Water Treatment Performance Research Articles

UV 222 nm Emission from KrCl* Excimer Lamps Greatly Improves Advanced Oxidation Performance in Water Treatment

UV 222 nm Emission from KrCl* Excimer Lamps Greatly Improves Advanced Oxidation Performance in Water Treatment

Characteristics of a PVDF-Tin Dioxide Membrane Assisted by Electric Field Treatment.

Polymeric membranes have good properties for filtering water. In this paper, a membrane made from polyvinylidene fluoride (PVDF) polymer with 15 wt%, 17.5 wt%, and 20 wt% polymer content, with the addition of 1 wt% of tin dioxide with electric field treatment, is presented. The electric field used was DC 15,000 V. The membrane was tested to determine its characteristics and properties. The physical properties were examined with a scanning electron microscope, and the mechanical properties of the membrane were tested by tensile testing. The maximum tensile stress was obtained at 0.746 MPa, and the minimum tensile stress was obtained at 0.487 MPa. Microscopic examination of the membrane’s surface identified the shape, the structure of the fibers formed, and the amount of agglomeration. The flow rate, membrane flux, and normalized water permeability (NWP) were tested, using the water treatment performance test to measure the membrane’s filtering ability.

Recent Advances in Adsorptive Nanocomposite Membranes for Heavy Metals Ion Removal from Contaminated Water: A Comprehensive Review.

Water contamination is one of the most urgent concerns confronting the world today. Heavy metal poisoning of aquatic systems has piqued the interest of various researchers due to the high toxicity and carcinogenic consequences it has on living organisms. Due to their exceptional attributes such as strong reactivity, huge surface area, and outstanding mechanical properties, nanomaterials are being produced and employed in water treatment. In this review, recent advances in the use of nanomaterials in nanoadsorptive membrane systems for wastewater treatment and heavy metal removal are extensively discussed. These materials include carbon-based nanostructures, metal nanoparticles, metal oxide nanoparticles, nanocomposites, and layered double hydroxide-based compounds. Furthermore, the relevant properties of the nanostructures and the implications on their performance for water treatment and contamination removal are highlighted. The hydrophilicity, pore size, skin thickness, porosity, and surface roughness of these nanostructures can help the water permeability of the nanoadsorptive membrane. Other properties such as surface charge modification and mechanical strength can improve the metal adsorption effectiveness of nanoadsorptive membranes during wastewater treatment. Various nanocomposite membrane fabrication techniques are also reviewed. This study is important because it gives important information on the roles of nanomaterials and nanostructures in heavy metal removal and wastewater treatment.

Hydrodynamic cavitation as an efficient water treatment method for various sewage:- A review.

With the development of industry and the rapid growth of population, the current water treatment technologies face many challenges. Hydrodynamic cavitation as a green and efficient means of water treatment has attracted much attention. During the hydrodynamic cavitation, enormous energy could be released into the surrounding liquid which causes thermal effects (local hotspots with 4600 K), mechanical effects (pressures of 1500 bar) and chemical effects (hydroxyl radicals). These conditions can degrade bacteria and organic substance in sewage. Moreover, the combination of hydrodynamic cavitation and other water treatment methods can produce a coupling effect. In this review, we summarize the methods of hydrodynamic cavitation and the performance of water treatment for different types of sewage. The application of hydrodynamic cavitation reactors with different structures in water treatment are also evaluated and discussed. The design and optimization of high-performance hydrodynamic cavitation reactor are the most crucial issues for the application of hydrodynamic cavitation in water treatment. Finally, recommendations are provided for the future progress of hydrodynamic cavitation for water treatment.

High performance polypyrrole coated carbon-based electrocatalytic membrane for organic contaminants removal from aqueous solution

Electrocatalytic filtration process adopting the electrocatalytic membrane as both filtration membrane and active electrode showed great prospect on the organic pollutant removal from water. In this work, a high-performance metal-free polypyrrole (PPy) coated carbon-based electrocatalytic membrane (PPy@CCM) was developed through the facile and controllable electro-polymerization deposition method. Structural properties and electrochemical performance of the prepared PPy@CCM were characterized systematically. The influences of preparation parameters and operational parameters on water treatment performance of PPy@CCM were also investigated. Results indicates that the spherical PPy particles uniformly distributed on the surface of PPy@CCM. Coating with PPy particles can significantly improve the hydrophilicity and electrochemical activity of CCM, therefore PPy@CCM has lower hydraulic resistance and higher water treatment performance than CCM. The phenol and chemical oxygen demand (COD) removal rates obtained by PPy@CCM are up to 99.51% and 89.90%, respectively, under the optimal condition of 2.0 V cell potential, 2.50 g·L−1 Na2SO4, 1.5 ml·min−1 flow rate and 50 mg·L−1 phenol, and only 0.5 kWh·kgCOD−1 energy consumption is consumed. In addition, PPy@CCM also exhibits good treatment performance in different water matrixes. Moreover, PPy@CCM has good stability for several cycle operation and considerable applicability for different types of organic pollutants removal. The oxidation mechanism study reveals that PPy@CCM has both direct and indirect oxidation activity during the electrocatalytic filtration treatment, and the coating of PPy can improve the direct oxidation ability and ·OH yield of CCM.

Confinement of Prussian Blue Analogs Boxes Inside Conducting Polymer Nanotubes Enables Significantly Enhanced Catalytic Performance for Water Treatment

AbstractTubular nanoreactor with unique void‐confinement effect has captured great attention for catalytic applications but is challenging in controllable fabrication and realizing a synergistically enhanced performance. Herein, a template polymerization‐guided synthetic strategy is presented to confine hollow Prussian blue analog boxes inside conducting polypyrrole nanotubes (H‐CoFe PBA@PPy NTs) as efficient peroxymonosulfate activator toward catalytic oxidation of toxic organic contaminants. This delicately designed H‐CoFe PBA@PPy NTs display a superior kinetic rate constant compared with the pristine CoFe PBA cubes (7.9 fold) and H‐CoFe PBA boxes (22.6 fold). Experimental evidence reveals that the generation of multiple reactive oxygen species in the nanotubes plays a vital role for the significantly enhanced catalytic efficiency for dye degradation. The superior catalytic performance is attributed to the intrinsic bimetallic CoFe PBA to provide abundant active sites, distinct nanotubular structure to concentrate the reactant molecules within a confined space, and excellent electron/mass transport property. This work presents new horizons for the design of high‐efficiency and stable catalysts with space confinement effects to promote future advanced water treatment technology.

Preparation and performance of electrocatalytic carbon membranes for treating micro-polluted water

Porous carbon membranes (PCMs) with three functions of adsorption, electrocatalytic oxidation and membrane filtration were prepared from coconut shell activated carbon using carboxymethyl cellulose (CMC, 10 wt%) and benzoxazine resin (BR, 10 wt%-40 wt%) as the binder components. The morphology and microstructure of PCMs were characterized by SEM, XRD, Raman and nitrogen adsorption. An electrocatalytic membrane reactor (ECMR) was constructed using PCMs as the anode materials to investigate their water treatment performance. Results show that the PCMs have well-developed hierarchical macro, meso and micropores, whose macropore size decreases with the particle size of the activated carbon. The mechanical strength and electrical conductivity of the PCMs increased with BR content and carbonization temperature. The water flux decreased as the average particle size of the activated carbon decreased and the iodine value decreased with decreasing BR content. The PCM performed best with an excellent comprehensive performance in adsorption, electrocatalytic oxidation and filtration when it was prepared from an activated carbon of average particle size of 37.9 μm using a BR content of 30 wt% and a carbonization temperature of 950 °C. For the micro-polluted Lingshui River water in Dalian, the removal of COD, UV254, turbidity and bacteria with the ECMR reached 94.3%, 90.5%, 96.3% and 100%, respectively, and heavy metal ions (Pb2+, Cu2+, Zn2+, Ni2+) were removed to levels below the detection limits, and the anti-fouling performance was good. The excellent performance in treating micro-polluted water is ascribed to the combined effects of adsorption, electrocatalytic oxidation and filtration.

Boosting non-radical oxidation in peroxydisulfate activation with carbonaceous catalytic membranes by coupling structural defects and nitrogen doping sites

Non-radical oxidation is a critical pathway of peroxydisulfate (PDS) activation for organic degradation with metal-free carbonaceous nanomaterial. In this study, reduced graphene oxide (rGO) sheets with carbon to oxygen atomic ratios of 2.9 and 6.6 (rGO2.9 and rGO6.6) were composited with pristine or nitrogen-doped carbon nanotubes (CNTs or N-CNTs) to fabricate rGO2.9/CNTs, rGO2.9/N-CNTs, rGO6.6/CNTs, and rGO6.6/N-CNTs catalytic membranes. These membranes were employed to perform in-situ catalytic oxidation to remove N4-acetyl-sulfamethoxazole (NSMX) as the target pollutant in continuous filtration mode. The results showed that rGO6.6/N-CNTs coupled structural defects and nitrogen (N)-doping sites to obtain superior water flux and efficient NSMX removal via PDS activation. After 50 h of continuous filtration experiments, rGO6.6/N-CNTs exhibited NSMX removal rates (rNSMX) of 16.3 mg.m−2.h−1 at a carbon loading dosage of 8 g.m−2, which was 3.1-, 2.2-, and 1.4-times higher than the values for rGO6.6/CNTs, rGO2.9/N-CNTs, and rGO2.9/CNTs, respectively. N-doping sites took precedence over structural defects in activating PDS and enhanced the catalytic stability of carbon mats. In addition, surface chemical characterization and radical quenching experiments verified that the singlet oxygen (1O2) and surface-active species dominated in NSMX degradation as non-radical pathways. Although carbon loading, PDS dosage, initial pH, inorganic ions, and natural organic matter (NOM) influenced in-situ catalytic oxidation, both higher rNSMX and lower transmembrane pressures were achieved with rGO6.6/N-CNTs in real water matrices as compared to rGO6.6/CNTs. Further rational tailoring of carbonaceous catalytic membranes should focus on improving the catalytic stability and anti-fouling performance in advanced water treatment.

Promotion and mechanisms of Bdellovibrio sp. Y38 on membrane fouling alleviation in membrane bioreactor

Membrane fouling is a major bottleneck limiting the widespread application of membrane bioreactors (MBR). In this study, Bdellovibrio sp. Y38, an obligate bacteriophage bacterium of Bdellovibrio-and-like organisms (BALOs), was enriched into highly concentrated culture medium (106-107 PFU/mL), and daily dosed into the MBR to investigate its effects on membrane fouling mitigation. The strain Y38 prolonged the membrane fouling cycle from 73 days to 90 days, indicating its membrane fouling alleviation potentials. The concentration of BALOs was increased 625 times higher than the control group after the whole operation, resulting in the concentration of chemical oxygen demand and nucleic acids in the liquid phase of the MBR system being significantly increased by 169.8 ± 1.5% and 126.7 ± 2.2%, respectively. The biomass growth rate was reduced by 27.2 ± 0.7% from day 0 to day 54. These results indicated the predation potential of Bdellovibrio sp. Y38 on the microorganisms in the sludge. The improvement of homogenized sludge and filtration and settling performance by the strain Y38 alleviated the membrane fouling. Compared with the control group, the macromolecular proteins in SMP and EPS were partially declined, and the polysaccharide in EPS decreased by 14.0 ± 3.9%, and the ratios of protein content to polysaccharide content (PN/PS) in SMP and EPS significantly increased by 35.6 ± 16.8% and 57.8 ± 6.1% at the middle stage, respectively, indicating the strain Y38 could alleviate membrane fouling by reducing and modifying SMP and EPS. Furthermore, the relative abundance of γ-proteobacteria decreased from 13.2% to 5.1% at the pre-middle stage, and Planctomycetes decreased from 1.5% to 0.8% at the end-stage, which were probably responsible for the membrane fouling mitigation. In addition, the strain Y38 had few impacts on the water treatment performance of MBR. There findings provide a promising strategy for in situ membrane pollution mitigation via exogenous additions of BALOs.

Modification of ultrafiltration membrane with antibacterial agent intercalated layered nanosheets: Toward superior antibiofouling performance for water treatment

Membrane fouling, especially biofouling induced by biofilm formation on membranes, can result in frequent cleaning or even replacement of membranes. Fabrication of membrane with excellent antibiofouling property is quite attractive due to its effectiveness and low-impact on the operation of membrane-based process. Herein, a cationic antibacterial agent, quaternary ammonium compound (QAC), was intercalated into the interlayer spaces of the MgAl layered double hydroxide (QAC/LDH) by self-assembly. The QAC/LDH composite was incorporated into polyethersulfone (PES) ultrafiltration (UF) membrane (PES-QLDH). The QAC/LDH enhanced the hydrophilicity, water flux, and resistance to organic fouling for the PES-QLDH membrane. The PES-QLDH membrane exhibited superior antibiofouling performance than the control PES membrane, with deposition of a thinner biofilm layer consisted of almost dead cells. The superior antibacterial activity inhibits the adhesion and growth of bacteria on the membrane surface, effectively retarding the formation of biofilms. Importantly, the synergistic effect of QAC and LDH in the PES-QLDH membrane resulted in a high biocidal activity based on both direct and indirect killing mechanisms. The PES-QLDH membrane maintained a stable and high antibacterial activity after several fouling-cleaning cycles. These results imply that the PES-QLDH membrane provides an effective and promising strategy for its long-term application in wastewater treatment.

Chemically induced alteration in PAC characteristics and its influences on PAC/UF water treatment: Implications for on-line membrane cleaning with NaClO

The integrated PAC/UF technique has gained increasing applications in water treatment systems. However, the fouling and substantial PAC deposition on membrane surfaces remain perennial hurdles. To tackle these issues, on-line membrane cleaning with NaClO should be frequently performed to sustain the membrane permeability, leading to the inevitable contact between NaClO and PAC particles, which may significantly change the PAC properties, hence the entire performance of water treatment during the next round of operation. This study simulated the two reactions between PACs and NaClO (i.e. deposited PAC with high-concentration NaClO and suspended PAC with low-concentration NaClO) based on the current practice of on-line membrane cleaning, and further investigated the impacts of NaClO-induced PAC variations on PAC/UF performance. The results showed that (i) the adsorption capacities of altered PACs for humic acid (HA), bovine serum albumin (BSA) as well as contaminants in surface water were seriously weakened because of the decreased specific surface area and pore volume; (ii) The altered PAC surface became more hydrophilic, presumably leading to the higher deposition on membrane surface. Besides, (iii) the PAC deposition amounts were all enhanced by the presence of BSA, while substantially decreased by HA. Further addition of Ca2+ with HA dramatically increased PAC deposition probably by forming the cross-linked molecular chains to connect PAC-PAC or PAC-membrane. As a result, membrane fouling in PAC/UF water treatment system was remarkedly aggravated when the altered PACs were applied due to NaClO exposure. Meanwhile, the surface water treatment performances in terms of CODMn removal, UV254 removal and turbidity removal significantly decreased, implying the adverse impacts of employing such altered PAC in the practical water treatment system. Given on-line chemical cleaning is frequently conducted during a long-term operation, the current study raised serious concerns on membrane cleaning induced PAC variations and potentially negative influences on the real-life PAC/UF water treatment process.

A novel ceramic-based thin-film composite nanofiltration membrane with enhanced performance and regeneration potential

The rational design of a ceramic-based nanofiltration membrane remains a significant challenge due to its performance and fabrication cost. Herein, we report a high-performance ceramic-based thin-film composite (TFC) membrane fabricated via a typical interfacial polymerization on an interwoven net substrate assembled by titanium dioxide (TiO2) nanowires. The chemical properties and morphologies were systematically investigated for ceramic substrates and their corresponding TFC membranes. Due to the significantly improved hydrophilicity of the TiO2 framework, more reactive amine monomers were uniformly adsorbed on the modified surface of the ceramic substrate, yielding an ultrathin polyamide layer with less resistance. In addition, the smooth surface and decreased pore size of the TiO2 framework contributed to forming a defect-free polyamide layer. As a result, the obtained ceramic-based TFC membrane evinced high permeance of 26.4 L m−2 h−1 bar−1 and excellent salt rejection efficiency, leading to simultaneous improvements compared with the control TFC membrane without the TiO2 framework. Notably, the potential regeneration ability of the ceramic-based TFC membrane could be achieved via facile low-temperature calcination and re-polymerization process due to the varied thermostability between the polyamide layer and the robust ceramic substrate. The operation of regeneration helped to prolong the lifetime and decrease the cost for the ceramic-based TFC membrane. This research provides a feasible protocol to fabricate sustainable ceramic-based nanofiltration membranes with enhanced performance for water treatment.

Efficient degradation of trimethoprim by catalytic ozonation coupled with Mn/FeOx-functionalized ceramic membrane: Synergic catalytic effect and enhanced anti-fouling performance

In this study, the flat microfiltration ceramic membrane (CM) was modified by wet impregnation method (Mn-Fe-CM) to catalyze ozone (O3) for the oxidative degradation of trimethoprim (TMP). The conventional characterization test showed that the Mn-Fe binary oxides (Mn/FeOx) with the crystal structure of FeMnO3 were successfully loaded on the membrane and the catalytic performance of Mn-Fe-CM for O3 was apparently enhanced as compared to CM. Consequently, compared with O3 oxidation alone, the degradation and mineralization efficiencies of TMP in the O3/Mn-Fe-CM system were both improved and 98.6% of TMP could be removed within 10 min. The degradation efficiency of TMP decreased with the increasing pH and the addition of Cl-、HCO3–、PO43-, while humic acid (HA) exhibited negative effect on the TMP removal. Radical scavenger experiment and electron paramagnetic resonance (EPR) analysis confirmed that direct oxidation by O3 played an important role in the degradation of TMP, while hydroxyl radical (·OH) and 1O2 also participated. Fe(II) could act as an intermediate to transfer electrons and accelerate the transformation of Mn(III) to Mn(II) and Mn(IV) to Mn(III) during the ozonation process, which definitely strengthened the synergic catalytic effect of Mn-Fe-CM. The proposed degradation mechanism of TMP mainly contained hydroxylation, carbonylation, demethoxylation and deamination. Due to the strong catalytic ozonation performance for organic pollutants degradation, the O3/Mn-Fe-CM system revealed better anti-membrane fouling ability, strong cyclic usage performance and high applicability for the actual surface water treatment.

In-situ chemical formation of strong stability GO/rGO hybrid membranes for efficient treatment of organic pollutant

In this study, a strong stability graphene oxide (GO)/reduced graphene oxide (rGO) hybrid membranes were successfully prepared by in-situ chemical reduction method. As the reducing agent, ammonia can effectively promote the deoxygenation of GO surface and the restoration of π-conjugation to produce rGO sheets. Moreover, the weakening of hydration and the enhancement of π-π conjugation promoted the interlayer force of GO/rGO membranes; as a result, the hybrid membranes exhibited extraordinary stability in strong acid and alkali solutions. In organic dyes separation application, the hybrid membranes displayed excellent rejection performance, and the rejection rate up to 100%. In addition, they also showed higher water flux (23.72 L m-2h−1 bar−1) comparing to pristine GO membranes (14.35 L m-2h−1 bar−1) and rGO membrane (8.66 L m-2h−1 bar−1). This work will promote the application scope of graphene-based membranes and provide better performance in water treatment.

PH-responsive laminar WSe2 membrane with photocatalytic antifouling property for ultrafast water transport

Separation membrane with tunable nanochannels displays desirable performance in water treatment. While designing nanogating membranes with superior permeability and antifouling properties still remains a challenge. Here, we report a smart pH-responsive nanogating membrane by assembling two-dimensional polyacrylic acid (PAA) grafted tungsten selenide (WSe2) nanosheets. The nanochannel size of WSe2/PAA membrane varies with the swell or shrink of PAA chains that are regulated by pH, therefore leads to controllable separation capabilities towards mixed molecules solution. The membrane exhibits ultrafast water permeability because of the expanded interlayer space between WSe2 nanosheets and weak interaction between WSe2 and water molecules. Moreover, by virtue of the photocatalytic characteristic of WSe2, the membrane shows enhanced antifouling property. This WSe2/PAA nanogating membrane has great potential applications in nanofluidics system and complex chemical separation.

Strategies to Enhance ZnO Photocatalyst's Performance for Water Treatment: A Comprehensive Review.

Despite the photocatalytic organic pollutant degradation using ZnO started in 1910-1911, many challenges are still ahead, and several critical issues have to be addressed. Large band gap, and short life-time of photogenerated electrons and holes are critical issues negatively affect the photocatalytic activity of ZnO. Various approaches have been introduced to overcome these issues including intrinsic doping, extrinsic doping, and heterostructure. This review introduces unique and deep insights into tuning of the photocatalytic activity of ZnO. It starts by description of how to tune the photocatalytic activity of pristine ZnO through tuning its morphology, surface area, exposed face, and intrinsic defects. Afterward, the review explains how the Z-scheme approach succeed to address the redox weakened issue of heterojunction approach. In general, this review provides a clear image that helps the researcher to tune the photocatalytic activity of pristine ZnO and its heterostructure.

Optimising Operational Reliability and Performance in Aerobic Passive Mine Water Treatment: the Multistage Westfield Pilot Plant

A three-stage pilot system was implemented for passive treatment of circumneutral, ferruginous seepage water at a former opencast lignite mine in southeast Germany. The pilot system consisted of consecutive, increasingly efficient treatment stages with settling ponds for pre-treatment, surface-flow wetlands for polishing and sediment filters for purification. The overall objective of the multistage approach was to demonstrate applicability and operational reliability for successive removal of iron as the primary contaminant broadly following Pareto’s principle in due consideration of the strict site-specific effluent limit of 1 mg/L. Average inflow total iron concentration was 8.4(± 2.4) mg/L, and effluent concentration averaged 0.21(± 0.07) mg/L. The bulk iron load (≈69%) was retained in settling ponds, thus effectively protecting wetlands and sediment filter from overloading. In turn, wetlands and sediment filters displayed similar discrete treatment efficiency (≈73% each) relative to settling ponds and thus proved indispensable to reliably meet regulatory requirements. Moreover, the wetlands were found to additionally stimulate and enhance biogeochemical processes that facilitated effective removal of secondary contaminants such as Mn and NH4. The sediment filters were found to reliably polish particulate and redox-sensitive compounds (Fe, As, Mn, NH4, TSS) whilst concomitantly mitigating natural spatiotemporal fluctuations that inevitably arise in open systems. Both treatment performance and operational reliability of the multistage pilot system were comparable to the conventional treatment plant currently operated on site. Altogether the study fully confirmed suitability of the multistage passive setup as a long-term alternative for seepage water treatment on site and provided new insights into the performance and interrelation of consecutive treatment stages. Most importantly, it was demonstrated that strategically combining increasingly efficient components may be used for optimisation of treatment performance and operational reliability whilst providing an opportunity to minimise land consumption and overall costs.

Liquid Crystal‐Based Water Treatment Membranes

AbstractWater pollution is on the rise across the world and must be tackled since it leads to water shortage and poor water quality in the near future. Water has been cleaned and renewed using a variety of processes, but each has its own set of limitations. In this context, the membrane technology‐based strategy is one among the various available strategies and, moreover, it has the potentiality to tackle these problems in a more effective way. Furthermore, one of the ongoing challenges in this area of research is to identify the new and cost‐effective membranes for water treatment. Among the newly available various materials, certain materials such as carbon nanotubes and polymerized liquid crystals have attracted a great deal of interest and the pore alignments in these materials is generally a vital factor for the high water permeability, thus the pore alignment can be easily achieved for polymerized liquid crystals than for carbon nanotubes. Therefore, a critical and complete review of emerging trends in liquid crystal‐based polymer membranes for wastewater treatment is presented in this paper. Further, the different types of membranes based on the type of liquid crystal, properties, water treatment performances, advantages, and limitations have been discussed.

Tuning the Microstructure of a Zwitterion-Functionalized Polyethylenimine Loose NF Membrane for Dye Desalination

Developing a highly efficient and anti-fouling nanofiltration (NF) membrane for the desalination of dye wastewater is one of the hot environmental issues. In this study, loose NF membranes were facially prepared by glutaraldehyde (GA)-diffused crosslinking zwitterion-functionalized polyethylenimine (PEI-SBMA) and subsequent tannic acid (TA) surface modification. The microstructure of the membrane was tuned by optimizing the crosslinking condition to enhance the selectivity of dye/salt. The anti-fouling performance of the membrane was improved by the functionalization of the zwitterion and the adjustment of TA coating. Under optimal preparation conditions, the membrane performed high dye rejection [higher than 99% for fuchsin acid (AF) and methyl blue (MB)] and a high dye/salt selectivity of 93.95 with a water permeance of 118.5 LMH/bar, which were about 7.2 times and 49.5% higher than the membrane without crosslinking, respectively. In addition, the membrane showed enhanced anti-fouling ability and good long-term stability. The way of gradient crosslinking by GA diffusion to tune the microstructure of the loose NF membrane and the combination of zwitterions and TA coating could be useful candidates to enhance the membrane performance for water treatment.

Synergistic process using calcium peroxide and ferrous iron for enhanced ultrafiltration of Microcystis aeruginosa-laden water

Algal blooms and eutrophication in natural surface water not only pose a threat to human health, but also adversely affect the water purification process. Ultrafiltration (UF) has been proved to be effective for the retention of algal cells, but its further application is still restricted by the relatively limited removal of algal organics and membrane fouling. To enhance the UF performance, a synergistic process using calcium peroxide and ferrous sulfate (CaO2/FeSO4) was proposed for the treatment of Microcystis aeruginosa-laden water. The results suggested that the removal of algal cells and organics, fluorescent components were effectively increased with the synergism of CaO2 and FeSO4. The particle size distribution and morphology revealed that the size of algal pollutants apparently increased due to the formation of algal flocs. With CaO2/FeSO4 pretreatment, the terminal specific flux of polyethersulfone and polyvinylidene fluoride membranes were increased by 75.0% and 56.5%, individually. The fouling resistances were significantly reduced, and the fouling mechanism transition to cake filtration was delayed. The membrane interface properties including morphologies and functional groups were characterized, further verifying the effectiveness. The in-situ formed Fe3+ integrated with Ca(OH)2 showed excellent coagulation effect, thus promoting the agglomeration of algal foulants. Simultaneously, the generated hydroxyl radical could improve the oxidative degradation of algal organics. In conclusion, the CaO2/FeSO4 strategy has great advantages and application prospects in enhancing UF performance for Microcystis aeruginosa-laden water treatment.