Toshiba releases Habuki pretreatment system for sewage treatment facilities that use the Oxidation Ditch

Toshiba Infrastructure Systems & Solutions Corporation (Toshiba) today announced the launch of Habuki, a pretreatment system with a novel rotating fiber unit for sewage treatment facilities that use the Oxidation Ditch (OD). Installed as a pretreatment  in OD facilities, it delivers low-power, efficient pretreatment that significantly reduces the pollution load on the reaction tanks that decompose and remove pollutants from sewage. Habuki is Japan's first sewage treatment system to combine a pretreatment system using a rotating fiber unit and the OD. It has great commercial potential, as Japan has about 1,000 sewage treatment facilities that use the OD.

Habuki uses a rotating fiber unit to pretreat sewage. The rotating fiber unit is shaped to form a three-dimensional mesh that adheres to and holds a large number of microorganisms. Its constant rotation holds aerobic microorganisms on its surface, and promotes microorganism activity that enhances treatment capacity.

Data on the reduction rate of dissolved biochemical oxygen demand (BOD) and dissolved total nitrogen (T-N) in water discharged from Habuki confirms that it reduces pollutants by more than 70% in about 15 minutes. Since sludge is retained in the fiber unit, its retention time is longer and the proportion of protozoa is larger, realizing a 10-20% reduction in excess sludge against the conventional OD. As the fiber unit rotates and comes into contact with oxygen in the air, the need for aeration is eliminated, and the low-power, simple structure is easy to maintain and manage.

A number of trends are affecting sewage treatment facilities, including the need for optimization and expansion; energy conservation measures to promote carbon neutrality; and measures to address aging facilities. Any capacity increase usually requires the addition of a new line of reaction tanks. Habuki increases the capacity of existing reaction tanks, eliminating the need for new ones, winning reductions in construction costs. It also cuts energy use by reducing the pollution load flowing into reaction tanks, which can reduce power consumption per volume of treated water for aeration by approximately 20% to 40%. Even when repairing aging reaction tanks and aeration systems, Habuki can be temporarily installed to increase the treatment capacity of existing reaction tanks, allowing work to proceed without any loss of the facility's capacity.

In preparing to commercialize Habuki, Toshiba carried out joint research and demonstration operations with the Japan Sewage Works Agency, and conducted tests at Ujiie Water Treatment Center in Sakura City, Tochigi Prefecture, from April 2022 to December 2023. The verification tests confirmed its performance in energy saving and capacity increases, and Toshiba has now released the product.