The precipitation of the mineral struvite (magnesium ammonium phosphate) precipitation is proven chemistry for the pre-treatment of landfill leachate. New work in the International Journal of Environment and Waste Management suggests that sustainable sources of the requisite phosphorus are urgently needed and posits that ash from waste fishbones could be such a source.
M. Darwish, M.H. Puteh, and A. Aris of the Universiti Teknologi Malaysia in Johor and A. Abdul Kadir of the Universiti Tun Hussein Onn Malaysia, also in Johor, are investigating the possibilities.
“One of the major environmental problems related to solid waste management is the landfill leachate,” the team writes. “Leachates generated from municipal landfills are high strength waste streams that contain high concentrations of many pollutants, such as ammonium nitrogen, organic matter, and heavy metals,” they add. The researchers point out that landfill leachate can be processed using anaerobic biological treatment but this is only efficient if the ammonia content of the leachate can be reduced as ammonia is toxic to the microbes needed for this type of treatment.
The team explains how phosphorus-rich fishbone ash can be mixed with magnesium oxide before adding to landfill leachate. The two components react with noxious and odorous nitrogen compounds in the leachate, which form the “ammonium” part of the struvite which then comes out of solution as a solid material that can then be processed further safely.
The researcher’s tests with this approach to struvite precipitation show that it works well when compared with conventional phosphorus and magnesium starting materials for this kind of cleanup of noxious leachate from landfill. They were able to demonstrate some 70 percent removal of ammonium nitrogen from sample leachate with their approach. “Compared to previous works, the application of Mg-P mixture to actual landfill leachate is competitive, taking into consideration the achieved side advantages,” the team concludes.
Darwish, M., Puteh, M.H., Aris, A. and Abdul Kadir, A. (2021) ‘Utilisation of fish waste bones ash for struvite precipitation in actual landfill leachate’, Int. J. Environment and Waste Management, Vol. 28, No. 2, pp.209–218.