Role of membrane pore size in tertiary flocculation/adsorption/ultrafiltration treatment of municipal wastewater

Flocculation, adsorption onto powered activated carbon (PAC), and ultrafiltration (UF), alone and in combination, were tested for tertiary treatment of the secondary effluent from municipal wastewater treatment at the Ashkelon plant (in southern Israel). Encouraging and reliable results of total organic carbon (TOC) of <3 mg/l were achieved with a combination of 130 mg/l FeCl₃, 0.6 g/l PAC and UF. The relative contribution of the UF membrane to the reduction of TOC changed with the molecular weight cut-off (MWCO) of the membrane, from a negligible 2.9% for a 100-kDa-MWCO membrane to 17% for 10- and 2-kDa membranes. The latter membranes, however, developed significant fouling, with a 35% drop in flux during first 30 min of the filtration cycle. The flux drop for the 50- and 100-kDa membranes was in the low range of 3%. The optimal MWCO interval of 20- to 50-kDa in combination with flocculation/PAC pretreatment gave a significant reduction in organic content with minimal membrane fouling. Detailed GC–MS analysis showed that the combined treatment gave very efficient retention of organic compounds with molecular weights below 800 Da, with the consequent absence of harmful compounds in the tertiary effluent. It was therefore concluded that the recommended flocculation/adsorption protocol constitutes an effective pretreatment for UF and that the obtained tertiary effluent can be used for unrestricted irrigation.     

共混比及聚合物浓度对PVC/PVB相容性及超滤膜性能结构的影响

通过混合焓的计算,对不同共混比和聚合物浓度的聚氯乙烯(PVC)/聚乙烯醇缩丁醛(PVB)共混比体系的相容性进行预测,并通过稀溶液黏度(DSV)法、运动黏度法和目视法进行相应验证;以N,N-二甲基乙酰胺(DMAc)为溶剂,通过湿相转换法(NIPS)制备PVC/PVB共混平板超滤膜,并对超滤膜的性能和结构进行测试,系统地研究了PVC/PVB共混铸膜液的组成对平板超滤膜的结构及其分离性能的影响,为通过PVB共混改性PVC膜材料制备超滤膜提供了理论依据。     

浆内凝胶方式提高纸板挺度的新工艺研究

将醇溶性脲醛树脂添加至高浓度纸浆中,75～80℃下加热纸浆数分钟,使树脂初步凝胶并黏附、包裹于纤维表面,抄片并将纸页加热干燥时,树脂充分凝胶固化,从而提高了纸板的挺硬性。研究结果表明：在高浓纸浆的pH为4～5、加热保温6 min的处理条件下,脲醛树脂具有很高的留着率,同时也能增加纸板的环压强度,增幅可达50%以上。对醇溶性脲醛树脂有协同留着、协同增强的效应,可使树脂的留着率高达92%,纸页环压强度增幅达68%。脲醛树脂合成成本低廉、原料易得,将其作为纸板增挺剂,具有现实意义。     

水解-接触氧化-UF-RO工艺处理印染废水及水回用工程

以浙江某企业的印染废水处理及水回用工程为例,介绍了水解-接触氧化-UF/RO工艺的处理情况,该工程处理水量为3 000 m3/d,废水原水电导率为500μS/cm,COD为900 mg/L,SS质量浓度为400 mg/L,色度为650倍。运行结果回用水量2 000 m3/d,回用水的电导率小于20μS/cm,COD小于3 mg/L,回用水水质稳定,达到企业生产用水水质要求。回用水处理费用为3.305元/m3。     

浸渍纸生产技术与生产中常见质量问题探讨

简要介绍浸渍纸生产技术涉及的工艺、设备和原料,并针对生产中常见的质量问题进行了分析探讨.     

改性脲醛树脂对提高淀粉胶粘剂耐水性能的研究

为进一步提高淀粉胶粘剂的耐水性能,在传统脲醛树脂(UF)和淀粉胶粘剂合成工艺的基础上,以环氧氯丙烷(ECH)作为UF的接枝共聚改性剂,制备环氧型UF;然后将环氧型UF与传统淀粉胶粘剂进行复配,制备改性淀粉胶粘剂。以耐水剪切强度作为考核指标,采用正交试验法优选出制备改性UF的较佳工艺条件。结果表明:当n(F)∶n(U)=2.0∶1、m(ECH)=8 g、缩聚温度为90℃和接枝共聚时间为75 min时,制成的改性UF可明显提高复配淀粉胶粘剂的耐水性能。     

基于超滤处理工艺的洗车废水循环利用技术

以超滤为核心工艺处理洗车废水,对比了采用混凝沉淀-砂滤和单独采用砂滤作为预处理时的出水指标,两种工艺对浊度的去除率分别为99．4％和99．1％,对COD的去除率为69．5％和53．4％,对阴离子表面活性剂（Anionic surfactant,AS）的去除率为69．2％和27．6％。结果表明,采用适合的预处理单元,以超滤为核心的处理工艺在洗车废水循环回用方面具有可行性。     

UF_4氟化反应及其反应动力学

利用自行研制的氟化挥发实验装置,通过UF4和F2之间的气-固反应制备UF6。实验中将傅里叶红外光谱技术用于氟化过程的在线监测,并用XRD和ICP-MS分析方法对反应产物和氟化残余物进行了表征,在此基础上对工艺流程进行了评估。研究表明,氟化反应工艺合理、红外光谱技术在线监测方法可行。研究还表明低温下抽真空的方法能有效除去产物UF6中的HF杂质。利用球形颗粒缩小未反应核模型,对实验数据进行拟合,得到反应温度300℃、氟气体积分数为5%时氟化反应速率常数为0.002 7min-1。     

Recovery and concentration of phenolic compounds in blood orange juice by membrane operations

Cross-flow ultrafiltration (UF) and osmotic distillation (OD) were implemented on laboratory scale to obtain formulations of interest for food and/or pharmaceutical industry starting from the blood orange juice produced in the Calabria region. The freshly squeezed juice, after a depectinization step, was submitted to an UF process in order to recover natural antioxidants, such as hydroxycinnamic acids, hydroxybenzoic acids, flavanones, flavan-3-ols, and anthocyanins. The UF permeate, with an initial total soluble solids (TSS) content of 10.5°Brix, was concentrated by OD up to a final concentration of 61.4°Brix.     

Influence of Process Variables on the Reactivity of Low Formaldehyde Emission Urea-Formaldehyde Resin

One of the important characteristics of the thermosetting resins such as urea-formaldehyde resin is the cure property. This is an invaluable characteristic for determining the processing capabilities of the resin. Differential scanning calorimetry (DSC) measurements are ideally suited to achieve this end. This paper presents the results of the effect of process variables on the enthalpy of cure of a low formaldehyde emission UF resin prepared by a four-stage process as described in the text. Response surface methodology (RSM) was used to design and the analyze the experiments. Urea (U) was added to the reaction mixture according to a pre-determined program of varying the number of additions and the duration between the additions during the second stage of the process. A mathematical relationship between the process variables and enthalpy of cure was established. The urea-formaldehyde (UF) resin was prepared under optimum conditions. Experiments were performed with the resin so prepared to determine the energy of activation of the curing reaction catalyzed by ammonium chloride.