Arsenic removal by iron and manganese coated sand.

In this study, as a promising technique for the treatment of both As(III) and As(V) at the same time in a single reactor, a column reactor containing both manganese-coated sand (MCS) and iron-coated sand (ICS), at different configuration of MCS and ICS, was used to treat wastewater contaminated with As(III). Prior to column experiments, batch experiments for the adsorption of As(V) by ICS were performed with variation of solution pH, ionic strength and types of background ions to investigate the effect of these parameters on the As(V) adsorption behaviour. As(V) adsorption onto ICS was quite similar with the variation of ionic strength by using NaNO3 as a background ion as well as in the presence of different types of background ions except phosphate. The adsorption curves shifted to the lower pH region with the increase of the initial arsenic concentration due to the finite number of adsorption sites on the ICS. For model prediction on the adsorption of As(V) onto ICS, the MINEQL program employing an inner-sphere complexation and a diffuse layer model was used. Model predictions generally agreed well with experimental results. From the column test, column system packed with equal ratio of MCS and ICS was identified as the best system due to a promising oxidation efficiency of As(III) to As(V) by MCS and adsorption of As(V) by both MCS and ICS.     

Arsenic removal from groundwater by a newly developed adsorbent.

A novel adsorbent, which had been developed for phosphate adsorption, was adopted for arsenic removal from groundwater. Adsorption isotherm, pH dependence of the isotherm and adsorption rate were studied by batch method. Furthermore, by using a granular adsorbent of 1.8 mm diameter which is commercially available, lab-scale experiments of continuous adsorption treatment of actual groundwater containing arsenic at 50 mg m(-3) were conducted to examine the performance of the adsorbent. A large amount of arsenic, i.e., 10 g As kg(-1), was adsorbed at pH 7.0 and 10 mg As m(-3) in equilibrium concentration. It was only a 5% higher amount compared to conventional activated alumina. However, twice the bed volume, i.e., total volume of effluent divided by empty column volume, was achieved till breakthrough by using this novel adsorbent. This may be because the pH decrease, which enlarges apparent adsorption capacity of the adsorbent, is caused by a self-pH decrease function of the adsorbent. The self-pH decrease function must be delivered by dissociation of Al (III) aquoion. The proton release was clearly observed in batch experiments.     

纳米铁除磷的影响因素及吸附模式研究

研究了纳米铁投加量、PO3-4浓度、温度、pH对纳米铁去除人工配制磷酸盐废水中PO3-4的影响,并验证了纳米铁对PO3-4的吸附模式.试验表明:磷酸盐初始浓度一定时,增加纳米铁的投加量能增大对PO3-4的吸附;纳米铁投加量一定时,纳米铁的平衡吸附量则随PO3-4初始浓度的增加而增大;25℃时纳米铁对PO3-4的吸附能力最强,升高或降低温度,吸附能力均下降;pH对纳米铁去除PO3-4的影响较大,pH=4时的吸附能力最强,增大或降低pH,吸附能力均下降;纳米铁对PO3-4的吸附符合Freundlich方程而不符合Langmuir方程.     

Phosphorus removal and recovery from wastewater by tobermorite-seeded crystallisation of calcium phosphate.

Investigations were focused on the development of a technology for phosphorus (P) recovery straight from wastewater. Facing the finiteness of the natural resources of this essential nutrient, the declared goal must be the sustainable use of available phosphorus sinks such as wastewater treatment plants (WWTP) for the generation of P rock substitutes. A feasible method for simultaneous elimination and recovery of phosphorus from wastewater proved to be the P-RoC process - the phosphorus recovery from wastewater by induced crystallisation of calcium phosphate, applying tobermorite-rich waste compounds of the construction industry. The experiments were performed in fixed bed-, stirred- and expanded bed reactors in laboratory--as well as in pilot-scale experiments. The efficiency and longevity of the P-RoC process was determined by the supply of Ca ions and the initial P concentration. Total P (P-tot) contents in the generated crystallisation products of up to 13% P-tot (30% P2O5) were achieved. Mineralogical investigations proved the formation of a hydroxy-apatite-(HAP)-like coating onto the seed material's surface. Reuse options for the generated crystallisation products, such as substitute for phosphate rock or as new fertiliser, were assessed.     

磷酸铵镁和磷酸钙法处理厌氧上清液的比较

比较了Mg:P和Ca:P物质的量之比、pH及碳酸盐碱度对磷酸铵镁(MAP)和羟基磷灰石(HAP)结晶法去除厌氧出水中磷的影响,并对产物进行了扫描电镜-能谱分析(SEM-EDX).结果表明,在磷酸盐浓度为63 mg/L、pH为7.4的条件下,MAP法的除磷率最高能达47.9%,HAP法除磷率最高达40%.当pH升高到8.5～9.0,MAP法除磷率可达95%,出水pH小于8.0;为达到相同去除率,HAP法的pH需升高到9.5～10.0,其出水的pH为8.0～8.5.MAP法除磷更易得到较高纯度的晶体产物,且CO2-3对MAP晶体的纯度无明显影响,而HAP法除磷所得的产物中含有非晶态杂质.     

含铁矿物吸附剂除磷机理研究及中试应用

研究了含铁矿物吸附剂吸附含磷废水的各项性能,通过静态试验得出此吸附剂的最佳吸附条件,并以此为依据进行了动态小试试验和中试试验。结果表明,含铁矿物吸附剂的吸附平衡时间为45h,吸附等温线较符合Freundlich方程,pH约为5时吸附量达到最大,除铁离子和铝离子外,水体中无机阴离子和阳离子对磷酸盐的吸附影响不大。用1mol/L的NaOH溶液对饱和吸附剂解吸再生,解吸率达到90%以上。在合适的填充体积和进水流速下,含铁矿物吸附剂连续吸附除磷可以达到良好的效果,中试试验装置连续运行了约105d,出水TP达到了《地表水环境质量标准》(GB3838—2002)(Ⅲ类湖、库)要求。     

金属基吸附剂去除水体中磷酸盐的研究进展

磷是生命组成必不可少的元素,同时也是导致水体富营养化的主要限制因子之一.目前,磷在地球上的流失率极高,过量的磷进入水体导致水体富营养化的形势日益加剧,迫切需要一种技术高效去除水体中的磷.吸附法由于操作简单、价格低廉,在过去20年里展现出优异的除磷性能,且其中金属基吸附剂尤其是基于锆(Zr)、镧(La)的金属的吸附剂已成...     

Simultaneous removal of nitrate and phosphate using cross-flow micellar-enhanced ultrafiltration (MEUF).

The feasibility of cross-flow micellar-enhanced ultrafiltration (MEUF) was investigated to remove nitrate and phosphate simultaneously. At the above critical micelle concentration (CMC), a cationic surfactant added in wastewater forms micelles, which have positive charge on their surface. Anionic contaminants such as nitrate and phosphate can be bound on the micelles by electrostatic interaction, and the micelle-pollutants complex is removed effectively by ultrafiltration. In this study, a cross-flow MEUF system was designed and investigated the feasibility of MEUF for field application. A cationic surfactant, cetylpyridinium chloride (CPC), was used, and the synthetic wastewater was treated by the polyacrylonitrile membranes with molecular weight cut-off (MWCO) of 30,000 Da and 10,000 Da. With the molar ratio of CPC to total pollutants of > 3, > 86% of nitrate and > 91% of phosphate were removed, respectively, and > 97% of CPC was also rejected. The flux was maintained 20-30% of the flux of distilled water. Therefore, it is feasible to remove nitrate and phosphate simultaneously using the cross-flow MEUF system.     

An approach for phosphate removal with quartz sand, ceramsite, blast furnace slag and steel slag as seed crystal

The phosphate removal abilities and crystallization performance of quartz sand, ceramsite, blast furnace slag and steel slag were investigated. The residual phosphate concentrations in the reaction solutions were not changed by addition of the ceramsite, quartz sand and blast furnace slag. The steel slag could provide alkalinity and Ca(2+) to the reaction solution due to its hydration activity, and performed a better phosphate removal performance than the other three. Under the conditions of Ca/P 2.0, pH 8.5 and 10 mg P/L, the phosphate crystallization occurred during 12 h. The quartz sand and ceramsite did not improve the phosphate crystallization, but steel slag was an effective seed crystal. The phosphate concentration decreased drastically after 12 h after addition of steel slag, and near complete removal was achieved after 48 h. The XRD analysis showed that the main crystallization products were hydroxyapatite (HAP) and the crystallinity increased with the reaction time. Phosphate was successfully recovered from low phosphate concentration wastewater using steel slag as seed material.     

Online estimation of VFA, alkalinity and bicarbonate concentrations by electrical conductivity measurement during anaerobic fermentation

This paper describes the use of electrical conductivity for measurement of volatile fatty acids (VFA), alkalinity and bicarbonate concentrations, during the anaerobic fermentation process. Two anaerobic continuous processes were studied: the first was a laboratory reactor for hydrogen production from molasses and the second was a pilot process for anaerobic digestion (AD) of vinasses producing methane. In the hydrogen production process, the total VFA concentration, but not bicarbonate concentration, was well estimated from the on-line electrical conductivity measurements with a simple linear regression model. In the methane production process, the bicarbonate concentration and the VFA concentration were well estimated from the simultaneous on-line measurements of pH and electrical conductivity by means of non-linear regression with neural network models. Moreover, the total alkalinity concentration was well estimated from electrical conductivity measurements with a simple linear regression model. This demonstrates the use of electrical conductivity for monitoring the AD processes.     

Enhanced removal of phosphate from water by fabricating a novel dual metal MIL-101(Fe/Zr)

Metal-based compounds are promising adsorbents for phosphate.A novel dual metal-organic framework as an effective adsorbent for phosphate was synthesized by a solvothermal method.The structure analysis revealed that the as-prepared adsorbent (denoted as MIL-101(Fe/Zr)) possessed a porous polyhedral structure with a large specific surface area of 479.1 m2/g and a pore width of 3.4 nm.The X-ray diffraction pattern and Fourier transform infrared spectra suggested that the MIL-101(Fe/Zr) shared a similar structure with MIL-101(Fe),implying successful incorporation of Zr atoms as a second metal into the MIL-101(Fe) structure.Kinetic adsorption of PO43—by MIL-101(Fe/Zr) conformed to the pseudo-second-order model and intraparticle diffusion model,while adsorption isotherm fitted the Freundlich model well (R2=0.978 5).It is suggested that such an adsorption belonged to multiply-layer adsorption.The adsorption capacity of MIL-101(Fe/Zr) was to be 66.00 mg/g.MIL-101(Fe/Zr) performed well at a wide range of pH 2.0~10.0 and high ionic strength (0~40 mg/L NaCl).A structural analysis indicated that the complexation interaction was mainly responsible for PO43—adsorption.These findings can inspire preparation of other dual metal MOFs adsorbent for phosphate removal and recovery from water.     

仿岩溶碳酸氢钙加固风积沙的试验研究

分别以仿岩溶碳酸氢钙(CFPK)溶液和毛乌素沙地风积沙为固沙材料和加固对象,通过化学试验、力学试验、水理试验以及微观试验,探究二氧化碳压强和反应时间对CFPK溶液浓度的影响,分析CFPK溶液固化沙的工程性能,揭示其加固机理。结果表明：CFPK溶液浓度随着二氧化碳压强的增大而增大,随着反应时间的增加先增大而后保持稳定。呈散粒状的风积沙经过CFPK溶液处理后,其表面形成一层固结层,具有较高的表面强度、较好的抗风蚀性和耐水性。随着CFPK溶液用量的增加,固化沙的表面强度和抗风蚀性能逐渐提高。仿岩溶碳酸氢钙可在沙颗粒间分解形成具有胶结作用和填充作用的碳酸钙,能够有效加固风积沙。     

镧改性、钠基和钙基膨润土净化污染河水中磷的效果

研究镧改性、钠基和钙基三种膨润土对河水中磷的去除效果.将1.6 g的镧改性、钠基、钙基膨润土分别投入到800 mL的清河河水中,清河水水质为劣Ⅴ类.试验结果表明镧改性膨润土的磷去除效果优于其他两种,对河水中总磷的平均去除率为77.41%,磷含量在第7天达到Ⅳ类水水质标准.同时镧改性膨润土对氮和含碳有机物也有一定的去除效果,在第7天对总氮的去除率达到最高值50.78%,在第3天对含碳有机物的去除率为18.34%.     

Comparison between a moving bed bioreactor and a fixed bed bioreactor for biological phosphate removal and denitrification

Moving bed bioreactors (MBBR) and fixed bed bioreactors (FBBR) were compared for biological phosphorus removal and denitrification. The sorption denitrification P-elimination (S-DN-P) process was selected for this study. Results indicated that all nutrients were removed by the FBBR process compared with the MBBR process: 19.8% (total COD), 35.5% (filtered COD), 27.6% (BOD(5)), 62.2% (acetate), 78.5% (PO(4)-P), and 54.2% (NO(3)-N) in MBBR; 49.7% (total COD), 54.0% (filtered COD), 63.2% (BOD(5)), 99.6% (acetate), 98.6% (PO(4)-P), and 75.9% (NO(3)-N) in FBBR. The phosphate uptake and NO(3)-N decomposition in the FBBR process during the denitrification phase were much higher than for the MBBR process despite being of shorter duration. Results obtained from this study are helpful in elucidating the practical implications of using MBBR and FBBR for the removal of bio-P and denitrification from wastewater.     

应用双道原子荧光仪测定水中砷及汞

本文阐述了原子荧光法测定水中砷、汞的基本原理,样品的前处理方法。提出了样品测试的仪器条件以及在样品测试过程中的注意事项,实验结果说明该方法适用、可靠。     

人工湿地填料除砷效率及影响因素试验研究

人工湿地是净化含砷水体的重要途径之一,而填料是决定人工湿地除砷效果的关键因素。通过填料如砾石、锰砂、沸石和陶粒的理化性质的测定,以及各种填料的吸附动力学、吸附等温线和吸附影响因素试验,研究了填料的除砷性能及影响因素。结果表明:4种填料均能在24 h内达到吸附平衡,一级动力学方程和二级动力学方程能很好地拟合其吸附过程;锰砂、陶粒、沸石和砾石最大吸附容量依次为36.62,25.39,11.96,7.04 mg/kg,Freundlich方程能较好地拟合填料的等温吸附过程;在0.25~0.50 mm范围内,粒径对锰砂和陶粒吸附砷影响不显著;溶液中氨氮浓度在0.50~2.50 mg/L范围内几乎不影响填料对砷的吸附;当砷初始浓度低于0.4 mg/L时,磷酸盐在0.25~0.50 mg/L范围内对填料吸附砷的影响不显著;砷初始浓度高于0.4 mg/L时,随着磷酸盐浓度从0.25 mg/L增加至0.50 mg/L时,陶粒对砷的最大吸附量降低了2.57 mg/kg,对锰砂的吸附量降低了1.85 mg/kg。     

不同浊度下的泥沙对水体镉、铅、砷去除的影响分析

针对流域突发性重金属污染,不同浊度下的泥沙对重金属有一定的去除效果.以浊度为指示指标,通过试验研究了常温(25℃)和低温(5℃)条件下浊度50～650 NTU(Nephelometric Turbidity Unit)范围内泥沙对重金属镉、铅、砷吸附去除的影响.试验结果表明:泥沙对重金属镉、铅、砷的去除效果为铅>镉>砷...     

Influence of design, physico-chemical and environmental parameters on pharmaceuticals and fragrances removal by constructed wetlands

The ability of several mesocosm-scale and full-scale constructed wetlands (CWs) to remove pharmaceuticals and personal care products (PPCPs) from urban wastewater was assessed. The results of three previous works were considered as a whole to find common patterns in PPCP removal. The experiment took place outdoors under winter and summer conditions. The mesocosm-scale CWs differed in some design parameters, namely the presence of plants, the vegetal species chosen (Typha angustifolia versus Phragmites australis), the flow configuration (surface flow versus subsurface flow), the primary treatment (sedimentation tank versus HUSB), the feeding regime (batch flow versus continuous saturation) and the presence of gravel bed. The full-scale CWs consisted of a combination of various subsystems (ponds, surface flow CWs and subsurface flow CWs). The studied PPCPs were ketoprofen, naproxen, ibuprofen, diclofenac, salicylic acid, carbamazepine, caffeine, methyl dihydrojasmonate, galaxolide and tonalide. The performance of the evaluated treatment systems was compound dependent and varied as a function of the CW-configuration. In addition, PPCP removal efficiencies were lower during winter. The presence of plants favoured naproxen, ibuprofen, diclofenac, salicylic acid, caffeine, methyl dihydrojasmonate, galaxolide and tonalide removal. Significant positive correlations were observed between the removal of most PPCPs and temperature or redox potential. Accordingly, microbiological pathways appear to be the most likely degradation route for the target PPCPs in the CWs studied.     

KDF滤料去除自来水中铅、铬和镉的试验研究

选用合金滤料(KDF55)对自来水进行深度处理,以研究对水中铅、铬和镉的去除效果。试验结果表明,KDF55对水中重金属离子有较好的去除效果,在保证一定接触时间的条件下,对自来水中铅、铬和镉的去除率分别为77.9%、86.5%和70.1%。研究表明:KDF55对自来水中铅、铬和镉有稳定的去除效果。     

Simultaneous copper, cobalt and phenol removal from aqueous solutions by alternating biosorption and biodegradation

A strategy for removal of heavy metals and phenol from wastewaters is proposed. It involves consecutive cation biosorption by fungi, phenol biodegradation by the yeast association Candida sp. 2326 + Candida sp. 2327 and regeneration. Copper and cobalt removal from aqueous solutions containing 80-120 mg/L phenol by biosorption, using Rhizopus archizus cells immobilized onto poly (vinyl alcohol), was investigated by conducting a series of batch experiments. The removal efficiencies were 81% for Cu and 5% for Co. The residual concentrations of Cu (1.9 mg/L) and of Co (9.5 mg/L) did not change the biodegradation dynamics of phenol. A quantitative biodegradation of 120 mg/L phenol proceeded within 22 h. After biodegradation of phenol, the removal efficiencies achieved by biosorption after regeneration were 90% for Cu and 44% for Co. It was found that copper and cobalt form positively charged complexes with phenol. This complex formation hinders the retention of Cu and Co by the biosorbent and reduces the uptake of their cations.