Urine a source for struvite: nutrient recovery – A review

Department of Civil Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711 103,

West Bengal, India

E-mail: guptaanirban@hotmail.com

Manuscript received online 01 February 2019, accepted 14 March 2019

Urine is not a waste but can be a raw source for struvite (MgNH₄ PO₄ .6H₂O) which can be used as a substitute of fertilizer, since direct usage of urine have demerits such as it is not easy to store large quantity of urine at a place prior to use, it is also not economic to transport collected urine in large volumes, it will have some soil-nutrient ill effects, urine when not properly disposed it can lead to eutrophication, odor problem, contamination to drinking water bodies and have pathogen risk for humans but with struvite use these issues can be minimized and it is cheap to transport solid struvite. Because of the increasing prices in the market of chemical fertilizers, struvite production is important for the recovery of nutrients. Fertilizer industries also produce Greenhouse gases while struvite, when produced at large scale these emissions from industries, will be minimized because it will reduce the burden of fertilizer industries of producing more quantity of chemical fertilizers. Production of chemical fertilizer required phosphate which is available by extracting phosphate ores resulting in exploitation of this natural resource. The struvite can be produced by chemical or electrochemical processes by using salts of magnesium or by using magnesium plates respectively with urine as a source. This review will help in understanding that why it is essential to produce struvite. The chemistry behind the precipitation of struvite, what essential nutrients it has so that it can be used as an alternative to fertilizers for plant growth, its economic value and with this many environmental problems can be reduced.