White pollution
White pollution is a unique environmental pollution in cities in my country. A large number of discarded plastic products can be seen everywhere in various public places. They come from nature. Made by humans, when ultimately attributed to nature, they are not easily absorbed by nature, thus affecting the ecological environment of nature. From the perspective of saving resources, since the main source of plastic products is petroleum resources that are facing depletion, they should be recycled as much as possible. However, because the production cost of recycling at this stage is much higher than the direct production cost, it is difficult to do so under the current market economy conditions. Faced with the increasingly serious problem of white pollution, people hope to find a plastic substitute that can replace the performance of current plastics without causing white pollution. Biodegradable plastics have emerged. This new functional plastic is characterized by reaching a certain level. After its service life is discarded, under specific environmental conditions, its chemical structure undergoes significant changes, causing some performance losses and appearance changes, resulting in degradation, which is harmless or less harmful to the natural environment. For example, starch-filled plastics first contain starch that is rapidly decomposed by amylase secreted by microorganisms in the soil within a short period of time to form cavities, resulting in a decrease in the mechanical properties of the film. At the same time, the autooxidant added in the formula reacts with metal salts in the soil. Peroxide is generated, which breaks the polyethylene chain and degrades it into small fragments that are easily swallowed by microorganisms and are absorbed by the natural environment, while also improving the soil.
The earth is our home, and this home is being surrounded by garbage. As the masters of the 21st century, we cannot just worry and complain, but we must take action, and we must take green action. Garbage is not useless, and waste is not useless. It is not technically difficult to recycle and recycle garbage. The difficulty lies in the fact that waste is simply thrown away, mixed and piled up to become garbage. Therefore, as educated and civilized people in the new century, we should participate in garbage source classification activities with a little effort and contribute to purification. Make a little contribution to our living space and give a piece of love.
Domestic waste is a by-product of human life. With the rapid development of social economy and the high concentration of urban population, the production of domestic waste is gradually increasing. General domestic waste can be divided into five categories: waste paper, plastic, glass, metal and biological waste. The main harms of garbage to human life and the environment are:
First, it takes up too much land. Garbage piled up on the outskirts of cities has occupied a large amount of farmland. Nowadays, the average Beijinger produces 440 kilograms of garbage per year, and the city’s annual output is about 4 million tons, which is equivalent to two and a half Jingshan Mountains. There are more than 4,500 garbage dump sites in Beijing, covering an area of ??more than 10,000 acres. Garbage also stays in nature for a long time: 1-5 years for cigarette butts and wool fabrics; 2 years for orange peels; 13 years for painted wooden boards; 30-40 years for nylon fabrics; 50 years for leather; 80-100 years for cans; 100 years for plastics —200 years; glass 1,000 years. To this end, we must not only create less waste, but also pay attention to waste classification, recycling, and turning waste into treasure. Use less disposable chopsticks, water cups, lunch boxes and other products and use more reusable products to reduce the consumption of precious forest resources; use less plastic bags and use shopping bags instead to reduce the harm of "white pollution" in the city; purchase fluorine-free refrigerators, Environmentally friendly appliances such as air conditioners protect the ozone layer; use less high-concentration detergents and use phosphorus-free laundry detergent to reduce water pollution.
Second, pollute the air. Garbage is a complex mixture. During transportation and open-air stacking, organic matter decomposes to produce odor and releases a large amount of ammonia, sulfide and other pollutants into the atmosphere, including more than 100 kinds of organic volatile gases. These releases contain many carcinogens and teratogens. Plastic film, paper scraps and dust fly in the wind to form "white pollution".
Third, polluting water bodies. Harmful components in garbage can easily wash into ground water bodies through rainwater. During the process of garbage stacking or pit filling, a large amount of acidic and alkaline organic pollutants will be produced, and heavy metals in the garbage will be dissolved. The leachate produced by garbage pollution sources will penetrate into the groundwater through the soil; if the garbage is directly discarded into rivers, lakes or oceans, it will cause more serious pollution.
You see: plastic bottles and lunch boxes floating on the surface of the Summer Palace and the North Sea, plastic bags, bread paper, etc. scattered on the forest roads in Xiangshan and Badachu and hanging on branches. Some tourists only seek their own convenience, causing pollution to the tourism environment. If animals accidentally eat white garbage, it will not only harm their health, but even cause death.
Fourth, soil dregs. Direct application of garbage to farmland, or use of garbage on farmland after simple treatment will destroy the soil's aggregate structure, physical and chemical properties, and water and fertilizer retention capabilities. In particular, if plastic bags and plastic sheets are buried in farmland, the roots of crops will not grow, farmland yields will be reduced, and the food available for people to eat will be reduced.
Fifth, fire hazard. Garbage contains a large amount of combustibles, which will produce methane and other combustible gases during natural storage. It can easily cause fires when exposed to open flames or spontaneous combustion. With the increase in the organic matter content of urban garbage and the change from open-air scattered storage to centralized storage, and the use of simple covering in long-term storage, the hazards of biogas generated by garbage have become increasingly prominent. Garbage explosion accidents continue to occur, causing heavy losses.
Sixth, the nest of harmful organisms. Garbage not only contains pathogenic microorganisms, but also provides food, habitat and breeding ground for rats, birds, mosquitoes and flies, and is also the source of infectious diseases.
In summary, the seriousness and urgency of the urban garbage problem are obvious. In order to turn this waste into treasure, we must do a good job in recycling and utilization of waste. Did you know? Recycling 1 ton of waste paper can produce 800 kilograms of good paper, save 17 trees, save more than half of papermaking energy, and reduce 35% of water pollution; 1 ton of waste plastic can recycle at least 600 kilograms of gasoline and diesel; using waste Remaking glass from glass can not only save raw materials such as quartz sand and soda ash, but also save electricity; using scrap metal to smelt metal can save a lot of energy consumption and reduce air pollution; and some peels, eggshells, vegetable leaves, leftovers, etc. Kitchen waste can be processed through compost fermentation and turned into green fertilizer.
Therefore, we must vigorously carry out publicity and education on the classification and collection of garbage at source through various mass media such as television, radio, newspapers and information networks; we must promptly formulate regulations on garbage classification and collection that are suitable for national conditions, and strictly enforce Implementation; consider conducting in-depth and detailed pilot work on garbage source classification and collection in some units; and further discuss with everyone to improve management methods so that garbage source classification and collection can be widely carried out as soon as possible. Let us work together to promote garbage classification and recycling, eliminate garbage pollution, turn waste into treasure, and save resources with a little effort. This will enable Beijing to win the right to host the 2008 Olympic Games with a new look, and at the same time provide ourselves with a beautiful and healthy living space.
Plastic products are widely used around the world as new materials that are lightweight, waterproof, and anti-corrosion.
Plastics were first used in agricultural mulch films, which brought great development to agricultural production, allowing crops to grow in any season and promoting market consumption. According to market statistics, from 1990 to 1995, the production of plastics has grown at an annual rate of 8.9%, and has swept the entire earth. It can be called a "white revolution". But while it provides convenience to people, it also brings a "white disaster" to people.
To date, "white pollution" has become a well-known new term. It mainly refers to the pollution caused by various foam plastic bags, agricultural mulch films, etc. to the environment, and has received widespread attention from society.
Taiwan Province of China promulgated a ban on "white products" in 1994, and then lifted the order a year later.
Hangzhou City issued a notice as early as 1995 banning the local use of disposable foam plastic tableware.
Guangzhou City promulgated a government order in June 1997, stipulating that the production, sale and use of disposable non-degradable plastic lunch boxes will be banned in the city starting from September 1 of that year.
Based on this, in January 1999, the State Economic and Trade Commission issued Order No. 6 of 1999, clarifying that disposable foam plastic tableware, as an outdated product, should be completely eliminated by the end of 2000. From 2001, A complete ban on production, sale and use.
As can be seen from the above materials, more than a year has passed since the deadline, but disposable foam tableware can still be seen everywhere, and the government has also changed from the forced "ban on white" at that time. His attitude became "ambiguous", he often did things perfunctorily, and the "ban on white hair" became a dead letter.
In view of the above situation, we have conducted various investigations and research, reviewed various materials, and obtained various aspects of the various new substitutes developed and put on the market by the country so far, and conducted analysis. Summarize.
During the difficult journey, we went to the Xigu District Environmental Protection Bureau. In the Environmental Protection Bureau, we received a warm welcome. During the conversation, we realized the true composition of "white pollution" and had a preliminary understanding of "white pollution". "The concept of harm, and also have some understanding of the current solutions to control "white pollution" (a question and answer record is prepared). We went to the Xinhua Bookstore, the Provincial Library, and the school library, but there was very little information on "white pollution". The only ingredients were polyethylene, polypropylene, and polyvinyl chloride, which hindered the research process. In order to get rid of the difficulties, we decided to take advantage of today's information technology - the Internet. We found a vast space on the Internet, which gave us a deeper understanding of "white pollution". And it helped us a lot in writing the paper. With the above foundation, we decided to further understand the "white pollution" in Lanzhou area. We successively interviewed Hualian Supermarket, Electricity Supermarket, and some retail stores and stalls. We are deeply shocked that so many plastic belts and foam lunch boxes are discarded every day and every year, and people turn a blind eye to it all. We feel that if we do not improve the quality of residents, it will be too difficult to solve the problem of "white pollution". (A survey form is available)
"White pollutants" have such strong vitality. We will describe the serious harm it will bring to our lives in the following content. First, let’s understand what plastic is made of.
1. The composition of "white pollutants"
"White pollution" mainly refers to white foamed plastic lunch boxes, various plastic bags, agricultural mulch films, etc.
Pollution caused by the environment. But "white pollution" is not what people usually think of plastic products. As we all know, plastic is a new material with excellent comprehensive properties and a consumer product. In general, it is also a substance. Every substance has its life cycle, and the entire process to the end of its life cycle is the degradation process. Therefore, plastic itself is also degradable. It is just because of the stabilization technology, that is, the addition of light and heat stabilizers, antioxidants, etc., that delays or inhibits its inherent degradability. Moreover, there are more than 300 kinds of plastics, of which more than 40 are commonly used, but only a small part of them can actually become white pollution. Therefore, "white pollution" cannot be equated with plastic.
The main components of "white pollution" are: polyethylene (PE), polyvinyl chloride (PV), polypropylene (PP),
Polystyrene resin (PS) . Let’s take a look at them one by one below:
Polyethylene:
Polyethylene is a thermoplastic resin produced by the addition polymerization of ethylene. Depending on the polymerization conditions, polyethylene with relative molecular weights ranging from 10,000 to 1,000,000 can be obtained. Polyethylene is slightly white particles or powder, translucent, non-toxic and odorless, has good chemical stability and is resistant to acid and alkali corrosion. Polyethylene is commercially classified as low, medium and high density. Generally used for packaging is low density (0.92g/cm3-0.93 g/cm3) without plasticizer
Polypropylene:
Relative molecular weight is 80,000-20 Between ten thousand. The polypropylene backbone has a methyl side chain. If all the methyl groups are distributed on one side, it is called isotactic polypropylene; if the methyl groups are regularly distributed on both sides of the main chain, it is called syndiotactic polypropylene; if the methyl groups are randomly distributed on the main chain, it is called atactic polypropylene. Polypropylene. Polypropylene is usually a translucent solid, odorless and non-toxic, with a density (0.90g/cm3-0.91g/cm3), higher mechanical strength than polyethylene, and good heat resistance.
Among the three types of polypropylene, isotactic polypropylene has the largest output. Titanium trichloride-diethyl aluminum chloride is used as a catalyst to polymerize propylene in hydrogenated saturated gasoline to obtain isotactic polypropylene.
Polyvinyl chloride:
With a relative molecular weight of 50,000 to 120,000, polyvinyl chloride generates a polymer through free radical addition polymerization and is a thermoplastic resin. Amorphous white powder, no fixed melting point, density (1.35g/cm3-1.45g/cm3), and good chemical stability. Melted in cyclohexanone, chlorobenzene, dimethylformamide, toluene-acetone mixed solvent, etc.
Polystyrene:
The average relative molecular mass is about 200,000. Colorless and odorless transparent resin with good light transmittance. The surface is glossy, flammable, and the density is (1.05g/cm3-1.07g/cm3). It has excellent waterproofing, corrosion resistance, and electrical insulation.
Production methods: bulk polymerization, suspension polymerization, emulsion polymerization. Here we introduce the ontology aggregation method. Add an initiator and a small amount of additives to the styrene monomer. Now perform low-temperature polymerization in the prepolymerization kettle to prepare the prepolymer. Then transfer it to the polymerization tower for high-temperature heating and maintain a certain temperature in sections. When the reaction is completed, the polystyrene will be molten. Ethylene is extruded into strips, cooled and hardened in water, and cut into pellets for packaging.
The above are the main ingredients of "white pollution". In addition, plasticizers, foaming agents, heat stabilizers, antioxidants, etc. are also added to these pollutants. .
2. The main causes of white pollution are extremely harmful:
1. The main reasons: Plastic waste is not properly managed and disposed of, waste is not collected in categories, and what can be recycled is not recycled. The final disposal method of waste is basically exposed piles or shallow burials. Some towns use the banks of rivers, rivers, and lakes as natural garbage dumps. Transportation and tourism, except for railways, have not yet established a garbage collection system that is compatible with production and operation, and the garbage produced in the operation process is left unchecked. Weak management, lack of relevant regulations on plastic packaging waste, and people's relatively weak awareness of the environment have led to widespread abuse and random dumping, which is not the responsibility of the plastic products themselves.
2. Main hazards:
"White pollution" mainly refers to the two negative effects of "visual pollution" and "potential harm" to the environment.
"Visual pollution" refers to the damage caused to the city appearance and landscape by plastic waste scattered in the city and discarded by people.
For example, there are a large number of polystyrene foamed plastic tableware scattered along the railway lines, in rivers and lakes, and ultra-thin plastic bags flying in the sky or hanging on branches. These all bring bad visual stimulation to people, and people react strongly to this.
"Potential crisis" refers to the environmental problems caused by plastic waste entering the natural environment and being difficult to degrade.
The hazards mainly include the following points: It is not easy to recycle, because recycling requires use The cost is high, but the utilization rate is low. It can be said that it is unprofitable for businesses. Moreover, because its recycling price is very low, it is difficult to attract the general public to carry out "white recycling" work.
As a result, it is difficult to recycle. - Difficult to degrade. The recycled white waste is difficult to process. At this stage, the main treatment methods are incineration and landfilling. If they are burned, a large amount of toxic smoke will be produced, polluting the atmosphere, and promoting the formation of acid rain. As for If it is buried in a landfill for 100 years, it will remain in its original state and cannot be absorbed by nature.
And it will be extremely harmful to the land, changing its pH, affecting the absorption of nutrients and water by crops, resulting in agricultural
Industrial production is reduced. As for plastic products discarded in water or on land, they not only affect the environment, but also can lead to death if swallowed passively
. This destroys the ecological balance.
High temperatures decompose toxic substances. Plastic products do not contain toxic substances. However, the equipment used for recycling is not perfect, the technology is crude, and many manufacturers do not have legal business licenses, resulting in the failure of reproduction
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When the temperature of plastic products reaches 65°C, toxic substances will precipitate and penetrate into the food, causing damage to important parts of the human body such as the liver, kidneys, reproductive system and central nervous system. harm.
3. The reasons why "white pollution" has a broad market and the related problems in the treatment process
As mentioned above, we have mentioned the document of the Economic and Trade Commission, which clearly states: "Completely eliminate all foamed plastics by the end of 2000." But today, foamed plastic still exists, why does it have such strong vitality! The reasons are as follows: Products made from degradable materials are immature. Because its production process is complicated, its price is 1 to 2 times higher than "white
products". Of course, people are not willing to "sacrifice the chaff for the more expensive". On the other hand, the performance of degradable materials
finished products is not as good as that of "white products" because the production process of "white products" has been mature after years of experience
Summary , and new materials have just been developed, and some require a large amount of wood. Although
the products degrade, they cause pollution and damage to the ecology and water bodies. It doesn't hit hard enough. Nowadays, restaurants and restaurants sell "white products", which are widely used, openly and blatantly conduct market transactions. They turn a blind eye to national regulations, which has led to the "ban" in recent years. "White" work has become "white taboo". The quality of citizens needs to be improved. The quality of a citizen reflects the national quality of a country. However, people's awareness of environmental protection is still very weak so far, and the habit of throwing away waste items is still very common. This phenomenon will It brings great harm to our natural environment, and the emergence of this phenomenon brings huge difficulties to the recycling of "white waste items". The facilities for recycling and reusing "white pollution" are not complete enough. As mentioned before: the recycling rate of "white pollution" is low, mainly because of our country's backward technology and insufficient capital investment. Therefore, some new products that have been researched in our country cannot be put into production. Go in. Manufacturers have shifted from "public" to "semi-public". With the introduction of the national "white ban" policy, manufacturers of "white
products have also moved from urban production to rural and suburban areas, and from public production to In semi-public production, because the conditions are relatively poor, the products produced are substandard, and this phenomenon brings difficulties to the government's "ban on white goods." :
From the above examples, we can see that there are two main methods to solve "white pollution" today: recycling of waste plastics and biodegradable plastics.
A: Recycling of waste plastics (that is, recycling waste plastics as resources for development and utilization.)
(1) Directly as materials, some renewable plastic products can be Recycled, processed and then made into new plastic products.
(2) Preparation of synthetic polymer units. Polymers are polymerized from monomers, and under certain conditions monomers can be made from waste plastics. For example, polyester plastics are made into monomers through alcoholysis.
(3) Preparation of fuel oil. Crack the polymer chains at high temperatures. For example, polyethylene and polypropylene can decompose into low molecular petroleum hydrocarbons at high temperatures, and then fractionate to obtain various fuel oils.
B: Biodegradable plastic.
(1) Natural polymer transformation method. It uses starch, cellulose, chitin, lignin, seaweed and other natural polymers as raw materials, and transforms these molecules through chemical modification and polymerization methods to synthesize plastics that are easily biodegradable.
(2) Chemical synthesis method.
Simulate the natural polymer structure, starting from simple water molecules, and attaching active groups such as amide groups, peptide groups, and ester groups to the polymer chains of the plastic. The compounds containing these groups are similar to the structural fragments of natural proteins and oils. Easily biodegradable.
(3) Microbial fermentation method. Many microorganisms can use certain organic matter as carbon source to secrete polyester and polysaccharide polymers through metabolism. These molecules are easy to degrade and can be further regenerated. use.
However, due to the different structures of plastics and the inclusion of some special additives, some plastics are not suitable for recycling; there are also fragments of some plastics that have been processed and initially explained, which degrade very slowly in the natural environment and cannot be completely solved. "Potential harm" to the environment. Therefore, while controlling "white pollution" on the one hand, we should also actively prevent the emergence of new sources of "white pollution" on the other hand. For this reason, my country's environmental protection department proposed that the prevention and control of white pollution should implement the principle of "taking publicity and education as the leading role, strengthening management as the core, recycling as the main means, and product substitution as the supplement."
Of course, "white pollution" is a world problem. Due to its limited development, we cannot study it in depth. What we can do now is limited to collecting, organizing and compiling information. But by studying this issue, we can also understand "white pollution" in general.
Although we have understood the management and solutions of "white pollution" in today's world, we are still unable to completely solve it. During the research process, we deeply felt that the low quality of people has seriously damaged the environment. Only by improving people's environmental awareness is the most feasible way to solve "white pollution".