Effectiveness of water softening residuals as components of road deicing chemicals: Model analysis of freezing point depression

Water softening residuals disposal is a worldwide issue due to the lack of effective reuse alternatives. The current principal disposal methods of landfilling and land application are quite costly due to the dewatering and transportation costs involved, and these operations can also cause potential...

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Bibliographic Details
Published in:Journal of environmental management 2021-09, Vol.293, p.112888-112888, Article 112888
Main Author: Mathews, Alexander P.
Format: Article
Language:English
Subjects:
Activity coefficient
Biodegradable deicer
Freezing point depression
Reuse
Water softening residuals
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Summary:Water softening residuals disposal is a worldwide issue due to the lack of effective reuse alternatives. The current principal disposal methods of landfilling and land application are quite costly due to the dewatering and transportation costs involved, and these operations can also cause potential environmental harm from leaching of the additives used in the treatment process. This research is aimed at the use of water softening residuals in the production of biodegradable road deicers that would be beneficial in replacing the highly corrosive and environmentally harmful chloride salts that are currently used for road deicing. Experimental data developed show that calcium magnesium acetate (CMA) and calcium magnesium propionate (CMP) deicers produced using water plant sludges are effective in deicing applications. A mathematical model is developed for predicting freezing point depression of CMA and CMP deicers as a function of molal concentration. The model predictions are found to match well with the experimental data, providing confidence in the use of this model for the effective design water softening sludge based deicers. The information developed herein provides options for the sustainable management of softening residuals and the concommitant mitigation of environmental harm associated with road deicing operations. •Reuse of wáter softening residuals in the production of biodegradable road deicers is explored•Water plant sludge based calcium magnesium acetate (CMA) and calcium magnesium propionate (CMP) are found to be effective deicers•A mathematical model is developed to predict freezing point depression of CMA and CMP salts
ISSN:0301-4797
1095-8630
DOI:10.1016/j.jenvman.2021.112888