The reason why the drainage of thermal power plants is wastewater and not sewage means that the water quality is not seriously polluted.
Wastewater from thermal power plants are mainly due to the increase in water temperature, because the drainage of the thermal power plant is cooling water. As for the main components, it is not much different from the quality of the incoming water. One is that the gases dissolved in the water are reduced and the other is the anti-scaling agent added. to avoid scale. The dosage is very low.
Main components: This type of wastewater contains a large amount of suspended solids, ash, high levels of salt and some organic matter
Examples of treatment are following:
p>First, use microfiltration to remove any particles suspended in the water. The mass fraction is 99% BOD, 98% DCO, 73% total nitrogen and 17% total phosphorus. At the same time, the total number of bacterial colonies. the water is reduced to 3 to 4/L. Then acid is added to lower the pH to remove CO2, and finally it is desalinated by NF to reach boiler water quality. The Eraring Thermal Power Station at the Australian Pacific Power Station currently uses NF to treat this type of wastewater. It treats 1,000 to 15,000 m3 of wastewater every day, which not only reduces the load on the municipal water supply system, but also saves thermal energy. plant $800,000 in operating costs each year. The thermal power plant is preparing to expand its electricity production, and its water consumption will also increase accordingly. It is estimated that by 2010, the amount of treated wastewater will reach 5,000 m3/d, and the benefits will be extremely considerable.
Water treatment plantsx worn out seems to have nothing to do with electricity production. However, with the development of science and technology and the increasing awareness of environmental protection among the people, sewage treatment plants can not only treat sewage, but also transform the organic matter in sewage into energy.
In 1980, the U.S. Environmental Protection Agency required Los Angeles city officials to improve the quality of wastewater treatment or the city would be prohibited from discharging its treated wastewater into the Pacific Ocean. As a result, the Los Angeles municipal government invested hundreds of millions of dollars in a large-scale renovation and expansion of the wastewater treatment plant. The wastewater discharged after treatment by the renovated treatment plant fully meets the standards. What's even more interesting is that they use thesludge left after wastewater treatment to produce electricity, truly turning waste into treasure.
The Los Angeles Wastewater Treatment Plant, opened in 1985, can treat 100 million gallons (378,500 cubic meters) of sludge (the sticky residue from initial wastewater treatment) per day , which are then recycled. This sludge is transformed into fuel; at the same time, when the wastewater passes through 18 microbial wastewater treatment tanks, a large amount of methane can also be produced. The above two fuels can be used for thermal power generation, with a total electricity production of 25,000 kilowatts. In addition to 60% of the electricity produced for the treatment plant's own use, 40% can be supplied to other companies.
To transform the sludge into fuel, an evaporator must be installed. The use of an evaporator allowsand save 25 to 30% more energy than using a general dryer. The sludge is dried in the evaporator and becomes powder. This powder is a good fuel. The sludge regeneration fuel is fed into a fluidized bed reactor to be vaporized and then burned under anoxic conditions, using the energy it generates to produce electricity. Burning in this way can better improve the high thermal efficiency and significantly reduce nitrogen oxides in the exhaust gas.