic system and adversely impacting human health. Azo dyes are synthetic macromolecules, which are persistent, recalcitrant, and non-biodegradable. Several physicochemical technologies have been proposed for azo dye mitigation. Still, some limitations are observed, such as high operational cost and energy requirement, complicated procedures, incomplete mineralization, and secondary waste generation. Alternately, remediation by microbes is considered a clean, effective, and safe technology to detoxify azo dyes from wastewater. The biological treatment can exploit fungi, yeast, bacteria, and algae, which have received attentiveness because of their eco-friendliness. This review highlights the decolorization and degradation of dyes by various microbes, acting as biological tools against azo dyes. It also discusses the azo dye degradation mechanism and factors affecting the degradations.

Journal ArticleDOI
TL;DR: In this article, the feasibility of using hybrid treatment system based on coagulation/flocculation, adsorption and filtration processes for real textile wastewater treatment was investigated.
Abstract: This research investigates the feasibility of using hybrid treatment system based on coagulation/flocculation, adsorption and filtration processes for real textile wastewater treatment. Ferric Chloride (FeCl3) was used as a coagulant, Nano Zero-Valent Iron (nZVI) as adsorbent and Micro Zeolite (MZ) as filter media for the removal of chemical oxygen demand (COD), total suspended solids (TSS), color, total nitrogen (TN) and turbidity from raw textile effluents. Batch and continuous feed scaling-up studies (full design and set-up studies) were conducted to evaluate the performance of the integrated treatment system to treat about 1.5 lit/min of real textile wastewater in about 1.2 h in six operating runs (I, II, III, IV, V, VI). The obtained results showed the enhanced COD, TSS, TN, turbidity and color removal ability for all runs. The average removal reached 97.5% for COD, 98% for TSS, 98.4% for color, 86.1% for TN and 93.5% for turbidity. An economic evaluation study was conducted for treating 200 m3/day textile effluents to evaluate the commercial applicability of the system. All data gained from batch, continuous feed and economic studies verified the efficiency of applying coagulation/flocculation, adsorption and filtration integrated treatment system at low cost for real textile effluent remediation.

Journal ArticleDOI
TL;DR: In this article, the authors evaluated the effect of seven different feature selection methods (filter, wrapper, and embedded methods) on enhancing the prediction accuracy for total nitrogen (TN) in the WWTP influent flow.
Abstract: Wastewater characteristics prediction in wastewater treatment plants (WWTPs) is valuable and can reduce the number of sampling, energy, and cost. Feature Selection (FS) methods are used in the pre-processing section for enhancing the model performance. This study aims to evaluate the effect of seven different FS methods (filter, wrapper, and embedded methods) on enhancing the prediction accuracy for total nitrogen (TN) in the WWTP influent flow. Four scenarios based on FS suggestions were defined and compared by three supervised Machine Learning (ML) algorithms, i.e. Artificial Neural Network (ANN), Random Forest (RF), and Gradient Boosting Machine (GBM). Input parameters, as daily time-series including pH, DO, COD, BOD, MLSS, MLVSS, NH4-N, and TN concentration, were used. Data set divided into train and unseen test data-sets, and performance precision of all models was carried out based on Root Mean Square Error (RMSE), Mean Absolute Error (MAE), and correlation coefficient (R2). Results reveal that scenario IV which was suggested by Mutual Information, including NH4-N, COD, BOD, and DO had the best result rather than other FS methods. Furthermore, decision tree algorithms (RF and GBM) revealed better performance results in comparison to neural network algorithm (ANN). GBM generalized the dataset patterns very well and produced the best performance on unseen data-set, which shows the effectiveness of this state-of-the-art ML algorithm for wastewater components prediction.

Journal ArticleDOI
TL;DR: In this paper, the basic operational characteristics of microbial fuel cells and microbial electrolysis cells using wastewater as fuel have been highlighted, along with challenges related to their operation, as well as possible integration with other technologies, have all been critically discussed.
Abstract: The application of bioelectrochemical systems mostly aims to be used for the generation of electricity or chemicals. The quest to generate energy that is both sustainable and environmentally friendly over the last few years has accelerated the growth in research activities in bioelectrochemical cells, namely: microbial fuel cells (MFCs), microbial electrolysis cells (MECs), microbial desalination cells (MDCs), and microbial electrolysis desalination cells (MEDCs). Microbial fuel cells and microbial electrolysis cells are considered the most developed technologies among these various types of bioelectrochemical systems. This investigation, intends to highlight the basic operational characteristics of MFCs and MECs using wastewater as fuel. The prospects associated with this novel technology, along with challenges related to their operation, have all been highlighted in this investigation. The application of bioelectrochemical systems, as well as possible integration with other technologies, have all been critically discussed. Moreover, the current work identified key factors impeding the commercialization of these technologies, including lower efficiencies, mass transfer limitations, porosity, and protonic conductivity. Other factors include the mechanical and chemical stability of materials, along with their biocompatibility. In summary, the application of bioelectrochemical systems futuristically will revolve around energy generation, mitigation of toxic gas emissions, wastewater treatment, bioanalysis, and environmental remediation.

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed studies on WO3, one of the most promising photocatalysts for solar water treatment technology, focusing on its properties, synthesis/preparation methods and strategies for improving its performance.
Abstract: Photoelectrocatalysis (PEC) is an advanced oxidation water treatment technology which combines the strengths of both heterogeneous photocatalysis and anodic oxidation for the effective degradation of organic pollutants in water. At the heart of this technology is the search for photocatalytic materials that exhibit excellent photo(electro)catalytic properties. In this article, we reviewed studies on WO3, one of the most promising photocatalysts for solar water treatment technology. Specific attention was paid to its properties, synthesis/preparation methods and strategies for improving its performance. Discussions were presented on some reports wherein the semiconductor and/or its composites were used to catalyse the degradation of organic pollutants in water.

Journal ArticleDOI
TL;DR: In this paper, the response surface methodology (RSM) was evaluated for optimizing the Hexavalent Chromium (Cr (VI)) removal efficiency using synthesized adsorbent, i.e., Fe3O4-NPs loaded on activated carbon.
Abstract: In the present paper, the Response Surface Methodology (RSM) was evaluated for optimizing the Hexavalent Chromium (Cr (VI)) removal efficiency using our synthesized adsorbent, i.e., Fe3O4-NPs loaded on activated carbon (AC-Fe3O4-NPs). For studying the characteristics of synthesized catalyst, the different analyses, e.g., pHpzc, XRD, FE-SEM, and VSM was utilized. As detected in results, a suitable correlation could be perceived between the values obtained by experiments and the values predicted by the quadratic model (P 0.99). The experimentally obtained maximum adsorption capacity of AC-Fe3O4-NPs for Cr (VI) adsorption was estimated to be 15.24 mg/g.

Journal ArticleDOI
TL;DR: The insights from cultivating microalgae in wastewater sources and the promising technologies to convert them into useful bioproducts will be beneficial to the developments of future upstream and downstream processes.
Abstract: Microalgae has been utilised in various applications ranging from pharmaceuticals, cosmetics, supplements, liquid fuels as well as food source for human and animals. The upscaling of microalgae production to meet the demand for global consumption has yet to be realized as there are many factors to be considered in the upstream and downstream processing of microalgae biomass. For upstream processing, the high cultivation cost which poses a major setback can be reduced by cultivating the microalgae in wastewater sources, which are widely available and at the same time can lead to bioremediation of these waste sources. The contents of microalgae biomass from wastewater can also be used to produce the desired bioproducts. For downstream processing, the efficiency of traditional processes has long hindered the progression of microalgae to products, hence, the discovery of advanced technologies which can yield higher productivity and good quality products have been studied and upscale to a pilot scale to verify its feasibility. Separation techniques like liquid biphasic system and membrane separation are potential in achieving high yield and separation efficiency to recover valuable products from microalgae and these processes are environmentally friendly and cost-effective. The insights from cultivating microalgae in wastewater sources and the promising technologies to convert them into useful bioproducts will be beneficial to the developments of future upstream and downstream processes.

Journal ArticleDOI
TL;DR: In this paper, the state of the art of the previous treatment processes has been discussed in detail, where each technique has its own merits and challenges, and the efficiencies of EAOPs follow the order as PEF > EF > AO and can mineralize the recalcitrant organic pollutants completely.
Abstract: Hazardous organic pollutants have been attracting heightened interest in recent years due to their persisting properties, low biodegradability, and negative influence on aquatic life, wildlife, and humans even at low concentrations. Considering their dangerous effect on the environment, several treatments using different techniques were adopted to remove them from water and wastewater. Herein, electrochemical advanced oxidation processes (EAOPs), especially anodic oxidation (AO), electro-Fenton (EF), heterogeneous electro-Fenton (HEF), and photoelectro-Fenton (PEF), have been thoroughly reviewed and found to be promising compared to conventional methods. The state of the art of the previous treatment processes has been discussed in detail, where each technique has its own merits and challenges. These processes depend on their operating conditions mainly pH, current density, nature of electrodes used, and conductivity of the solution, etc. The efficiencies of EAOPs follows the order as PEF > EF > AO and can mineralize the recalcitrant organic pollutants completely.

Journal ArticleDOI
TL;DR: In this paper, a comprehensive review of the existing healthcare structures, ECs pathways to the environment, management practices, and effective treatment options for removing ECs from hospital wastewater (HWW).
Abstract: A wide range of emerging contaminants (ECs), such as pharmaceutically active compounds, personal care products (PCPs), endocrine-disrupting compounds (EDCs), and hormones are released into hospital wastewater (HWW). These contaminants can enter into natural environments, such as aquatic and terrestrial ones, thereby threatening human health and aquatic life. Conventional wastewater treatment plants are not designed to treat all types of chemical and biological contaminants, thereby allowing the release of these contaminants into water bodies, such as rivers, streams, and groundwater. Accordingly, adequate measures and advanced technologies should be implemented to prevent the discharge of ECs into aquatic environments. Reducing environmental health risks of HWW is particularly important amid the persistence of the COVID-19 pandemic. Although the necessary guidelines and legislation for wastewater treatment are available, efficient removal of ECs from HWW requires the applications of advanced treatment technologies. This paper provides a comprehensive review of the existing healthcare structures, ECs pathways to the environment, management practices, and effective treatment options for removing ECs from HWW. A critical evaluation of the current research advances, knowledge gaps, and directions for future research is also presented.

Journal ArticleDOI
TL;DR: In this article, a comprehensive view of the treatment of textile wastewater and its reuse after proper treatment by membrane technologies at both pilot and full-scale applications is provided, where both physical and biological treatment methods are examined separately.
Abstract: Textile industries consume huge amount of water, which is more than that is consumed by most of the other industries. Wastewater generated from textile industries contains high concentrations of pollutants, thus, the wastewater needs to be treated before discharging. Besides, since large amount of wastewater is produced, reuse of treated wastewater should be considered in environmental aspects. Since textile wastewater contains mainly dyestuffs, it must be treated effectively using environmentally friendly technologies. Membrane processes are widely used in textile wastewater treatment, as they have distinct advantages over conventional wastewater treatment methods. Most of the research done so far has been conducted in lab-scale, but gradually both pilot and full-scale systems have been applied. This review provides a comprehensive view of the treatment of textile wastewater and its reuse after proper treatment by membrane technologies at both pilot- and full-scale applications. For this purpose, physical and biological treatment methods were examined separately. As a result of the examination, it was observed that according to the characteristics of textile wastewater and discharge standards, hybrid systems were generally used in the literature and very good results were obtained in terms of both filtration and treatment performance. Besides, cleaning methods and economic feasibility for the membrane processes are also investigated in textile wastewater treatment. Furthermore, due to the fact that full-scale studies are less in comparison to pilot-scale studies, deficiencies in processes are mentioned in order to support future research studies.

Journal ArticleDOI
TL;DR: In this article, the presence of SARS-CoV-2 RNA in sewage in Mexico based on RdRP, S, and N gene analysis was evaluated from the early stage of the epidemic to July 2020.
Abstract: The SARS-CoV-2 virus causing COVID-19 is spread in sewage by the stool of infected individuals, and viral material in sewage can be quantified using molecular tools. This study aimed to monitor the presence of SARS-CoV-2 RNA in sewage in Mexico based on RdRP, S, and N gene analysis. The influent, effluent, and activated sludge from two domestic wastewater treatment plants (WWTP) were evaluated from the early stage of the epidemic to July 2020. Additionally, sampling points in sewer systems were examined, comparing two different RNA-concentration methods: centrifugal ultrafiltration and adsorption-based methods. The adsorption method resulted in RNA titration that was two orders of magnitude higher than with ultrafiltration (up to 3.38 log10 copies RdRP gene/mL of sewage). The surveillance of SARS-CoV-2 RNA in the influent of two WWTP correlated with the cumulative COVID-19 cases in Queretaro city. The higher RNA level in secondary sludge compared to influent suggests that viral RNA becomes concentrated in activated sludge. This result supports SARS-CoV-2 RNA removal in WWTP, where all effluent samples were negative for virus quantification. This work proves that wastewater-based epidemiology is a very valuable tool in developing countries where diagnostic tests for COVID-19 are limited.

Journal ArticleDOI
TL;DR: The emerging non-degradable pollutants in natural ecosystems, such as microplastics, have been identified as a threat to humans and wildlife, mainly aquatic species, by getting incorporated into the food chain due to their sizes.
Abstract: Microplastics are the emerging non-degradable pollutants in natural ecosystems. It impacts humans and wildlife, mainly aquatic species, by getting incorporated into the food chain due to their sizes (

Journal ArticleDOI
TL;DR: In this article, the characteristics of extracellular polymeric substances (EPS) released by bacteria play a crucial role in microbial aggregation during wastewater treatment, and various environmental factors including substrate, anaerobic and aerobic conditions might contribute to the formation and properties of EPS, and thereby affect the properties of microbial aggregation and sludge.
Abstract: Extracellular polymeric substances (EPS) released by bacteria play a crucial role in microbial aggregation during wastewater treatment. Various environmental factors including substrate, anaerobic and aerobic conditions might contribute to the formation and properties of EPS, and thereby affect the properties of microbial aggregation and sludge. To reveal the relationship between these environmental factors and EPS properties, the characteristics of EPS generated in four types of sludge were investigated, including anammox granular sludge (ANMX), aerobic granular sludge (AGS) fed with glucose as carbon source (AGS-GLUC), AGS fed with liquor wastewater as carbon source (AGS-LIQ), and flocculent sludge from a real sewage plant (FLOC). Results indicated a positive correlation of EPS contents with granulation of sludge. As the dominant content of EPS, an increased proteins (PN) concentration facilitated the formation of microbial aggregates and the granulation of sludge. Bacteria in anaerobic environment (i.e., ANMX) or in aerobic environment with easily biodegradable carbon sources (i.e., AGS-GLUC) would generate more PN and EPS; yet, these conditions restrained the generation of humic acid (HA). The sludge from the sewage treatment plant (i.e., FLOC) had the lowest EPS and PN content, but the highest HA, showing flocculent structure sludge. In addition, a higher protein/polysaccharide (PN/PS) ratio and a lower zeta potential of EPS were conductive to sludge granulation. The hydrophobicity of EPS confirmed via analysis of chemical structures by FTIR would improve the microbial aggregation.

Journal ArticleDOI
TL;DR: A comprehensive review of PSF ultrafiltration and microfiltration membranes modification via various techniques as well as novel modifiers for water purification by paying attention to various issues inherent in the modification process is presented in this paper.
Abstract: Polysulfone (PSF) membranes have been widely used for wastewater treatment due to their desired properties like stability, high mechanical strength and ease of modification. The modification of PSF membranes presents a great opportunity in improving their performance in the field of wastewater treatment. This review presents a comprehensive review of PSF ultrafiltration (UF) and microfiltration (MF) membranes modification via various techniques as well as novel modifiers for water purification by paying attention to various issues inherent in the modification process. Recent studies on nanomaterial as well as hydrophilic macromolecules used for the modifications of PSF UF/MF membranes for water treatment application have been comprehensively analysed. These modified membranes exhibited a remarkable improvement with regards to water permeability, salt rejection and anti-fouling features of PSF modified membranes when compared to the neat PSF membranes. The modification techniques such as coating, grafting/blending, layer by layer and deposition are discussed. Besides, the impacts of these modifiers on the performance of the membranes for wastewater treatment as well as their environmental impacts are discussed. Based on the literature review, it is obvious that nanomaterial/hydrophilic macromolecules modified PSF membranes have unique features that can contribute to the advancement of innovative nanocomposite membranes with enhanced capacities for wastewater treatment.

Journal ArticleDOI
TL;DR: In this article, the presence of microplastics in 11 samples of popular brands of bottled mineral water in Iran using a staining method and stereomicroscope analysis, MPs were detected in 9 out of the 11 sample brands.
Abstract: Microplastics (MPs) have recently been detected in different products and environmental samples, ranging from wastewater to drinking water, as well as in products consumed by humans. However, few studies have addressed the contamination by MPs in bottled mineral water. Therefore, in the present study, the contamination by MPs was investigated from 11 samples of popular brands of bottled mineral water in Iran. Using a staining method and stereomicroscope analysis, MPs were detected in 9 out of the 11 sample brands. The amount, shape, and color of MPs varied in different bottles. The most detected MPs were in the shape of fragment (93 %) and fiber (7%), with an average concentration of approximately 8.5 ± 10.2 particles/L. In addition, there were no MPs in 20 % of the collected samples, which was the reason for the observed high variation of SD. The presence of MPs was demonstrated by FTIR and Raman stereoscopy and the most likely polymers found were PET, PS, and PP. Finally, four scenarios were investigated for daily and annual human exposure to microplastics. The study results indicate that the human daily and annual intake were negligible when compared using Valmet textures; approximately 0.015 P/kg/bw/day and 5.35 P/kg/bw/year for adults and approximately 0.065 P/kg/bw/day and 23.43 P/kg/bw/year for children.

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TL;DR: In this paper, the authors highlight the potential of microalgae species using wastewater for the production of different categories of carotenoids and discuss the integrated approach that can be implemented for the biosynthesis of these value-added products along with wastewater treatment.
Abstract: Carotenoids are natural pigments known for their various health benefits for humans together with various other applications in diverse industries. Considering the high market value of carotenoids in the food and health sector, sustainable production of these metabolites for commercial applications is the need of time. Among various microbial alternatives, microalgae are considered as a rich source of carotenoids along with other metabolites and received special attention. However, commercial microalgae production is not fully developed and diversity of data is available regarding the cost-effectiveness of algal biomass production. Recent studies employing novel technologies and methods, coupled with the utilization of wastewater for algal cultivation are providing an innovative way forward. Implementation of wastewater for the cultivation of microalgae offers an economical, sustainable, and environmentally friendly method of resource utilization and urban wastewater management. This review intends to highlight the potential of microalgae species using wastewater for the production of different categories of carotenoids. The review will discuss the integrated approach that can be implemented for the biosynthesis of these value-added products along with wastewater treatment. Different techniques and factors which can be utilized for the upstreaming and downstreaming of the algal carotenoids will also be addressed in detail along with their challenges. Possible recommendations for the coupling of microalgae with wastewater as an effective method of waste remediation and as a source of potential products are also proposed.

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TL;DR: In this paper, a review aimed to synthesise the research efforts on the removal of penicillins via a variety of separation, degradation and biological processes was presented, and it was observed that isotropic microporous microfiltration membranes are not effective for rejecting PENs, due to their large uniform pore size distribution.
Abstract: Penicillins (PENs) are β-lactam antibiotics with significant environmental toxicology. This review aimed to synthesise the research efforts on the removal of PENs via a variety of separation, degradation and biological processes. It was observed that isotropic microporous microfiltration membranes are not effective for rejecting PENs, due to their large uniform pore size distribution. Researchers favoured the application of Nanofiltration membrane and adsorption as separation technologies. Carbon-based adsorbents were the most efficient class of adsorbents for PENs removal from water. Lewis acid-base interactions, hydrogen bonding, electrostatic attraction and π – π interactions were the main adsorption mechanisms. Generally, the ultraviolet irradiation assisted-advanced oxidation processes (AOPs) and the Fenton-like processes outperformed the electrochemical and ultrasonic assisted-AOPs for PENs degradation. AOPs must be incorporated with other methods of treatment to minimise potential costs in terms of energy, time, equipment, and chemicals. For biological processes for PENs removal, anaerobic treatment processes were observed to be more efficient for the removal of PENs than aerobic processes. With the exception of microfiltration and electrocoagulation, most other processes were found to be effective for the removal of PENs from water, albeit with some disadvantages. From the review, it can be surmised that there has been great research progress on the subject and many new findings have been obtained in recent times though there is still much work to be done.

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TL;DR: In this article, the potential application of plant-based coagulants as suitable alternatives to Chemical Coagulant due to their biodegradability, economical, non-toxic, and lower sludge volume, and treatment cost; is being studied in industrial wastewater treatment.
Abstract: Chemical coagulants have been extensively used in wastewater treatment from industrial processes due to their removal efficiencies. Notwithstanding, recent studies have reported concerns over the existence of lingering or incurable diseases, resulting from residues of metals from these non-degradable chemical coagulants which remain in the water even after treatment. The sludge produced from the treatment has also been affirmed to be hazardous and non-biodegradable, causing harm to the environment. The potential application of plant-based coagulants as suitable alternatives to chemical coagulants due to their biodegradability, economical, non-toxic, and lower sludge volume, and treatment cost; is being studied in industrial wastewater treatment. Presented in this review is the state of heart of revolutionary technique for green coagulant preparation, their properties, and application in wastewater treatment. Highlighted is the current development on improving and purification techniques of the coagulants, and probable use of dual or combine coagulants. The review also critically identifies notable research gaps based on the current limitations in previous research to valorizing potential applications.

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TL;DR: In this article, five different cathodes made of low-cost materials were tested in microbial electrolysis cell (MEC) and the results showed quantitatively the electrochemical and performance transitions of MEC according to the cathode component changes.
Abstract: Microbial electrolysis cell (MEC) is an innovative electrochemical technology that decomposes organic matter in anode and produces hydrogen in cathode. It is imperative to use a high-performance and a low-cost cathode material to make the application of MEC economically viable. In this study, five different cathodes made of low-cost materials were tested in MECs. The materials included activated carbon (AC) and nickel powder (Ni) as a cathode catalyst; polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) as a catalyst binder; stainless steel mesh (SSM) as a cathode substrate or a cathode itself. Among the tested cathodes, Ni/AC/PTFE obtained the best performance, followed by Ni/AC/PVDF, AC/PVDF, flamed-oxidized SSM (SSM/F) and SSM. Ni/AC/PTFE exhibited the best performance in hydrogen production rate (HPR, 1.88 L/L d), hydrogen purity (97.5%), coulombic efficiency (124%), energy efficiency (216%), cathodic capacitance (0.9924 F), along with the lowest cathodic impedance (35 Ω). The worst performed SSM showed as follows: 0.57 L/L d of HPR, 71% of hydrogen purity, 36% of coulombic efficiency, 62% of energy efficiency, 0.0008 F of cathodic capacitance and 62 Ω of cathodic impedance. This study shows quantitatively the electrochemical and performance transitions of MEC according to the cathode component changes.

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TL;DR: In this paper, the most promising approach of electrochemical oxidation (EO) technology, introduces its basic principles, and describes the research progress and application status of electrode materials, electrochemical reactors and electrocatalysts.
Abstract: Over the years, industry, agriculture and other human activities have discharged a large number of organic pollutants into the natural environment. Among these, persistent organic pollutants (POPs), mainly represented by polychlorinated biphenyls (PCB) and aldrin, have attracted intense attention. To achieve the safe discharge of wastewater, a variety of treatment technologies have been used to effectively eliminate the POPs in water. This article reviews the currently most promising approach of electrochemical oxidation (EO) technology, introduces its basic principles, and describes the research progress and application status of electrode materials, electrochemical reactors and electrocatalysts. At the same time, the effects of operating conditions such as current density and electrolyte type on the degradation effect are discussed. Finally, the performance of the combination of EO technology and other water treatment technologies is summarized. In these processes, we discussed in detail the directions for improvement and potential mechanisms of EO technology, and found that the choice of appropriate operating conditions can not only improve the processing efficiency, but also reduces the processing cost. For example, for different POPs, different supporting electrolytes are selected and the pH value of the reaction is controlled. However, we should note that electrode optimization is always the core of EO technology improvement, and the use of high-efficiency electrocatalysts and the combination of combined processes are promising for the broader use of EO technology.