Cement plant hazardous waste treatment method
Date：2019-08-21 16:50 Source：cementepcViews:
Hazardous waste treatment methods can be divided into three categories: physical method, physicochemical method and biological method.Many of these methods are common to chemical production.
(1) solid waste treatment
For cement plant solid waste (waste residue), the common physical treatment process includes: compaction, crushing, sorting.
(2) liquid waste treatment
For cement plant liquid waste (waste liquid), the common physical treatment process including: settlement, air flotation, centrifugal, filtration, distillation, and so on, and blowing off, micro filtration, ultrafiltration, nanofiltration and other processes are less used.
(3) waste residue treatment
The physicochemical methods commonly used to treat waste residues include heat treatment (incineration, pyrolysis), solidification/stabilization.
Physical and chemical treatment processes commonly used for waste liquid include coagulation, chemical precipitation, acid-base neutralization, REDOX, adsorption and desorption, ion exchange, incineration, etc., while replacement, electrolysis, extraction, electrodialysis, reverse osmosis, photodecomposition and other processes are rarely used.
Biological method is only applicable to organic waste, among which the organic solid waste used in cement plant includes composting method and anaerobic fermentation method, and the activated sludge method and anaerobic digestion method used in organic waste liquid.
Hazardous waste disposal, is refers to the use of hazardous waste incineration and other change its physical and chemical method, biological characteristics, to reduce the amount of waste generated, solid hazardous waste volume, reduce or eliminate their dangerous composition, or will eventually hazardous waste in accordance with the requirements of the environmental protection regulations of the premises or facilities and no back to the activity.
The methods of disposing hazardous waste mainly include geological disposal and Marine disposal.Marine disposal includes deep sea dumping and sea incineration.Land disposal includes tillage, permanent storage or retention storage, land landfill, deep well perfusion and deep formation disposal, among which land landfill disposal technology is the most widely used.Marine disposal is now banned by international conventions, but geological disposal is still the most commonly used waste disposal method in the world.
1. Landfill method
Landfills are the ultimate means of disposing of hazardous waste.This method includes site selection, landfill design, construction landfill operation, environmental protection and monitoring, site utilization and other aspects.In essence, hazardous waste is spread into a thin layer of a certain thickness, which is compacted and covered with soil.This processing technique has been widely used at home and abroad.Land filling method is usually divided into sanitary land filling and safe land filling.
2. The incineration method
Incineration is a comprehensive process of high temperature decomposition and deep oxidation.Through incineration, inflammable hazardous waste can be oxidized and decomposed to achieve the purpose of reducing volume, removing toxicity, recycling energy and side I products, which is a better way of solid waste treatment.
Incineration has the advantage of rapidly and substantially reducing the volume of combustible hazardous waste.For example, in some newly designed incinerators, the waste volume after incineration is only 5% or less of the original volume.Through incineration, some hazardous wastes can destroy their structure or kill pathogenic bacteria, so as to achieve the purpose of detoxification and disinfestation.In addition, heat can be provided by incineration.
The disadvantages of incineration: first, the incineration of hazardous waste will produce a large number of acidic gases and incomplete combustion of organic components and slag, such as direct discharge into the environment, will inevitably lead to secondary pollution;Second, the investment and operation management fees of this method are high. In order to reduce secondary pollution, the incineration process must be equipped with pollution control facilities and complex test instruments, which further increases the treatment costs.
3. The curing method
Solidification method is to mix cement, plastic, water glass, asphalt and other coagulants with hazardous wastes for solidification, so that the harmful substances contained in the sludge are sealed in the solidified body and are not leachated, thus achieving the goal of stabilization, harmless and reduction.
The solidification process reduces the permeability of the waste and makes it into a high-strain final product, thus turning hazardous waste into harmless waste.
4. The chemical method
Chemical method is a kind of chemical properties of hazardous waste, through acid and alkali neutralization, REDOX and precipitation, etc., to convert harmful substances into harmless final products.
Many hazardous wastes can be detoxified through biodegradation, and the detoxified wastes can be accepted by soil and water bodies.At present, biological methods include activated sludge, gasification pool, oxidation pond and so on.
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