METHOD OF TREATING ORGANIC WASTEWATER AND SLUDGE AND TREATMENT APPARATUS THEREFOR

摘要

With respect to a technology of not only removing phosphorus in the form of crystal of magnesium ammonium phosphate (hereinafter referred to as "MAP") from a wastewater containing phosphorus and nitrogen but also recovering MAP crystals, there are provided a method and apparatus for efficiently recovering MAP crystals of high purity and high quality. In particular, a method of treating sludge, characterized in that a sludge mixture liquid generated by a biological treating system of organic wastewater is treated by an anaerobic digestion tank to thereby perform sludge digestion; then a magnesium source is added to the anaerobic digestion tank so as to form and grow MAP crystal grains in the anaerobic digestion tank; the sludge mixture liquid containing the MAP crystals is withdrawn from the anaerobic digestion tank; solid matter containing the MAP crystal grains is separated and recovered from the withdrawn sludge mixture liquid; and portion of the sludge mixture liquid after the separation and recovery of MAP crystal grains is returned to the anaerobic digestion tank.