Kuraray has developed an epoch-making wastewater treatment system unit that largely cuts surplus sludge generated at industrial and municipal wastewater treatment plants without using any chemical additives. This system will be displayed at the Safety and Technology Japan 2006 Exhibition to be held at thr Tokyo Big Sight October 4 to 6 (Wednesday to Friday), 2006.
The system developed by Kuraray is composed of a biological treatment unit, a sludge elimination tank and a sedimentation tank. In the biological treatment unit, a biocarrier for immobilization of effective microorganisms composed of PVA gel (Kuraray Co., Ldt.) is utilized, which allows for a reduction of the tank size to approximately one fifth of those in current use. The sludge elimination tank enhances the endogenous decay of the sludge by controlling the amount of organic matter in the porcess, which in effect starves the microorganisms, thus reducing their numbers. Through many trail tests it has been demonstrated that removal of surplus sludge from the tank is rarely necessary. In addition, capital investment and running costs are cut, reflecting the fact that this system does not require ozone or any other special chemicals to reduce the sludge volume.
In addition, the system is very flexible in that it can usually be installed in existing wastewater treatment facilities. Kuraray is promoting the system for wastewater treatment facilities of various industries including food, chemical, semiconductor, crystalline liquid and dyeing operations, as well as to local municipalities for treatment of domestic wastewater.
Conventionally, the activated sludge process, which utilizes biomass to break down organic matter, has been utilized for wastewater treatment. However, a large amount of surplus sludge (excess biomass) is generated by the microorganisms as they consume the waste organic compounds, which has to be removed from the tank and disposed of either by land application, landfilling or through incineration. This process is considered to be a serious problem due to cost and deleterious environmental impacts.
Sludge volume reduction systems launched by other firms generally utilize ozone or other chemicals to bread down surplus sludge into soluble components and return it to the biological treatment unit for further processing. For these systems, there have been considerable issues regarding installment space and high investment costs because such processes can require chemicals and heat to and a large reactor to accomplish their task of sludge decomposition.
First Year: ¥500 million; Third Year: ¥2,000 million