The treatment and utilization of human excreta has a long history. As early as the Spring and Autumn Period and the Warring States Period, our people built toilets to store fertilizer. India and other Asian countries have had the custom of composting feces and garbage since ancient times. As early as 3000 BC ~ 65438 BC+0000 BC, during the Minoan civilization in ancient Greece, some people used the method of burying pits and covering soil to treat garbage. /kloc-In the 8th century, Edinburgh, a big city in Scotland, recorded the collection, classification, sale and reuse of garbage.
After entering the 20th century, with the development of productive forces, the population further concentrated in cities. Now 80% of the population in the United States are in cities. In China, the speed of population urbanization is also accelerating rapidly, and the rise of township enterprises makes the non-agricultural population increase rapidly. Due to the rapid improvement of people's consumption level, the discharge of "three wastes" is increasing day by day, and pollution incidents are increasing day by day. The garbage problem has become a serious environmental problem. Since the mid-1960s, environmental protection has been paid more and more attention by the public and governments all over the world, especially in developed countries. Pollution prevention and waste utilization technology has developed rapidly, forming a series of treatment methods, which have become an important content and foundation of environmental science and environmental engineering.
(2) Modern waste utilization
Since the 1970s, in developed countries such as the United States, Britain, Germany, Japan, France and Italy, due to the shortage of waste disposal sites and high disposal costs, the impact of the oil crisis has made the resource problem more prominent. The concept of "resource recycling" was put forward by Japanese scientific and technological circles for the first time, which attracted the attention of the international community, and the recycling of waste was also increasingly concerned. Many countries have formulated relevant laws and regulations, and we can also see the development trend from passive disposal to active utilization in legislation. For example, the United States enacted the Waste Disposal Law in 1965, which was revised as the Resource Recovery Law in 1970 and the Resource Protection and Recycling Law in 1976, clearly stipulating that all kinds of wastes, especially solid wastes, are not allowed to be discarded at will and must be used as resources. In order to realize the recycling of waste, many countries have adopted a series of policies and measures to encourage waste utilization, such as establishing special waste exchange and recycling institutions to engage in the direct and effective utilization of waste. In the early 1980s, the US Environmental Protection Agency set up 200 waste exchange points and 3,000 recycling centers nationwide.
Some European countries began to develop transnational waste exchange systems from 1970s to 1980s. The German Chemical Industry Association first set out to cooperate with neighboring Austria, Luxembourg, the Netherlands, Belgium and Denmark and signed waste exchange agreements. Western Europe * * * same body chamber of commerce and industry established waste exchange market in 1978. Sweden, Denmark, Finland and Norway in Northern Europe established the Nordic Waste Exchange, which promoted the development of waste recycling.
In addition to these management measures, the scientific and technological circles in various countries have also put forward many waste utilization processes, and waste gas, waste liquid and waste residue can be converted into resources under suitable conditions. For example, a large amount of organic matter contained in municipal waste can be used as auxiliary fuel of coal after sorting and processing, and can also be decomposed into fuel oil at high temperature; Some waste liquid mixed with waste can be degraded by microorganisms to produce biogas and high-quality fertilizer; High-valent metal materials such as germanium can be recovered from waste smoke and dust; It is common that waste residue is used to produce building materials.
China's environmental protection policy of "comprehensive utilization, turning harm into benefit" put forward at the United Nations conference on human environment in 1972 was confirmed at the first environmental protection conference held in Beijing from August 5 to 20, 1973, and was written into 1979' s Environmental Protection Law of People's Republic of China (PRC) (for Trial Implementation).
In fact, since the founding of New China, China has attached great importance to the comprehensive utilization of waste materials from the private sector to governments at all levels. By the end of 1995, there were 2,800 renewable resources management companies (or waste companies) at or above the county level, urban and rural recycling outlets10/2,000, and various renewable resources comprehensive processing and utilization plants 1500, with about 730,000 employees. 1950 ~ 1995 * * Recover all kinds of waste materials177.5 billion yuan, with a total recovery of 350 million tons, including recycled raw materials in metallurgy, chemical industry, light industry, handicrafts and other industries, such as scrap steel/kloc-0.65 million tons, old nonferrous metals of 4.87 million tons, and old ones. The comprehensive utilization benefit is considerable, only 198 1 ~ 1995, and the non-ferrous metals extracted from the recovered waste residue and waste liquid reach 86,500 tons, with an output value of 1000 billion yuan; 4,800 kg of gold, 765,438+065,438+0 tons of silver and 65,438+0,990 kg of platinum group metals were extracted from the waste components containing gold, silver and platinum group metals.
(3) Present situation of waste utilization
Yesterday, the cause of waste utilization did make great achievements, but mankind will not be satisfied with what has been achieved. Thinking about environmental protection focuses on how to deal with waste after it is produced, which is a terminal treatment idea. 1989 In May, the Governing Council of the United Nations Environment Programme put forward a new concept of "cleaner production". At the Canterbury (UK) meeting in June 1990, the content of this concept was clarified: cleaner production is a preventive environmental strategy aimed at technology and products, aiming at reducing the risks of production to human body and environment; For the production process, cleaner production focuses on saving raw materials and energy, eliminating toxic raw materials, and reducing the quantity and toxicity of all emissions and wastes before they leave the process; For products, the strategic focus of cleaner production is to minimize the negative impact in the whole life cycle of products, that is, from the collection of raw materials to the final disposal of products.
The strategic idea of developing cleaner production is a great progress in waste utilization or recycling, which broadens the vision of environmental protection and promotes the transformation from terminal management to all-round management of all links in the whole production process. But this is designed for new technology, and the utilization and resource utilization of waste accumulated on the earth is still very arduous. Even so, we should be guided by the idea of cleaner production to avoid secondary pollution and new environmental problems.
Almost at the same time as the concept of cleaner production was put forward, the US Congress passed the Pollution Prevention Law in 1990, which clearly put forward the concept of pollution prevention. Although it has no legal effect, it is a guide to action, detailing the pollution prevention system and different levels. It includes the removal, treatment and recovery of waste, reducing and eliminating pollution sources. Finally, this "elimination of pollution sources" represents the ultimate goal of the new concept of pollution prevention. This bill marks the beginning of a new era of environmental protection. It is the product of the experience and lessons of chemical pollution control since the 1960s, and it is a "new chemical baby" conceived by people. Since the 1990s, this "baby" has attracted the attention of all parties, and has been given many pleasant names, such as environmental benign chemistry and green chemistry. Finally, the US Environmental Protection Agency adopted the name of green chemistry. 1995 March 16, US President Bill Clinton announced the establishment of the "Green Chemistry Challenge Plan", which aims to promote cooperation in chemical pollution prevention and industrial ecological research, encourage and support major creative scientific and technological breakthroughs, and fundamentally reduce the use of chemical pollution sources, which also raises the concept of waste utilization to a new height.
Green chemistry aims to study chemicals and chemical processes that are technically and economically feasible, without negative impact on the environment or as little as possible. In order to achieve this goal, the National Science Foundation of the United States and the Environmental Protection Agency set up special funds to support important green chemistry research topics with practical prospects. In the same year, the United States also established the "Presidential Green Chemistry Challenge Award", which is the only presidential award in the field of chemistry and chemical engineering, in recognition of outstanding units and individuals in green chemistry research and development. In 1996 and 1997, five projects (excellent new synthetic route, excellent new reaction conditions, safer compound design, small enterprises and academic research) won prizes.
Green chemistry not only has great social and environmental benefits, but also is a new direction of chemical development. Its fundamental purpose is to re-examine and reform the existing chemistry and chemical industry from the viewpoint of saving resources and preventing pollution. Therefore, this is an important strategic task of contemporary chemistry. Undoubtedly, it is also a brand-new topic in the research of waste utilization and resource utilization.