共查询到19条相似文献,搜索用时 171 毫秒
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微滤膜处理铁污染地下水的效果及膜污染控制研究 总被引:2,自引:0,他引:2
采用新型超高分子质量聚乙烯管式微滤膜为过滤介质,研究了微滤和曝气氧化/微滤组合工艺处理铁污染地下水的效果及机理。运行初始,微滤对铁的去除率为50%左右,曝气氧化/微滤组合工艺对铁的去除率可达90%以上,比单独微滤提高了40%~60%;运行后期管式膜表面生成铁质活性滤膜,单独微滤对铁的去除率也能达到90%以上。在前期膜污染以铁等无机物污染为主,后期为铁质活性滤膜和滤饼层污染。大流量水力冲洗和稀HC l浸泡可有效去除膜污染,NaC lO碱洗对膜过滤性能的恢复作用较小。 相似文献
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反渗透深度处理炼化废水的应用研究 总被引:1,自引:0,他引:1
采用反渗透工艺深度处理经连续微滤(CMF)预处理后的炼化废水.试验结果表明,反渗透对CMF出水COD的去除率高于93%,电导率降低了95%.出水可回用作循环冷却水系统补给水,有较好的经济效益和社会效益. 相似文献
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采用自行设计的混凝沉淀/微滤一体化装置对长江(重庆段)原水进行净水处理,比较了不同混凝剂投加量下的处理效果。试验结果表明,聚合氯化铝(PAC)的适宜投加量范围为25~30mg/L;在增加PAC投量(30~40mg/L)的强化混凝条件下连续运行,对浊度、氨氮、CODMn和UV254的去除率分别可达100%、(55%~64%)、(40、6%~50.7%)、(67%~74.6%)。在连续运行的前12个周期内,微滤膜的过滤性能缓慢下降,J/J0降低到95.8%,此后膜过滤性能保持稳定。混凝沉淀/微滤工艺处理效果好,出水水质稳定,适宜处理长江(重庆段)原水。 相似文献
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《Planning》2014,(7)
本文采用粉末活性炭-微滤(PAC-MF)组合工艺处理微污染地表水,考察了组合工艺对水中典型污染的去除效果。试验结果表明,粉末活性炭与微滤组合工艺能显著降低微污染水源中CODMn、浊度和紫外吸光度值(UV254),其平均去除率分别为62.4%、97.6%和51.2%,采用PAC-MF组合工艺处理微污染地表水能够达到优良的出水水质,并能够显著提高膜通量。 相似文献
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Autopsy of high-pressure membranes to compare effectiveness of MF and UF pretreatment in water reclamation 总被引:1,自引:0,他引:1
A pilot-plant study was designed to compare the effectiveness of microfiltration (MF) and ultrafiltration (UF) as pretreatment for high-pressure membranes in reclamation of biologically treated wastewater effluent. Granular media, filtered secondary effluent from a full-scale wastewater treatment plant, was fed to MF and UF units that operated in parallel. Each of these filtrates served as the feedwater to two reverse osmosis (RO) units and one nanofiltration (NF) unit that operated in parallel. The decline in specific flux was substantially lower for high-pressure membranes receiving UF than MF pretreatment over the course of each of four pilot plant runs that lasted from 1 to 7 weeks. The removal of organic matter as measured by dissolved organic carbon (DOC) was somewhat higher by UF than MF pretreatment (about 15% by UF compared with 11% by MF). Addition of ferric chloride ahead of the UF unit, but not ahead of the MF unit, may account for this additional removal of organic matter. However, the additional DOC removal appeared insufficient to explain the differential in foulant accumulation between high-pressure membranes receiving UF and MF pretreatment. Extensive autopsy analyses of these high-pressure membranes showed from 35% to 56% less organic carbon on those receiving UF rather than MF pretreatment. A more specific indicator of a differential in organic fouling was the accumulation of polysaccharides and this showed from 27% to 38% less on UF- than on MF-pretreated membranes. Yet another possible source of foulants is inorganic material given that the inorganic and organic weight percentages were nearly equal (56% vs. 44%) on the membrane surface. One specific source was aluminum added for phosphorus removal. Less fouling of high-pressure membranes pretreated by UF than MF could be due to the following: (1) a small, but very important, colloidal fouling fraction may have passed through MF but was rejected by UF pretreatment; (2) organic fouling was not related to organics in either the MF or UF filtrates but rather to organics that are generated in situ by microbial activity on the membrane surface; and/or (3) less passage of colloidal Al-P that carried over from secondary wastewater treatment. 相似文献
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The effects of microfiltration (MF) as pretreatment for reverse osmosis (RO) on biofouling of RO membranes were analyzed with secondary wastewater effluents. MF pretreatment reduced permeate flux decline two- to three-fold, while increasing salt rejection. Additionally, the oxygen uptake rate (OUR) in the biofouling layer of the RO membrane was higher for an RO system that received pretreated secondary wastewater effluent compared to a control RO system that received untreated secondary effluent, likely due to the removal of inert particulate/colloidal matter during MF. A higher cell viability in the RO biofilm was observed close to the membrane surface irrespective of pretreatment, which is consistent with the biofilm-enhanced concentration polarization effect. Bacterial 16S rRNA gene clone library analysis revealed dominant biofilm communities of Proteobacteria and Bacteroidetes under all conditions. The Cramer-von Mises test statistic showed that MF pretreatment did not significantly change the bacterial community structure of RO membrane biofilms, though it affected bacterial community structure of non-membrane-associated biofilms (collected from the feed tank wall). The finding that the biofilm community developed on the RO membrane was not influenced by MF pretreatment may imply that RO membranes select for a conserved biofilm community. 相似文献
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Comparing microfiltration-reverse osmosis and soil-aquifer treatment for indirect potable reuse of water 总被引:8,自引:0,他引:8
Microfiltration (MF) followed by reverse osmosis (RO) and soil-aquifer treatment (SAT) are the two principal technologies considered for indirect potable reuse of wastewater. This study, conducted at the Northwest Water Reclamation Plant, Mesa (Arizona), evaluated MF/RO and SAT (>6 months residence time) treated tertiary effluent with respect to organics removal. Effluent organic matter was characterized as total organic carbon (TOC), by UV absorbance (UVA), solid-state carbon-13 nuclear magnetic resonance spectroscopy, and size exclusion chromatography. Several trace organic micropollutants, including EDTA, NTA, and alkylphenolethoxylate residues, were analyzed by GC/MS. The study revealed that final TOC concentrations of MF/RO and SAT are 0.3 and 1.0 mgl(-1), respectively. Based on the characterization techniques used, the character of bulk organics present in final SAT water resembles the character of natural organic matter present in drinking water. Depending on the molecular weight cut-off, RO membranes can efficiently reject high molecular weight organic matter (characterized as humic and fulvic acids). However, approximately 40-50 percent of the remaining TOC in permeates consists of low molecular weight acids and neutrals representing a molecular weight range of approximately 500Da and less. In the SAT treated effluent, EDTA and APECs were removed to approximately 4.3 and 0.54 microg/l, respectively, but were below the detection limit in the MF/RO treated effluent. 相似文献
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Treatability of organic fractions derived from secondary effluent by reverse osmosis membrane 总被引:1,自引:0,他引:1
Dissolved organic matters (DOMs) from two batches of secondary effluent collected from a local water reclamation plant were fractionated using column chromatographic method with non-ionic resins XAD-8, AG MP-50 and IRA-96. Seven isolated fractions were obtained from the fractionation study and these fractions were quantified using DOC, UV(254) and SUVA values. The fractionation study revealed that the secondary effluent samples comprised about 47.3-60.6% of hydrophobic and 39.4-52.7% of hydrophilic solutes. The treatability of each isolated fraction was investigated by subjecting each fraction to reverse osmosis (RO) treatment individually. It was noted that RO process could achieve high DOC rejections for acid and neutral fractions (ranging from 80% to 98% removal) probably due to the negative charge of RO membrane. The results obtained also indicated that hydrophobicity of DOMs is significant in determining treatability of organic species by RO process. The performance of RO in terms of DOC rejection of un-fractionated secondary effluent was also investigated to assess possible effects of interactions among organic fractions on their treatability by RO process. It was noted that DOC rejection associated with the un-fractionated secondary effluent was generally higher (ranging from 2% to 45%) than the corresponding rejection obtained from each individual fraction isolated from the secondary effluent. This finding suggested there is a beneficial interaction among the fractions that in turn has contributed towards a better overall DOC rejection performance by RO treatment. 相似文献
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Cost factors and chemical pretreatment effects in the membrane filtration of waters containing natural organic matter 总被引:2,自引:0,他引:2
This paper compares the membrane processes available for water treatment. Membranes have the advantage of currently decreasing capital cost, a relatively small footprint compared to conventional treatment, generally a reduction in chemicals usage and comparably low maintenance requirements. Three membrane processes applicable to water treatment, micro- (MF), ultra- (UF), and nanofiltration (NF), are compared in terms of intrinsic rejection, variation of rejection due to membrane fouling and increase in rejection by ferric chloride pretreatment. Twelve different membranes are compared on the basis of their membrane pore size which was calculated from their molecular weight cut-off. A pore size of < 6 nm is required to achieve substantial (> 50%) organics removal. For a fouled membrane this pore size is about 11 nm. UV rejection is higher than DOC rejection. Coagulation pretreatment allows a higher rejection of organics by MF and UF and the cut-off criterion due to initial membrane pore size is no longer valid. A water quality parameter (WQP) is introduced which describes the product water quality achieved as a function of colloid, DOC and cation rejection. The relationship between log (pore size) and WQP is linear. Estimation of membrane costs as a function of WQP suggests that open UF is superior to MF (similar cost at higher WQP) and NF is superior to tight UF. Chemical pretreatment could compensate for the difference between MF and UF. However, when considering chemicals and energy costs, it appears that a process operated at a higher energy is cheaper at a guaranteed product quality (less dependent on organic type). This argument is further supported by environmental issues of chemicals usage, as energy may be provided from renewable sources. 相似文献
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Treatment of nanofiltration and reverse osmosis concentrates: comparison of precipitative softening, coagulation, and anion exchange 总被引:1,自引:0,他引:1
Disposal and treatment of concentrate from nanofiltration (NF) and reverse osmosis (RO) are major challenges to implementing membrane treatment processes. Intermediate treatment of membrane concentrate, between primary and secondary membrane stages, has the potential to increase membrane recovery rates and decrease the volume of concentrate produced. To achieve this, however, there is a need to better understand treatment of membrane concentrate. As a result, this work systematically evaluated lime softening, ferric sulfate coagulation, and magnetic ion exchange (MIEX) as individual, intermediate treatment processes for membrane concentrate. Six membrane concentrates, from NF and RO, with varying concentrations of calcium, dissolved organic matter (DOM), and sulfate were chosen for this study. Maximum removal of calcium was achieved by lime softening, whereas maximum removals of DOM and sulfate were achieved by MIEX. The results of this work show that intermediate treatment of NF/RO concentrate is capable of producing treated concentrate with water quality approximately equal to the initial source water. 相似文献