Garbage classification refers to the classification of garbage into different categories according to its different components, attributes, utilization value and impact on the environment, and according to the requirements of different disposal methods.
Domestic garbage can generally be divided into four categories: recyclable garbage, kitchen garbage, harmful waste and other garbage. At present, the commonly used garbage disposal methods mainly include comprehensive utilization, sanitary landfill, incineration and composting.
Recyclable garbage includes paper, metal, plastic, glass, etc. Through comprehensive treatment and recycling, pollution can be reduced and resources can be saved. If every 1 ton of waste paper is recycled, 850 kilograms of paper can be made, 300 kilograms of wood can be saved, and pollution is reduced by 74% compared with the same output; Every 1 ton plastic beverage bottle can recover 0.7 tons of secondary raw materials; Every recovered 1 ton of scrap steel can produce 0.9 tons of steel, which saves 47% cost compared with ore smelting, reduces air pollution by 75%, and reduces water pollution and solid waste by 97%.
Kitchen waste includes food waste such as leftovers, bones, vegetable roots and leaves. After in-situ composting by biotechnology, 0.3 tons of organic fertilizer can be produced per ton.
Hazardous wastes include waste batteries, waste fluorescent tubes, waste water silver thermometers, expired drugs, etc. These wastes need special safety treatment.
Other wastes include bricks and tiles, waste residue, toilet waste paper and other wastes that are difficult to recycle. Sanitary landfill can effectively reduce the pollution of groundwater, surface water, soil and air.
Classification of medical wastes.
Disposable medical devices after use, whether the needles are cut or not, and whether they are contaminated by body fluids, blood and excreta of patients, are all medical wastes and should be managed as medical wastes.
All kinds of glass (disposable plastic) infusion bottles (bags) that are not contaminated by patients' blood, body fluids and excreta after use are not medical wastes and need not be managed according to medical wastes. However, this kind of waste cannot be used for its original purpose when it is recycled, and should be used for other purposes according to the principle of not endangering human health.
1. Landfill treatment
Landfill is an effective method to absorb a large amount of municipal solid waste, and it is also the final treatment method of all the residues in the garbage treatment process. At present, the direct landfill method is widely used in China.
The so-called direct landfill method is to fill the garbage into the prepared pit, cover and compact it, make it undergo biological, physical and chemical changes, decompose organic matter, and achieve the purpose of reduction and harmlessness.
2. Incineration treatment
Incineration is a method of putting garbage into a high-temperature furnace to fully oxidize the combustible components in it, and the generated heat is used for power generation and heating. The garbage conversion energy system jointly developed by Westinghouse and O 'Connor Company has been successful. When incinerating garbage, the incinerator of this system can convert garbage with humidity of 7% into dry solid for incineration, and the incineration efficiency is over 95%. At the same time, the high temperature on the surface of the incinerator can convert heat energy into steam, which can be used for heating, air conditioning equipment and steam turbine power generation.
3. Composting treatment
Domestic garbage is stacked, stored and fermented at 70℃, and organic matter is decomposed into inorganic nutrients by the decomposition ability of microorganisms in garbage. After composting, domestic garbage becomes sanitary and odorless humus. It can not only solve the way out of garbage, but also achieve the purpose of recycling. However, domestic waste compost has a large amount and low nutrient content, so long-term use is easy to cause soil hardening and groundwater deterioration. Therefore, the scale of compost is not easy to be too large.