Fenton-双泥SBR工艺深度处理难降解反渗透浓缩液

采用Fenton试剂处理反渗透浓缩渗滤液(简称浓缩液),并探讨了双泥SBR工艺对Fenton处理后浓缩液与人工配水混合处理的可行性.结果表明,Fenton氧化对COD、TN和NH3-N的平均去除率分别为43.5%、22.5%和19.5%.对溶解性有机物(DOMs)的去除率为52.5%,其中胡敏酸(HA)、富里酸(FA)...     

Microbial fouling of a reverse osmosis municipal water treatment system

Microbial fouling of a municipal water treatment system using reverse osmosis was investigated. From a combination of growth and molecular assays, it was discovered that the prefilter unit concentrated and facilitated microbial growth, and such growth led to microbial fouling of the reverse osmosis unit. Few cells were observed in the prefilter influent, but substantial microbial contamination was observed in the prefilter effluent, and this correlated with increasing headloss across the prefilter. The effluent caused microbial fouling of the leading elements of the reverse osmosis unit, as determined by reduced permeate flow, analysis of the elements, and assays of the membrane foulant. Both the introduction of microorganisms to the reverse osmosis unit from the prefilter unit and headloss across the prefilter could be effectively controlled through cleansing of the prefilter housing unit with sulfuric acid. Such treatments must be performed at appropriate intervals to prevent subsequent microbial growth in the prefilter unit.     

响应面法优化Fenton处理难降解反渗透垃圾浓缩渗滤液

采用了基于中心复合设计(CCD)的响应面分析方法(RSM)研究了Fenton试剂处理难降解反渗透垃圾浓缩渗滤液过程中初始pH、FeSO4.7H2O用量、[H2O2]/[Fe2+]摩尔比3个因素对浓缩液中COD去除率的影响。由Design Ex-pert 7.1软件设计分析实验数据,得到了一个二次响应曲面模型,模型具有较高的回归率(R2=0.9699),与实验结果吻合程度较高。该模型显示COD的去除率与3个因素之间不是简单的单调函数关系,它们彼此之间存在一个最佳数值而使去除率达到最高。H2O2与Fe2+之间具有很强的相互增效作用,COD的去除由氧化作用和混凝作用共同完成。在最佳pH值为3.75,FeSO4.7H2O投加量为17.91 mmol/L、[H2O2]/[Fe2+]摩尔比为1.36的反应条件下,COD去除率能达到最高值(72.25%)。     

污水再生处理微滤-反渗透工艺经济分析

近年来,微滤-反渗透(MF-RO)工艺在污水再生处理领域中的应用越来越受到关注,但其设备投资和运行成本较高,需要建立科学、高效的运行管理机制和投入产出机制,以提高其经济效益。系统研究了北京市某再生水厂微滤-反渗透(MF-RO)工艺的设备投资及运行费用等情况。再生水成本主要由设备折旧费和运行成本组成,其中运行成本所占比例较高,而在运行成本中所占比例最高的是膜更换费、电费和药剂费。目前该厂再生水销水量约为7 000 m3/d,运行负荷率仅为33.33%,导致再生水成本较高,总成本约达5.29元/m3,其中设备折旧费为0.83元/m3,运行成本约为4.46元/m3。因此提高运行负荷率,即提高销水量,是降低再生水成本的关键。     

Behavior of pharmaceuticals and drugs of abuse in a drinking water treatment plant (DWTP) using combined conventional and ultrafiltration and reverse osmosis (UF/RO) treatments

The behavior along the potabilization process of 29 pharmaceuticals and 12 drugs of abuse identified from a total of 81 compounds at the intake of a drinking water treatment plant (DWTP) has been studied. The DWTP has a common treatment consisting of dioxychlorination, coagulation/flocculation and sand filtration and then water is splitted in two parallel treatment lines: conventional (ozonation and carbon filtration) and advanced (ultrafiltration and reverse osmosis) to be further blended, chlorinated and distributed. Full removals were reached for most of the compounds. Iopromide (up to 17.2 ng/L), nicotine (13.7 ng/L), benzoylecgonine (1.9 ng/L), cotinine (3.6 ng/L), acetaminophen (15.6 ng/L), erythromycin (2.0 ng/L) and caffeine (6.0 ng/L) with elimination efficiencies ≥94%, were the sole compounds found in the treated water. The advanced treatment process showed a slightly better efficiency than the conventional treatment to eliminate pharmaceuticals and drugs of abuse.     

超滤/反渗透双膜技术深度处理印染废水

由于印染废水具有高盐度,可生化性差,使常规方法难于处理完全.采用超滤和反渗透双膜技术处理实际印染废水,考察了不同超滤膜对废水的预处理性能,研究了BW30和CPA2两种反渗透膜在不同操作条件下对印染废水的处理效果,并分析了相关膜通量下降的原因.结果表明,超滤能有效地去除废水浊度和大分子有机物,为反渗透提供良好的进水水质.两种反渗透膜的产水化学需氧量(COD)均小于10 mg/L,电导率小于80/μS/cm,其对有机物和盐的去除率分别可达99%和93%以上,显示该产水能回用于大部分印染工序.BW30膜产水水质稍好于CPA2,但通量低于CPA2.     

应用于维生素C凝结水处理反渗透膜清洗策略

针对沈阳某药厂维生素C生产工艺中凝结水产量大、处理成本高和杂质复杂等问题,提出了采用反渗透技术对工艺凝结水进行处理。在前期确定的最优操作条件基础上持续运行,研究了运行临界通量、清洗时机和清洗方式等工艺条件。结果表明,在本工艺条件下,反渗透膜系统的临界通量介于1.1 L/(m2.min)到1.2 L/(m2.min)之间,斜率变点分析法确定的可逆膜污染周期为10 d;加强型清洗策略EFM(enhanced flux maintenance)的操作是针对不可逆膜污染的一种有效清洗方式,EFM持续30 min为宜,NaClO和NaOH都是有机污染的有效清洗剂,膜的平均恢复率分别为85.4%和81.6%,显示出实际应用的可行性,具有推广价值。     

Study of using microfiltration and reverse osmosis membrane technologies for reclaiming cooling water in the power industry.

A study of using dual membrane technologies, microfiltration (MF) and reverse osmosis (RO), for reclaiming blowdown of the cooling tower was conducted at ZJK power plant, Hebei province, China. The study shows that the combined MF-RO system can effectively reduce water consumption in the power industry. The results indicate that MF process is capable of producing a filtrate suitable for RO treatment and achieving a silt density index (SDI) less than 2, turbidity of 0.2 NTU. The water quality of RO effluent is very good with an average conductivity of about 40 micros/cm and rejection of 98%. The product water is suitable for injection into the cooling tower to counteract with cooling water intrusion. After adopting this system, water-saving effectiveness as expressed in terms of cycles of concentration could be increased from 2.5-2.8 times to 5 times.     

A pilot application of recycled discarded RO membranes for low strength gray water reclamation

Environmental Science and Pollution Research - Reuse of recycled RO membranes after oxidative treatment as ultrafiltration membranes promise to bring membrane filtration at par with conventional...     

Economic feasibility of solar-powered reverse osmosis water desalination: a comparative systemic review

Environmental Science and Pollution Research - Due to disparities in the allocation of rainwater and drought, extreme exploitation of groundwater reservoirs has depleted water supplies in many...     

Heavy metal retention and partitioning in a large-scale soil-aquifer treatment (SAT) system used for wastewater reclamation

Soil aquifer treatment (SAT) of wastewater relies on extensive biogeochemical processes in the soil and aquifer to achieve large-scale and economic reclamation of municipal effluents. Removal of trace metals from the wastewater is a prime objective in the operation, but the long-term sustainability of the adsorptive filtration capacity of the soils is an open question. Solid/solution partitioning (measured by the distribution coefficient, K(d)) and solid/solid partitioning (measured by selective sequential dissolution, SSD) of heavy metals were measured in soils sampled from active recharge basins in a wastewater reclamation plant and were compared to the adjacent pristine dune. K(d) values for the adsorption of Cu, Ni and Zn, measured in short-term adsorption experiments positively and significantly correlated with solution pH. Quantitative estimation of Cu, Ni and Zn adsorption on multi-sorbents indicated that surface adsorption and precipitation on Fe oxides and/or carbonate may be the major mechanisms of metal retention in these soils. SSD analyses of metal partitioning in soils exposed to approximately 20yr of effluent recharge showed that all solid-phase components, including the most stable 'residual' component, competed for and retained added Cu and Zn. Copper preferentially partitioned into the oxide component (32.0% of the soil-accumulated metal) while Zn preferentially partitioned into the carbonate component (51.6% of the soil-accumulated metal).     

煤化工废水高效反渗透工艺运行效果及膜污染特征

高效反渗透(high efficiency reverse osmosis,HERO)工艺是工业废水零排放系统浓盐水浓缩减量的关键,其运行效果显著影响浓盐水蒸发结晶的效能,直接决定系统运行的稳定性和运行成本。针对我国北方某煤化工厂废水零排放系统中的HERO工艺运行效果及膜污染特征进行了分析,以明确HERO系统的关键问题。结果表明：澄清池和弱酸阳床可有效实现废水中硬度离子的去除,其他离子与污染物主要由反渗透(RO)单元去除。废水中溶解性有机物(DOM)主要以腐殖酸类物质和微生物代谢产物(SMP)类物质为主,且腐殖酸类物质主要为微生物源。预处理阶段对SiO₂无针对性控制措施,混凝除硅效果较差(去除率29.43%),HERO进水SiO₂质量浓度较高,导致RO膜出现显著的硅复合污染,其中1段第1根膜污染物以硅和有机物耦合物、微生物及其代谢产物为主,二段最后1根膜表面出现大量颗粒状硅垢。因此,针对此HERO工艺,需进一步强化SiO₂的去除并实现其有效清洗,是缓解膜污染并提升系统稳定性的重要措施。     

压力延迟渗透过程水通量的模型与验证

近年来,盐差能作为一种来源广泛、储量可观的绿色可再生能源受到广泛关注。其中,压力延迟渗透（pressure retarded osmosis,PRO）是一种基于渗透过程的极具前景的盐差能利用技术。压力延迟渗透过程中的水通量与最终的能量产出密切相关,因此建立水通量模型对该过程的机理研究、系统设计都具有重要意义。初步建立了在考虑浓差极化和反向盐渗透影响时,压力延迟渗透过程的水通量模型,并使用不同浓度NaCl汲取液（0.5、1和2 mol·L-1）进行了实验实证。模型在低渗透压汲取液条件下拟合良好。此外,为了进一步提高拟合精度,从模型推导和实验测定2个方面分别讨论了可能的提高途径。     

正渗透中驱动溶质反渗模型的建立与实验验证

正渗透过程能够有效运行的一个前提条件是要求驱动溶质反向扩散的通量非常小。为了深入了解正渗透过程中驱动溶质反渗对膜分离过程的影响,以现有的浓差极化模型为基础,建立正渗透过程不同操作模式下驱动溶质的反渗通量以及膜通量的数学模型。为证明模型的准确性,以NaCl为驱动液做一组序批式实验,测出不同初始渗透压下的水通量和反渗通量,将实验值与模型预测值比较,发现模型的预测结果与实验结果高度吻合。     

Laboratory and field evaluation of a pretreatment system for removing organics from produced water

Co-produced water from the oil and gas industry accounts for a significant waste stream in the United States. This "produced water" is characterized by saline water containing a variety of pollutants, including water soluble and immiscible organics and many inorganic species. To reuse produced water, removal of both the inorganic dissolved solids and organic compounds is necessary. In this research, the effectiveness of a pretreatment system consisting of surfactant modified zeolite (SMZ) adsorption followed by a membrane bioreactor (MBR) was evaluated for simultaneous removal of carboxylates and hazardous substances, such as benzene, toluene, ethylbenzene, and xylenes (BTEX) from saline-produced water. A laboratory-scale MBR, operated at a 9.6-hour hydraulic residence time, degraded 92% of the carboxylates present in synthetic produced water. When BTEX was introduced simultaneously to the MBR system with the carboxylates, the system achieved 80 to 95% removal of BTEX via biodegradation. These results suggest that simultaneous biodegradation of both BTEX and carboxylate constituents found in produced water is possible. A field test conducted at a produced water disposal facility in Farmington, New Mexico confirmed the laboratory-scale results for the MBR and demonstrated enhanced removal of BTEX using a treatment train consisting of SMZ columns followed by the MBR. While most of the BTEX constituents of the produced water adsorbed onto the SMZ adsorption system, approximately 95% of the BTEX that penetrated the SMZ and entered the MBR was biodegraded in the MBR. Removal rates of acetate (influent concentrations of 120 to 170 mg/L) ranged from 91 to 100%, and total organic carbon (influent concentrations as high as 580 mg/L) ranged from 74 to 92%, respectively. Organic removal in the MBR was accomplished at a low biomass concentration of 1 g/L throughout the field trial. While the transmembrane pressure during the laboratory-scale tests was well-controlled, it rose substantially during the field test, where no pH control was implemented. The results suggest that pretreatment with an SMZ/MBR system can provide substantial removal of organic compounds present in produced water, a necessary first step for many water-reuse applications.     

Removal of toxic ions (chromate, arsenate, and perchlorate) using reverse osmosis, nanofiltration, and ultrafiltration membranes

Rejection characteristics of chromate, arsenate, and perchlorate were examined for one reverse osmosis (RO, LFC-1), two nanofiltration (NF, ESNA, and MX07), and one ultrafiltration (UF and GM) membranes that are commercially available. A bench-scale cross-flow flat-sheet filtration system was employed to determine the toxic ion rejection and the membrane flux. Both model and natural waters were used to prepare chromate, arsenate, and perchlorate solutions (approximately 100 μg L⁻¹ for each anion) in mixtures in the presence of other salts (KCl, K₂SO₄, and CaCl₂); and at varying pH conditions (4, 6, 8, and 10) and solution conductivities (30, 60, and 115 mS m⁻¹). The rejection of target ions by the membranes increases with increasing solution pH due to the increasingly negative membrane charge with synthetic model waters. Cr(VI), As(V), and rejection follows the order LFC-1 (>90%) > MX07 (25–95%)  ESNA (30–90%) > GM (3–47%) at all pH conditions. In contrast, the rejection of target ions by the membranes decreases with increasing solution conductivity due to the decreasingly negative membrane charge. Cr(VI), As(V), and rejection follows the order CaCl₂ < KCl  K₂SO₄ at constant pH and conductivity conditions for the NF and UF membranes tested. For natural waters the LFC-1 RO membrane with a small pore size (0.34 nm) had a significantly greater rejection for those target anions (>90%) excluding (71–74%) than the ESNA NF membrane (11–56%) with a relatively large pore size (0.44 nm), indicating that size exclusion is at least partially responsible for the rejection. The ratio of solute radius (r_i,s) to effective membrane pore radius (r_p) was employed to compare ion rejection. For all of the ions, the rejection is higher than 70% when the r_i,s/r_p ratio is greater than 0.4 for the LFC-1 membrane, while for di-valent ions (, , and ) the rejection (38–56%) is fairly proportional to the r_i,s/r_p ratio (0.32–0.62) for the ESNA membrane.     

Enhanced removal of lead(II) and cadmium(II) from water in alum coagulation by ferrate(VI) pretreatment.

A laboratory study demonstrated that ferrate pretreatment significantly enhanced lead and cadmium removal in alum coagulation, under the conditions of natural surface water. The enhancement of lead removal was approximately 21 to 37% by ferrate pretreatment at a dosage of 1 to 5 mg/L. The enhanced removal of cadmium by ferrate pretreatment at a dosage of 1 to 5 mg/L exceeded the removal by alum coagulation alone 2-to 12-fold. Cadmium is much more difficult to remove than lead in alum coagulation. The performance of ferrate in enhancing the removal of lead and cadmium in alum coagulation was better than that of ferric chloride. The removal of lead and cadmium was highly pH-dependent, following the general trend of higher pH being related to higher removal. Satisfactory removal of cadmium could be expected by ferrate pretreatment combined with adjusting the pH of the water.     

Potential of BAC combined with UVC/H2O2 for reducing organic matter from highly saline reverse osmosis concentrate produced from municipal wastewater reclamation

The organic matter present in the concentrate streams generated from reverse osmosis (RO) based municipal wastewater reclamation processes poses environmental and health risks on its disposal to the receiving environment (e.g., estuaries, bays). The potential of a biological activated carbon (BAC) process combined with pre-oxidation using a UVC/H₂O₂ advanced oxidation process for treating a high salinity (TDS ∼ 10 000 mg L⁻¹) municipal wastewater RO concentrate (ROC) was evaluated at lab scale during 90 d of operation. The combined treatment reduced the UVA₂₅₄ and colour of the ROC to below those for the influent of the RO process (i.e., biologically treated secondary effluent), and the reductions in DOC and COD were approximately 60% and 50%, respectively. UVC/H₂O₂ was demonstrated to be an effective means of converting the recalcitrant organic compounds in the ROC into biodegradable substances which were readily removed by the BAC process, leading to a synergistic effect of the combined treatment in degrading the organic matter. The tests using various BAC feed concentrations suggested that the biological treatment was robust and consistent for treating the high salinity ROC. Using Microtox analysis no toxicity was detected for the ROC after the combined treatment, and the trihalomethane formation potential was reduced from 3.5 to 2.8 mg L⁻¹.     

印染生化尾水反渗透深度处理工艺膜污染成因分析

为阐明印染生化尾水反渗透膜处理时膜污染的成因,使用小试装置进行40h膜污染实验,研究膜污染速率、污染程度以及可逆性,同时应用扫描电子显微镜一EDS能谱仪、傅里叶变换红外光谱仪、电感耦合等离子发射光谱仪、总有机碳测定仪等仪器对进水水质、膜表面污染物的形态和组成等进行表征。结果表明,膜表面主要是碳酸钙无机污染和钙与有机物络合污染,无机污染占主导,且可逆性差,有机污染物主要含有--OH和～c-c官能团;单一去除废水中有机物污染物（TOC去除率达88％）对膜污染缓解不明显,但钙离子的去除可显著缓解膜污染,膜通量可增加72．6％;同时去除有机物和钙离子,膜通量可增加80．4％。