MBR和UF深度处理石化废水的比较研究

为给某石化企业的反渗透（RO）系统提供水质良好且稳定的进水，分别采用膜生物反应器（MBR）和超滤（UF）工艺对该厂二沉池出水进行了深度处理试验，考察了进、出水的浊度及COD、SDI等指标。结果表明：UF系统的出水浊度平均为0．18NTU，COD平均为22．1mg／L，SDI平均为2．50；MBR系统的出水浊度平均为0．14NTU，COD平均为20．1mg／L，SDI平均为2．22。MBR的出水水质比UF更稳定，且具有较强的耐冲击负荷能力。     

Autopsy of high-pressure membranes to compare effectiveness of MF and UF pretreatment in water reclamation

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.     

Purification of oily wastewater by hybrid UF/MD

Investigations on the treatment of oily wastewater by a combination of ultrafiltration (UF) and membrane distillation (MD) as a final purification method have been performed. A tubular UF module equipped with polyvinylidene fluoride (PVDF) membranes and a capillary MD module with polypropylene membranes were tested using a typical bilge water collected from a harbour without pretreatment. The permeate obtained from the UF process generally contains less than 5 ppm of oil. A further purification of the UF permeate by membrane distillation results in a complete removal of oil from wastewater and a very high reduction of the total organic carbon (99.5%) and total dissolved solids (99.9%).     

双膜法在市政污水处理厂的应用

天津市某污水处理厂再生水回用工程采用双膜法工艺,近期设计规模为2.0×10^4m^3/d,本文介绍了其工艺流程、设备配置情况、工程设计参数等.运行结果表明,采用双膜法对废水进行处理后出水水质良好,可以达到回用标准,其中超滤出水浊度为0.01～0.04 NTU,反渗透产水电导率＜ 15 μs/cm,脱盐率大于99％.经济性分析结果显示,该双膜法再生水回用工程的吨水运行成本为1.584元,具有良好的经济及环境效益.     

Distillery wastewater treatment by the membrane-based nanofiltration and reverse osmosis processes

A hybrid nanofiltration (NF) and reverse osmosis (RO) pilot plant was used to remove the color and contaminants of the distillery spent wash. The feasibility of the membranes for treating wastewater from the distillery industry by varying the feed pressure (0-70 bar) and feed concentration was tested on the separation performance of thin-film composite NF and RO membranes. Color removal by NF and a high rejection of 99.80% total dissolved solids (TDS), 99.90% of chemical oxygen demand (COD) and 99.99% of potassium was achieved from the RO runs, by retaining a significant flux as compared to pure water flux, which shows that membranes were not affected by fouling during wastewater run. The pollutant level in permeates were below the maximum contaminant level as per the guidelines of the World Health Organization and the Central Pollution Control Board specifications for effluent discharge (less than 1,000 ppm of TDS and 500 ppm of COD).     

Water recovery from treated urban wastewater by ultrafiltration and reverse osmosis for landscape irrigation

Techno-economic feasibility of water recovery from secondary effluents of an urban wastewater treatment plant (WWTP) for landscape irrigation was investigated considering two distinctive strategies: ultrafiltration (UF)/chlorination and UF/reverse osmosis (RO). Experimental performance evaluations were conducted separately for UF membranes and for different RO trans-membrane pressures. The quality of the effluent recovered by the UF/RO system was in accordance with the national and international guidelines. The produced reuse water was first class quality according to the national guideline for all parameters except sodium adsorption ratio (SAR), which can be eliminated readily by direct addition of KCl into the recovered water. Estimated field-scale costs indicated that UF/RO yielded a total cost of US$12,500,000–13,600,000 with annual operating cost being US$482,000–533,000 at 5–20 bar. The economic estimations guaranteed reimbursement with US$7,600,000–7,400,000 net present value, 0.22–0.39 year payback time, US$0.44–0.49/m³ treatment cost, and a benefit/cost ratio of 0.57.     

Effect of biological wastewater treatment on the molecular weight distribution of soluble organic compounds and on the reduction of BOD, COD and P in pulp and paper mill effluent

Pulp and paper mill wastewater was characterizated, before (influent) and after (effluent) biological wastewater treatment based on an activated sludge process, by microfiltration (8, 3, 0.45 and 0.22mum) and ultrafiltration (100, 50, 30 and 3kDa) of the wastewater samples into different size fractions. Various parameters were measured on each fraction: molecular weight distribution (MWD) using high performance size exclusion chromatography (HPSEC), total organic carbon (TOC), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus (Tot-P), phosphate phosphorus (PO(4)-P), electrical conductivity, pH, turbidity, charge quantity and zeta potential. The MWD, TOC and COD(Cr) results indicated that the majority of the material present in both the influent and effluent was in the medium molecular weight (MW) range (i.e. MW<10kDa) with three main MW sub-fractions. There were no significant differences in the range of the MWD between the influent and effluent samples. The magnitude of the MWD in the effluent was about one half that in the influent, the greatest reduction being in the 6kDa fraction. The 3kDa fractions of both the influent and effluent showed a considerable increase in BOD(7), probably due to the removal of compounds harmful to bacteria in 3kDa ultrafiltration. Influent turbidity decreased considerably in microfiltration (8-0.22mum). As the turbidity was removed by 0.22mum filtration, the anionic charge quantity started to decrease. Particles in the influent and effluent contained 19-29% and 14-20% of the total phosphorus, respectively. The major phosphorus fraction was in the form of soluble phosphate.     

A dual membrane UF/RO process for reclamation of spent rinses from a nickel-plating operation--a case study

The objective of this work was to conduct treatability studies on rinse wastewater from process lines of a typical nickel-plating plant for reuse. The study comprised of three steps: (1) a plant process review and the treatability of different combinations of simulated spent rinses in the laboratory; (2) a variability monitoring of a combined rinse at the plant and a treatability study on a combined rinse in the laboratory; (3) a pilot study for reclamation of the combined rinse on site. The study established an optimum dual membrane ultrafiltration (UF)/reverse osmosis (RO) process for treating a combined liquor of spent alkaline, acidic and nickel-plating rinses which resulted in a treated water of a quality suitable for reuse as substitute for town water for the purpose of rinsing. The results of this study provided a good guide to the selection of a UF pretreatment combined with an RO membrane unit as the treatment system. The pilot plant had successfully operated for 6 months, consistently producing a high quality product water (< 95 microS cm-1) at an overall water recovery of 67.5%. The quality of reclaimed water was better than town water used at the factory. The product water from the pilot plant has been used as substitute of town water for in-process rinsing at the factory with no detrimental effects for 3 months.     

微滤/反渗透净化污水厂二级处理出水

以微絮凝和微滤作为反渗透的预处理工艺,采用连续流微滤-反渗透集成膜工艺深度处理城市污水厂二级生物处理出水,比较了投加聚合氯化铝和氯化铁进行微絮凝控制微滤膜污染的效果.结果表明,投加氯化铁对微滤膜污染具有更好的控制效果;微滤出水浊度＜0.5 NTU,对TOC的去除率为50%左右,对UV260的去除率＜30%.     

A^2O/高压脉冲电絮凝/O3-BAC/膜法处理焦化废水

吕梁三泉焦化工业园区污水处理厂率先采用A^2O/高压脉冲电絮凝/高密度澄清池/臭氧-活性炭滤池/超滤/反渗透组合工艺处理焦化废水。该组合工艺设计紧凑,技术先进,处理效果好。在废水处理量为9550 m^3/d,进水COD、氨氮、SS、电导率、浊度、总硬度、Cl-平均浓度分别为574 mg/L、44.2 mg/L、275 mg/L、5600μS/cm、146 NTU、210 mg/L和740 mg/L时,系统出水所有指标均远优于《工业循环冷却水处理设计规范》(GB/T 50050—2007)规定的再生水水质标准,并全部实现达标回用。本工程直接运行费用合计为4.47元/m^3。     

锦州港污水处理厂改扩建工程设计实例

锦州港污水处理厂主要处理船舶压载废水,原废水处理工程仅对废水中的油进行了处理.对污水处理厂升级改造后,根据原水电导率将废水分为海水压载水和淡水压载水,并采用不同处理工艺进行处理,出水COD、BOD5、SS、NH3-N和油浓度都能稳定达到<辽宁省污水综合排放标准>(DB 21/1627-2008).     

混凝/砂滤结合GAC/UF法处理洗车废水的研究

采用混凝、沉淀-砂滤-GAC-UF工艺对洗车废水进行回用处理,结果表明该工艺的处理效果良好,出水水质可满足洗车水回用的水质要求。混凝、沉淀、砂滤预处理工艺对浊度、LAS和氨氮的去除效果较好,可大大减轻后续深度处理工艺的负荷,延缓GAC／UF反应器的堵塞进程;GAC单元对LAS的去除率〉70％,是整个系统去除LAS的主要单元;UF单元对浊度的去除率〉90％,是出水浊度的有效控制单元。采用该工艺处理洗车废水并回用,每年可节省费用约1．2万元,经济效益显著。     

Impact of microfiltration treatment of secondary wastewater effluent on biofouling of reverse osmosis membranes

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.     

不锈钢生产废水的处理回用与重金属资源化利用

介绍了某工业园区不锈钢废水处理及重金属资源化工艺设计方案。针对不锈钢废水酸度高、pH值波动大、氟离子含量高、重金属浓度高、COD低的特点,采用CaCO3滤床/分级沉淀/过滤的废水处理工艺,实现50%的废水回用率和镍铬等重金属的资源化。该工艺对废水中COD、总铬、总镍、总铁和氟的去除率分别为67.3%、99.7%、99.8%、99.8%及97.0%。出水水质达到《钢铁工业水污染物排放标准》(GB 13456—92)和《污水综合排放标准》(GB 8978—1996)的一级标准,回用水水质达到不锈钢企业的用水要求。水回用及重金属资源化后的收益为4.02元/m3。     

Integrated pretreatment with capacitive deionization for reverse osmosis reject recovery from water reclamation plant

Reverse osmosis (RO) reject recovery from the water reclamation process was demonstrated feasible using an integrated pretreatment scheme followed by the Capacitive Deionization (CDI) process. The RO reject had an average total dissolved solids (TDS) of 1276 ± 166 mg/L. Water recovery of 85% with water quality comparable with the RO feed was achieved. Pretreatments using biological activated carbon (BAC) and BAC–ultrafiltration (UF) attained total organic carbon (TOC) removal efficiencies of 23.5 ± 6.0% and 39.9 ± 9.0%, respectively. Organics removal of RO reject was attributed to simultaneous adsorption and biodegradation in the BAC pretreatment, while further biodegradation in the submerged UF membrane tank provided additional organics removal. Membrane and CDI fouling was reduced by pH adjustment of the pretreated RO reject to approximately 6.5, which prolonged the CDI operation time by at least two times. The CDI process was able to achieve more than 88 and 87% TDS and ion removals, respectively, while PO₄³⁻ and TOC removals were at 52–81% and 50–63%, respectively.     

Water Management In Textile Industry: Technical And Economic Aspects

Textile industry is an intensive water use sector. Consequently, enormous quantities of wastewater are generated from different manufacturing processes. Numerous opportunities for water reuse could be exploited by rational management of water use and reuse via segregation and upgrading of specific effluents using membrane filtration systems comprising ultrafiltration (UF) and reverse osmosis (RO). This paper is an endeavor to develop technoeconomic indicators for extended water reuse applications in textile industry using UF and RO. Extensive data gathered from a typical Egyptian dye house have been utilized to rationalize water use and reuse management based on different levels of pollutants in waste streams. A developed rationale enabled the identification of four applicable intervention scenarios comprising three reuse scenarios ranging from limited reuse (about 25%) to maximum reuse (about 87%) and a total end of the pipe treatment scenario. The financial assessment for a typical wastewater load (about 3500 r m/day) reveals that the maximum reuse scenario comprising UF, two stage RO in addition to direct use and low press RO is the most preferred one. Further, sensitivity analysis indicates that the annual cost of the total end of pipe treatment scenario will equal the annual cost of the maximum reuse scenario when the unit cost are US$ 0.5, 0.43 and 0.3 per cubic meter for wastewater treatment, RO and UF respectively.     

The effects of food waste disposers on the wastewater system: a practical study

Domestic food waste disposers (FWDs) have recently come to prominence as a possible alternative for disposal of organic waste, to reduce the quantities of this type of waste sent to landfill. There has been little research undertaken on the potential effects of food waste on the wastewater system, and it is believed no previous practical studies have been undertaken in the United Kingdom. In this study, food waste was ground in an FWD and analysed for chemical oxygen demand (COD), biological oxygen demand (BOD), ammonia, total nitrogen, total phosphorus, total suspended solids and rapidly settleable solids to determine their effects on the wastewater system. The largest impacts were on COD, BOD and suspended solids, compared with the amounts of these determinands that currently arrive at sewage treatment works (STW). Experiments using settled samples showed that a relatively high proportion of nitrogen, phosphorus, COD and BOD would pass through to secondary treatment at the STW.     

Pretreatment of Afyon alcaloide factory's wastewater by wet air oxidation (WAO)

In this study, pretreatment of Afyon (Turkey) alcaloide factory wastewater, a typical high strength industrial wastewater (chemical oxygen demand (COD)=26.65 kgm(-3), biological oxygen demand (BOD(5))=3.95 kgm(-3)), was carried out by wet air oxidation process. The process was performed in a 0.75 litre specially designed bubble reactor. Experiments were conducted to see the advantages of one-stage and two-stage oxidation and the effects of pressure, pH, temperature, catalyst type, catalyst loading and air or oxygen as gas source on the oxidation of the wastewater. In addition, BOD(5)/COD ratios of the effluents, which are generally regarded as an important index of biodegradability of a high-strength industrial wastewater, were determined at the end of some runs. After a 2h oxidation (T=150 degrees C, P=0.65 MPa, airflowrate=1.57 x 10(-5)m(3)s(-1), pH=7.0), the BOD(5)/COD ratio was increased from 0.15 to above 0.5 by using the salts of metals such as Co(2+),Fe(2+),Fe(2+)+Ni(2+),Cu(2+)+Mn(2+) as catalyst.     

Application of ceramic membranes with pre-ozonation for treatment of secondary wastewater effluent

Membrane fouling is an inevitable problem when microfiltration (MF) and ultrafiltraion (UF) are used to treat wastewater treatment plant (WWTP) effluent. While historically the use of MF/UF for water and wastewater treatment has been almost exclusively focused on polymeric membranes, new generation ceramic membranes were recently introduced in the market and they possess unique advantages over currently available polymeric membranes. Ceramic membranes are mechanically superior and are more resistant to severe chemical and thermal environments. Due to the robustness of ceramic membranes, strong oxidants such as ozone can be used as pretreatment to reduce the membrane fouling. This paper presents results of a pilot study designed to investigate the application of new generation ceramic membranes for WWTP effluent treatment. Ozonation and coagulation pretreatment were evaluated to optimize the membrane operation. The ceramic membrane demonstrated stable performance at a filtration flux of 100 gfd (170 LMH) at 20 °C with pretreatment using PACl (1 mg/L as Al) and ozone (4 mg/L). To understand the effects of ozone and coagulation pretreatment on organic foulants, natural organic matter (NOM) in four waters - raw, ozone treated, coagulation treated, and ozone followed by coagulation treated wastewaters - were characterized using high performance size exclusion chromatography (HPSEC). The HPSEC analysis demonstrated that ozone treatment is effective at degrading colloidal NOMs which are likely responsible for the majority of membrane fouling.     

Conventional and thermophilic aerobic treatability of high strength oily pet food wastewater using membrane-coupled bioreactors

Although thermophilic treatment systems have recently gained considerable interest, limited information exists on the comparative performances of membrane-coupled bioreactors (MBR) at thermophilic and conventional conditions. In this study aerobic MBRs operating at room temperature (20 degrees C) and at lower thermophilic range (45 degrees C) were investigated for the treatment of dissolved air flotation (DAF) pretreated pet food wastewater. The particular wastewater is characterized by oil and grease (O & G) concentrations as high as 6 g/L, COD of 51 g/L, BOD of 16 g/L and volatile fatty acid (VFA) of 8.3 g/L. The performances of the two systems in terms of COD, BOD and O & G removal at varying hydraulic retention time (HRT) are compared. COD removal efficiencies in the thermophilic MBR varied from 75% to 98% and remained constant at 94% in the conventional MBR. The O & G removal efficiencies were 66-86% and 98% in the thermophilic and conventional MBR, respectively. Interestingly, high concentrations of VFA were recorded, equivalent to 50-73% of total COD, in the thermophilic MBR effluent. The observed yield in the thermophilic MBR was 40% of that observed in the conventional MBR.