BACKGROUND: This work is focused on phosphorus recovery from anaerobically digested organic fraction of municipal solid waste (referred to as "digestate") as a fertiliser. The main purpose was to propose and test modifications to the electrodialytic process that increase phosphorus extraction, improve the quality of the fertiliser by removing contaminants, and reduce hydraulic retention time to This article is protected by copyright. All rights reserved. allow for smaller system footprints. Strategies tested were: i) lowering the pH of the digestate suspension to below 4.5 using the electrochemical reactions and enhance phosphorus solubilisation from the waste; ii) change the configuration of the electrodialytic cell from 3-to 2-chambers; and iii) stir the sample to shorten the duration of the extraction.RESULTS: Results show that the acidification of digestate by the electrochemical reactions was effective to enhance phosphorus extraction yield. Three-chamber electrodialytic experiments enabled the removal of heavy metals from digestate, producing phosphorus-rich solutions with a low level of metals. This resulted in the production of high quality fertiliser which can be used for agricultural applications. The modification of electrodialytic cell set-up from 3-chamber to 2-chamber did not result in an increase of the phosphorus extraction yields nor did it contribute to the removal of metals from the liquid phase of digestate. The reduction of the hydraulic retention time of electrodialytic extraction of phosphorus from 16d to 9d was attained by the use of stirring and by the electrodialytic acidification.CONCLUSIONS: The increase of phosphorus recovery was accomplished. 90% of phosphorus was successfully extracted from digestate and transformed into struvite.

Circular economy (CE) is a novel concept that promotes sustainable management of energy and materials in the industry. Contrary to linear economy, CE focuses on minimalizing the amount of waste and promoting its use as secondary materials. The article explores the implications of applying CE in the field of: air protection technologies, such as carbon capture and storage, waste treatment, and wastewater treatment technologies. The article concentrates on the current environmental challenges and the modern aspects of circular economy. The main obstacle of circular economy is the requirement for constant economic growth without accounting for environmental externalities.

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