Electrochemical treatment of pentachlorophenol in water and pulp bleaching effluent

Adsorbable organic halides (AOX) compounds produced during bleaching of pulp are recalcitrant and known to have eco-toxic effect. We have studied the removal of pentachlorophenol (PCP) as a model AOX compound in water as well as in pulp bleaching effluent of a bamboo based mill by electrochemical treatment in batch mode. It was found that 10 mg L⁻¹ of PCP in water was removed almost completely in <10 min at a current density of 6 mA cm⁻² in the presence of 1000 mg L⁻¹ NaCl serving as an electrolyte and source of chloride ions. The initial rate of PCP removal was found to decrease at alkaline pH (9.3) as compared to that at acidic pH (5.5). PCP removal in neutralized raw pulp bleach effluent (containing 1830 mg L⁻¹ of chloride) was very slow and incomplete even after 2 h of electrochemical treatment at a current density of 15 mA cm⁻². Various pretreatments of raw bleach effluent such as, alkaline sulfide using sodium sulfide, alkaline reduction using ferrous sulfate and coagulation using potash alum were evaluated. Electrochemical treatment of potash alum pretreated effluent (spiked with PCP) could achieve >90% removal of initial colour, COD and PCP in <1 h. The treatment scheme presented here may be a promising technology for removal of AOX, COD and colour from pulp bleaching effluent. The estimated cost of combined treatment (potash alum coagulation + electrochemical) is US$ 0.7–0.9 per cubic meter of the raw pulp bleach effluent.     

斯托克斯定律在炼油厂催化-常压装置的应用

介绍了斯托克斯(Stokes)定律与电脱盐(EDD)原理,叙述了2者结合在炼油厂常压-催化车间的应用,解决了油与无机盐及水的分离问题.(1)增加液-液旋流分离器,使进污水汽提塔的污水含油量降低了89%,解决了焚烧炉下火雨及炉膛超温的问题;(2)先后2次改造电脱盐流程及电脱盐罐,并应用鼠笼式平流电脱盐技术,使脱后含盐质量分数由8.74mg/L降为1.45 mg/L,含水的质量分数由0.43%降为0.11%,脱盐率由81.4%增加到96.4%.可保护催化剂,提高催化液收收率,降低成本,并稳定安全生产.     

Hydroxyapatite photocatalytic degradation of calmagite (an azo dye) in aqueous suspension

The hydroxyapatite (HAP) is prepared by precipitation method and examined for the photocatalytic degradation of calmagite, a toxic and non-biodegradable azo-dye compound. The physicochemical properties of hydroxyapatite material were characterized using BET surface area, XRD, FT-IR, and SEM analysis. The FT-IR analysis of the hydroxyapatite revealed that the peak intensity due to absorbance of surface PO₄³⁻ group centered at wave number 1030 cm⁻¹ is drastically decreased upon exposure to UV for 1 h. The study includes dark adsorption experiments at different pH conditions, influence of the amount of catalyst, and effect of pH on photocatalytic degradation of dye, chemical oxygen demand (COD) removal, biological oxygen demand (BOD₅) increase and SO₄²⁻ and NO₃⁻ ions evolution during the degradation. At optimum photocatalytic experimental conditions the same is compared with commercial degussa P-25 TiO₂. The photocatalytic treatment significantly reduced the COD (92% removal) and increased the BOD₅/COD ratio to 0.78. Considerable evolution of SO₄²⁻ (8.5 mg L⁻¹) and NO₃⁻ (12.2 mg L⁻¹) ions are achieved during the degradation process, thus reflecting the usefulness of the hydroxyapatite photocatalytic treatment in calmagite removal in wastewater.     

Reverse osmosis of diluted skim milk: Comparison of results obtained from vibratory and rotating disk modules

This paper investigates the reduction of ionic concentration and carbon oxygen demand (COD) in dairy process waters modelled by one volume of skim milk diluted with two volumes of water using shear-enhanced reverse osmosis. Initial COD and conductivity were, respectively, 36,000 mg O₂ L⁻¹ and 2000 μS cm⁻¹. We have compared the performances of a VSEP vibratory pilot and of a single rotating disk-stationary membrane module equipped with the same Desal AG membrane (Osmonics). Membrane shear rates were varied by changing the vibration frequency in the VSEP and the disk rotation speed or adding radial vanes in the other module. In all tests the permeate COD was reduced below 15 mg O₂ L⁻¹. Permeate fluxes reached a maximum of 180 L h⁻¹ m⁻² at a transmembrane pressure (TMP) of 4 MPa at initial concentration with the VSEP at its resonant frequency and with the disk equipped with 6 mm high vanes rotating at 2000 rpm. Permeate conductivity fell from 60 μS cm⁻¹ at 1 MPa to about 18 μS cm⁻¹ at 4 MPa. In concentration tests, corresponding permeate fluxes at the maximum volume reduction ratio reached (VRR = 8), were 55 L h⁻¹ m⁻² for the VSEP and 60 L h⁻¹ m⁻² for the rotating disk at a TMP of 4 MPa. Permeate conductivities increased exponentially with VRR from 18 to 210 μS cm⁻¹ for the rotating disk and to 250 μS cm⁻¹ for the VSEP. However the mean conductivity of collected permeate varied from 38 μS cm⁻¹at highest shear rate to 60 at lower shear rates. This study shows that these filtration systems permit to obtain reusable water from this high initial COD model effluent with one single reverse osmosis step.     

新型入口对石膏旋流器工作性能的影响

针对火电厂石膏旋流器分级效果不理想的问题,设计具有分离块和隔板的新型入口,以改善石膏旋流器的工作性能。采用Fluent软件,应用Reynolds应力模型(RSM)与离散相模型(DPM)模拟新型入口中不同粒度颗粒的运动情况,模拟结果表明:随颗粒粒径增大,颗粒的运动半径与运动距离均增大,不同粒径颗粒在新型入口内能实现初步分级。对普通入口与新型入口石膏旋流器分别进行性能实验,获得不同工况下生产能力、出流浆液密度以及旋流器分级效率等指标参数,经比较可知,采用新型入口后,石膏旋流器底流质量浓度明显增大,10～30 μm石膏颗粒的分级效率有显著提高,最大增幅可达15%,同时,6 μm以下石膏颗粒的底流夹细现象也有一定程度的改善,但由于入口段流动阻力增大,生产能力略有下降。     

Mechanistic approach of the combined (iron–TiO2) photocatalytic system for the degradation of pollutants in aqueous solution: an attempt of rationalisation

Kinetics of oxidative photodegradation of Monuron (3-(4-chlorophenyl)-1,1-dimethylurea) in different photocatalytic systems (iron, TiO₂ and combined system iron + TiO₂) were investigated and compared. The influence of iron addition on TiO₂ photocatalyst and of TiO₂ on the photocatalytic cycle Fe(III)/Fe(II) were carefully studied. A very positive effect of iron addition was observed. This phenomenon was more and more pronounced when TiO₂ concentration was lower. In a suspension of TiO₂ (24 mg L⁻¹) with addition of Fe(III) (3 × 10⁻⁴ mol L⁻¹) the measured rate constant was similar to that obtained in a suspension of TiO₂ with a concentration more than 20 times higher (500 mg L⁻¹). The mechanistic approach carried out in this study allows us to identify the main reactions governing the combined system and a photochemical cycle was proposed. The optimisation of the photocatalytic systems was obtained when each photocatalyst plays a specific role: Fe(III) as a main OH radicals source and TiO₂ as an oxidizing agent of Fe(II).     

油井采出液预分水用轴向水力旋流器的实验研究

高含水油井采出液的高效预分水是目前油气集输处理领域面临的关键难题之一,轴向水力旋流器因具有结构紧凑、分离效率高等优点而得到了国内外的广泛关注。本文针对自主研发的油井采出液预分水用轴向水力旋流器开展了室内实验研究。与切向水力旋流器对比,轴向水力旋流器不仅分离效率更高,而且油出口处的油滴聚结长大近1.8倍,在分水率高于50%的情况下,水出口处的含油浓度低于1000mg/L;轴向水力旋流器压降较低,且压降比与分流比呈线性相关。分流比、含水率和流量对分离性能均有显著影响,其中分流比的变化直接影响油核的大小和稳定性,室内样机的最佳分流比为0.45,当含水率为90%、处理量为1.00m³/h时分水率与含油浓度分别为62.9%和432.8mg/L;含水率高于75%时分离性能良好;室内样机的最佳流量为1.50m³/h。自主研发的轴向水力旋流器不仅满足性能要求,而且在操作弹性、可控性方面较切向水力旋流器均有一定的提升。     

电脱盐污水模块化聚结除油中试研究

针对电脱盐污水含油特征,提出了分步分级模块化聚结除油的方法 ,并进行了中试试验。结果表明,该方法对入口含油质量浓度为150~3 550 mg/L的电脱盐污水的除油率达90%以上,净化水出口含油质量浓度稳定50mg/L,表现出操作弹性大、快速高效及低压降的特点。该技术在电脱盐污水除油领域具有良好的适用性,为电脱盐污水除油处理提供了新的技术思路。     

Decolorization of synthetic dyes by hydrogen peroxide with heterogeneous catalysis by mixed iron oxides

Heterogeneous catalysts based on magnetic mixed iron oxides (MO·Fe₂O₃; M: Fe, Co, Cu, Mn) were used for the decolorization of several synthetic dyes (Bromophenol Blue, Chicago Sky Blue, Cu Phthalocyanine, Eosin Yellowish, Evans Blue, Naphthol Blue Black, Phenol Red, Poly B-411, and Reactive Orange 16). All the catalysts decomposed H₂O₂ yielding highly reactive hydroxyl radicals, and were able to decolorize the synthetic dyes. The most effective catalyst FeO·Fe₂O₃ (25 mg mL⁻¹ with 100 mmol L⁻¹ H₂O₂) produced more than 90% decolorization of 50 mg L⁻¹ Bromophenol Blue, Chicago Sky Blue, Evans Blue and Naphthol Blue Black within 24 h. The fastest decomposition proceeded during the first hour of the reaction. In addition to dye decolorization, all the catalysts also caused a significant decrease of chemical oxygen demand (COD). Individual catalysts were active in the pH range 2–10 depending on their structure and were able to perform sequential catalytic cycles with low metal leaching.     

旋流分离技术在甲醇制烯烃工艺废水处理中的应用

旋流分离技术在液-固分离和油水分离方面有广泛的应用,针对甲醇制烯烃废水处理中存在的问题,分别研究了急冷水旋液分离器和水洗水旋流除油器,应用于急冷水中催化剂微粉的脱除及水洗水中的油蜡类物质的分离。研究成果应用于某化工企业180万吨/年DMTO装置的水处理系统,并对其急冷水和水洗水水质进行了长期的监测,主要监测指标为急冷水旋液分离器进出口悬浮物含量和水洗水旋流除油器进出口油含量。工业运行结果表明：急冷水一级旋液分离器和二级旋液分离器的效率分别能达到50%和80%,对急冷水进行了有效的澄清,同时对外排相进行了有效的提浓;水洗水除油器的分离效率可达到60%,对油蜡类物质具有较好的分离效果。旋流分离技术的应用,减少了水系统中管路及设备堵塞,保证了装置的稳定运行。     

水力旋流器分离细颗粒的试验研究

介绍了用于细颗粒分离的水力旋流器的基本结构形式及主要结构参数。并针对旋流器雷诺数、分流比、旋数等无因次参数对压力特性的影响进行了细致的试验研究,找出了这些参数与欧拉数和压降比的相互关系。所有试验均在不含气的条件下进行。结果表明,随着雷诺数、分流比和旋数的分别加大,水力旋流器的压力降呈增加趋势,压降比则呈下降趋势。另外,针对当量直径45μm尿素复合颗粒进行了分离特性研究。结果表明,随着雷诺数的加大,分离效率逐步提高,但并非雷诺数越大越好;对于分流比,则只在低雷诺数时有利于分离效果的改善;旋数分别为9、16和29的实验结果表明,旋数16的总体效果为最优。     

注气对油水分离水力旋流器流场影响模拟分析

采用雷诺应力湍流模型、混合模型和离散相模型对注气型油水分离水力旋流器进行数值模拟,得到其内部流场的速度分布和油滴粒子运动轨迹,分析对比了注气前后进口流量、分流比和充气量对分离效率的影响,数值计算结果与文献实验值进行了比较。结果表明,充气后流场速度增加,油滴粒子逃逸时间缩短,旋流器分离效率提高5%~10%,在一定条件下气浮对旋流分离起到强化作用。     

除油旋流器内油滴粒径的分布

引　言随着油田水处理技术的发展 ,除油旋流器的使用越来越普遍 .油滴粒径是影响油水分离旋流器性能的一个重要因素 ,它直接影响到旋流器的分离效率及含油污水处理能力 ,防止油滴破碎是油水分离旋流器研究者们共同感兴趣的问题 ,本文研究了旋流器进口粒径变化与旋流器各段分离效率之间的关系以及进口流量、分流比等对旋流器各段边壁油滴粒径的影响 .1　实验装置实验流程如图 1所示 .清水由螺杆泵输送 ,通过螺杆泵可以调节旋流器的进口流量 .油由计量泵注入螺杆泵入口管线中 ,与水充分混合 ,通过调节计量泵的流量可以调节油水混合物的油含量 …     

Numerical Simulation of Oil‐water Hydrocyclone Using Reynolds‐Stress Model for Eulerian Multiphase Flows

A three‐dimensional oil‐water turbulent flow and oil separation process in a double‐cone liquid‐liquid hydrocyclone (LLHC) is numerically simulated using FLUENT software. The Euler‐Euler approach and Reynolds‐stress model are combined and adopted in this simulation to handle the challenging situation of anisotropic turbulent two‐phase flow with a higher volumetric ratio (over 10%) in the dispersed phase. It is visualized well in the simulation how separation, aggregation and shift of oil and water proceed in the LLHC. The oil separation efficiency is determined based on flow field and phase concentration distribution. The simulation is verified by comparing predicted and measured separation efficiency in the LLHC.     

炼厂电脱盐破乳剂的研究

应用悬滴法测定了油水相之间的界面张力,以此检验多种原油破乳剂的表面活性;通过瓶试法考察了表面活性较高的几种破乳剂产品的脱水性能;在此基础上,将优选出来的原油破乳剂产品与自制脱钙剂复配,进行模拟电脱盐评价,通过比较原油脱金属效果,考察破乳剂最终的使用性能。     

超声电脱盐联合预处理原油脱盐脱水

A technology of ultrasonic-electric united desalting and dewatering of crude oil is studied. The ultrasonic setup is designed to form a standing-wave field, which is more efficient for agglomeration of water particles. The desalting and dewatering results of the ultrasonic-electric united process are compared with those of the electric process. For high salt-contenting crude oil （40-70 mg·L ^-1）, the salt content is still above 10.0 mg·L^-1 after crude oil has been treated by two-stage electric desalting process in refinery, which cannot meet the need of refinery. Ultrasonic-electric united process is a novel technology for treating the high salt-contenting oil. On the optimal operating conditions of the ultrasonic-electric united process, the salt content of crude oil can be reduced from 67 5 mg·L^-1 to 3.97 mg·L ^-1 by one-stage ultrasonic-electric united process, and the water content falls below 0.3% （by volume）. The results show that the ultrasonic-electric united process is more effective than the electric process in high salt-contenting oil desalting. This technology should be useful in the refinery process.     

超声波技术在陕北混合原油脱盐装置上的应用

超声波破乳技术具有能耗低、效果好、无污染等特点,是一种新兴的原油破乳技术。针对陕北混合原油,采用超声波技术在陕西延长石油集团延安炼油厂、永坪炼油厂和榆林炼油厂的5套原油脱盐工艺进行了应用试验,应用结果表明:采用超声波技术后,可完全停止使用破乳剂,平均脱后原油含盐量由3—5 mg/L降低至3 mg/L以下;总排水含油量平均由242.5 mg/L降至76.6 mg/L,能够减少高含水污油的生成量;同时操作过程稳定,各级电脱盐罐电流明显降低,经济效益显著。该技术具有较好的推广应用前景。     

交直流三级电脱盐技术在炼油工业上的应用

采用先进的交直流三级电脱盐装置,改造炼油厂前原油的脱盐工艺,实现了原油的深度脱盐,原油含盐由脱前〉２００ｍｇ／Ｌ降到脱后的〈３．２ｍｇ／Ｌ以下,从而延长了常减压装置的开工周期,减少了催化裂化装置催化剂的耗量。     

改造电脱盐装置降低原油脱后含盐量

塔河分公司350万t/a重油改质项目投用以来,2#电脱盐装置脱后含盐、含水一直无法达到设计要求,为此塔河分公司组织进行电脱盐技术攻关,从电场、电极板、分配板、变压器等多个方面对电脱盐罐进行改造,脱盐脱水效果明显好转.     

Treatability studies on domestic wastewater using UV/H2O2 process

Advanced oxidation processes (AOPs) are emerging and promising technology both as an alternative treatment to conventional wastewater treatment methods and enhancement of current biological treatment methods especially dealing with highly toxic and low biodegradable wastes. In this paper, the results of domestic wastewater treatment using H₂O₂/UV process in both batch and continuous mode are presented. Over 95% reduction in COD was achieved in less than 60 min of reaction time. Optimum conditions for pH and H₂O₂ dosage for this process was found to be 3 and 50 mg L⁻¹, respectively. A pretreatment in the form of removal of turbidity is recommended for the success of the process in the long run. Electric energy required is estimated to be 10 kWh kg⁻¹ COD on the average.