PURPOSE: To decompose thiourea by microorganisms efficiently, by a method wherein nutriment is added to thiourea-containing waste liquid, and microorganisms belonging to the Pseudomonas family and having ability to decompose thiourea are propagated in the waste liquid.
CONSTITUTION: To the waste liquic containing thiourea in a concentration of 50W1,000ppm, is added nutriment such as a carbon source (e.g., carbohydrates, lower alcohols, organic acids), a nitrogen source (e.g., ammonium sulfate, pepton), inorganic salts (e.g., NaCl, KH2PO4) and organic micronutrients (e.g., amino acids, vitamins, a yeast extract). The waste liquid is then maintained in an aerobic condition at a pH of 7.0W8.0 at a temperature of 10W35°C for 1W5 days for cultivation to propagate microorganisms belonging to the Pseudomonas family. Thiourea is reduced in amount with the lapse of the cultivation time, and is completely decomposed in a period of time of 24W48hr. After the microorganism treatment, the waste liquid is perfectly made free of difficulty separable substances such as thiourea.
NISHIYAMA TOORU
KANOU HIDEO
