Treatment of laundry wastewater using polyethersulfone/polyvinylpyrollidone ultrafiltration membranes

Identification of Membrane Fouling with Greywater Filtration by Porous Membranes: Combined Effect of Membrane Pore Size and Applied Pressure

Membrane fouling caused by complex greywater synthesized by personal care products and detergents commercially available for household applications was investigated using dead-end microfiltration (MF) and analyzed systematically by a multistage Hermia blocking model as a first attempt. The highest flux decline was associated with the smallest pore size of the membrane (0.03 μm). This effectiveness was more pronounced at higher applied pressures to the membrane. A cake layer was formed on the membrane consisting mainly of silica particles present as ingredients in greywater. Although organic rejection was low by the porous MF membrane, the organic compound contributed to membrane fouling in the filtration stage. With a 0.03 μm pore size of the membrane, dominant fouling mechanisms were classified into three stages as applied pressure increased, such as complete pore blocking, intermediate pore blocking, and cake layer formation. Specifically, during the early stage of membrane filtration at 1.5 bar, membrane fouling was determined by complete pore blocking in the 0.10 μm pore size of the membrane. However, the later stage of membrane fouling was controlled mainly by intermediate pore blocking. Regardless of the applied pressure, pore constriction or standard blocking played an important role in the fouling rate with a 0.45 μm pore size of the membrane. Our results also support that complex formation can occur due to the concentration of organic and inorganic species present in simulated greywater. Thus, strategic approaches such as periodic, chemically enhanced backwashing need to be developed and tailored to remove both organic and inorganic fouling from MF membranes treating greywater.

Nanoplastics removal from spiked laundry wastewater using electro-peroxidation process

Microplastics and nanoplastics (NPs) in laundry wastewater (LWW) are major sources of plastic particles in wastewater treatment plants. Unlike microplastics, almost no information exists in the literature on the degradation of NPs in LWW. In this work, the degradation of NPs in commercial LWW by the electro-peroxidation process is investigated. The obtained results demonstrated that already existing ions in LWW such as Cl- contribute to faster degradation of NPs and a complete removal could be obtained as fast as 40 min. In addition, three-dimensional excitation and emission matrix fluorescence analysis was performed, which revealed humic acid-like, aromatic proteins-like, and fulvic acid-like compounds could be oxidized after 20, 40, and 60 min of treatment respectively. The effects of operating parameters on the process performance were then examined by response surface methodology (RSM) models. The results showed that initial TOC concentration was the most important parameter influencing negatively the percentage of NP degradation. Afterward, optimization of the process revealed that the energy consumption could be minimized at 31.2 mA/cm2, 0.025 mol/L [Na2SO4], and 52 min treatment time for 52.2 mg/L initial TOC. Finally, analysis of treated LWW showed no toxicity on Daphnia magna. This study showed that the electro-peroxidation process can completely degrade NPs in LWW without any remaining toxic compounds.

Performance Evaluation of UF Membranes Derived from Recycled RO Membrane, a Step towards Circular Economy in Desalination

Reverse osmosis (RO) spiral wound membrane generation reached 93.5% in 2020, resulting in 14,000 tons of used RO membranes being discarded annually into landfills, which is unprecedented. The current study aims to chemically convert the end-of-life RO membrane, followed by its performance evaluation and microbial removal efficiency on three different sources of water, i.e., tap water (TW), integrated constructed wetland permeate (ICW-P), and membrane bio-rector permeate (MBR-P), respectively. This was accomplished by selecting 6 years of spent Filmtech (LC-LE-4040) thin film composite type brackish water reverse osmosis (BWRO) membrane, followed by alkaline and acidic cleaning for 2 h. Finally, the conversion was carried out by 6% sodium hypochlorite (NaOCl) with 300,000 ppm/h exposure by active system (AS) using the clean in place CIP pump at 2 bars for 10 h duration. The membrane demonstrated 67% water recovery and 1% saltwater rejection, which means RO membrane now converted into recycled RO (R-RO) or (UF) by removal of the polyamide (PA) layer. Water recovery was 67% for TW, 68% for ICW-P, and 74% for MBR-P, respectively, with the consistent saltwater rejection rate of 1% being observed, while R-RO exhibited an effective COD removal of 65.79%, 62.96%, and 67.72% in TW, ICW-P, and MBR-P, respectively. The highest turbidity removal of 96% in the ICW-P was also recorded for R-RO. For morphological properties, SEM analysis of the R-RO membrane revealed a likewise appearance as a UF membrane, while pore size is also comparable with the UF membrane. The most probable number (MPN) also showed complete removal of total coliforms after passing through the R-RO membrane. These features made the R-RO membrane an excellent choice for drinking water treatment and wastewater treatment polishing steps. This solution can help developing nations to be efficient in resource recovery and contribute to the circular economy.

Ultra-Low-Pressure Membrane Filtration for Simultaneous Recovery of Detergent and Water from Laundry Wastewater

Reusing water and excess detergent from the laundry industry has become an attractive method to combat water shortages. Membrane filtration is considered an advanced technique and highly attractive due to its excellent advantages. However, the conventional membrane filtration method suffers from membrane fouling, which restricts its performance and diminishes its economic viability. This study assesses the preliminary performance of submerged, gravity-driven membrane filtration—under ultra-low trans-membrane pressure (△P) of <0.1 bar—to combat membrane fouling issues for detergent and water recovery from laundry wastewater. The results show that even under ultra-low pressure, the membrane suffered from compaction that lowered its permeability by 14% under △P of 6 and 10 kPa, with corresponding permeabilities of 2085 ± 259 and 1791 ± 42 L/(m2 h bar). Filtration of a detergent solution also led to up to 8% permeability loss due to membrane fouling. During the filtration of laundry wastewater, 80−91% permeability loss was observed, leading to the lowest flux of 15.6 L/(m2·h) at △P of 10 kPa, 38% lower than △P of 6 kPa (of 25.2 L/(m2·h)). High △P led to both the membrane and the foulant compaction inflating the filtration resistance. The system could recover 83.6% of excess residual detergent, while most micelles were rejected (ascribed from 71% of COD removal). The TDS content could not be retained, disallowing maximum resource recovery. A gravity-driven filtration system can be self-sustained with minimum supervision in residential and industrial laundries. Nevertheless, a detailed study on long-term filtration performance and multiple cleaning cycles is still required in the future.

Greywater as an Alternative Solution for a Sustainable Management of Water Resources—A Review

In this paper, a comprehensive review on greywater is presented. Emphasis is given to the techniques used to treat and recover greywater, and special emphasis is placed on the risk of the existence of the novel coronavirus “SARS-CoV-2” in greywater and the possibility of its spread via the reuse of this water. In general, greywater is considered wastewater collected from domestic sources, with the exclusion of toilet water (which is considered as blackwater). Greywater represents 50 to 80% of the total volume of wastewater all over the world. This review provides various aspects related to greywater, such as origins, characteristics, and existing guidelines for greywater proper treatment and reuse. Several approaches and techniques have been developed to study the performance of different greywater treatment systems. These methods are critically discussed in this article. In the context of sustainable development, water management, and taking into account the scarcity of water resources, particularly in arid and semi-arid areas, the use of treated greywater is one of the alternatives methods that can reduce the burden of withdrawals from the resource. In addition, some successful examples of greywater valuation experiences in Tunisia were examined.

Water recovery and on-site reuse of laundry wastewater by a facile and cost-effective system: Combined biological and advanced oxidation process

Combined biological and physicochemical process was selected for treatment of laundry wastewater. The results show that after microbial adaptation, almost 91% of COD was removed at food to microorganism (F/M) ratio of 0.12 gBOD/gMLSS·d. Dehydrogenase activity of the biomass showed an increasing trend and finally reached 3.8 μgTFgbiomass.d corresponding to the highest process performance. 16SrRNA fragment and phylogenetic analysis identified Pseudomonas pharmacofabricae and Bacillus spp. as the dominant bacteria. The effluent of the biological process was then injected into the UV/O3 process for complete removal of residual COD and detergent. Finally, microfiltration and ultrafiltration were used to remove any remaining suspended solids. The operating cost analysis showed that 0.65 €/m3 treated wastewater is required for treatment of the laundry wastewater. Accordingly, the suggested combination of the biological and physicochemical process could be a promising and highly efficient process for treatment and reuse of laundry wastewater.

Greywater as a sustainable source for development of green roofs: Characteristics, treatment technologies, reuse, case studies and future developments

Municipal activities are one of the most important water users worldwide; thus, the treatment and reuse of greywater for non-potable purposes helps to reduce a remarkable amount of consumed water within urban communities. To achieve greywater reuse standards, and remove surfactants, micropollutants, organic matters, microorganisms and other pollutants various methods including physical, chemical and biological processes have been used. Treated greywater can be used on site for different purposes: carwash, toilet flushing, fire protection, green roofs, green walls, non-food irrigation etc. Among them, the use of greywater is very important in the expansion of the green roofs. Green roofs offer many benefits to urban areas such as decreasing air pollution, reducing building cooling needs, promoting mental health of habitants, noise reduction and aesthetics improvement. Therefore, this article provides an overview mainly from two aspects, the possibilities of greywater reuse by studying the characteristics and available options for greywater treatment and its benefits toward the developing green roofs.

A Way to Membrane-Based Environmental Remediation for Heavy Metal Removal

During the last century, industrialization has grown very fast and as a result heavy metals have contaminated many water sources. Due to their high toxicity, these pollutants are hazardous for humans, fish, and aquatic flora. Traditional techniques for their removal are adsorption, electro-dialysis, precipitation, and ion exchange, but they all present various drawbacks. Membrane technology represents an exciting alternative to the traditional ones characterized by high efficiency, low energy consumption and waste production, mild operating conditions, and easy scale-up. In this review, the attention has been focused on applying driven-pressure membrane processes for heavy metal removal, highlighting each of the positive and negative aspects. Advantages and disadvantages, and recent progress on the production of nanocomposite membranes and electrospun nanofiber membranes for the adsorption of heavy metal ions have also been reported and critically discussed. Finally, future prospective research activities and the key steps required to make their use effective on an industrial scale have been presented

Recent Advances in the Synthesis of Nanocellulose Functionalized–Hybrid Membranes and Application in Water Quality Improvement

The increasing discharge of voluminous non or partially treated wastewaters characterized by complex contaminants poses significant ecological and health risks. Particularly, this practice impacts negatively on socio-economic, technological, industrial, and agricultural development. Therefore, effective control of water pollution is imperative. Over the past decade, membrane filtration has been established as an effective and commercially attractive technology for the separation and purification of water. The performance of membrane-based technologies relies on the intrinsic properties of the membrane barrier itself. As a result, the development of innovative techniques for the preparation of highly efficient membranes has received remarkable attention. Moreover, growing concerns related to cost-effective and greener technologies have induced the need for eco-friendly, renewable, biodegradable, and sustainable source materials for membrane fabrication. Recently, advances in nanotechnology have led to the development of new high-tech nanomaterials from natural polymers (e.g., cellulose) for the preparation of environmentally benign nanocomposite membranes. The synthesis of nanocomposite membranes using nanocelluloses (NCs) has become a prominent research field. This is attributed to the exceptional characteristics of these nanomaterials (NMs) namely; excellent and tuneable surface chemistry, high mechanical strength, low-cost, biodegradability, biocompatibility, and renewability. For this purpose, the current paper opens with a comprehensive yet concise description of the various types of NCs and their most broadly utilized production techniques. This is closely followed by a critical review of how NC substrates and their surface-modified versions affect the performance of the fabricated NC-based membranes in various filtration processes. Finally, the most recent processing technologies for the preparation of functionalized NCs-based composite membranes are discussed in detail and their hybrid characteristics relevant to membrane filtration processes are highlighted.

Water recovery by treatment of food industry wastewater using membrane processes

This work presents a proposal for the recovery of water through the treatment of food industry wastewater using membrane processes. Three wastewater streams from the different manufacturing steps were identified as possible sources of water recovery: (1) wastewater from the washing of ionic exchange resins and (2) wastewater from the concentration stage of animal proteins (type 1 and 2). The wastewater streams were treated as effluent mixtures; each one with different level of pollution. The principal characteristics of the effluent mixtures were identified as high conductivity and the presence of organic matter. Under these conditions, ultrafiltration and reverse osmosis were carried out for the treatment of wastewater. The ultrafiltration process was tested at an industrial-level plant and the reverse osmosis process was applied at a pilot-plant level. The results showed the feasibility of the proposed treatment for water recovery. The data demonstrates an efficiency greater than 95% in all the quality parameters and therefore, a high quality in the recovered water was obtained by membrane processes. According to the chemical composition of wastewater, the reversible fouling was linked to salts and protein retention, promoting the formation of a cake layer as reversible resistance; whereas, irreversible fouling was minimum during wastewater treatment.

Detergent and Water Recovery from Laundry Wastewater Using Tilted Panel Membrane Filtration System

Increasing global concern on clean water scarcity and environmental sustainability drive invention in water reclamation technology. Laundry wastewater reclamation via membrane technology faces the challenge of membrane fouling. This paper assesses a tilting-the-filtration-panel filtration system for the treatment of real laundry wastewater filtration aimed for water and detergent reuse. Results showed that the panel tilting significantly improved fouling control and enhanced permeability due to enhanced contact of air bubbles with the membrane surface, which induced continuous detachment of foulant from the membrane surface. The combination of aeration rate and tilting angle resulted in up to 83% permeability enhancement from 109 to 221.4 ± 10.8 (L/m²·h·bar). The system also offers 32% detergent recovery. Overall findings suggest that the system offers an attractive approach for both fouling management and detergent recovery and can potentially be applied under a simple setup in which filtration can be driven by gravity/hydrostatic pressure.

Antifouling and antimicrobial polyethersulfone/hyperbranched polyester-amide/Ag composite

This study provided a facile approach for the development of antifouling and antibacterial polyethersulfone (PES) composite film. Mainly, hyperbranched polyester-amide (PESAM) was used as both the reducing and capping agent for the in situ formation of AgNPs. The nanoparticles were intensively investigated using Fourier transform infrared spectroscopy (FTIR), ultra-violet spectroscopy (UV-vis), scanning and transmission electron microscopy (SEM & TEM) and X-ray diffraction (XRD). AgNPs were narrowly distributed with an average particle size of about 6 nm. PESAM was mixed with PES to realize free-standing film using the phase inversion method. The inclusion of PESAM in the composite film significantly improved hydrophilicity as confirmed by the contact angle measurements. Furthermore, SEM and EDX investigations confirmed that PESAM induced the in situ formation of AgNPs not only on the film surface but also inside its macro-voids. The composite film (PES/PESAM/Ag) displayed significant antibacterial potential against Gram positive and Gram negative bacteria. Overall, the described method paves the way towards development of advanced PES composite films with antimicrobial properties for broad application areas that include desalination membranes or active packaging materials.

Gene expression programming for process parameter optimization during ultrafiltration of surfactant wastewater using hydrophilic polyethersulfone membrane

Surfactants are the emerging contaminant and cause a detrimental effect on the ecosystem. In this study, an attempt is made to removal anionic surfactant Sodium dodecyl sulfate (SDS) containing wastewater using hydrophilic polyvinylpyrollidone (PVP) (5-15 wt%) modified polyethersulfone (PES) ultrafiltration membrane. The influence of operating variables on membrane performance was also sequentially analyzed using tests and three numerical modeling methods such as multiple linear regression (MLR), multiple Ln-equation regression (MLnER), and gene expression programming (GEP). Contact angle value of 10 wt% PVP modified PES membrane decreased up to 23.8°, whereas the neat PES membrane is 70.7°. This study indicates that the required hydrophilic property was improved in the modified membrane. The water flux and porosity also enhanced in PVP modified PES membranes. In performance evaluation, the optimum operating variable condition of transmembrane pressure (TMP), feed concentration, and the temperature is found to be 3 bar, 100 ppm, and 25 °C, respectively. Among the models, GEP has a good correlation with experimental anionic surfactant SDS filtration data. GEP performs better than other model with respect to statistical parameter and error terms. This study provides an insight into an adaptation of novel numerical modeling methods for the prediction of membrane performance to the treatment of surfactant wastewater.

Hybrid System Coupling Moving Bed Bioreactor with UV/O3 Oxidation and Membrane Separation Units for Treatment of Industrial Laundry Wastewater

This paper describes the investigations on the possibilities of treatment of wastewater generated in an industrial laundry with application of a combined biological-photooxidation- membrane system aimed at water recycle and reuse. The two treatment schemes were compared: 1) scheme A consisting of a treatment in a moving bed biological reactor (MBBR) followed by microfiltration (MF) and nanofiltration (NF), and 2) scheme B comprising MBBR followed by oxidation by photolysis enhanced with in situ generated O₃ (UV/O₃) after which MF and NF were applied. The removal efficiency in MBBR reached 95–97% for the biochemical oxygen demand; 90–93% for the chemical oxygen demand and 89–99% for an anionic and a nonionic surfactants. The application of UV/O₃ system allowed to decrease the content of the total organic carbon by 68% after 36 h of operation with a mineralization rate of 0.36 mg/L·h. Due to UV/O₃ pretreatment, a significant mitigation of membrane fouling in the case of both MF and NF processes was achieved. The MF permeate flux in the system B was over two times higher compared to that in the system A. Based on the obtained results it was concluded that the laundry wastewater pretreated in the MBBR-UV/O₃-MF-NF system could be recycled to any stage of the laundry process.

A review on the preparation, characterization and potential application of perovskites as adsorbents for wastewater treatment

Perovskite are among the popular materials utilized in many areas of modern industrialization because of their low price, high stability, excellent oxidation activity, adsorptive, catalytic, optical, magnetic, electronic and ferroelectric properties. Over the years, widespread usage of perovskite nanoparticles has been reported due to its various applications which include an environmental catalyst, fuel cells, chemical sensors, magnetic materials, oxygen permeable membranes and adsorbents for wastewater treatment. Various synthetic methods such as the sol-gel method, proteic method, Pechini method, combustion, co-precipitation, and chelating precursor method have been applied in producing perovskites. Therefore, this review assembles the current knowledge on the processes involved in the preparation of perovskites, their characterizations and potential applications in wastewater treatment. Challenges and future opportunities of perovskite-based materials are discussed as well as obstacles against their extensive uses. Conclusions have also been drawn proposing a few suggestions for future research.

Potential of siltstone and its composites with biochar and magnetite nanoparticles for the removal of cadmium from contaminated aqueous solutions: Batch and column scale studies

The present study is the first attempt to evaluate the pilot and batch scale adsorption potential of siltstone (SS) and its nanocomposites with biochar (EDB/SS), magnetite nanoparticles (MNPs/SS) and MNPs/EDB/SS for Cd removal from contaminated water. The SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were characterized with FTIR, XRD, BET, SEM, TEM, TGA and point of zero charge (PZC). The effects of adsorbent dosage, contact time, initial Cd concentration, pH and presence of competing ions were evaluated on the Cd removal and its adsorption. The order for Cd removal was: MNPs/EDB/SS > MNPs/SS > EDB/SS > SS (95.86-99.72% > 93.10-98.5% > 89.66.98-98.40% > 74.90-90%). Column scale experiments yielded maximum retention (95%) of Cd even after 2 h of injection at 100 mg Cd/L. The exhausted SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were reused without losing significant adsorption potential. Similarly, maximum Cd adsorption (117.38 mg/g) was obtained with MNPs/EDB/SS at dose 1.0 g/L. The results revealed that coexisting cations reduced the Cd removal due to competition with Cd ions. The experimental results were better explained with Freundlich isotherm model and pseudo 2nd order kinetic models. The results revealed that SS and its composites can be used efficiently for the removal of Cd from contaminated water.

Roles of surfactants in pressure-driven membrane separation processes: a review

Surfactants widely exist in various kinds of wastewaters which could be treated by pressure-driven membrane separation (PDMS) techniques. Due to the special characteristics of surfactants, they may affect the performance of membrane filtration. Over the last two decades, there are a number of studies on treating wastewaters containing surfactants by PDMS. The current paper gives a review of the roles of surfactants in PDMS processes. The effects of surfactants on membrane performance were discussed via two aspects: influence of surfactants on membrane fouling and enhanced removal of pollutants by surfactants. The characteristics of surfactants in solution and at solid-liquid interface were summarized. Surfactants in membrane filtration processes cause membrane fouling mainly through adsorption, concentration polarization, pore blocking, and cake formation, and fouling degree may be influenced by various factors (feed water composition, membrane properties, and operation conditions). Furthermore, surfactants may also have a positive effect on membrane performance. Enhanced removal of various kinds of pollutants by PDMS in the presence of surfactants has been summarized, and the removal mechanism has been revealed. Based on the current reports, further studies on membrane fouling caused by surfactants and enhanced removal of pollutants by surfactant-aided membrane filtration were also proposed.

Performance of a novel ABR-bioelectricity-Fenton coupling reactor for treating traditional Chinese medicine wastewater containing catechol

In this study, a novel anaerobic baffled reactor-bioelectricity-Fenton (ABR-BEF) coupling reactor, combining an ABR, microbial fuel cell (MFC), and Fenton system, was used to treat traditional Chinese medicine (TCM) wastewater containing catechol. The bio-electrochemical degradation of the catechol reached 99.7% after 8 h at dissolved oxygen (DO) concentration of 4 mg/L in the cathodic chamber. The removal rates of chemical oxygen demand (COD) reached 91.7%, when the ratio rate was 1 and the DO concentration was 4 mg/L. Moreover, the maximum open-circuit voltage and power density of the coupling reactor reached 424.9 mV and 77.1 mW/m³, respectively. According to the PICRUSt analysis, carbohydrate metabolism took up the most abundant function of metabolism and the enrichment of membrane transporters may relieve TCM wastewater toxicity. These results suggest that the ABR-BEF coupling reactor could be applied as an efficient approach to treat TCM wastewater.

Combined UMBAF-MBAF process treating detergent wastewater

A combined process of the upflow multimedium biological aerated filter (UMBAF) and the multimedia biological aerated filter (MBAF) treating detergent wastewater was investigated in this study. Results showed that the optimal filtration rate of the combined system was 1.4 m/hr while the optimized performance was observed at air to water ratio of 2:1. The average removal rate of chemical oxygen demand (COD), linear alkyl benzene sulfonate sodium (LAS), and total phosphate (TP) was up to 91.4%, 88.5%, and 40%, respectively, while the average effluent concentrations of COD, LAS, and TP under stable operation states were 35.0 mg/L, 7.0 mg/L, and 4.4 mg/L, respectively. UMBAF played a major role in TP removal; the removal of COD in the combined UMBAF and MBAF process was consistent with the general formula C = C₀ e ^{-(ah + b)} , while the kinetic model of LAS removal in the combined UMBAF and MBAF process could be expressed by L = L₀ e^{-(mh + n)} . The combined UMBAF-MBAF process provides a promising technology for the treatment of detergent wastewater. The kinetic model of LAS removal in the UMBAF and MBAF units is helpful for the prediction of the treatment efficiency of organic pollutants. PRACTITIONER POINTS: A novel UMBAF-MBAF process was developed treating detergent wastewater. The average removal rate of COD, LAS, and TP by the combined process was up to 91.4%, 88.5%, and 40%, respectively. Kinetic models for the UMBAF-MBAF process were investigated.

A Comprehensive Literature Study on Microfibres from Washing Machines

The ubiquitous finding of microplastic in the abiotic and biotic environment has gained a lot of attention recently in the media, scientific community and among the general public. One of the known sources of microfibres is the washing of textiles. It would be a conceivable option to install filters in domestic washing machines that would sift out microplastics to prevent this pollution. The aim of this paper was to conduct a comprehensive literature search on microplastics filters in washing machines published already. Although the results of this research show that there has been an effort to find solutions for this problem in a worldwide context, there has been no known proven system that prevents microfibre release in the aquatic environment which does not have a harmful influence on the washing behaviour and/or washing results.

Combined Application of Coagulation/Flocculation/Sedimentation and Membrane Separation for the Treatment of Laundry Wastewater

The wastewater from industrial laundries has a high quantity of contaminants from the washing process, as well as chemical additives. Aiming at the treatment of this type of wastewater, the present study evaluated the performance of a combined coagulation/flocculation/sedimentation process (C/F/S) and membrane separation to treat laundry wastewater in relation to physicochemical parameters of water quality. For this purpose, a Doehlert experimental design was applied to the C/F/S step using the natural coagulant Tanfloc POP® with maximum color and turbidity removal efficiency obtained of 80.27% and 86.50%, respectively, under conditions of pH of 6.4 and a coagulant concentration of 110 mg·L−1. The supernatant from the C/F/S step was used in the sequential microfiltration (MF) and ultrafiltration (UF) experiments. The maximum values of color, total nitrogen, dissolved solids, and turbidity removal were similar to MF and UF membranes at transmembrane pressure of 1.4 bar, with the greatest flow of permeates (92.2 L·h−1·m−2) presented by the MF membrane at 1.4 bar. The total efficiency of the combined C/F/S-MF process indicated the quality of the treated wastewater since it reduced 98.4% of the color, 99.1% of turbidity, 71.7% of the surfactants, and more than 55% of the total dissolved solids (TDS), chemical oxygen demand (COD), and total organic carbon (TOC) from the industrial laundry wastewater. This study showed that the C/F/S-MF combined process could be an efficient treatment of laundry wastewater.

Evaluation of photocatalytic fuel cell (PFC) for electricity production and simultaneous degradation of methyl green in synthetic and real greywater effluents

Recycling of alternative water sources particularly greywater and recovery of energy from wastewater are gaining momentum due to clean water scarcity and energy crisis. In this study, the photocatalytic fuel cell (PFC) employing ZnO/Zn photoanode and CuO/Cu photocathode was successfully designed for effective greywater recycling as well as energy recovery. The photoelectrodes were analyzed using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and fourier transform infrared (FTIR) spectroscopy. The PFC performance in terms of electricity generation and parallel methyl green (MG) degradation were evaluated under operating parameters such as electrolyte type, initial MG concentration and solution pH. The results showed that the addition of Na₂SO₄ electrolyte, MG concentration of 40 mg L^-1 and solution pH of 5.2 improved the short circuit current density (J_sc) and power density (P_max) in the as-constructed PFC. Such a system also afforded highest MG and chemical oxygen demand (COD) removal efficiencies after 4 h of irradiation. The photoanodes used in this study demonstrated great recyclability after four repetition tests. The COD removal was reduced to some extents when the PFC treatment was tested in the real greywater under optimal conditions. Various greywater quality parameters including ammoniacal nitrogen (NH₃-N), turbidity, pH and biochemical oxygen demand (BOD₅) were also monitored. The phytotoxicity experiments via Vigna radiate seeds indicated a reduction in the phytotoxicity.

Recent advances in hydrophilic modification and performance of polyethersulfone (PES) membrane via additive blending

The blending of additives in the polyethersulfone (PES) matrix is an important approach in the membrane industry to reduce membrane hydrophobicity and improve the performance (flux, solute rejection, and reduction of fouling). Several (hydrophilic) modifications of the PES membrane have been developed. Given the importance of the hydrophilic modification methods for PES membranes and their applications, we decided to dedicate this review solely to this topic. The types of additives embedded into the PES matrix can be divided into two main categories: (i) polymers and (ii) inorganic nanoparticles (NPs). The introduced polymers include polyvinylpyrrolidone, chitosan, polyamide, polyethylene oxide, and polyethylene glycol. The introduced nanoparticles discussed include titanium, iron, aluminum, silver, zirconium, silica, magnesium based NPs, carbon, and halloysite nanotubes. In addition, the applications of hydrophilic PES membranes are also reviewed. Reviewing the research progress in the hydrophilic modification of PES membranes is necessary and imperative to provide more insights for their future development and perhaps to open the door to extend their applications to other more challenging areas.

Coagulation behavior of kaolin-anionic surfactant simulative wastewater by polyaluminum chloride-polymer dual coagulants

In this study, polyaluminum chloride (PAC) and cationic polymers were used to treat kaolin suspension in the presence of sodium dodecyl benzene sulfonate (SDBS). Effects of PAC dosage, pH, and rotation rate on the coagulation efficiency and floc properties were studied. And the interaction of chemicals and kaolin-SDBS was discussed. Results showed that dual coagulants could decrease the influence of SDBS on the turbidity removal compared with PAC. PAC + polyacrylamide dual coagulant showed superior performance, and the maximal removal ratios of turbidity and dissolved organic carbon were 98.5 and 42.2%, respectively. Optimal coagulation performance was achieved at pH 5-7, where charge neutralization of Al hydrolysates and bridging of polyacrylamide were the primary mechanisms. And flocs with compact structure and small size were formed. Flocs coagulated by PAC were prone to be broken at the pH of raw water after introducing high rotation rate. After dosing polyacrylamide, floc size was enhanced under alkaline condition. Meanwhile, flocs showed stronger recoverability and an open structure because the regeneration mechanism was mainly the bridging effect of polyacrylamide.

A system coupling hybrid biological method with UV/O3 oxidation and membrane separation for treatment and reuse of industrial laundry wastewater

The possibilities of application of a three-step system combining hybrid biological treatment followed by advanced UV/O3 oxidation with in situ generated O3 and membrane separation (ultrafiltration (UF) and nanofiltration (NF)) to treat and reuse the wastewater from an industrial laundry are presented. By the application of a hybrid moving bed biofilm reactor (HMBBR), the total organic carbon concentration was reduced for about 90 %. However, since the HMBBR effluent still contained organic contaminants as well as high concentrations of inorganic ions and exhibited significant turbidity (8.2 NTU), its further treatment before a possible reuse in the laundry was necessary. The UV/O3 pretreatment prior to UF was found to be an efficient method of the membrane fouling alleviation. During UF, the turbidity of wastewater was reduced below 0.3 NTU. To remove the inorganic salts, the UF permeate was further treated during NF. The NF permeate exhibited very low conductivity (27-75 μS/cm) and contained only small amounts of Ca(2+) and Mg(2+); thus ,it could be reused at any stage of the laundry process.

Decolorization of distillery spent wash effluent by electro oxidation (EC and EF) and Fenton processes: A comparative study

In this study, laboratory scale experiments were performed to degrade highly concentrated organic matter in the form of color in the distillery spent wash through batch oxidative methods such as electrocoagulation (EC), electrofenton (EF) and Fenton process. The effect of corresponding operating parameters, namely initial pH: 2-10; current intensity: 1-5A; electrolysis time: 0.5-4h; agitation speed: 100-500rpm; inter-electrode distance: 0.5-4cm and Fenton's reagent dosage: 5-40mg/L was employed for optimizing the process of spent wash color removal. The performance of all the three processes was compared and assessed in terms of percentage color removal. For EC, 79% color removal was achieved using iron electrodes arranged with 0.5cm of inter-electrode space and at optimum conditions of pH 7, 5A current intensity, 300rpm agitation speed and in 2h of electrolysis time. In EF, 44% spent wash decolorization was observed using carbon (graphite) electrodes with an optimum conditions of 0.5cm inter-electrode distance, pH 3, 4A current intensity, 20mg/L FeSO4 and agitation speed of 400rpm for 3h of electrolysis time. By Fenton process, 66% decolorization was attained by Fenton process at optimized conditions of pH 3, 40mg/L of Fenton's reagent and at 500rpm of agitation speed for 4h of treatment time.