Direct drinking water treatment by spiral-wound ultrafiltration membranes

This paper presents the results of a research on direct drinking water treatment through an ultrafiltration pilot plant unit using spiral-wound membranes (3500 MWCO). The source of water is the Guarapiranga Reservoir, an eutrophicated water body located in the metropolitan region of São Paulo, Brazil. The data were collected during a period of almost 3400 h, from August 2005 to January 2006. The main objective of the study was to evaluate the membrane production capacity and contaminant removal efficiency. It was verified that the system was able to produce a high quality permeate with a flow close to the specified by the membrane manufacturer. The average permeate flow was 19.7 L.h⁻¹.m⁻², at 467 kPa and 25°C, with a global water recovery of almost 85%. The removal efficiencies for TOC, UV light absorption, and turbidity were 85%, 56%, and 95%, respectively. The results provide substantial evidence of the technical feasibility of spiral-wound UF membranes for direct drinking water treatment from euthrophicated sources, as an alternative for conventional drinking water treatment systems.     

一种新型反应器——生物气射流循环厌氧流化床的启动与运行特性

A novel anaerobic reactor, jet biogas inter-loop anaerobic fluidized bed （JBILAFB）, was designed and constructed. The start-up and performance of the reactor was investigated in the Process. of .artificial glucose wastewater treatment. With the wastewater recycle ratio of 2.5 ： 1, the recycled wastewater with biogas could mix sludge and wastewater in the JBILAFB reactor completely. The start-up of the JBILAFB reactor could be completed in less than 70 d through maintenance of hydraulic retention time （HR~I＂） and stepwise increase of feed total organic carbon （TOC） concentration. After the start-up, with the volumetric TOC loadings of 14.3 kg·m ^-3·d^-1, the TOC removal ratio, the effluent pH, and the volatile fatty acids （VFA）/alkalinity of the JBILAFB reactor were more than 80%, close to 7.0 and less than 0.4, respectively. Moreover, CH4 was produced at more than 70% of the theoretical value, The reactor exhibited high stability under the condition of high volumetric TOC loading. Sludge granules in the JBILAFB reactor were developed during the start-up and their sizes were enlarged with the stepwise increase of volumetric TOC loadings from 0.8 kg.m^-3.d ^-1 to 14.3 kg.m^-3.d^-1. Granules, an offwhite color and a similar spherical shape, were mainly comprised of global-like bacteria. These had good methanogenic activity and settleability, which were formed probably through adhesion of the bacteria. Some inorganic metal compounds such as Fe, Ca, Mg, Al, etc. were advantageous to the formation of the granules.     

Study of drinking water treatment by ultrafiltration of surface water and its application to China

In China, many water supplies depend on conventional water treatment. Due to unfit soil and water conservationin some regions of China, conventional water treatment has showed some defects for the poor quality of water resource. In addition, advances in membrane technology and increasing requirements on water quality have stimulated ultrafiltration (UF) for water treatment. In this research, OF test apparatus was set up to produce drinking water from raw water of the Binxian Reservoir (China). The performance of UF membranes was investigated. There was a linear relationship between membrane resistance and accumulated permeate water. Using coagulation before OF increased permeate flux and retarded membrane flux decline. Surprisingly, membrane permeate flux in a coagulation/UF process was higher than that in coagulation-sand filtration-UF process with raw water of medium turbidity. OF treatment provided effective turbidity removal. Iron, manganese and aluminum were removed completely. The UF membrane also perfectly removed all coliform bacteria. The reduction of total organic carbon was satisfactory. The treated water quality complied with China's drinking water guidelines. The Ames test showed that the mutagenic activities of membrane permeate water was negative.     

A combined photocatalytic slurry reactor–immersed membrane module system for advanced wastewater treatment

Photocatalysis with titanium dioxide semiconductor catalyst can effectively degrade recalcitrant organic pollutants present in biologically treated sewage effluents. Focusing on process efficiency and sustainability within a broader program, this study presents results obtained with a bench-scale hybrid treatment system. The process train comprised of a slurry (suspension) type continuous photocatalytic (CP) system and an immersed hollow fibre membrane micro-ultrafilter (MF/UF) unit. The CP reactor charged with 1 g/L P-25 catalyst removed 63% dissolved organic carbon (DOC) from a synthetic wastewater (representing biologically treated sewage effluent). The addition of 0.05 g/L of powdered activated carbon (PAC) increased DOC removal up to 76%. The start-up times to achieve 60% DOC removal were 31 min and 15 min, respectively. These results show a 16 times improvement in volumetric load over a comparable batch reactor system used in previous studies by our group.Slurry type photocatalytic reactors need subsequent particle separation to retain the catalyst in the system and allow the discharge of treated effluent. The immersed membrane module accomplished this without prior slurry settling step. Membrane feed pre-treatment with pH adjustment and particle charge neutralisation with aluminium chloride coagulant led to improved critical membrane fluxes, 15.25 L/m² h and 19.05 L/m² h, respectively. In each experiment MF/UF produced near zero turbidity permeate, completely retained the photocatalyst, and flocculation also improved the efficiency of DOC removal. Membrane fouling was controlled by particle aggregation rather than feed DOC levels, but the latter had significant impact on coagulant demand. The complete treatment train achieved up to 92% DOC reduction with 12 mg/L AlCl₃ dosage using in-line coagulation conditions. The results show that in-line coagulation offers a simple yet effective means to improve the performance of slurry type photocatalytic–MF/UF hybrid systems for advanced water and wastewater treatment applications.     

Integration of immersed membrane ultrafiltration with the reuse of PAC and alum sludge (RPAS) process for drinking water treatment

Effects of PAC and alum sludge generated from water treatment process on the effluent quality and fouling of immersed UF membrane were systematically investigated with representative source of natural water and the efficiency of coagulation, PAC adsorption and RPAS to treat natural surface water prior to UF were compared. It was found that the average turbidity removal by RPAS could reach up to 80.2%, and the turbidity removal of immersed membrane UF was independent of the influent, which could be kept at 99%. Particulates were reduced after being pre-treated by different processes, and particles with sizes ranging from 0.5 to 3.5 μm and larger than 13.5 μm were effectively removed by RPAS. UF coupled with RPAS pre-treatment got the best removal for DOM compared to other processes with average DOC and UV₂₅₄ removal 54.1% and 47.2% due to the high removal in the influent of UF. The residual alum content in the effluent of RPAS with UF was less than coagulation and bacteria were almost all removed by membrane. The membrane-fouling was mitigated by pre-treatment processes at different degrees, TMP of UF coupled with RPAS process was relatively stable in 15 d of run, the adsorption of PAC and large number of Al(OH)₃ complexes and precipitates for the foulant molecules might be an important mechanism.     

Removal of natural organic matter by ultrafiltration and nanofiltration for drinking water production

Water from Lake Butoniga near the town of Buzet, Croatia, was used as a source for drinking water production. Since lake water has a high concentration of trihalomethane precursors, a treatment was necessary. A process including ozonation, flocculation and filtration was chosen on the basis of preliminary work in a trial pilot plant with a capacity of 10 m³ h⁻¹. Although the chosen process succeeded in producing water that met the demands for drinking water, the efficiency of the removal of natural organic matter was relatively low. Ultrafiltration (UF) and nanofiltration (NF) processes were investigated as alternatives and possible upgrades of the process. Experiments were conducted at pilot plants with the Mavibran SP 006A and Romicon PM 10, PM 50, GM 80 and PM 500 OF membranes as well as with the Filmtec NF 45 NF membrane. Since most of the organic matter in the lake water was smaller than 6-8 kD, the use of the NF process was proposed. To avoid fouling of the NF membrane, we used flocculated and filtrated water from the trial plant as NF feed water. This combination produced water of high quality while process parameters remained stable over the entire period of investigation.     

水-有机溶剂混溶体系中催化抗体催化拆分布洛芳脂

The asymmetric hydrolysis of racemic ibuprofen ester is one of the most important methods for chiral separation of ibuprofen. In this work, a catalytic antibody that accelerates the rate of enantioselective hydrolysis of ibuprofen methyl ester was obtained against an immunogen consisting of tetrahedral phosphonate hapten attached to bovine serum albumin (BSA). The catalytic activity of the catalytic antibody in the water-miscible organic-solvent system composed of a buffer solution and N, N-dimethylformamide (DMF) was studied. With 6% DMF in the buffer solution (containing catalytic antibody 0.25 μmol, 0.2 mol•L－1 phosphate buffer, pH 8) at 37°C for 10 h, a good conversion (48.7%) and high enantiomeric excess (>99%) could be reached. The kinetic analysis of the catalytic antibody-catalyzed reaction showed that the hydrolysis in the water-miscible organic-solvent system with DMF in buffer solution followed the Michaelis-Menten kinetics. The catalytic efficiency (Kcat/Km) was enhanced to 151.91 L•mmol－1•min－1, twice as large as that for the buffer solution only.     

Synthesizing activated carbons from resins by chemical activation with K2CO3

We prepared activated carbons from phenol-formaldehyde (PF) and urea-formaldehyde (UF) resins by chemical activation with K₂CO₃ with impregnation during the synthesis of the resins. The influence of carbonization temperature (773-1173 K) on the pore structure (specific surface area and pore volume) and the temperature range at which K₂CO₃ worked effectively as an activation reagent, were investigated. The specific surface area and micropore volume of PF-AC and UF-AC increased with an increase of carbonization temperature in the range of 773-1173 K. We prepared activated carbon with well-developed micropores from PF, and activated carbon with high specific surface area (>3000 m²/g) and large meso-pore volume from UF. We deduced the activation mechanism with thermogravimetry and X-ray diffraction. In preparing activated carbon from PF, K₂CO₃ was reduced by carbon in the PF char. The carbon was removed as CO gas resulting in increased specific surface area and pore volume above 1000 K. In preparing AC from UF, above 900 K the carbon in UF char was consumed during the K₂CO₃ reduction step.     

Waste water recycling by ion-exchange: I. Complete desalination

Recycling of waste water by ion-exchange was studied on a bench scale. Secondary municipal effluent, which had undergone lime flocculation, served as a feed for the ion-exchange system. It was found that both the salt concentration and the organic matter content of the effluent could be reduced to produce high quality water, suitable for a wide range of agricultural and industrial applications. Salt concentrations was reduced from 15 meq/l (750 ppm as CaCO³) to about 1 meq/l (50 ppm as CaCO³) and the organic matter, from 70–100 mg/l COD (chemical oxygen demand) to 20 mg/l. The anion exchanger was regenerated with Ca(OH)₂ according to a new method recently developed. The treatment cost for a 2000 m³/day plant was calculated to be 18.0 ¢/m³.     

An unprecedented 2D isopolymolybdate with (3·4)(3·5·8)(3·4·5·6·8)(3·4·5·6) topology

A novel two-dimensional molybdenum oxide polymer, [Mo₄O₁₃]_n · 2nH₃O, has been prepared under specific hydrothermal conditions and characterized by IR spectroscopy and TG analysis. Single-crystal X-ray diffraction analysis reveals that compound 1 exhibits a (3, 4, 5, 6)-connected 2D layer structure with (3²·4)(3²·5³·8)(3·4²·5⁴·6·8²)(3⁴·4³·5⁴·6⁴) topology, which is constructed by two parallel molybdenum oxide dimeric chains (Mo₂O₁₀)_n bound together by the dimer of Mo₂O₉ subunits via the sharing of corners. Additionally, the electrochemistry activity of compound 1 is also reported.     

Synthesis of onion-like mesoporous silica from sodium silicate in the presence of α,ω-diamine surfactant

Mesoporous silicas with vesicular and onion-like morphologies were assembled through hydrogen-bonding pathway from sodium silicate as silica source and electrically neutral α,ω-diamine, Jeffamine D2000 surfactant (H₂NCH(CH₃)CH₂[OCH₂CH(CH₃)]₃₃NH₂) as template in aqueous media at different synthesis temperatures (25, 60 and 100 °C). Assembling the material at 100 °C afforded onion-like core shell mesoporous silica, while at relatively lower temperature, e.g. 25 and 60 °C, multilamellar vesicles were obtained. Mesoporous silica with onion-like morphology was also obtained by a two-step synthesis involving an aging period of 20 h at room temperature followed by a hydrothermal stage (1–12 h) at 100 °C. The heavily cross-linked (Q⁴/Q³ ratio of 4.43) onion-like mesophase silica exhibited high hydrothermal stability. The BET surface area, pore volume and KJS (Kruk-Jaroniec-Sayari) pore diameter of the onion-like mesoporous silica were found to be 464 m² g⁻¹, 1.16 m³ g⁻¹ and 7.2 nm, respectively.     

The Study on the Ceramic Membrane Wastewater Reuse System with Pre-Ozonation and Coagulation

A new wastewater reuse system using ozonation, coagulation and MF ceramic membrane (0.1 μm) filtration was developed. The testing was performed using secondary effluent treated at the wastewater treatment plant (WWTP) in Tokyo, Japan. The volume of treated water by the pilot study equipment is about 90 m³/day. The combination of pre-ozonation and coagulation processes achieves continuous stable membrane filtration with flux of 4m³/m²/day (167 LMH). A stable membrane filtration could be maintained by controlling ozone dosing rate depending on secondary effluent (raw water) quality fluctuation. The COD (Mn) removal ratio in raw water was 50 to 60%, and the color removal ratio satisfied 80% or higher. The quality of the treated water that was obtained from our pilot study was better than the California's standards.     

Poly(ether imide) membranes modified with charged surface‐modifying macromolecule—Its performance characteristics as ultrafiltration membranes

Modification of poly (ether imide) (PEI) ultrafiltration (UF) membranes was attempted by blending charged surface modifying macromolecule (cSMM). Compared to the pure PEI membrane, blending of PEI with cSMM resulted in blend membranes with enhanced UF characteristics such as lower hydraulic resistance (R_m) and higher pure water flux (PWF) coupled with higher water content (WC). Among the various modified membranes, blend membranes with 5 wt % cSMM concentration exhibited higher PWF (60.38 L m^?2 h^?1), WC (73.6%), protein permeate flux (27.12 L m^?2 h^?1) and lower flux decline rate (R_fd) (55.1%), R_m (5.21 kPa/L m^?2 h^?1), bovine serum albumin (BSA) rejection (87.1%). Meanwhile, the fouling resistant ability was studied by flux recovery ratio (FRR) after water and alkali cleaning, irreversible and reversible fouling rate. Higher FRR after water cleaning (95.07%), FRR after alkali cleaning (97.1%), reversible fouling rate (50.14%) and lower irreversible fouling rate (5%) exhibited by 5 wt % cSMM membranes showed its better antifouling ability compared to pure PEI and other blend membranes because of its higher hydrophilic nature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40320.     

钙钛矿型混合导体透氧膜SrFe0.6Cu0.3Ti0.1O3－δ的制备与表征

Dense membrane with the composition of SrFe0.6Cu0.3Ti0.1O3-δ （SFCTO） was prepared by solid state reaction method. Oxygen permeation flux through this membrane was investigated at operating temperature ranging from 750℃ to 950℃ and different oxygen partial pressure. XRD measurements indicated that the compound was able to form single-phased perovskite structure in which part of Fe was replaced by Cu and Ti. The oxygen desorption and the reducibility of SFCTO powder were characterized by thermogravimetric analysis and temperature programmed reduction analysis, respectively. It was found that SFCTO had good structure stability under low oxygen pressure at high temperature. The addition of Ti increased the reduction temperature of Cu and Fe. Performance tests showed that the oxygen permeation flux through a 1.5 mm thick SFCTO membrane was 0.35-0.96 ml·min ^-1·cm^-2 under air/helium oxygen partial pressure gradient with activation energy of 53.2 kJ·mol^-1. The methane conversion of 85%, CO selectivity of 90% and comparatively higher oxygen permeation flux of 5 ml·min^-1·cm^- 2 were achieved at 850℃, when a SFCTO membrane reactor loaded with Ni-Ce/Al2O3 catalyst was applied for the partial oxidation of methane to syngas.     

Achieving clean technology in the fish-meal industry by addition of a new process step

Fish-meal processing plants use large volumes of seawater to unload the fish from ships. Water to fish ratios range from 5 to 10 (m³ tonne⁻¹), producing an effluent high in chemical oxygen demand (COD) load, which is discharged to the sea. Alternative treatments were studied from economic and environmental aspects. The selected treatment involved two sequential steps: recycling of water during unloading and salvaging of reusable organic matter by chemical coagulation of soluble proteins with FeCl₃ followed by centrifugal separation. The recovered sludge was incorporated into the fish-meal process. Technical feasibility and cost implementation at industrial-scale were assessed. Results obtained at one plant demonstrated overall COD removal efficiencies of 93% for the clarified effluent (91% for proteins and 93% for fats and oil). Incorporation of the precipitated organic matter into the process increased productivity by approximately 7%.     

Facile preparation and separation performances of cellulose nanofibrous membranes

Ultrafiltration (UF) is a size selective pressure‐driven membrane separation process increasingly required for high efficient water treatment and suspended solids removal in many industrial applications. This study examined the morphology of as‐prepared cellulose nanofibers and then utilized the nanofibers dispersion to fabricate nanofibrous nanoporous membranes with potential wide applications in various fields including water treatment. The nanofibers were prepared using a simple and powerful mechanical high intensity ultrasonication following a pre‐chemical treatment of α‐cellulose. The cellulose nanofibers’ morphology, crystallinity, and yield were found to be influenced by pre‐chemical treatment. Cellulose nanofibrous membranes were fabricated from cellulose nanofibers dispersion on a porous support. A nanoporous structure with an extensive interconnected network of fine cellulose nanofibers was formed on the support substrate. The resulting membranes exhibited typical and high‐efficient UF performances with high water fluxes of up to 2.75 10³ L/m²/h/bar. The membranes also displayed high rejections for ferritin and 10 nm gold nanoparticles with a reactive surface area capable of rapidly decolorizing methylene blue from its aqueous solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43544.     

The effect of bentonite on the interaction of I with PbO

In the long-term disposal of nuclear fuel waste, the radioactive fission product ¹²⁹I requires special attention. This is because of its long half-life (1.7·10⁷ yr), and the fact that it exists in solution as an anion (I⁻ or IO₃⁻) and does not intereact strongly with most geological materials such as clays and rock. Mixtures of bentonite and sand are being evaluated as candidate buffer materials to surround nuclear fuel waste containers in an underground disposal vault in Canada. Since bentonite and sand sorb only minor amounts of I⁻, research is being conducted to identify materials that could be mixed with the buffer material to selectively ‘sorb’ ¹²⁹I⁻, and consequently retard its movement through the buffer after the waste containers are breached. PbO has been proposed as a potential buffer additive, since it has been found to be very effective in removing I⁻ from solution. However, when bentonite is present (≥75 wt% of the total solids) in the PbO/I⁻ system, the amount of I⁻ removed from a solution with an initial I⁻ concentration of 10⁻⁵ mol/l is significantly decreased. On the other hand, kaolinite has little effect. The same phenomenon occurs when bentonite is physically separated from the PbO by a semipermeable membrane. In the PbO/I⁻ system, X-ray diffraction analysis indicates that the Pb phases present are PbO, Pb₃(CO₃)₂(OH)₂, and 7PbO·PbI₂·2H₂O; however, when bentonite is present, 7PbO·PbI₂·2H₂O is not detectable. When bentonite is treated with NaOAc to remove carbonates and then added to the Pb/I⁻ system, the amount of I⁻ released into solution is much less than in the system containing untreated bentonite. Furthermore, the addition of CaCO₃ or a solution of NaHCO₃ to the Pb/I⁻ system causes a release of I⁻ into solution. The data indicate that bentonite affects the stability of 7PbO·PbI₂·2H₂O, shifting the equilibrium between it and Pb₃(CO₃)₂(OH)₂ by increasing the HCO₃⁻ activity in the system (the bentonite contains 0.29% carbonate-C). The results indicate that PbO would not be an effective additive to a buffer material in a nuclear fuel waste disposal vault for the selective removal of ¹²⁹I⁻ from solution.     

An improved Hummers method for eco-friendly synthesis of graphene oxide

An improved Hummers method without using NaNO₃ can produce graphene oxide nearly the same to that prepared by conventional Hummers method. This modification does not decrease the yield of product, eliminating the evolution of NO₂/N₂O₄ toxic gasses and simplifying the disposal of waste water because of the inexistence of Na⁺ and NO₃⁻ ions. For the first time, we also developed a prototype method of post-treating the waste water collected from the systems of synthesizing and purifying graphene oxide. The content of Mn²⁺ ions in the purified waste water was measured to be lower than the guideline value for drinking water.     

Peanut Shell Activated Carbon： Characterization,Surface Modification and Adsorption of Pb^2＋ from Aqueous Solution

Metal ion contamination of drinking water and waste water, especially with heavy metal ion such as lead, is a serious and ongoing problem. In this work, activated carbon prepared from peanut shell （PAC） was used for the removal of Pb^2＋ from aqueous solution. The impacts of the Pb25 adsorption capacities of the acid-modified carbons oxidized with HNO3 were also investigated. The surface functional groups of PAC were confirmed by Fourier transform infrared （FTIR） spectroscopy, X-ray photoelectron spectroscopy （XPS）, Boehm titration. The textural properties （surface area, total pore volume） were evaluated from the nitrogen adsorption isotherm at 77 K. The experimental results presented indicated that the adsorption data fitted better with the Langmuir adsorption model. A comparative study with a commercial granular activated carbon （GAC） showed that PAC was 10.3 times more efficient compared to GAC based on Langmuir maximum adsorption capacity. Further analysis results by the Langmuir equation showed that HNO3 [20% （by mass）] modified PAC has larger adsorption capacity of Pb^2＋ from aqueous solution （as much as 35.5 mg·g^-1）. The adsorption capacity enhancement ascribed to pore widening, increased cation-exchange capacity by oxygen groups, and the promoted hydrophilicity of the carbon surface.     

Pilot‐scale treatment of waste‐water from carbon production by a combined physical–chemical process

BACKGROUND: Due to its strong colour, high concentrations of fluorides and chemical oxygen demand (COD_Cr) and large amount of suspended solids (SS), the waste‐water from carbon production (WCP) seriously affects the stability of the circulating system of Guizhou Branch, Aluminium Corporation of China. In this paper, the performance of a pilot‐scale (24 m³ d^?1) combined treatment plant, consisting of chemical precipitation, coagulation, and Fenton oxidation, for the treatment of WCP was investigated. RESULTS: Lime precipitation and hydrated ferrous sulphate (HFS) coagulation, with polyacrylamide (PAM) as a coagulation aid, proved to be effective in the removal of colour (>70%), suspended solids (SS) (>90%) and fluoride (>80%) from the WCP. Subsequent Fenton oxidation combined with coagulation as a final treatment efficiently removed SS, F^?, COD_Cr, dissolved organic carbon (DOC) and colour. The average total removal efficiencies of these parameters in the pilot‐scale combined technology were as follows: SS = 98.8%, F^? = 95.7%, COD_Cr = 94.8%, DOC = 91.8% and colour = 98.3%, giving an average effluent quality: colour 24 (multiple), COD_Cr 168 mg L^?1, DOC 80 mg L^?1, F^? 38 mg L^?1 and SS 44 mg L^?1, consistent with the reusable water limits for the process. CONCLUSIONS: The current experimental results and the economic evaluation suggest that the combined process could be advantageous and feasible for the treatment of WCP. Copyright © 2009 Society of Chemical Industry