RITE-KIYOSE LABORATORY in Obayashi Corporation 

This development was aimed to achieve development of two technologies:thick organic wastewater treatment by photosynthetic bacteria and microalgaeinstead of activated sludge bacteria,and  processing surplus microorganismsinto materials for global environment conservation (use in agriculture,revegetation, purification of water areas), from 1991 to 1995.

About wastewater treatment, it is examined mainly that remove nutrient salts by algae from treatment water of thick organic wastewater by photosynthetic bacteria. As a result, it is found that this wastewater treatment system by algae removed 70〜80% of the total nitrogen from treatment water of domestic grade wastewater at a temperature between 20 and 25 degrees C in 5 resident days.

About production of materials for conserving environment, it is examined the method of processing surplus algae, which stems from wastewater treatment using microorganisms, into the materials utilized as additive to soil for the use in agriculture or revegetation. The applicability of this method is also investigated. As a result, it is found that the algae carbonized at the temperature between 300 and 400 degrees C remain a stable soil improvement material when mixed with soil and accelerate the root growth of plants when added at the mixture ratio of 2.5% to soil. And more,it is examined the method to utilize unprocessed algae. As a result, in several ways to make the materials from algae it reduces the energy requirement that the soil is made fertile by adding algae at a mixing ratio of 1% to soil and disintegrating.

From the above mentioned results, it is suggested the total system that culture algae using treatment water of domestic wastewater, which stems from urban region of half drying area, and the immature soil is made fertile by adding unprocessed algae