Phosphorous recovery from iron (III) phosphate sludge

Abstract

Phosphorous is an essential element for all living beings with no possible substitute. Phosphorous is a chemical element and is therefore not finite, however the workable findings of phosphorous minerals are. Due to the rapid population growth and depleting phosphorous reserves, there is both an environmental as well as an economical reason to recover phosphorous. As a step towards sustainability and a lower environmental impact, Eka Chemicals wishes to recover phosphorous from the iron (III) phosphate sludge. The aim of this master thesis is to investigate how a waste stream, rich on iron (III) phosphate, can be utilized and how phosphates can be separated and recycled, at Eka Chemical´s plant in Trollhättan. From this master thesis it can be concluded that removing unwanted substances from the sludge is the only short-term method which has shown enough satisfying recovering results to be a potential method to be implemented on site. However a suitable user has to be found in order for the approach to be successful. Using the sludge as raw material for the manufacturing of snail pesticide is one alternative and using it as fertilizer is another. Both the extraction as well as the method of changing the precipitation is possible alternatives for long-term approaches in order to reach the goal of waste prevention rather than waste treatment. However other factors such as economy also have to be taken into account when choosing the best alternative