Patent ID: 7727398

Claim:
A method of discoloring colored wastewater from industries, restaurants, agroforestry, agriculture, livestock raising and restaurants, comprising mixing the wastewater with an acidic substance to acidify the wastewater to a pH no higher than 4; then filtering the acidic wastewater through a filter layer comprising a mixture of charcoal and acid-treated sawdust made from sawdust which had been used for production of fungi, pH of the filter layer being adjusted to an alkaline pH of at least 10 for the filtering by contacting of the filter layer with an alkaline adjuster, the filtering separating from the wastewater a fraction thereof containing components which imparted color to the wastewater; and then passing the wastewater through a filter material comprising acid-treated charcoal embedded with autochthonous microorganisms thereby to adsorb remaining color-imparting components onto the filter material.