|
|
Industrial wastewater treatment
Water and people's lives, especially in the modern social life, grow with each passing day and the production of people's demand for water. However, the water resource is limited. According to reports, China's per capita fresh weight of 2400 tons, for the world average of 1/4, in 149 countries worldwide, ranking 110th freshwater resources per capita in China, belongs to the freshwater resource poor countries. And the spatial and temporal distribution of water resources in China is extremely uneven, water more than 500 city nationwide, wherein a plurality of serious water shortage, water shortages in northern area is particularly serious, per capita fresh water is only 240 tons. Worrying is the total freshwater is decreasing, the cost of water increases, water waste is very serious. Water resources in northern China excessive overdraft, has formed the funnel topography, water level dropped, rivers, lakes have dried up, the deterioration of ecological environment. The shortage of freshwater resources has become an urgent problem in china.
China's freshwater resources decrease, and the pollution is serious. With the development of society, the impact of water resources has become an important factor of industrial development, only about 10% at present the city sewage treatment rate is up to the emission standard, the rest of the sewage waste water directly discharged into the rivers, lakes, sea. High water consumption, recycling rate is low, serious pollution of our industrial system of water resources utilization problems. Serious pollution of the environment and the limited water resources reducing increasingly, water quality worsening, is one disaster after another. But China's industrial water consumption is high, repeated use less water, reclaimed water utilization rate is not high, according to statistics, the average rate of only 40%~50% repeated use of our industrial water. According to statistics, because of water pollution, unsafe phenomenon occurred about 300000000 people in China have been drinking, among them 190000000 people drinking water is exceed the standard. Meteorologists forecast in 2100, global warming, the earth's surface will have 1/3 area into desert, at that time, the drought will threaten the half of the world, the survival of mankind. These phenomena are serious water pollution, so the industrial sewage treatment project implementation will brook no delay.
With the increasing demands for environmental protection, sewage treatment industry has demonstrated its necessity and urgency, for various sewage treatment emissions become the basic requirements of each enterprise. In the industrial wastewater treatment plant, sewage source of instability and various sewage factory's complex ingredients, put forward very high requirements on process and control mode of industrial wastewater treatment. Now many of the signs on the surface, the shortage of water resources will undoubtedly become the bottleneck of sustainable economic development, so in the world more and more attention to water treatment and water reuse, further improve the quality of water through a variety of techniques, improve economic benefits. And industrial wastewater treatment process, through the anaerobic and aerobic treatment, sewage gas, heat and other renewable energy can provide two times the energy for industrial production, realize the waste to treasure, the purpose of recycling economy.http://fanyi.baidu.com/translate?query=工业污水处理&lang=zh2en###
Along with our country economy rapid development, people's living standards gradually improved, and brought a series of environmental problems, especially the water environment pollution. The Chinese government attaches great importance to the degree of water pollution is also gradually increase, China's large and medium-sized city life sewage and industrial wastewater have been taken to control certain methods, but small towns sewage treatment situation is not optimistic. Most of China's medium and small cities and towns have no sewage treatment the local water environment, but also affects the health of the residents, but also seriously hindered the development of China's economy. So the improvement of water environment, protection of water resources in China, has become the brook no delay.
At present in the water pollution control technology, China has been able to provide the following technology in traditional activated sludge technology, various new activated sludge process such as: SBR and oxidation ditch technology, hydrolysis acidification aerobic technology and various types of stabilization pond sewage treatment technology, the technology has played a prominent role in water pollution, improve water environment, marking China's development of the cause of the sewage treatment industry to a new stage. Sewage treatment technology of industry of our country began to study from the "seven five" National Science and technology research. "Seven five" and "eight five" project in the oxidation pond, land treatment and compound ecosystem of natural processing technology more, with these results for the design basis, established a number of oxidation pond, land treatment of sewage demonstration project. In the artificial processing technology, "eight five" on high load activated sludge, biofilm, high load integrated oxidation ditch technology are discussed. Sewage sludge disposal problems paid attention to in the "Nine Five" key science and technology, sewage treatment and supporting the development of complete sets of. Research results have been used in a large number of industrial wastewater treatment plant. Through the efforts of seven five, eight five and nine five period, our country has made great achievements in the industrial wastewater treatment technology. At this stage, focus on industrial wastewater treatment in China has shifted from technology research to the implementation of specific projects.
Internationally, water pollution control mass is started after the Second World War, with the rapid development and expansion of 50 time economy of 60 time more and more serious environmental pollution. Industrial wastewater treatment facilities, the city drainage pipelines and industrial sewage treatment plants up and running plays a key role in water pollution control. To 70 time end, USA has invested nearly hundreds of billions of dollars to build more than 18000 city industrial wastewater treatment plant, the UK, France, Germany is a huge amount of money spent to build a 7000 to 8000 seat city industrial wastewater treatment plant. On the state of water pollution in these industrial sewage treatment plant put into improving plays a decisive role in important, and has accumulated rich experience in the management of water pollution.
Now, the level of industrial wastewater treatment in these countries have been further improved, built a number of removal efficiency of nitrogen and phosphorus in facilities, play an important role to improve the water quality and water environment protection.
The issue of environmental protection, the State Council stipulates all industrial pollution sources must meet the emission standard. The treated wastewater can be recycled, China is a water scarce country, but also on the temporal spatial distribution is extremely uneven, many areas and the city of serious water shortage. So the water resource is a kind of protection. Therefore, considering the environmental factors, such as water flooding in many aspects, for industrial wastewater treatment is very necessary. Therefore, measurement of effective combination of process conditions, the latest automation instrumentation, control system using PLC technology, will provide an effective method for the control of industrial sewage treatment control system.
In the next 10 years, the project construction investment industrial sewage treatment in China will be more than two hundred and fifty of which equipment investment of about thirty of industrial wastewater treatment. By the technical reformation of advanced, practical craft tradition, extensive application of advanced automatic control technology in environmental protection engineering, is to promote environmental protection and industrial upgrading, to achieve an important environmental development strategy. In this situation the industrial sewage treatment automatic control system is a great social benefit, environmental benefit and economic benefit of the project.
Any country of the world economic development, will promote the progress of the society, the promotion of industrial and agricultural production capacity, make the people's life has been further improved, but also bring different levels of pollution, sewage is also one of the sources of environmental pollution caused by. The source of pollution caused great attention of governments around the world, water pollution control and environmental issues will be included in the world environment organization schedule. China is a serious water shortage in the country, although China's average annual water resources amount to 2800000000000 m2, rank the whole world the sixth, the per capita water resources total quantity has reached 2220m2, ranking 110th in the world, China has been listed as one of the world's 13 water shortage countries. At present our country more than 300 city water, the city of serious water shortage has 5O. According to China economic information network statistics, the national press at present normal water shortage, a total of about 30000000000 ~ 40000000000 cubic meters, because of lack of water caused economic losses of up to 230000000000 per year. Lack of water resources and the resources of ditch water pollution, has the serious influence to people's daily life, a serious impact on China's economic construction and development. Therefore the construction conforms to our country national condition the sewage plant automatic control system to reduce industrial sewage treatment costs, improve the environment, the establishment of sustainable development and harmonious society, to maintain China's rapid economic development has the vital significance.
The main design content is the industrial wastewater treatment technology and the industry control system design of the composition and PLC of sewage disposal system, mainly consists of the following content:
(1) introduced the basic content of chemical plant industrial wastewater treatment, including the development status of chemical industrial wastewater treatment and industrial wastewater treatment process;
(2) introduced the basic structure and working principle of PLC, and the industrial wastewater treatment control system design and analysis;
(3) the commissioning and operation of industrial wastewater treatment system.
(4) the design and analysis of industrial wastewater treatment system;
(5) the design and analysis of industrial wastewater treatment system;
The city's sewage, sewage, domestic sewage and production or through local treatment of industrial enterprises after the production of sewage, are discharged into the drainage system. These removal in wastewater contains large amounts of carbohydrates, amino acids, protein, plant and animal fat, ammonia, urea, soap and synthetic detergent, also contain bacteria, viruses and other large amounts of human pathogenic microorganisms. Treated sewage, the final way out only three: the discharged water to irrigate the fields; and repeated use.
Wastewater pollutants can be classified differently according to the chemical properties and physical form. Firstly, according to the chemical properties of substances in the sewage, pollution can be divided into the organic substance and inorganic substances, the chemical elements of nitrogen, carbon, phosphorus mainly. According to the physical form, the pollutants in sewage can be divided into suspended solid or granular pollutants, colloid pollution matter and dissolved pollutants.
Although BOD20. Biochemical oxygen demand of sewage can describe accurately, but the determination of the time is too long, need 20 days. Taking into account the aerobic decomposition rate in the first few days the fastest, at the temperature of 20 DEG C, sewage five day biochemical oxygen demand (BOD5), accounting for about 70% of BOD20 to 80%, so the BOD5 as organic concentration index to measure the polluted water. Chemical oxygen demand (COD) is characterized by the ability to accurately express the content of organic matter in the sewage, and in a short time, but it is not like the BOD that microbial oxidation of organic content.
Stability of aerobic organic pollutants, under the action of microorganisms, with the help of microbial The new supersedes the old. and degradation to inorganic compounds, inorganic compounds such as water, carbon dioxide, nitrate ion stability. Many kinds of organic compounds, its generality is degraded under the action of microorganisms, dissolved oxygen should waste water, so in the practical engineering, the comprehensive pollution index below several expressed: chemical oxygen demand (Chemical Oxygen Demand, mg/L COD), biochemical oxygen demand, or biochemical oxygen demand (Bio-chemical Oxygen Demand, BOD) mg/L, total oxygen demand (Total Oxygen Demand) mg/L, total organic carbon (Total Organic Carbon) mg/L.
Different environmental industrial wastewater treatment, industrial wastewater treatment of different objects, will need to have different industrial wastewater treatment process. Therefore, in the choice of treatment process of industrial wastewater will need local sewage situation seriously considered, as well as the actual industrial sewage processing environment.
Method of industrial wastewater treatment mainly include physical, chemical, physical and chemical, and biological etc.. These methods according to the actual situation can now, single use, can also according to different sewage mixed use. At present, the general method of industrial sewage treatment by biological treatment, supplemented by physical method and chemical method. Industrial wastewater treatment processes commonly used are the following.
(1) the traditional activated sludge process. The traditional activated sludge method is a kind of industrial wastewater treatment method is the most ancient, the industrial wastewater treatment key component is the methane tank and sedimentation tank,
The process of organic matter in the sewage pool of stay in gas, biogas digesters in microbial adsorption sewage of most organic matter, and in the biogas pool was oxidized into inorganic substances, and then in the sedimentation tank after part of activated sludge after the need to return to the methane tank. The advantage of this process is: pool of small volume, high organic removal rate, high sludge loading, low power consumption, low operation cost. This technology has some shortcomings: large investment, meet the national standard related index range small, ordinary methane tank cover more, easy to produce sludge bulking, phosphorus and nitrogen removal rate is low.
(2) A/O. A/O method is a kind of industrial development is based on conventional activated sludge of the wastewater treatment process, in which A represents Anoxic (hypoxia), O represents (aerobic). A/O method is a kind of anoxic - aerobic biological wastewater treatment process. This process is formed by adding nitrification aerobic tank and anoxic tank - reaction system, very good to deal with the nitrogen content of sewage, has a significant effect on . But the nitrification reaction system needs to be well controlled, so that the process put forward higher requirements management, which is a big disadvantage of this process.
The A2/O method. An industrial A2/O method is developed based on traditional activated sludge process on the sewage treatment process, including A2, A-A, before a A represents Anaerobic (anaerobic), a represents Anoxic (hypoxia); O (aerobic). A2O method for nitrogen and phosphorus removal effect is very good, especially suitable for nitrogen and phosphorus removal in industrial wastewater treatment requirements of high. A2/O is an anaerobic anoxic aerobic wastewater treatment process. Therefore, the removal of phosphorus and nitrogen have special requirements of the city industrial wastewater treatment plant, the general preferred A2/O process.
The A/B method. A/B is the abbreviation of adsorption biodegradation process, this process has no initial precipitation, the aeration tank is divided into high and low load of two segments, and were precipitated and sludge return system independent. A high efficiency AB method, and the strong buffer capacity. The high load period of residence time is about 20~40min, the biological flocculation and adsorption effects, at the same time of incomplete oxidation of, removal of BOD is above 50%. Meet the B segment and the conventional activated sludge process, low load. For industrial wastewater treatment with high concentration, the AB method has good applicability, energy efficiency and higher. Especially in the sludge digestion and utilization of biogas technology, the most obvious advantage. However, AB sludge yield larger, A sludge organic matter content is very high, so we must add sludge stabilization treatment, it will increase the investment and cost. In addition, because A removed more BOD, caused by the lack of carbon source, nitrogen removal technology is difficult to achieve the requirements of. For the wastewater concentration and low places, B segment is also difficult, so it is difficult to play advantage.
So overall, the AB process is suitable for wastewater with high concentration, sludge digestion and subsequent processing facilities in large and medium scale city industrial wastewater treatment plant, and has obvious energy saving effect, but the city industrial wastewater treatment plant nitrogen requirements, generally should not be used.
The SBR method. SBR method for activated sludge for short, is a kind of biological wastewater treatment technology in accordance with certain operating time order batch, is also a kind of intermittent aeration mode according to operation of the activated sludge wastewater treatment technology, also known as sequencing batch reactor activated sludge process. The biggest difference between water treatment technology with the traditional SBR method is that it is in time sequence segmentation each unit process, the time division operation instead of spatial segmentation operation, non steady state of biochemical reaction instead of biochemical reaction, static instead of Dynamic Precipitation ideal sedimentation. Activated sludge method, the mechanism of the reaction and the removal of pollutants and the traditional basic same, just run the operation in different ways. The whole process is intermittently for a single operating unit, but through the multiple unit scheduling after continuous operation, in the principle.
工业废水处理
水和人的生活息息相关，特别是在现代社会生活以及生产中人们对水的需求量与日俱增。然而，水资源是有限的。根据报道我国人均拥有淡水量为2400吨，为世界平均值的1/4，在全球149个国家，我国人均淡水资源位居第110位，属于淡水资源贫乏的国家。而且我国水资源时空分布极不均衡，全国500多个城市缺水，其中多个缺水严重，北方地区缺水现象尤其严重，人均拥有淡水量仅有240吨。令人担忧的是淡水总量日益减少，用水成本不断升高，淡水浪费非常严重。我国北方地区水资源过度的超采，己形成漏斗地势、水位下降、河水断流、湖泊干涸、生态恶化。淡水资源的短缺己经成为我国急需解决的问题。
我国淡水资源不断减少，而且污染现象较为严重。随着社会的发展，水资源已经成为影响工业发展的重要因素，目前全国城市污废水的处理率也就是达排放标准的只有10%左右，其余的污废水都直接排入河川、湖泊、海洋。耗水量高、重复利用率低、污染严重是我国工业系统水资源利用的突出问题。严重的环境污染使有限的水资源日益减少、水质日益恶化，无疑是雪上加霜。 现代工业中的生产工艺和设备对水质的要求越来越高。但是我国工业用水耗费高，重复利用水少，中水使用率不高，据有关资料显示，我国的工业用水重复利用率平均只有40%~50%。根据统计，由于水质的污染，我国已有大约3亿人的饮水发生了不安全现象，其中1.9亿人的饮水是超标水。气象学家预测，2100年全球变暖加剧，地球表面将有1/3的面积变为沙漠，那时，干旱将威胁到全球一半的大陆人类的生存。这些现象都是水污染产生的严重后果，因此工业污水处理项目的实施将刻不容缓。
随着环境保护呼声越来越高，工业的污水处理已经体现出其必要性和紧迫性，对于各种污水进行处理后排放成为各企业基本的要求。在工厂的工业污水处理过程中，污水来源的不稳定以及工厂中各种污水的成分的复杂性，对工业污水处理的工艺和控制方式提出了非常高的要求。现在众多的迹象表面，水资源的短缺将无疑成为制约经济持续协调发展的瓶颈，因此在世界各国越来越重视水处理和水的再利用，通过各种技术进一步提高供水质量，提高经济效益。并且工业污水处理过程中，经过厌氧和好氧处理，污水中的沼气、热量等再生能源可以为工业生产提供二次能源，真正实现变废为宝、循环经济的目的。
随着我国经济的讯速发展，人民的生活水平逐步的提高，随之带来一系列的环境问题，特别是水环境的污染。我国政府对水污染的重视程度也正在逐步提高，目前我国对大中城市的生活污水和工业污水己经采取了一定的治理方法，但中小城镇污水的处理情况不容乐观。我国大部分中小城镇没有污水处理设施 ，这不仅污染了当地的水环境，同时也影响了居民的身体健康，而且严重阻碍了我国经济的发展。所以改善水环境，保护我国紧缺的水资源，已经成为刻不容缓的事情。
目前在水污染治理技术上，我国已能提供下列工艺技术传统活性污泥法技术、各种新型活性污泥工艺如：SBR法和氧化沟技术等、酸化水解好氧技术和多种类型的稳定塘技术等，这些污水治理技术已经在水体污染、改善水体环境方面发挥了突出的作用，标志着我国工业污水处理事业发展到了一个崭新的阶段。我国工业污水处理技术从“七五”国家科技攻关开始逐步进行研究。“七五”和“八五”攻关项目在氧化塘、土地处理和复合生态系统等自然处理技术方面的研究比较多，以这些成果为设计依据，建立了一些氧化塘、土地处理等污水示范工程。在人工处理技术方面，“八五”对高负荷活性污泥、高负荷生物膜、一体化氧化沟技术进行了深入研究。污水厂污泥处置问题在“九五”科技攻关中受到重视，并配套开发成套的污泥处理。研究成果己被应用在大批工业污水处理厂中。经过七五、八五和九五期间的努力，我国在工业污水处理技术方面取得了非常大的成就。现阶段，我国工业污水处理的工作重点已经从工艺技术的研究转移到具体项目的实施。
国际上，大规模的水污染治理是在第二次世界大战后才开始的，随着50年代经济的迅速发展同时带来的60年代日益严重性的环境污染而展开的。工业污水处理设施中，城市排水管线和工业污水处理厂的建立和运行在水污染控制中发挥着重要的骨干作用。到70年代末，美国已经投入了有近数千亿美元兴建了18000余座城市工业污水处理厂，英国、法国、德国更是耗费了巨额的资金兴建了7000至8000座城市工业污水处理厂。这些工业污水处理厂的投入对国家的水体污染改善起了重要的决定性作用，也为人类治理水污染积累了丰富的经验。
现在，这些国家的工业污水处理水平又有了进一步的提高，兴建了一批具有脱氮除磷功效的设施，对水体质量改善和水环境保护起了重大的作用。
环境保护问题，国务院明确规定所有工业污染源都必须达到排放标。其中处理过的污水还可以循环再利用，我国是一个水资源匮乏的国家，而且时空分布上极不均匀，许多地区和城市严重缺水。所以水资源也是一种保护。因此，从环保、注水等多方面的因素考虑，对于工业污水处理非常的有必要。因此，有效的结合目前最新的工艺状况、计量自控检测仪表使用、PLC 控制系统技术，将为当前工业污水处理控制系统提供有效的自控方法。
在未来的10年里，我国工业污水处理项目工程建设投资将超过两千五百亿元，其中工业污水处理设备投入约三百亿元。采用先进、实用的技术改造传统工艺，在环境保护工程中广泛应用先进的自动控制技术，是推动环保产业升级，实现环保发展战略的重要环节。在这种形势下工业污水处理自动化控制系统无疑是一个具有巨大的社会效益、环境效益及经济效益的研究课题。
世界任何国家的经济发展，都会推动社会的进步、促进工业和农业生产能力，使人民生活得到进一步有效的改善，但是也随之带来不同程度的环境污染，污水也是造成环境污染的来源之一。这个污染源的出现引起了世界各国政府的重要关注，治理水污染及环境的课题将被列入世界环保组织的工作日程中。我国是一个严重缺水的国家，虽然我国年平均水资源总量达到了28000 亿m2，位居全世界第6 位，人均水资源总量也达到了2220m2，位居世界第110 位，已经被联合国列为世界上13个缺水国家之一。目前我国约300多个城市缺水，其中严重缺水城市有5O个。据中国经济信息网分析统计，全国按目前正常需要，年缺水总量约为300 亿～400 亿立方米，因为缺水造成的经济损失每年达2300 亿。超过洪涝灾害。水资沟的匮乏和水资源的污染，己经严重的影响到了人民的日常生活，严重的影响了我国的经济建设和发展。因此建设符合我国国情的污水厂自动控制系统对降低工业污水处理成本、改善环境、建立可持续发展社会和和谐社会、保持我国经济高速发展具有重要的意义。
