Economic feasibility of phosphorus recovery through struvite from liquid anaerobic digestate of animal waste

Although the struvite crystallization process has proven to be an effective process for the recovery of nutrients from wastewater, this process has not been widely used due to the excessive use of chemicals. In this study, the optimal production conditions, yield, and economic feasibility of struvite using the anaerobic digestion of livestock wastewater were investigated. In addition, the economic feasibility of adding zeolite to improve the productivity of struvite and additionally remove nitrogen was evaluated. The result of the experiment on the struvite yield change according to the molar ratios at pH 9.0 showed that the struvite yield ratio was 99.0% of the stoichiometric yield at the Mg2+ :NH4+ :PO43- molar ratios of 1.2:1.0:1.1. As a magnesium source, MgCl2, concentrated seawater in the seawater desalination process, and MgO were compared, and when MgO was used, struvite productivity and economic efficiency were the best. Also, while the addition of zeolite greatly increased the struvite production and zeolite was also sold as a soil conditioner, the struvite sales benefit was estimated to be 103% of the operating cost.

Automated summary

This study investigated the optimal production conditions and economic feasibility of producing struvite from livestock wastewater, as well as the addition of zeolite to improve productivity and remove nitrogen. Results showed that using MgO as a magnesium source led to the best struvite productivity and economic efficiency. The addition of zeolite greatly increased struvite production and sales benefit, estimated to be 103% of the operating cost.