TITLE Development of Waste-water Treatment Systems with High-efficiency Usage of Ozone
(Joint Program to Promote Technological Development with the Private Sectors)



In the ozone treatment system with a gas-liquid ratio (gas flow rate/liquid flow rate) > 1, more than 90% of total electric power is consumed by the ozone generator. For the large power consumption, the ozone consumption efficiency (the amount of ozone consumed/the amount of zone generated) of ozone treatment system acquired in the conventional technique has only been 70 to 80%. This paper reports a research being conducted by IDEC Izumi Corporation to develop a waste-water treatment system capable of achieving an ozone consumption efficiency of 98% or more.

In 1999, we developed gas-liquid mixing equipment that efficiently mixes ozone and liquid to the level of gas-liquid ratio > 1. In 2000, we built a prototype of 2 m3/h flow-rate ozone treatment system that employed this newly developed gas-liquid mixing equipment, and achieved the ozone consumption efficiency of 98% or more.

Because the waste-water flow at actual applications will be over 2 m3/h and vary in each application, we built in 2001 an ozone treatment system with a higher flow rate. The problem finding and solving activity through the development has contributed to the accumulation of technology required to design the products for practical applications.

In the development of year 2001, we developed the 12 m3/h gas-liquid reactor part, utilizing the technology obtained in designing the 2 m3/h model. We solved various problems which arose during the development, and obtained the technology necessary for designing large ozone treatment systems. The 12 m3/h gas-liquid reactor part has achieved an ozone consumption efficiency of 99% or more in simulated waste-water tests, exceeding the efficiency target originally set at 98%.

A series of development through 2001 has achieved highly efficient usage of ozone. This result is utilized to provide the ozone treatment system for dissolving persis tent agents, such as phenol, at a 20 to 30% less energy consumption, posing less burden on the environment compared to the conventional systems.