Absorption of phosphate ion in swine urine using CMC gel

Takigami, Machiko*; Amada, Haruyo*; Nagasawa, Naotsugu; Hiroki, Akihiro; Kasai, Noboru; Yoshii, Fumio; Tamada, Masao

Shortage of phosphorus becomes a serious problem in the world. The removal of phosphorus in swine urine is a big concern for the environmental conservation. To solve both problems, absorbent to absorb phosphorus in swine urine was developed using carboxymethyl cellulose (CMC) and Iron. The gel formation proceeded instantaneously when CMC and Iron (III) chloride were mixed, while gel was not formed immediately when Iron (II) chloride was used. Oxidation of Iron (II) to Iron (III) occurs gradually in Iron (II) aqueous solution. However, addition of CMC to the Iron (II) solution promoted the oxidation to form gel. The rate of gel formation could be controlled by addition of acid to CMC-Iron (II) mixture. The resultant gel absorbed phosphorus in swine urine. The absorption was about 97% in swine urine containing 78 mg/L of phosphorus.