Discussion on zero emissions in the caustic soda industry
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The environmental situation is becoming increasingly severe. I am interested in learning about the achievement of zero wastewater discharge in the caustic soda industry, and I hope that colleagues can share information on the actual situations in their respective plants. Emissions and emission targets.
It is said that this can now be achieved, but a water treatment unit needs to be built.
Zero emissions? Don’t even think about it; as long as it meets the standards, emissions are allowed. Wastewater treatment is a costly process, and what managers want is to maximize profits. The wastewater from all factories in the area is collected together and sent to specialized companies for treatment; therefore, many factories do not have the capability to treat their own wastewater
This post was last edited by mkp369 on 2012-12-17 at 15:09. Recently, I reviewed the various scientific and technological achievements presented at the 2012 Soda Ash Annual Conference: Tianjin Alkali Plant’s improvements to belt filters for the filtration of heavy soda ash, as well as Dahuahua Group’s research on enhancements to vacuum belt filters. The washing water equivalent in these systems ranges from 0.5 to 0.55 m3/t of soda ash, with the moisture content of heavy soda ash being around 13%. If such results can indeed be achieved, then it is possible to achieve zero emissions; in fact, maintaining proper balance of the mother liquor is key to achieving zero emissions in soda ash production systems.
Although the washing equivalent can be reduced to very low levels, since the mother liquor circulates within the system, the impurity content brought in from salts increases with each cycle, which ultimately affects product quality. Therefore, it is still necessary to have a water treatment system; this is exactly what Tianji does – it regularly removes a portion of the mother liquor to improve product quality. Another best practice is to use a large caustic soda plant along with a smaller ammonia-alkali plant, plus a small calcium chloride production line; this way, true zero emissions can be achieved.
Otherwise, the salt is washed at the source, being treated very thoroughly.