I. Introduction
The reuse of waste plastic packaging materials is an important circular economy issue, from the clean production in the production process, the waste recycling after production, to the recycling and disposal of secondary assembly or processing, and the post-consumer recycling and disposal. In advanced countries or economically backward areas, the recycling of waste plastics is a very common practice. However, in regions with poor economic conditions, waste recycling and recycling often only sees resource recycling, and it does not pay attention to harmlessness. Processing technologies, which often shift waste water and waste gas from internal production costs to social external costs that pollute rivers, rivers, lakes and the atmosphere, cause serious environmental problems. In fact, the recycling and recycling of waste plastics should take into account the fact that resource recycling and harmlessness are fairly easy. This paper shares with you the practical experience of recycling disposable plastic foam lunch boxes in Shanghai over three years.
II. Wastewater, waste gas and noise source of waste plastic recycling
The most commonly used process for the recycling and recycling of waste packaging materials is the regenerative granulation method, and a few of them are used for oilification, incineration heat energy conversion, or comminution and addition. Therefore, during the re-use process, it is unavoidable to use the cleaning, crushing, and heating process conditions. This will result in cleansing wastewater, dehydrated wastewater, crushed noise, heated odors, or high-temperature heated flue gas exhaust. The problem of exhaust emissions.
The above-mentioned regeneration process is added after pulverization, and it is the easiest to deal with to achieve the requirement of harmlessness. The main reason is that the disposal wastes are mainly waste from clean wastes or wastes with high cleanliness. There is basically no cleaning or dehydration drying. Dry process, as long as the smash stage, do sound insulation. As for the packaging materials used by consumers, a plastic lunch box or a vest bag for market shopping is taken as an example. Once consumers use it, they are mixed with impurities and even mixed with urban waste. These waste packaging materials must be cleaned. The process of crushing and dewatering requires a lot of waste water disposal. Even if you do not use traditional recycling granulation methods to dispose of waste packaging materials, using oil technology or incinerators, you must also pay attention to the waste gas treatment during heating, especially the emissions from incinerators. An example of how the actual regeneration process of a disposable plastic lunch box is combined with a harmless process will be described below.
Third, examples of harmless comprehensive utilization
For the purpose of Baosteel's professional disposal of waste disposable plastic lunch boxes, the measures for environmental protection and harmlessness are described below:
1. The harmless example of waste water is introduced:
At present, Baolv Company handles more than 150 tons of raw plastic lunch boxes each month. Since the lunch boxes are very dirty and greasy, they must be washed with large quantities of water, and the average daily water consumption is 100-200 tons. However, these washed waste waters are organic waste water for ordinary household use. They contain no heavy metals, no color or high concentrations of ingredients, have fairly easy handling conditions, and the water for cleaning plastic lunch boxes does not require very high water quality. Therefore, we The wastewater is filtered and precipitated, degreasing treated, and returned to the cleaning tank for reuse. According to the local tap water price is 1.5 yuan, industrial sewage charges 0.5 yuan, a total of two yuan fee. Because of the reuse of the medium water, the daily cleaning water can be recovered to about 80-160 tons, which saves 160-320 yuan per day.
What is more special is that the local area has always been a dyeing and finishing and fine chemical base. The special industrial sewage treatment plant is very happy to receive the organic waste water from the cleaning lunch box. This will help the growth of beneficial bacteria or the high concentration of waste water in the biological treatment process. The neutralization effect was one of the reasons for choosing the site at the time. For this reason, the waste water from the cleaning tank is reused to recover the remaining wastewater from the filtration process. When the BOD content is as high as 1500 or more, it does not meet the secondary discharge standard. Instead, these organic wastes are directly sent to the wastewater treatment plant. Regulating the pool and the high concentration of liquid to neutralize the effect, of course, sewage charges will be raised some more.
It is worth mentioning that, just across from the Baolin Plant, there is an eyeglass factory. It is necessary to use pure water to clean the lenses. However, these waters are still very clean. Therefore, the two factories use each other for comprehensive utilization. These lenses are cleaned. Water charges 50% off the water price to supplement the water source for cleaning lunch boxes. This will save a portion of the cost of running water, and the entire Green Plant will also be able to achieve zero discharge of wastewater.
2. The harmless example of exhaust gas is introduced:
After the disposable plastic lunch box has been cleaned and dehydrated, it needs to use an extruder to regenerate the plastic particles by hot melting. The heating temperature is as high as 180-220°C. This stage of production will change or destroy the molecular bonds of the plastic itself and cause odor. happened. While the waste disposable plastic lunch boxes themselves are filled with meals, the oil (salad oil, soy sauce, vinegar, and other seasonings) must be left behind. Although these oils undergo a three-stage cleaning process, they cannot be completely removed, so during the regeneration of the particles, When these fats and oils are heated at high temperatures, they will evaporate and dissipate in the air, creating atmospheric pollution. The taste of this pollution is almost exactly the same as the fumes emitted from the kitchens and restaurants. With red grease. Such air pollution problems will endanger the health of workers and will inevitably be protested by the surrounding residents.
In order to effectively control the air pollution, we installed a large suction hood above the extruder to collect all the fumes and related fumes generated during the heating process, and then electrostatic precipitators to strongly adsorb the grease. Through the bag machine, after three layers of adsorption, ensure that the chimney is discharged into the atmosphere after reaching the standards, and sometimes the gas in the flue gas is discharged into the existing sewage tank when replacing the dust bag or cleaning the electrostatic precipitator. The use of water washing to achieve the purpose of purifying the air, because the factory to take the water reuse facilities, the height of the pool of water does not necessarily reach the point of washing, so washing is only used as an auxiliary or temporary alternative measures.
3. Introduction of harmless examples of noise
To dispose of waste plastic packaging materials, it is necessary to use crushers for crushing, and crushing opportunities are used to generate different levels of noise. The source of noise is nothing more than the direct and indirect driving sound when the motor is in operation. The direct sound is waste plastic packaging materials and crushing. The impact of the machine blade contacting the collision friction will indirectly cause the pulverizer itself to resonate and bring about different levels of noise. The crusher made in China is often particularly good in terms of the thinness or material quality of the steel plate, and the resulting noise is also particularly large.
In order to prevent noise, Baosteel's crusher is equipped with a rubber liner on the crusher base to reduce the beating of the equipment and to prevent the connected parts from resonance. However, when indirect noise does not occur in the machine, direct noise prevention and control is the main target. After field experience, if the outer layer of the crusher is packed with two layers, the middle air layer is used as the noise barrier, and the input port is reused. Strips of rubber and plastic hanging, this can reduce the direct noise of about 60% or more, to effectively eliminate noise.
Baolv Plastic Resources Recycling Co., Ltd. General Manager Huang Longbin
The reuse of waste plastic packaging materials is an important circular economy issue, from the clean production in the production process, the waste recycling after production, to the recycling and disposal of secondary assembly or processing, and the post-consumer recycling and disposal. In advanced countries or economically backward areas, the recycling of waste plastics is a very common practice. However, in regions with poor economic conditions, waste recycling and recycling often only sees resource recycling, and it does not pay attention to harmlessness. Processing technologies, which often shift waste water and waste gas from internal production costs to social external costs that pollute rivers, rivers, lakes and the atmosphere, cause serious environmental problems. In fact, the recycling and recycling of waste plastics should take into account the fact that resource recycling and harmlessness are fairly easy. This paper shares with you the practical experience of recycling disposable plastic foam lunch boxes in Shanghai over three years.
II. Wastewater, waste gas and noise source of waste plastic recycling
The most commonly used process for the recycling and recycling of waste packaging materials is the regenerative granulation method, and a few of them are used for oilification, incineration heat energy conversion, or comminution and addition. Therefore, during the re-use process, it is unavoidable to use the cleaning, crushing, and heating process conditions. This will result in cleansing wastewater, dehydrated wastewater, crushed noise, heated odors, or high-temperature heated flue gas exhaust. The problem of exhaust emissions.
The above-mentioned regeneration process is added after pulverization, and it is the easiest to deal with to achieve the requirement of harmlessness. The main reason is that the disposal wastes are mainly waste from clean wastes or wastes with high cleanliness. There is basically no cleaning or dehydration drying. Dry process, as long as the smash stage, do sound insulation. As for the packaging materials used by consumers, a plastic lunch box or a vest bag for market shopping is taken as an example. Once consumers use it, they are mixed with impurities and even mixed with urban waste. These waste packaging materials must be cleaned. The process of crushing and dewatering requires a lot of waste water disposal. Even if you do not use traditional recycling granulation methods to dispose of waste packaging materials, using oil technology or incinerators, you must also pay attention to the waste gas treatment during heating, especially the emissions from incinerators. An example of how the actual regeneration process of a disposable plastic lunch box is combined with a harmless process will be described below.
Third, examples of harmless comprehensive utilization
For the purpose of Baosteel's professional disposal of waste disposable plastic lunch boxes, the measures for environmental protection and harmlessness are described below:
1. The harmless example of waste water is introduced:
At present, Baolv Company handles more than 150 tons of raw plastic lunch boxes each month. Since the lunch boxes are very dirty and greasy, they must be washed with large quantities of water, and the average daily water consumption is 100-200 tons. However, these washed waste waters are organic waste water for ordinary household use. They contain no heavy metals, no color or high concentrations of ingredients, have fairly easy handling conditions, and the water for cleaning plastic lunch boxes does not require very high water quality. Therefore, we The wastewater is filtered and precipitated, degreasing treated, and returned to the cleaning tank for reuse. According to the local tap water price is 1.5 yuan, industrial sewage charges 0.5 yuan, a total of two yuan fee. Because of the reuse of the medium water, the daily cleaning water can be recovered to about 80-160 tons, which saves 160-320 yuan per day.
What is more special is that the local area has always been a dyeing and finishing and fine chemical base. The special industrial sewage treatment plant is very happy to receive the organic waste water from the cleaning lunch box. This will help the growth of beneficial bacteria or the high concentration of waste water in the biological treatment process. The neutralization effect was one of the reasons for choosing the site at the time. For this reason, the waste water from the cleaning tank is reused to recover the remaining wastewater from the filtration process. When the BOD content is as high as 1500 or more, it does not meet the secondary discharge standard. Instead, these organic wastes are directly sent to the wastewater treatment plant. Regulating the pool and the high concentration of liquid to neutralize the effect, of course, sewage charges will be raised some more.
It is worth mentioning that, just across from the Baolin Plant, there is an eyeglass factory. It is necessary to use pure water to clean the lenses. However, these waters are still very clean. Therefore, the two factories use each other for comprehensive utilization. These lenses are cleaned. Water charges 50% off the water price to supplement the water source for cleaning lunch boxes. This will save a portion of the cost of running water, and the entire Green Plant will also be able to achieve zero discharge of wastewater.
2. The harmless example of exhaust gas is introduced:
After the disposable plastic lunch box has been cleaned and dehydrated, it needs to use an extruder to regenerate the plastic particles by hot melting. The heating temperature is as high as 180-220°C. This stage of production will change or destroy the molecular bonds of the plastic itself and cause odor. happened. While the waste disposable plastic lunch boxes themselves are filled with meals, the oil (salad oil, soy sauce, vinegar, and other seasonings) must be left behind. Although these oils undergo a three-stage cleaning process, they cannot be completely removed, so during the regeneration of the particles, When these fats and oils are heated at high temperatures, they will evaporate and dissipate in the air, creating atmospheric pollution. The taste of this pollution is almost exactly the same as the fumes emitted from the kitchens and restaurants. With red grease. Such air pollution problems will endanger the health of workers and will inevitably be protested by the surrounding residents.
In order to effectively control the air pollution, we installed a large suction hood above the extruder to collect all the fumes and related fumes generated during the heating process, and then electrostatic precipitators to strongly adsorb the grease. Through the bag machine, after three layers of adsorption, ensure that the chimney is discharged into the atmosphere after reaching the standards, and sometimes the gas in the flue gas is discharged into the existing sewage tank when replacing the dust bag or cleaning the electrostatic precipitator. The use of water washing to achieve the purpose of purifying the air, because the factory to take the water reuse facilities, the height of the pool of water does not necessarily reach the point of washing, so washing is only used as an auxiliary or temporary alternative measures.
3. Introduction of harmless examples of noise
To dispose of waste plastic packaging materials, it is necessary to use crushers for crushing, and crushing opportunities are used to generate different levels of noise. The source of noise is nothing more than the direct and indirect driving sound when the motor is in operation. The direct sound is waste plastic packaging materials and crushing. The impact of the machine blade contacting the collision friction will indirectly cause the pulverizer itself to resonate and bring about different levels of noise. The crusher made in China is often particularly good in terms of the thinness or material quality of the steel plate, and the resulting noise is also particularly large.
In order to prevent noise, Baosteel's crusher is equipped with a rubber liner on the crusher base to reduce the beating of the equipment and to prevent the connected parts from resonance. However, when indirect noise does not occur in the machine, direct noise prevention and control is the main target. After field experience, if the outer layer of the crusher is packed with two layers, the middle air layer is used as the noise barrier, and the input port is reused. Strips of rubber and plastic hanging, this can reduce the direct noise of about 60% or more, to effectively eliminate noise.
Baolv Plastic Resources Recycling Co., Ltd. General Manager Huang Longbin
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