Electrocoagulation process for the post-treatment of anaerobically treated urban wastewater

Suitability of the electrocoagulation (EC) process for the post-treatment of anaerobically treated urban wastewater was assessed, in batch system employing real effluent from an upflow anaerobic sludge blanket (UASB) reactor. Response surface methodology (RSM) was used to optimize three important process parameters, namely current density, electrolysis time and initial pH. At the optimum conditions of pH 7.07, electrolysis time 18.0 min and current density 15.0 mA/cm², chemical oxygen demand (COD), turbidity and phosphate removal efficiencies observed were 71.0%, 98.5% and >99.9%, respectively, which were very close to the model-predicted values. High removals of suspended solids (SS; 87.5%), biochemical oxygen demand (BOD) (83.3%) and total coliforms (99.994%) were also obtained at the optimum conditions.     

Feasibility study for reclamation of a secondary treated sewage effluent mainly from industrial sources using a dual membrane process

A feasibility study for reclamation of a secondary treated sewage effluent mainly from industrial sources (60%) in Singapore has been conducted using a dual membrane UF-RO process. The pilot system had a treatment capacity of 2 m³/h. The UF unit and RO unit were operated at 70–80% and 40% water recovery, respectively. Six-month run for the pilot was carried out to study the stability and fouling tendency of membranes.

The characteristics of the raw feed indicated that ammonia-N was consistently high at 30–50 mg/L. Very high fluctuations in iron (0.3–3.7 mg/L), turbidity (1–27.1 NTU) and TOC (3.2–56.7 mg/L) were observed. Nitrate was low at <0.2 mg/L. The results of the study showed that dosage of alum in the UF process significantly reduced organic foulants and phosphate scalants. The polymeric RO membrane could tolerate organics from industrial wastewater and performed >96% salt rejection at the end of the study after 6 months. The study concluded the dual membrane process was capable of reclaiming the sewage effluent mainly from industrial sources for industrial use.     

Pilot study for reclamation of secondary treated sewage effluent

A pilot study for reclamation of secondary treated sewage effluent in Singapore was conducted using a MF/RO system with the capacity of 20 m³/d. A 0.1 μm MF membrane from Asahi and RE-4040-FL RO membrane from Saehan were used in this study. The pilot plant consists of six spiral-wound RO elements. The RO train was configured in single stage. The pilot plant was designed with automatic control system and it was operated continuously (24 h) during the study. Trial runs on various flux rates of the RO membrane at different operating pressures were conducted over 3 months. The pilot results showed that the optimal operation flux rate of the RO membrane ranged from 10 to 15 gal/f²/d (GFD) for this application. The normalized flux after CIP was 97% of the initial one. At a flux rate of 10 GFD and water recovery of 50%, the average operating pressure of 57 psi was noted corresponding to a high normalized flux of 38 L m⁻² h⁻¹ MPa⁻¹ at 25°C. Rejections of the RO membrane in terms of conductivity, TOC, ammonium and nitrate were higher than 96%,97%,90% and 85%, respectively. It was concluded that the RO permeate quality in terms of conductivity, turbidity, TOC, ammonium, nitrate, hardness, total bacteria and total coliform matched the quality of high-grade water (NEWater) for use in the electronics industry.     

外排废水处理后回用于循环水系统

将炼油装置达标外排废水引入废水回用系统,经过絮凝-沉淀-过滤-中空超滤处理后回用于循环水系统,回用水量占补水总量的40%￣60%。工业性应用试验结果表明,使用合格的回用水每年可以减少新鲜水用量53万m3,同时减少废水外排量,年创净效益103.5万元,具有良好的经济效益和社会效益。     

Processing of composite industrial effluent by reverse osmosis

Reverse osmosis (RO) is a well‐established process for water desalination and effluent treatment and it is anticipated that its application could be extended to complex mixtures of industrial effluents. Pilot‐scale experiments using a spiral‐wound thin‐film composite (TFC) polyamide membrane were carried out to investigate the potential of RO for processing a composite effluent, which was a mixture of various wastewaters from bulk drug and pharmaceutical factories. Separation performance was evaluated at various feed pressures (0–70 bar) and feed concentrations (2–30 gdm^?3), and was found to improve with increasing pressure. High rejection of dissolved solids (～98%), COD, BOD and almost complete removal of color were achieved with reasonable flux rates and water recovery. The effect of concentration polarization and fouling on flux and rejection rates as functions of time was evaluated. An approximate cost estimate for an aerobic process vis‐à‐vis a RO membrane process for treatment of the composite effluent is presented. Copyright © 2003 Society of Chemical Industry     

Mineralization of organic N originating in treated effluent used for irrigation

Reclaimed wastewater and, particularly, secondary effluent used for irrigation, may contain considerable amounts of mineral and organic N. The knowledge regarding N-transformations of effluent-originated organic N in soil is not well established. A method based on ion-exchangers (IE) was developed to remove the mineral N and other ionic species from the effluents, enabling a better follow-up of the reactions of effluent-originated organic N. Modifications of two incubation methods were used to evaluate net mineralization rates and the contributions of ammonification and nitrification of the effluent-originated organic N. A mixture of the ion-exchangers, IRN-77 (H⁺) and IRN-78 (OH^–), was found effective in removing mineral N and other ions from effluents without significantly affecting the content of organic N. In suspension-based experiments performed with a microbially active calcareous clay soil, the nitrification started after about a 1 to 4 d lag (higher lag associated with higher BOD), and the total mineral N reached plateau values after about 9 to 14 d. The time estimated for completion of ammonification of the organic N in the well-mixed and aerated suspensions was 3 to 6 d. Soil incubations were performed after adding the IE-treated effluents to small soil columns. Ammonification of both soil and effluent-originated organic N occurred concomitantly with the nitrification, making the evaluation of rates more complicated. Tracing the time differences in total mineral N between the soils irrigated with the IE-treated effluent and the blank (no added N) enabled the estimation of first order rate constants for the net mineralization of the effluent-originated organic N in: a sandy loam (0.3 wk^–1), a loess (0.4 wk^–1), and in the calcareous clay (1.1 wk^–1). About two thirds of the organic N added to the soils in the columns during the pre-incubation stage were not retained in the soils, whereas ammonium was practically not leached out. The relatively fast movement of the effluent-originated organic N in soil and its mineralization characteristics indicate that this fraction significantly affects the short (days) and middle (weeks) range transformations of N in effluent-irrigated soils.     

Optimization of continuous electrocoagulation-adsorption combined process for the treatment of a textile effluent

The aims of this study is to design and optimize the functioning of a full continuous combined process based on electrocoagulaion-adsorption on crude Tunisian clay to treat a real textile effluent. The clay characterization shows that the used clay is a rich-smectite clay. The response surface methodology (RSM) technique based on Box-Behnken design (BBD) was used to optimize the process. At optimum conditions which are initial pH solution of 8.24, effluent flow rate of 0.5 L·min^-1, voltage of 70 V, and added suspension of clay flow rate of 100 ml·min^-1 the achieved color, chemical oxygen demand (COD) and total suspended solid (TSS) removal efficiencies were respectively 96.87%, 89.77% and 84.46% with 0.75USD·m^-3 as total cost. The additional laboratory experiments at optimum conditions agree with the predicted results, which confirm the accuracy and the capability of RSM to predict results in the defined space. Finally the designed process could be a good eco-friendly alternative to treat and reuse wastewater in industrial process with reasonable cost.     

工业污水回用中试工艺流程的探讨

针对94^#装置R350二沉池排水进行污水回用中试研究,中试装置规模为4t/h。根据水质特点、回用目的以及制水成本等多方面因素考虑,设计了一种工艺流程,并在中试过程中对该工艺流程不断改进,使其更加合理．取得了预期的水处理效果。     

制药工业废水中CODCr与BOD5的相关性及应用研究

建立一种只需测定工业废水中化学需氧量（简称CODcr）,就可推算出生化需氧量（BOD5）的方法,对21个样品进行分析测定CODcr和BOD5,经线性回归找出两者的相关性;试验表明CODcr和BOD5间具有良好的线性相关性,其中r=0.9958,该方法应用于制药工业废水的处理和控制,具有简便、适应性好、省时省力等优点。     

Development of a bioprocess combined with membrane technology for the treatment and recycling of textile effluent

A mixed culture of dye-decolorising Pseudomonas spp. was immobilised on polyurethane foam, and used in a bench-scale continuous culture bioreactor to treat textile effluent for colour removal. The provision of soluble wheat starch (0.2% w/v) to the culture medium promoted growth of biomass and enhanced decolorisation of effluent in the bioreactor. The bioprocess was further combined with membrane filtration technology to improve the quality of treated effluent. The treated effluent showed 90, 82 and 60% reduction in COD, BOD₅ and toxicity levels, respectively, and had potential for re-use in dyeing processes. The colour difference of the cotton fabrics dyed using the treated effluent samples compared to those dyed using normal supply water was found to be industrially acceptable. The described process could improve treatment efficiency and allow water recycling within the textile factory.     

Processing of biscuit industrial effluent using thin film composite nanofiltration membranes

Nanofiltration (NF) is a membrane-based separation process having significant potential for the treatment of industrial effluents to enable water reuse. It has the ability to remove low molecular weight trace contaminants from water, which cannot be separated by conventional treatment methods. In the present investigation, a thin film composite polyamide membrane was synthesized by interfacial polymerization technique and evaluated for the treatment of biscuit industrial effluent. The synthesized membrane was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy to elucidate structure and intermolecular interactions, crystallinity, thermal stability and cross-sectional morphology, respectively. The influence of operating parameters such as feed pressure 0–21 kg/cm² and total dissolved solids (TDS) of 3160 ppm on water flux and impurity rejection was determined. An average flux of 11.63 L/m² h was obtained at a constant pressure of 21 kg/cm². The TDS, chemical oxygen demand (COD), and biochemical oxygen demand (BOD) rejections were found to be 53.62, 80, and 74%, respectively, at a water recovery of 65%. A statistical mechanical model was used to validate the experimental data. Based on this study, a detailed economic estimation for processing biscuit effluent of 1 m³/h feed capacity using commercial NF system is presented. The study revealed that the synthesized NF membrane could be an effective alternative for the treatment of various industrial effluents as well as to reduce the load on reverse osmosis process for desalination of seawater and effluent treatment through high degree of COD and BOD separation.     

Separation of nitrocellulose fine particles from industrial effluent with organic polymers

Polymers were used in the experiments to determine optimum type and dosage requited for effective treatment of an industrial effluent containing nitrocellulose fine particles. It was found that (a) contact flocculation filtration was not effective for treating the nitrocellulose-manufacturing wastewater due to the high initial turbidity; (b) mixing, flocculation, and settling of the wastewater with cationic polyelectrolyte and bentonite clay gave greater than 95% turbidity removal; (c) with the same optimum chemical dosages, mixing, flocculation and centrifugation also gave about 97% turbidity removal; and (d) with the same optimum chemical dosages, mixing, flocculation, sedimentation and filtration removed 99.9% of the wastewater turbidity.     

Study of the cytotoxicity of reactive dyeing effluent treated by Fenton oxidation

Fenton oxidative wastewater treatment of CI Reactive Black 5 and CI Reactive Blue 19 effluent was performed after a simulated laboratory‐scale dyeing process, and the cytotoxicity of the treated effluent was evaluated using human skin cell lines. Among the components for Fenton oxidation, the human skin cell results showed that iron(II)sulfate at 150 mm did not show any significant cytotoxic effect, while other components, such as Glauber's salt solution (20 g l^?1; 14%), CI Reactive Black 5 (30 mg l^?1; 24%), caustic soda (5 g l^?1; 30%), CI Reactive Blue 19 (30 mg l^?1; 32%), hydrogen peroxide (0.01 m ) and soda ash (5 g l^?1) showed cytotoxic potential; the reagent sodium sulfite (30 mm ; 48%) exhibited the strongest cytotoxicity level. Fast decolorisation (>95%) was achieved within 10 min for CI Reactive Black 5, while for CI Reactive Blue 19 it took longer (1.5 h) to achieve the same decolorisation. Studies showed that decolorisation for both dyes followed second‐order kinetics. In spite of the remarkable efficacy of the Fenton oxidation process in removing colour within a short period of time, the resulting treated wastewater (within a reaction time of 1.5 h) also showed cytotoxicity towards the human HaCaT skin keratinocyte cell line. This observation can be explained by the strong oxidant and intermediate species produced during the advanced oxidation process, and a treatment step using sodium sulfite and a prolonged residence time can help to reduce the cytotoxicity.     

Electrotreatment of industrial copper plating rinse effluent using mild steel and aluminum electrodes

BACKGROUND: Heavy metals from aqueous streams can be removed effectively using electrochemical techniques. Although both mild steel (MS) and aluminum (Al) electrodes have long been considered for the treatment of different waste‐waters, unfortunately the reported optimum treatment time, current density, pH and background electrolyte concentration vary greatly. In this work, an electrochemical technique was used for the removal of Cu from electroplating rinse water collected from a local plating industry using MS and Al as electrode materials. RESULTS: Removal of Cu during electrotreatment is due to the combined effect of hydroxide precipitation and electrodeposition. The discharge limit of Cu (3 mg L^?1) was achieved with both the electrodes and electrode arrangements. Both MS and Al electrodes showed similar performance for removing copper, however, a lower increase in pH was observed with the MS electrode under identical experimental conditions. NaCl added to increase the solution conductivity decreases Cu removal and inhibits oxide layer formation during electrotreatment. The effluent contains about 6.8 mg L^?1 Zn and its discharge limit (4 mg L^?1) was achieved within the first 10 min of treatment. CONCLUSIONS: Results obtained from experiments demonstrate that the stipulated limit of both Cu and Zn can be achieved during treatment of industrial plating effluent using MS and Al as electrode materials, depending on current density and treatment time. Copyright © 2009 Society of Chemical Industry     

超滤膜在工业循环冷却排污水回用中的应用

在循环冷却排污水的现场中试试验之中，采用超滤（UF）系统作为整个中水回用系统的预处理方法，经过近180h的试验，取得此种超滤膜在运行过程中的水质水量衰减状况曲线以及反冲周期。由试验结果可以看出，用超滤系统作为循环冷却排污水的预处理系统，其产水的水质指标已经达到反渗透系统的进水水质指标，产水水量符合标定水量，建议超滤产水进入反渗透系统，进行反渗透系统的运行安全性试验，并通过试验进一步寻找反渗透系统的化学清洗周期。     

炼油厂MBR出水回用循环冷却水的试验研究及工业应用

为实现炼油厂处理后污水可回用于循环冷却水系统,通过旋转挂片腐蚀试验和静态阻垢试验,筛选出适合于炼油厂污水回用循环冷却水条件下的水稳配方,经动态模拟试验和现场应用,该配方具有良好的阻垢缓蚀性能.     

高岭土和三氯化铝废水制备聚合氯化铝研究

研究了以高岭土和工业三氯化铝废水为原料制备净水剂聚合氯化铝的新技术和新工艺,研究了反应催化剂、物料配比、微波反应对工艺的影响,得到的产品质量达到了国家标准。     

Anodic,cathodic and combined treatments for the electrochemical oxidation of an effluent from the flame retardant industry

The electrochemical oxidation of an effluent from the manufacture of phosphorus based flame retardants was studied. To reach a residual concentration of reduced phosphorus lower than 10 mg L⁻¹, in compliance with Italian law for industrial wastewater disposal, anodic oxidation using a boron-doped diamond (BDD) anode and electro-Fenton (EF) treatment were tested. The effects of some factors are optimised and a comparison of the reaction pathways is also presented. A combined treatment using EF with BDD conducted in an undivided cell is shown not to enhance the data obtained with BDD while a novel combined treatment using EF and BDD in a divided cell shows promising results when an anionic membrane is used as separation. In this last case the cell operates as two different batch reactors working with the same current. The anodic compartment, fed with raw effluent, provides partial oxidation, while the cathodic compartment, fed with the partially anodically oxidised solution, completes the treatment. When the effluent is transferred in the cathodic compartment, the anodic one is fed with fresh untreated solution. The advantage of this kind of coupling consists in the simultaneity of the two treatments which allows total oxidation with notable saving of charge and time.     

AOPs技术预处理腈纶废水研究进展

简述了腈纶废水的主要特点及危害,重点及全面描述了近年来国内外腈纶废水预处理中AOPs技术的研究和应用情况,并对不同AOPs预处理法(光催化氧化法、电催化氧化法、Fenton法和臭氧法)的基本原理进行了概述以及指出了各种方法的优缺点,同时分析了腈纶废水预处理所面临的问题以及对AOPs技术预处理腈纶废水应用前景提出了展望。