Abstract
An electrolytic crystallization process for recovering and removing phosphate from a high-strength wastewaters such as livestock and industrial wastewaters was developed. In the process, phosphate crystallizes with calcium, magnesium and ammonium on the cathode surface because of a rapid increase in cathodic pH by electrolysis. The crystalline substance formed on the cathode surface was considered to be a mixture of hydroxyapatite (HAp) and magnesium ammonium phosphate (MAP). However, the MAP content of the crystalline substance was not very high. From the mass balance in the, electrolytic cell, magnesium phosphate could be simultaneously formed by electrolysis. In addition, a large amount of potassium was also included in the crystalline substance. The efficiency of the formation of the crystalline substance markedly depended on the kind of electrode material, electrode surface roughness and electrode arrangement.
