Phosphorus recovery from sewage sludge ash: A case study in Gifu, Japan

Abstract

The full-scale plant for recovering P from sewage sludge ash (SSA) started operation at a wastewater treatment plant in Gifu City, Japan, in April 2010. P is released from SSA using the alkaline (NaOH) leaching technology and recovered as calcium hydroxyapatite (HAP). The full-scale plant recovers approximately 30-40% P i from SSA and supplies about 300 t/year of by-product P i fertilizer, named Gifu-no-daichi®, mainly to local farmers. The P i fertilizer, Gifu-no-daichi®, is sold through the JA-Zen-Noh (National Federation of Agricultural Cooperative Associations) in Gifu City with a favorable reputation from farmers. Gifu City has been increasing the volume of the fertilizer sales year by year and considers it is critical to make the P recovery process more efficient and stable.