造纸废水设计设计

摘 要制浆造纸工业是用水量相当大的工业，水资源的消耗量占世界第三，仅次于重金属工业和化工工业，即使采用最为先进、高效的处理技术，制造1吨纸也需要消耗60m3，同时产生大量污水。制浆造纸工业是第六大污染工业，排放了大量的气体、液体和固体污染物。造纸中段废水水量大，浓度高，难生物降解，很难达到排放标准。制浆造纸工业产生的废水中含有可吸附性有机卤化物，这些有机卤化物是由用氯化物漂白木质纤维过程中，含氯化合物与残余木质素产生的。制浆造纸工业废水中的大多数有机卤化物难降解，在水中停留的时间长。其中一些有机卤化物对生物具有致癌和致突变作用。因此，我们应对制浆造纸工业废水进行处理。我国是造纸大国，主要采用草浆造纸，造纸污水一直是环保的主要污染源之一。处理制浆造纸废水的方法很多，大体上分为：物理法、化学法、电化学法和生物法等等。现在出现了用好氧、厌氧、或好氧-厌氧组合工艺处理制浆造纸工业废水。实验发现在厌氧条件下处理造纸废水，氯化物的去除量最大。设计这些过程主要是为了降低制浆造纸废水中的COD和BOD。本文对制浆造纸废水及造纸中段废水的特点进行了介绍。UASB和SBR是世界上比较成熟的水处理工艺。本设计根据造纸中段废水的特点，采用UASB-SBR处理工艺，介绍了UASB和SBR在国内外的研究现状和进展，工作原理和工艺流程。UASB是升流式厌氧污泥床反应器的简称，UASB反应器在运行过程中，包含了极为复杂的生物反应过程。厌氧反应过程中有多种微生物参加了有机污染物的转化代谢过程，并将污染物最终转化为最终产物。参加反应的厌氧微生物主要包括水解-发酵（酸化）细菌、乙酸化细菌和产甲烷菌。SBR是一种间歇式活性污泥工艺，该方法按运行次序将一个周期分为进水期、反应期、沉淀期、排水期和闲置期5个阶段，并进行不断的周期反复对污水进行处理。该工艺进水和排水都是间歇式，一个周期中各个阶段的运行时间、反应池中混合液的浓度以及运行情况等都可以根据出水水质与运行功能要求等灵活掌握，只要有效地控制与变换各阶段的操作时间，就可以获得不同的污水处理效果。本处理工艺达到了令人满意的效果，出水BOD、COD、SS和NH3-N均达到国家二级标准，明显改变了接纳水体的环境质量。关键词：造纸中段废水、UASB、SBR、工艺流程ABSTRACTThe pulp and paper industry is a water intensive industry and ranks only third in the world, after primary metals and the chemical industries, in terms of freshwater withdrawal. Even with the most modern and efficient operational techniques, about 60 m3 of water is required to produce a ton of paper resulting in the generation of large volumes of wastewater. It is the sixth larges polluter discharging a variety of gaseous liquid and solid wastes. The medium waste water are larger amount high concentration of pollutant and difficulty to biodegrade. It is very difficult to be discharged with standards. Absorbable organic halides are generated in the pulp and paper industry during the bleaching process. These compounds are formed as a result of reaction between residual lignin from wood fibers and chlorine compounds used for bleaching. Many of these compounds are recalcitrant and have long-life periods. Some of them show a tendency to bio-accumulate while some are proven carcinogens and mutagens. Hence, it is necessary to remove or degrade these compounds from wastewater. Various methods have been developed for degradation of the medium waster water. They can be classified broadly as physical chemical electrochemical and biological methods. Different types of aerobic, anaerobic and combined biological treatment processes have been developed for treatment of pulp and paper industry wastewater. Maximum de-chlorination is found to occur under anaerobic conditions. These processes are designed specifically for reducing COD and BOD of waste water. This text introduces characteristic of waste water of pulp and paper wastewater. Nowadays UASB and SBR is the worlds more mature water treatment processes. According to the design of the Waste Water features, using UASB - SBR technology, UASB of SBR at home and abroad and the status and progress of research, working principle and process. SBR is a batch activated sludge process, according to the method of operation for a period of influent into cycle, the reaction period, Precipitation period, drainage period and idle period five stages, and the cycle repeated constantly to treat sewage. Participate in the reaction of anaerobic microorganisms including hydrolysis-fermentation (acidification) bacteria, acid bacteria and the production of methane bacteria. The process flow and drainage are intermittent, a cycle of all phases of the running time, The reaction mixture pool and the operation of concentration can all be according to water quality and operational functions such as flexibility, As long as the effective control and transform the stage of the operation time, can get different sewage treatment effect. The treatment process to achieve a satisfactory result, the effluent BOD, COD, SS and NH3-N reached the standard two countries, significantly changed the accepted body of water environmental quality.Key words: medium wastewater; UASB; SBR; technical process第一章 前言1.1 概述 1.1.1制浆造纸工业简介 制浆造纸工业中的制浆是指利用化学方法、机械方法或是化学与机械相结合的方法使植物纤维原料离解变成本色纸浆或漂白纸浆的生产过程；而造纸则是指纸浆抄造成纸产品的过程。制浆造纸工业的整个生产过程，包括从备料到成纸、化学品回收、纸张的加工等都需要大量的水，用于输送、洗涤分散物料及冷却设备等。尽管在生产过程中也有水的回收、处理及再用，但仍有大量的废水排入水体，造成了水环境严重污染。据1995年统计，中国造纸工业总排水量23.9亿 m3/a，仅次于化学工业及钢铁工业的年排水量，居第三位；化学耗氧物质排放量为321.4万t/a，占全国、工业排放量的1/3。据1994年统计，中国造纸工业排水中，悬浮物质总排放良为128。4万t/a，排水量之大的污染物浓度之高，使的造纸工业水污染治理已成为造纸行业乃至全社会关注的热点，也是造纸企业生存与发展的关键。造纸工业污染在美被列为六大公害之一，其排水量占全国排水量的1/15。在日本被列为五大公害之一。在瑞典及芬兰，造纸工业排水中的有机污染物排放量占全部工业排水中有机污染物的80%。由此可见，在世界范围内，解决造纸污水的污染问题迫在眉睫1。1.1.2制浆造纸废水的污染指标制浆造纸工业废水的主要污染物指标包括COD、BOD、pH值及SS。对磨木浆、化学机械浆等制浆废水，重金属离子也是重要污染物。对于硫酸盐法、烧碱法及中性亚硫酸盐半化学法制浆废水，其颜色也是值得重视的。制浆造纸废水中污染物的毒性问题已受到人们的普遍关注，漂白硫酸盐浆厂废水中的二垩英及可吸附的有机卤代物（AOX）的形成及其对环境的影响是目前造纸环保的重要研究课题，已受到了人们的普遍重视。 1.1.3造纸中段废水水质来源及特征：造纸废水的主要来源为蒸煮黑液、中段废水(筛洗漂废水)和白水。纸浆的洗涤、筛选、漂白废水通称为造纸中段废水，中段废水主要来源于打浆洗涤废水和抄纸废水，废水主要包括洗筛废水、漂白废水和造纸车间的多余白水，其颜色为黄褐色，带有较浓臭味，废水可生化性较差，因而废水低成本生化治理难度较大。它含有纤维素、半纤维素、木质素等多种成分。中段废水的色度高，SS和COD均较高，在COD的组成中，非溶解性COD较高，约占60以上，溶解性COD较低，而溶解性COD又是较难生物降解物质，可生化性差，属较难处理的废水之一。对于较高的黑夜提取率，碱回收系统正常运行的造纸厂来说，废水的吨浆COD排放负荷为208kg