How should waste liquids from coal-to-gas projects be treated?
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Many coal-to-gas projects have now been launched, and environmental impact assessments are carried out very strictly, especially regarding the treatment of waste emissions. I would like to ask my colleagues in the industry: what are the main components of the waste liquids generated during production? How is it usually handled? Can the current wastewater treatment processes meet the requirements? Will there be waste liquids, sludge, black water, and other substances containing catalysts? These wastes must not be easy to dispose of; what methods are being used to deal with them now?
During normal production, no wastewater is discharged. Waste includes ash, sludge, spent catalysts, crystalline salts, etc. The so-called unorganized emissions should refer to abnormal operating conditions.
It mainly depends on what type of process is used (gasification)； In the case of pressurized gasification of coal (using Seideng or BGL), phenol-containing wastewater is generated in the gas and water cooling and separation unit. This wastewater is first treated through phenol-amine recovery processes, and then subjected to further regeneration treatments. The volume of such wastewater is large and its treatment is challenging; however, by investing the necessary resources, it is still possible to meet **environmental requirements** ； In the case of water-coal slurry or dry powder gasification to produce SNG (HuiNeng and China Power Investment), the slag treatment unit generates wastewater, but this is easy to handle. There are also boiler blowdowns, etc. As for expensive catalysts, manufacturers specializing in conversion, methanation, and air separation adsorbents can recover them.
What are the common methods used to treat sludge and organic-containing waste? Can these wastes be disposed of using fuel?