Agrochemical nutrients reclamation from human urine and wastewater via struvite (MgNH₄PO₄·6H₂O) crystallization: a comprehensive review on recent developments

In recent years, nutrient reclamation from human urine and municipal wastewater has emerged as a major research domain because of the limited availability of agro-nutrients like phosphorous, nitrogen and potassium-based fertilizers. Human excreta and municipal wastewater coming from untreated sewage creates numerous adverse effects on water bodies in the form of eutrophication and red tide etc. In the last few years, certain practices have been developed which provide nutrient reclamation along with a sanitation value chain. Struvite crystallization is one of the leading approaches that offer nutrients reclamation like nitrogen, phosphorous and potassium via producing a slow-release fertilizer identified as struvite. This article aims to deliver a comprehensive view into how nutrient reclamation from human urine and municipal wastewater via struvite crystallization could be a sustainable approach and economical source of income. In the present review, we have compiled research reports from 2000 to 2020 on nutrient reclamation from human urine and municipal wastewater via struvite (MgNH₄PO₄·6H₂O) crystallization. Additionally, we also describe the different ways of improving struvite formation from human urine and municipal wastewater like a combination of physical adsorption with chemical precipitation, chemical precipitation with the electrochemical process and chemical precipitation along different stages of the treatment process.