Excess activated sludge reduction by using electromagnets and ferrite particles

Every year, the ratio of the sewarage treatment to population is increasing in Japan. Expansion in sewer networks is leading to the production of excess sludge which is one of the major problems in wastewater treatment plants. There are several approaches to treat the excess activated sludge. A new approach is to reduce excess sludge production by using magneto‐ferrite treatment. The Suzuki Lab of Akita University, Japan, is working on this project. We have succeeded in using magneto‐ferrite treatment in the lab scale to reduce sludge production. Ferrite particles and magnets are used in this method. Ferrite particles are nontoxic and safe for biological systems. They can be easily separated from the sludge by using magnets. However, the movement of the ferrite particles in the sludge is controlled by permanent magnets which can be made more effective by changing to electromagnets. In this paper, we describe an approach to use electromagnets instead of permanent magnets. Electromagnets can be controlled easily with an AC power supply. The results of our experiments have shown a good possibility for reduction of excess sludge. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Complex use of waste in wastewater and circulating water treatment from oil in heat power stations

Sewage and circulating water from oil of thermal power plants (TPP) generated in fuel-oil shops during washing of electrical equipment and its running into the storm drainage system from the industrial site has been considered in the paper. It has been suggested to use the carbonate sludge of water treatment modified with hydrophobing emulsion as a sorption material for waste and circulating water treatment in thermal power plants. The carbonate sludge is waste accumulated in clarifiers at the stage of natural water pretreatment. General technical characteristics of the sludge, such as moisture, bulk density, total pore volume, ash, etc., have been determined. It has been found that the sludge without additional treatment is a hydrophilic material that has low adsorption capacity and wettability with nonpolar compounds. Therefore, the sludge is treated with organosilicon compounds to reduce the moisture capacity and increase its floatation. Several types of sorption materials based on the carbonate sludge subjected to surface and volume hydrophobization have been developed. During the volume treatment, the hydrophobing compound has been introduced into the material along with the plastifier. In case of the surface treatment, heat-treated granules have been soaked into hydrophobing emulsion. It has been shown that surface hydrophobization is most economically advantageous, because it reduces the consumption of water-repelling agent, wherein the total pore volume and sorption capacity during surface hydrophobization increase by 45 and 25% compared to that during volume hydrophobization. Based on the obtained results, the most effective sorption material has been chosen. To produce this material, it is necessary to sequentially carry out mixing of carbonate sludge with the binder, granulation, calcination, impregnation with a waterrepellent emulsion, and drying of the finished material. The suggested technology to produce the material and use it as a sorbent allows efficient wastewater treatment from oil as well as reduction of anthropogenic pressure on the environment and economic costs of the station for nature protection measures.     

A Study of the Absorption of Nitrogen Oxides from the Boiler Flue Gases

In the past decade, the number of unsolved ecological problems has been steadily increasing. Among the numerous causes of this situation, the exposure of the environment to industrial waste should be mentioned. For example, enterprises of the fuel and energy industry emit a significant amount of hazardous substances into the atmosphere. Flue gases formed in boiler-houses and at thermal power stations get through flue gas stacks into the upper atmosphere and pollute it. In this work, a method is proposed for adsorption treatment of the flue gases from boilers fired with associated petroleum gas. The chemical composition of the associated petroleum gas of Romashkino oil field, the Republic of Tatarstan, is presented and the practicality of its use is demonstrated. Nitrogen oxides contained in the boiler flue gases result from oxidation of molecular air nitrogen during combustion of the fuel. In order to reduce the adverse effect of hazardous substances on the environment, the flue gases are to be compulsorily cleansed of nitrogen oxides. The use of the sludge resulting from coagulation and liming of natural water during the chemical water treatment at Kazan CHPP-1 as a sorption material is proposed. The chemical composition and technical characteristics of the sludge are presented. The properties of the sludge were studied using a laboratory fixed-sorbent-bed setup. The sorption capacity and water-absorption of the sludge were determined and curves of the kinetic and isothermal dependences of the nitrogen oxide adsorption by the sludge were constructed. The change in the nitrogen- oxide sorption capacity of the sludge depending on the sludge particle size was established. The optimal characteristics of a batch-type fixed-bed absorber were calculated. The results of calculating the economic and ecological effects of introducing the adsorption treatment of flue gases to remove nitrogen oxides for the boiler-house of AO Karpov Chemical Plant are provided.     

含油废水处理方法的研究

剖析了华能汕头燃机电厂含油废水难以处理的原因，并以该电厂的含油废水处理工艺的研究为例，通过在试验室采用常规凝聚剂和机械过滤方法的比较，以及采用碱式氰化铝混凝剂在碱性条件下的试验的比较，加药量大小的比较，找出了处理含油废水的经济、简便方法，实施这一方法治理废水后，多年来经地方环保部门现场抽样监测，废水的含油量符合国家环保排放标准。     

火力发电厂汽水取样装置改造

神华神东萨拉齐电厂汽水取样装置所有取样水经汇流后直接进入工业废水处理系统,未按清污分流、分类回收原则对样水进行回收利用,使品质较好的样水与水质较差的工业水混合,最终全部按工业废水进行处理回用,造成其中大量可回收样水浪费。针对此问题,设计了汽水取样装置样水回收改造方案,增加了样水回收装置,将可回收样水回收至排汽装置热水井进行再利用。改造后,样水回收装置运行稳定,经济效益良好,同时取得了明显的节能减排效果。     

剩余污泥改良生物滞留设施雨水径流控制效果

为应对城市面源污染控制及污水厂剩余污泥处置问题,用剩余污泥改良生物滞留设施基质,通过理化特性分析筛选适宜的掺泥比例范围,并考察剩余污泥基质生物滞留设施的雨水径流调控效果。结果表明：在上层15cm基质掺入比例≤44.8%的剩余污泥可有效提升生物滞留设施雨水径流调控能力。基质中掺泥比例越大,生物滞留设施雨水径流总量调控效果越优,而出水污染物浓度则呈现略有上升的趋势。与砂土基质相比,40%剩余污泥基质生物滞留设施的次径流总量削减率可提高16.9%,出水COD、TN、NH₄⁺-N和TP平均浓度分别为29.10 mg/L、3.25 mg/L、1.66 mg/L和0.093 mg/L,可满足GB 3838—2002《地表水环境质量标准》ΙⅤ类、Ⅴ类、Ⅴ类和Ⅱ类水质标准。     

滑动弧等离子体技术用于环境治理领域的研究进展

叙述了滑动弧放电的产生方法、物理属性和基本原理,以及滑动弧反应器结构及反应器在废气和废水处理等环境污染治理工程中的应用情况。利用自制的气液两相流滑动弧放电等离子体降解机理实验装置,对制药废水和DSD酸的浓缩废液进行了初步处理试验,结果表明,高浓度有机废水通过主处理器后,CODCr、BOD5、NH3—N等去除率均可达99％以上,具有良好的应用前景。     

1000MW燃煤机组工业废水处理系统存在的主要问题及改进措施

国电泰州发电有限公司一期2×1000MW超超临界燃煤机组为新建工程,其工业废水处理系统自调试、运行以来,暴露出一些问题,主要表现在污水泵故障、脱水机无泥可脱、乙二胺四乙酸（EDTA）回收困难、处理后废水未能完全利用等。对此,文章提出了相应的处理措施和建议,以求工业废水处理系统合理的运行与维护。     

污泥燃烧的热重实验研究

为了解某污水处理厂的污泥的热解特性,利用热天平对污泥进行了热重实验研究。从实验曲线可以看出,在20℃/min和40℃/min的升温速率下,干燥污泥存在3个失重峰;对实验数据进行了分析处理,采用微分法确定了热解反应的机理方程,求出了反应的动力学参数活化能E和频率因子A。     

水煤浆再燃降低锅炉NOx排放的实验研究

为明确锅炉采用水煤浆再燃技术时的整体NOx控制效果和影响因素,利用神华煤,在0.25 MW沉降炉上,分别以煤粉和水煤浆为再燃燃料,进行了再燃NOx控制实验。结果显示,水煤浆再燃时的脱硝效果优于煤粉;一定范围内,较高的再燃比有利于锅炉整体再燃脱硝;锅炉主燃区宜采用氧化性氛围,此时该处的过量空气系数与脱硝效果呈现二次曲线关系;水煤浆再燃脱硝率与再燃区过量空气系数成反比。实验证实,水煤浆是一种较优的再燃燃料,可被广泛应用,以实现对工业炉NOx排放的有效控制。     

沙角C电厂废水回用工程实践

沙角C电厂废水回用工程将生活污水、含油废水、含煤废水、锅炉排污水收集起来，集中处理后回用于全厂杂用水系统，并将化学除盐废水用于冲灰。废水处理工艺包括降温、除油、曝气、沉淀、澄清和杀菌，所用设备自动化程度高，运行安全可靠。废水经处理后，各项指标均达到回用标准。废水回用工程投产后，每年可节约新鲜水170万t，减少排放工业废水188万t，减少排放除盐废水14万t，经济、环境、社会效益显著。     

火电厂脱硫废水处理试验研究

对电厂湿法脱硫系统的废水水样,在实验室进行了处理试验,分析了脱硫废水水质,研究了pH、石灰剂量、混凝剂量、助凝剂等因素对处理效果的影响。     

反渗透装置一段压差迅速上升的原因分析

针对大唐南京发电厂2×660MW超超临界机组化学水处理系统反渗透装置运行期间一段压差迅速上升问题进行了分析,故障原因为合有高分子助凝剂（聚丙烯酰胺）的污泥脱水分离液进入反渗透系统,造成反渗透膜严重污堵;采用了离线物理清理和在线化学清洗相结合的方法,使反渗透装置恢复了正常运行。分析结果走明：在化学水处理设置有反渗透系统的新建电厂中,合有高分子聚丙烯酰胺的污泥脱水分离液,应单独排放到工业废水池或煤冲洗水复用系统中,以免造成后续反渗透系统膜元件的严重污染。     

西柏坡电厂废水零排放工程的设计与施工

西柏坡电厂废水治理系统分为废水回收和废水处理2 个部分。废水回收包括生活污水、酸及碱废水、凝结水精处理排水、冷却水塔检修时排水、主厂房地面冲洗水和杂用水的回收系统,回收后的废水用于除灰、渣或经处理后回用。废水处理包括弱酸处理、反渗透和外排系统,通过上述3 种方式,使电厂废水再生,重复使用。通过废水的回收和处理,实现了废水的零排放。由于废水零排放工程国内尚属首次,设计中难免会出现某些不足,通过与施工单位合作,克服了困难,使该工程于1999 年10 月投入运行。     

火电厂脱硫废水及脱水系统节能优化改造

针对包头东华热电有限公司存在的脱硫废水处理难度大、污泥排放困难,及脱水系统溢流水导致运行时间增加等问题,采取保留所有废水设施,通过在废水澄清池底部新接1路管路至脱水皮带机进行脱水,同时对脱水系统管路进行优化改造,减少废水系统的处理量、加药量以及压滤机的操作和维护,达到减少脱水区相关设备使用频次和降低生产成本的目的。改造后脱硫废水投运率达到100%。     

DH高效污水净化器技术在火电厂高浓度灰渣水处理中的应用

由于火电厂燃煤煤质多变,导致锅炉排渣量和冲渣水量上升,排水浓度增高。采用传统的渣水处理装置,沉淀效果差,排放严重超标。采用DH高效污水净化器技术将直流混凝、临界絮凝、离心分离、动态过滤、污泥浓缩工艺技术有机地集成为一体,在同一罐体内快速完成对高浓度灰渣水的多级净化,使水质达到排放或回用要求。该设备的处理能力强,最高可达90 000 mg/L,废水的设备停留时间小于30 m in。     

污泥干化焚烧系统在燃煤电站锅炉应用

污泥的干化焚烧是对城市污水处理厂产生的污泥进行无害化、减量化处置的较好方式,然而由于污泥所含水分难以去除、建设专用的焚烧锅炉投资大、低温焚烧易产生二恶英、存在二次污染等问题,使得污泥焚烧处置方式的推广受到影响,污泥处置的速度滞后,影响了污水处理事业的健康持续发展。通过选取恰当的烟气热源、选择简单适用的干化装置、设计合理的干化掺烧流程,利用燃煤电站锅炉的烟气余热对污泥进行干化后掺入煤中在锅炉进行焚烧,能够实现污泥干化过程的节能、污泥焚烧产热的资源化利用、高温焚烧清洁环保三重效益,为污泥处置开辟了一条新的途径。     

新型水处理乳化油废水的研究

燃料油水洗处理过程中产生的乳化油废水,色度深、含油量及化学耗氧量大大超标,不经处理直接排放将严重污染环境。由于研究了乳化油废水的处理方法,探讨了废水处理机理,从而,通过大量试验,研究出新型水处理剂WWP,能有效地用于处理乳化油废水,废水中油去除率达到100%,CODcr去除率达到90%。     

垃圾衍生燃料热解热重实验研究

本实验用热重分析法对含75%布、含50%、67%、75%、100%生活垃圾的RDF样品的热解进行研究,通过分析不同热解终温、不同升温速率、不同物料比、添加污泥与添加废石灰对RDF热解过程的影响,分析TG和DTG曲线的变化和特征点温度及不同阶段样品质量变化,计算热解率,研究表明,①热解终温增加,TG曲线向低温区移动,热解率增大,其中最大可达98.6%;②升温速率增加,热解反应向高温区移动,说明升温速率越低,越有利于热解反应进行;③对于生活垃圾与生物质不同配比的RDF热解,生活垃圾比重的增加导致TG曲线向高温区移动,挥发分析出温度延后;④添加污泥的RDF与添加废石灰的RDF相比,热解更充分,热解率由77.14%上升到92.46%。     

火电企业水资源综合利用及污染防治技术路线探讨

调研了91家火电企业,分析水务管理工作存在的问题,结合政策形势,探讨了水资源利用及污染防治的技术路线。技术路线分两步实施,第一步为全厂用水优化,实现水资源的梯级利用和分质处理、回用,实现高盐废水最少化;第二步为废水综合治理改造,无法回用、消耗及外排的高盐废水统一进入废水综合治理系统,通过预处理软化、浓缩减量、蒸发除盐及固废处置,实现废水回收利用。为火电企业探索水污染防治及综合利用提供参考。