title: Recovery of soluble chloride salts from the wastewater generated during the washing process of municipal solid wastes incineration fly ash.
abstract: Water washing is widely used as the pretreatment method to treat municipal solid waste incineration fly ash, which facilitates the further solidification/stabilization treatment or resource recovery of the fly ash. The wastewater generated during the washing process is a kind of hydrosaline solution, usually containing high concentrations of alkali chlorides and sulphates, which cause serious pollution to environment. However, these salts can be recycled as resources instead of discharge. This paper explored an effective and practical recovery method to separate sodium chloride, potassium chloride, and calcium chloride salts individually from the hydrosaline water. In laboratory experiments, a simulating hydrosaline solution was prepared according to composition of the waste washing water. First, in the three-step evaporation-crystallization process, pure sodium chloride and solid mixture of sodium and potassium chlorides were obtained separately, and the remaining solution contained potassium and calcium chlorides (solution A). And then, the solid mixture was fully dissolved into water (solution B obtained). Finally, ethanol was added into solutions A and B to change the solubility of sodium, potassium, and calcium chlorides within the mixed solvent of water and ethanol. During the ethanol-adding precipitation process, each salt was separated individually, and the purity of the raw production in laboratory experiments reached about 90%. The ethanol can be recycled by distillation and reused as the solvent. Therefore, this technology may bring both environmental and economic benefits.
authors.affiliation: a College of Environmental Sciences and Engineering, Beijing Key Laboratory for Municipal Solid Waste Utilization and Management , Peking University , Beijing 100871 , People's Republic of China.
authors.forename: Hailong
authors.initials: H
authors.lastname: Tang
authors.forename: Aris
authors.initials: A
authors.lastname: Erzat
authors.forename: Yangsheng
authors.initials: Y
authors.lastname: Liu
mesh_terms: D011232:Chemical Precipitation; D002712:Chlorides / Q000737:chemistry*; D060729:Coal Ash; D003460:Crystallization; D000431:Ethanol / Q000737:chemistry; D017745:Incineration; D059027:Recycling / Q000379:methods*; D012492:Salts; D012995:Solubility; D062065:Wastewater
chemical_list: D002712:Chlorides; D060729:Coal Ash; D000431:Ethanol; D012492:Salts; D062065:Wastewater
keywords: fly ash; recovery; soluble salts; washing process