制革工业废水是一种对水源生态环境严重污染的废水。它的生化需氧量高，悬浮物多，带有色泽及臭味，并含有硫化物、铬、植物鞣剂及酚类合成鞣剂等有害物质，是一种较难治理的工业废水。我国制革工厂目前有500多家(不包括乡镇企业)，以生产猪、羊、牛皮产品为主。猪皮生产占80％，每年生产猪皮6000-8000(万张)，牛皮800-900(万张)，羊皮2000-3000(万张)。制革行业每年排放废水7000万吨，约占全国工业废水总排放量的0.3％。据调查统计，目前只有30％的制革企业不同程度的简单处理了废水，其余的70％产生的废水未经任何处理，自然排放。对环境造成严重污染，对生态带来破坏[9]。 制革工艺主要包括腌制、浸灰（回软、脱脂、脱毛）、鞣制、以及后整理工序。大多数的废物和污染物是在湿加工过程（浸灰、鞣制）产生。我国大多数制革厂采用石灰脱毛和铬鞣技术，少数制革厂采用酶脱毛和铬鞣技术。 制革废水的处理方法，可归纳为物理方法、化学方法和生物处理方法。文献中介绍的生化处理方法适用于大中型制革厂的废水治理。本文比较了几种常用的生化法在处理制革废水中的应用，建议采用SBR法作为处理制革废水的工艺，具有其实用性和先进性。 一、制革工业废水的产生及特点 制革工业排放的废水特点是有机污染浓度高，悬浮物质多，水量大，废水成份复杂，其中含有有毒物质硫与铬。按照生产工艺过程制革工业废水由七部分组成：高浓度氯化物的原皮洗涤水和酸浸水、含石灰，硫化钠的强碱性脱毛浸灰废水、含三价铬的兰色铬鞣废水、含丹宁和没食子酸的茶褐色植鞣废水、含油脂及其皂化物的脱脂废水、加脂染色废水、各工段冲洗废水。其中，以脱脂废水，脱毛浸灰废水、铬鞣废水污染为严重。 1．脱脂废水：我国猪皮生产占制革生产的80％，在猪皮生产的脱脂废水中，油脂含量高达10000(mg／L)，CODcr20000(mg／L)。油脂废水占总废水4％，但油脂废水的耗氧负荷却占到总负荷的30-40％。 2．脱水浸灰废水：脱毛浸灰废水是硫化物的污染源。废水CODcr20000-40000(mg/L)，BOD54000(mg/L)，硫化钠1200-1500(mg/L)，pH为12，脱毛浸灰废水占总废水的10％，而耗氧负荷占总负荷40％。 3．铬鞣废水：铬鞣废水是三价铬的污染源。铬鞣过程，铬盐的附着率60％-70％，即有30％-40％的铬盐进入废水。铬鞣度水Cr3＋3000-4000(mg/L)，CODcr10000(mg/L)，BOD52000mg/l。 制革厂的各路废水集中后，称为制革综合废水。综合废水也是高浓度的有机废水，水质一般为pH＝8-10，SS2000-3000(mg/L)，BOD5500-2000(mg/L)，Cr3+60-100(mg/L)。S2-100-200(mg/L)，C1-200(mg/L)。 二、几种常用制革工业废水生化处理方式及特点 制革废水经过适当预处理废水中的硫化物、铬等对生化有抑制物质均可以降至要求以内，BOD／COD值约在0.35~0.40左右，生物降解性较好。因此生物处理技术广泛用于制革废水处理。 1．传统活性污泥法：活性污泥法创建于1917年，是利用河川自净原理的人工强化高效处理工艺，已成为有机性污水生物处理的主体。在制革废水的处理中，活性污泥法的应用是相当普遍的，如西德的Wam制革污水处理厂、Lonis Sonwe-izer皮革厂，日本“室”皮革株式会社，国内北京东风制革厂、常州皮革厂、哈尔滨制革厂等采用活性污泥法，该法对生化需氧量去除率在90％以上，化学需氧量在60％-80％之间。色度在50％-90％之间，硫化物在85％-98％之间。传统活性物泥法处理效率高，适用于处理要求高二水质相对稳定的污水，但它要求进水浓度尤其是有抑制物浓度不能高，而制革废水中的硫化物及铬在超过一定浓度时对生化有抑制，同时它不适应冲击负荷，需要高的动力和基建费用。
Tannery wastewater is a kind of wastewater that seriously pollutes the water source and ecological environment. It has high biochemical oxygen demand, many suspended solids, color and odor, and contains harmful substances such as sulfide, chromium, vegetable tanning agent and phenolic synthetic tanning agent. It is a kind of industrial wastewater that is difficult to treat. At present, there are more than 500 leather factories in China (excluding township enterprises), mainly producing pig, sheep and cow leather products. Pig skin production accounts for 80%, and the annual production of pig skin is 6000-8000 (10000), cow leather is 800-9 (10000), and sheep skin is 2000-30 (10000). The tannery industry discharges 70 million tons of wastewater every year, accounting for about 0.3% of the total industrial wastewater discharge in China. According to the survey and statistics, at present, only 30% of tannery enterprises have simply treated the wastewater in varying degrees, and the remaining 70% of the wastewater is discharged naturally without any treatment. Cause serious pollution to the environment and damage to the ecology [9]. The tanning process mainly includes pickling, Liming (softening, degreasing and depilation), tanning and finishing. Most of the wastes and pollutants are generated during wet processing (liming, tanning). Most tanneries in China use lime depilation and chrome tanning technology, and a few tanneries use enzyme depilation and chrome tanning technology. The treatment methods of tannery wastewater can be summarized into physical methods, chemical methods and biological treatment methods. The biochemical treatment method introduced in the literature is suitable for the wastewater treatment of large and medium-sized tanneries. This paper compares the application of several commonly used biochemical methods in the treatment of tannery wastewater. It is suggested that SBR method be used as the process for the treatment of tannery wastewater, which is practical and progressiveness. 1、 Production and characteristics of wastewater from tanning industry the wastewater discharged from tanning industry is characterized by high concentration of organic pollution, large amount of suspended substances, large amount of water and complex composition of wastewater, including toxic substances sulfur and chromium. According to the production process, the tannery industrial wastewater consists of seven parts: raw leather washing water and acid soaking water with high concentration of chloride, strong alkaline depilation and liming wastewater containing lime and sodium sulfide, blue chrome tanning wastewater containing trivalent chromium, tea brown vegetable tanning wastewater containing tannin and gallic acid, degreasing wastewater containing oil and its saponification, fatliquoring and dyeing wastewater, and washing wastewater of each section. Among them, degreasing wastewater, depilation liming wastewater and chrome tanning wastewater are the most serious pollution. 1. Degreasing wastewater: China's pig skin production accounts for 80% of leather production. In the degreasing wastewater of pig skin production, the oil content is as high as 10000 (mg / L) and codcr20000 (mg / L). Oil wastewater accounts for 4% of the total wastewater, but the oxygen consumption load of oil wastewater accounts for 30-40% of the total load. 2. Dehydration Liming wastewater: depilation liming wastewater is the pollution source of sulfide. Wastewater codcr20000-40000 (mg / L), bod54000 (mg / L), sodium sulfide 1200-1500 (mg / L), pH 12, depilation and liming wastewater accounts for 10% of the total wastewater, while oxygen consumption load accounts for 40% of the total load. 3. Chrome tanning wastewater: chrome tanning wastewater is the pollution source of trivalent chromium. In the chrome tanning process, the adhesion rate of chromium salt is 60% - 70%, that is, 30% - 40% of chromium salt enters the wastewater. Chrome tanning water Cr3 + 3000-4000 (mg / L), codcr10000 (mg / L), bod52000mg / L. The waste water from all roads of the tannery is called comprehensive tannery waste water after being concentrated. Comprehensive wastewater is also high concentration organic wastewater. The water quality is generally pH = 8-10, ss2000-3000 (mg / L), bod5500-2000 (mg / L), Cr3 + 60-100 (mg / L). S2-100-200(mg/L)，C1-200(mg/L)。 2、 Several commonly used biochemical treatment methods and characteristics of tannery industrial wastewater after appropriate pretreatment, the sulfide, chromium and other substances that inhibit biochemistry in the wastewater can be reduced to within the requirements, and the BOD / COD value is about 0.35 ~ 0.40, with good biodegradability. Therefore, biological treatment technology is widely used in tannery wastewater treatment. 1. Traditional activated sludge process: the activated sludge process was founded in 1917. It is an artificially enhanced and efficient treatment process based on the principle of river self purification. It has become the main body of biological treatment of organic sewage. In the treatment of tannery wastewater, the application of activated sludge method is quite common. For example, WAM tannery wastewater treatment plant in West Germany, lonis sonwe zer leather plant, Japan "Shi" leather Co., Ltd., domestic Beijing Dongfeng tannery, Changzhou leather factory and Harbin tannery adopt activated sludge method. The removal rate of biochemical oxygen demand is more than 90% and the chemical oxygen demand is between 60% - 80%. The chromaticity is between 50% - 90%, and the sulfide is between 85% - 98%. The traditional active sludge method has high treatment efficiency and is suitable for the treatment of sewage requiring relatively stable water quality of grade two, but it requires that the influent concentration, especially the concentration of inhibitors, should not be high, while the sulfide and chromium in tannery wastewater can inhibit biochemistry when they exceed a certain concentration. At the same time, it is not suitable for impact load and requires high power and capital construction cost.
客服1