In addition to landfill, compost and comprehensive utilization, incineration is also one of the commonly used methods to deal with municipal solid waste in the world at present. Therefore, in the first-tier cities such as Beijing, Shanghai, Guangzhou and Shenzhen, where the land use is intense and domestic garbage is under pressure, the municipal solid waste incineration has the advantages of fast processing, small floor space, significant reduction and harmlessness, The technical development of domestic waste incineration is accelerating year by year, and the proportion of this technology in urban domestic waste treatment and disposal is also getting higher and higher. Although this method can reduce and decontaminate rubbish, a large amount of fly ash is generated during incineration. Fly ash contains a high concentration of harmful heavy metals such as Cd, Pb, Cu, Zn and Cr that can be leached by water Substances and salts, therefore, how to rationalize the disposal of fly ash has become a hot and difficult problem in the field of environmental research all over the world.
Here, the inventory summarizes several major developed countries in the world on the fly ash disposal methods:
At present, there are mainly the following technologies for waste incineration fly ash treatment:
1. Curing cement - hazardous waste landfill.
Advantages: Cement curing technology is mature, the system is simple, easy to operate, lower curing costs.
Disadvantages: solidification of the safe landfill disposal costs are high, heavy metals in the long-term stability is poor, the strength of the cured body after treatment is low.
2. Fly ash melting technology.
Advantages: high capacity, generally can be reduced to 1/2 ~ 1/3 (volume); slag quality is stable, no heavy metal dissolution, renewable; completely decomposed two VA British and other organic pollutants.
Disadvantages: Exhaust gas containing volatile heavy metals such as Pb, Zn and Cd will be produced under high temperature conditions, and subsequent flue gas treatment devices shall be provided; the process is complicated; the energy consumption is high and the processing cost is high.
3. Fly ash cement kiln co-disposal technology.
Advantages: Due to incineration fly ash can replace raw materials, and cement kiln rotary kiln suitable for handling such hazardous wastes, the operation process is easy to control, pollutant disposal thoroughly, and can achieve resource utilization.
Disadvantages: fly ash must be properly pre-treated to reduce the content of soluble salts to meet the cement production requirements and to avoid heavy metal volatilization.
4. Fly ash sintering light aggregate processing technology.
Advantages: At the same time, the innocuous treatment and resource utilization of waste incineration fly ash can be realized simultaneously. Not only the heavy metal pollutants are effectively fixed, the dioxin pollutants are completely decomposed and destroyed, and the calcined products are provided with high-strength light aggregate The characteristics can be applied to pouring ordinary concrete and laying subgrade cushion.
Of course, while referring to these other mountains and stones, we must also consider the specific situation in our country. Based on the nature and handling characteristics of municipal solid waste incineration fly ash in China, the technology for the treatment and utilization of incineration fly ash must be considered both in terms of resource utilization and environmental impact. It is necessary to consider the feasibility of resource utilization of incineration fly ash, And environmental protection to find the best balance, but also to make the environmental characteristics of fly ash treatment products meet the defined criteria.
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