Extraction of nitrogen and phosphorus in the form of struvite from wastewater with high nutrients concentration

Summary

The world reserves of phosphate ore total about 7000 mln tons among them 40 mln tons are used annually in fertilizer production. It is estimated that this resource will be depleted by 2090. In this connection exploring alternative renewable phosphorus sources is a critical task; therefore much attention is paid to developing economical and technically available methods of phosphorus extraction together with nitrogen from different wastewater types; one of the methods being nutrients precipitation in the form of struvite (MgNH₄PO₄·6H₂O). Studies of struvite production from wastewater and its use as a fertilizer have been carried out in many countries of the world. Process schemes of struvite extraction from municipal wastewater, steel making and tanning wastes, coking process effluents, solid waste landfill filtrate, livestock and dairy farm wastewater as well as from black wastewater in the process of its decentralized processing have been developed. Studying the use of struvite as a fertilizer has been carried out almost 20 years already. Generally the prospects of investing in the production of this product for the agricultural sector are not disputed. The practice of production and supply of struvite as a fertilizer has been fairly developed in Japan. The application of struvite does not result in the increase of heavy metal concentration in farm crops. Fast dissolving fertilizers are not efficient when used on pastures or in forests where fertilization is practiced every few years. In this context the use of slowly dissolving fertilizers including struvite is more reasonable.

Key words

wastewater , nitrogen , phosphorous , struvite , filtrate of solid waste landfills , phosphatic fertilizers