Domestic waste

With the development of urbanization, the amount of garbage generated by the city is increasing, and then a problem is caused  municipal waste solutions. Now people’s living standards have improved, and the use of some high-end durable goods will increase, which will inevitably increase the difficulty of garbage disposal. The common treatment methods and advantages and disadvantages of garbage are as follows:

1. Stacked in the open air. This method simply stacks the garbage on the open space without any processing. Because of the low cost of this method, this method has been used frequently, especially in remote areas. However, the open dumping of garbage will occupy the land. In some places, the garbage dump covers an area of ​​several acres and uses valuable cultivated land. Also, open-air stacking will cause some of the garbage to deteriorate, and the spoiled garbage will emit an unpleasant smell, which will attract flies, which can spread diseases and are harmful to the health of surrounding residents. In addition, some substances containing sulfur will metabolize to produce a highly toxic gas, hydrogen sulfide. When hydrogen sulfide reaches a certain concentration, it will cause irreparable damage. When the concentration is extremely large, it will be life-threatening. When stacked in the open air, the electrolyte of the battery will flow out. The electrolyte of the battery is sulfuric acid, which acidifies the soil and prevents the crop from growing. Because this method has a great damage to the environment, the open-air stacking method is not generally used now.

2. Deep burial method. This method is to dig deep pits to bury the garbage so that it does not occupy the surface space. This method utilizes the decomposer-microbe in the soil, and the garbage can be buried without using the ground space. The microorganisms will also decompose some organic matter and will not attract flies, so some areas will use this method. However, microorganisms can only decompose a part of organic compounds, and organic substances such as polyethylene take four hundred years to decompose. Also, this method makes the waste battery pollute the land more easily. According to research, a button cell will pollute 6 billion liters of water. This is the water consumption of a person for a lifetime! The bacteria will be more harmful in the underground, some in the garbage. Bacteria accelerate in the soil and then enter the groundwater, which can invisibly pollute the water and harm the health of the residents.

3. Traditional incineration method. This method is to incinerate the waste and decompose it. Most of the cities chose this method because the incinerator occupies a small area and the garbage is easily cleaned after incineration. However, some objects cannot be burned, like glass and metal. There is also some organic matter burning to generate toxic gases, such as polyvinyl chloride, burning at 240 ° C – 340 C will decompose hydrogen chloride gas and diolefins containing double bonds, and then carbon burning at 400-470C will release toxic Gases, as well as some organic matter, undergo an addition reaction, making the original non-toxic substances toxic. Also, the battery will rupture at high temperatures, and the material inside is toxic. These toxic substances are discharged into the air with the smoke, and the damage will be even greater.

Because traditional methods have many drawbacks, and with the development of technology, there are many ways to deal with garbage, so we can use modern methods to treat garbage in a harmless way.

1. Fermentation method. For some kitchen waste, the manure can be put into the biogas tank for fermentation. In the biogas tank, the kitchen waste will be decomposed to generate methane, which can be used for power generation, cooking, lighting, etc. The fermented items can be used as fertilizer or feed.

2. High-tech incineration. Traditional incineration can damage the environment, and we can use technology to reduce the hazards of incineration. First, use high-power electromagnets to extract iron, nickel and batteries from the waste for recycling. The garbage is then compressed to make it smaller. The waste is then placed in an incinerator, the organic matter is decomposed at a high temperature of 500 degrees, and the gas is treated harmlessly. Then, the heat generated by the waste combustion is used to generate electricity. This can minimize the harm caused by organic matter, and make full use of the energy generated by combustion, which is less harmful to the environment, and can also reduce the consumption of ore fuel, killing two birds with one stone. However, this method has high technical requirements and high cost, especially for the harmless treatment of gases, so it is suitable for economically developed regions.

3. Reuse method. This method is to reuse the garbage, make the garbage harmless, and produce something that can be reused. This not only handles the garbage, but also generates useful things, which has turned waste into treasure. For metal waste, it can be remelted to make new items, which can reduce the dependence on metal ore in the production process and make full use of resources. It is very suitable to treat polymer organic substances such as plastics in this way because polymer organic substances are difficult to degrade, and incineration pollutes the air. It can be heated to the melting point of the organic matter, and the organic matter is fired into a liquid state and then subjected to purification treatment, and the impurities are removed and re-injected into the mold to form a new product.

Because organic compounds do not undergo chemical reactions during this process, no harmful gases are formed and naturally do not damage the environment. Moreover, most of these high molecular organic compounds are made from ethylene, ethane and propylene extracted from crude oil. Recycling and recycling can reduce the dependence on oil in the production process and achieve green production. This method is also very effective in disposing of used batteries. Waste batteries, whether they are incinerated or stacked or buried, can pollute the environment. If the used batteries are recycled, some of the internal materials can be reused, such as the zinc casing of the battery and the internal carbon electrode. If it is recycled, it not only treats the waste, but also saves resources.

4. High temperature composting of garbage. High-temperature waste compost refers to the method of fermenting and biodegrading waste at a certain temperature to make the garbage harmless. This method is relatively simple, has less investment, and can be garbage-resourced, so it is more popular. However, the problem of garbage composting is that the incoming garbage components need to be controlled, otherwise the quality of composting products will be very difficult to grasp. The sale of garbage compost products also needs to have a better market mechanism. Waste compost is more suitable for areas with high organic matter content in waste components.

5. Sanitary landfill method. This method is different from the deep-buried method mentioned above. The deep-buried method will pollute the environment of the landfill, but the sanitary landfill method will not pollute the environment. No matter which method is used to dispose of the garbage, some waste will be produced, and these wastes can only be landfilled.
Waste sanitary landfills must have facilities to prevent contamination of groundwater, the atmosphere and the surrounding environment, such as bottom lining treatment, biogas collection, landfill leachate and sewage treatment. The anti-seepage coefficient of the bottom lining of the sanitary landfill must be less than 10-7 cm/s. The advantage of landfill sanitary landfill is that the investment cost is low, and the disadvantage is that it takes up a lot of land. In the garbage disposal, it is necessary not only to pay attention to the cost, but also to consider the environment, topography and climate of the area. To proceed from the actual situation, choose the appropriate garbage disposal method according to the situation in this area.

In summary, I think the most suitable garbage disposal solutions for the city are as follows.

(1)Transportation + sanitary landfill

(2)Transportation + incineration + sanitary landfill

(3)Transportation + compost + sanitary landfill

(4)Transportation + Incineration + Composting + Sanitary Landfill