The quality of drinking water directly affects human health. Cities and towns should establish a sound water supply system to supply drinking water that meets the sanitary standards for drinking water (see water quality). Strict protection of water supply sources, improvement of raw water treatment (see water treatment plant) and careful maintenance of water supply network (see water supply network maintenance) are powerful measures to ensure excellent water quality.

air pollution control

2. Air pollution

Different areas have different requirements for air quality. Open places should maintain the natural quality of the air. The air in urban areas should be of high quality. The air quality requirements for local space of pollution sources, especially workshops, can be lower, but it should not endanger the health of workers or residents. In order to control air pollution, China has promulgated such laws and regulations as "Quality Standard for Atmospheric Environment" and "Hygienic Standard for Design of Industrial Enterprises". Air pollution is local, such as indoor pollution and individual chimney pollution; There are also regional ones, such as urban traffic pollution. Because the air is flowing, local pollution can become regional, and after the regional pollution scope is expanded, it will even become global. Air pollution will increase the amount of dust falling, reduce visibility, and make trees grow badly or even wither. However, the most important harm is affecting human health, from illness to death. 1952 London fog and haze caused by sulfur pollution in the atmosphere, resulting in 4000 deaths. Acid rain caused by air pollution harms plants and corrodes buildings in a wide range, which has aroused serious concern. The air pollution source is mainly the combustion of fossil fuels (coal, oil and natural gas). Pollutants discharged from some industrial production processes will also pollute the atmosphere, but generally only affect nearby areas. Strong winds and vehicle movements produce dust, which sometimes pollutes the atmosphere (see traffic engineering). Volcanic eruption is another source of pollution. Air pollutants mainly include: ① smoke and dust. All non-gaseous pollutants, also known as particulate matter, are mainly dust and smoke. Dust generally comes from topsoil. Smoke is the product of incomplete combustion, the main body is carbon particles, and other impurities are adsorbed. The harm of smoke and dust is to reduce the overall quality and visibility of the atmosphere. However, lead particles formed during the combustion of leaded gasoline and dust and smoke in industrial production will directly lead to diseases. ② Carbon monoxide. The product of incomplete combustion of fuel is a colorless and odorless toxic gas, which is slightly lighter than air and spreads quickly. In busy cities, carbon monoxide in the ground air comes from cars, and the concentration is sometimes as high as 10 ~ 100 ppm. Living in the air with the concentration of 100 ppm for 8 hours may affect people's mental activities. ③ Sulfur dioxide. Combustion products of sulfur-containing fossil fuels. In China, it mainly comes from coal-fired boilers and stoves. Corrosion of utensils, respiratory irritation. When chimneys spread into the sky, they are often oxidized into sulfur trioxide, forming sulfuric acid or sulfate, which will be dissolved in raindrops, and acid rain with pH below 5 will appear. ④ Nitrogen oxides. Nitrogen oxides such as nitric oxide and nitrogen dioxide are the products of fuel combustion at high temperature. Nitrogen in the atmosphere can be oxidized into nitric oxide at high temperature and then converted into nitrogen dioxide. Nitrogen oxides are reactants in atmospheric photochemical reactions, and their high concentration directly affects health. ⑤ Hydrocarbons. It is generally the product of incomplete combustion of gasoline. Low concentration has no direct harm to health, but it is a reactant in atmospheric photochemical reaction. ⑥ Oxidant for photochemical reaction. The reaction products of nitrogen oxides and hydrocarbons in sunlight, such as ozone, nitric oxide, nitrogen dioxide, peroxyacetyl nitrate (PAN), formaldehyde, acrolein and nitric acid, are all secondary pollutants. Their pollution parameter is total oxidant. The smog containing photochemical reaction oxidant is called photochemical smog, which has caused serious harm, and its comprehensive impact on health is still under study. When the concentration is about 0. 1ppm, it will stimulate the eye membrane and respiratory tract. In addition, nitric acid may be another factor causing acid rain. All landowners carbon dioxide. Under normal circumstances, due to the photosynthesis of plants and the respiration of organisms, the concentration of carbon dioxide in the atmosphere is generally in equilibrium. However, the increase of fossil fuel combustion makes the concentration of carbon dioxide in the atmosphere rise. Because of the greenhouse effect of carbon dioxide, some people think that it may lead to the increase of the average temperature of the earth's atmosphere and the melting of polar ice, resulting in serious environmental problems. Air pollution control measures, afforestation and urban greening are helpful to improve air quality, and building windbreaks can prevent dust from spreading. However, the prevention and control of air pollution mainly lies in: ① energy innovation. If possible, replace coal with pollution-free energy (solar energy, wind energy, geothermal water energy, electric energy and steam) or low-pollution energy (natural gas and oil). Pollution control should also be considered in the distribution of coal. Low-sulfur coal should be rationed to stoves and small-scale combustion equipment, and high-sulfur coal should be rationed to large-scale combustion equipment that is easy to take pollution prevention measures. Fuels with high sulfur content can be reduced by desulfurization technology. See Urban Gas Purification for gas desulfurization technology. ② Innovation of equipment and operation. Innovative dust removal equipment is helpful to reduce the amount of smoke and dust, and improving the efficiency of combustion equipment can reduce the pollution of carbon monoxide and hydrocarbons. Controlling the flame temperature can reduce nitrogen oxidation and carbon dioxide decomposition. The prevention and control of automobile exhaust pollution mainly depends on the innovation of automobile combustion system. There is a lot of research in this field and it is still being innovated. Lead particles in automobile exhaust can only be eliminated without adding lead gasoline. ③ Waste gas treatment. It is the last resort to prevent and control air pollution. The dust in flue gas can be separated from the airflow by filtration, washing, centrifugal separation, electrostatic dust removal, acoustic dust removal and other methods. There are many ways to remove sulfur dioxide from flue gas: limestone powder is blown into combustion chamber, and sulfur dioxide is used to synthesize ash; Absorb or adsorb sulfur dioxide with alkaline substances, and then use it; The flue gas is burned under the action of catalyst, so that sulfur dioxide is converted into sulfur trioxide, and when the flue gas is cooled, it is combined with condensed water to generate sulfuric acid. Nitrogen oxides in flue gas can also be removed by chemical methods.

solid waste disposal

3. Incineration

Disposal methods of solid waste include burial, incineration or processing and utilization. Incineration can also be regarded as a treatment method. Because the ashes still have to be disposed of. The collection and storage of solid waste, especially garbage, not only needs less money, but also affects environmental sanitation. ① Agricultural solid waste (straw, livestock manure) is generally organic and has been used as feed, fuel and fertilizer in rural areas of China. In recent 10 years, agricultural solid waste has been treated by biogas fermentation. Biogas is a clean and convenient fuel, and residue is a good fertilizer. When the amount of industrial solid waste is small, it is usually treated as garbage. When the quantity is large, consider using it first (see industrial waste residue and its application); Bury or burn when it cannot be used. Toxic and hazardous wastes should be treated harmlessly before burial, and those that cannot be treated should be sealed and buried. ③ Municipal solid waste is a mixture of municipal solid waste. In China, kitchen waste is usually collected separately from garbage to feed pigs and fertilize fields. The main methods of garbage disposal are burial, small amount incineration and composting. Burying includes filling the soil, filling the pit, turning the swamp into a site and dumping it in the sea. Abandoning the sea, even if there are no adverse consequences in the near future, is worrying in the long run. In the past, landfill was similar to simple dumping, which continued to pollute the environment and caused rodents. Now it is required to cover and compact the garbage dumped every day with soil, which is called sanitary burial. After the landfill is afforested, buildings can be built on it after 10 years or more. Sanitary landfill can be used to make fake mountains on the landfill, increase the amount of garbage buried and beautify the environment. Taking measures to recycle waste can reduce the amount of garbage.

4. Noise pollution control

Noise is the sound that interferes with people's rest, study, life and work, and even affects their health. Noise consists of many pure tones. The sound pressure (P) of pure tone (monophonic sound) can be expressed by the ratio of sound pressure level (Lp) to reference sound pressure (p0 is close to the hearing threshold of ordinary people, usually P0 = 2× 10-5 Pa), and its mathematical expression is LP = 20 1g (P/P0). The measurement of noise intensity is complicated, which should not only combine the frequency of pure tone, but also combine people's subjective feelings. There are many ways to measure, generally using sound level, and the unit is also decibel. The sound level meter can directly measure the sound level. When the sound level is increased by 40 decibels, the sound pressure is increased by about 100 times, and the interference is greatly increased. It is generally believed that hearing will not be affected if it is lower than 85 decibels. When the jet plane takes off, the noise reaches 150 dB, which makes people's eardrums ache. 160 decibel noise makes people deaf. Noise also affects people's central nervous system and cardiovascular system, which will lead to neurasthenia and cardiovascular diseases. Noise also affects speech and telephone use. Noise that can make people deaf will also affect the use of some instruments. Noise mainly comes from machinery (industrial noise) and vehicles (traffic noise). To control noise, firstly, noisy equipment is not needed, or the process should be reformed, such as riveting for welding; Or change the machinery, such as using a pile driver instead of a pile driver. Secondly, the structure and materials of machinery are innovated, such as improving the accuracy of parts, reducing collision, replacing metal materials with nonmetallic materials, adopting elastic components for transmission parts, adopting vibration isolation base or sound insulation cover for the whole machine, setting muffler at the exhaust port, streamlining the appearance of vehicles, etc. Third, the correct operation, such as the correct use of lubricants, the correct use of speakers and other audio equipment. Establishing sound barriers (such as fences and mounds) or using sound-absorbing and sound-insulating materials on the building surface, as well as reasonable urban planning, are also effective measures (see airport environmental protection).

5. Radioactive pollution control

Ionizing radiation produced by radioactive substances will endanger human health if it exceeds a certain dose. This ionizing radiation can be blocked by sealing radioactive materials with a certain thickness of lead plate or concrete. In nuclear power plants or industrial, medical and scientific research departments that use radioactive substances, as long as they operate and manage according to regulations, the harm can be avoided. Radioactive waste, whether gas, liquid or solid, must be stored below a certain level of ionizing radiation before it is allowed to enter the environment. In order to facilitate storage, it is often concentrated, and the concentrated waste gas and waste liquid must be solidified.

6. Thermal pollution control

Excessive combustion, air pollution and changes in features will change the environmental temperature and affect the local, regional or global natural ecological balance. Power stations and industrial cooling water are the most common sources of hydrothermal pollution. The direct discharge of cooling water into rivers and lakes will increase the water temperature, accelerate the metabolism of aquatic organisms and reduce dissolved oxygen, thus affecting fisheries and destroying the natural balance. Circulating cooling water system can be used to reduce the discharge of cooling water, or it can be cooled by cooling pool and then discharged into natural water.

7. Electromagnetic radiation control

With the rapid popularization of radio broadcasting, television and microwave technology, the power of RF equipment has doubled, which makes the intensity of electromagnetic radiation nearby reach the level that can directly threaten human health. The protection means of electromagnetic radiation is generally to set electromagnetic shielding devices around RF equipment or protected objects to reduce the intensity of electromagnetic radiation within the protection range to the allowable range. Electromagnetic shielding equipment mainly includes shielding cover, shielding room, shielding clothing, shielding helmet and eye mask. Different shielded objects use different devices. In addition, comprehensive prevention and control measures should be taken, such as reasonable layout to keep electromagnetic pollution sources away from densely populated residential areas; Improve electromagnetic equipment to reduce electromagnetic radiation to the environment; Improve the automation and remote control of electromagnetic equipment, and reduce the chances of workers being exposed to high-intensity electromagnetic radiation.