Kazuhiko Noto

Novel autotrophic nitrogen removal system using gel entrapment technology

A pilot plant involving a nitritation-anammox process was operated for treating digester supernatant. In the preceding nitritation process, ammonium-oxidizing bacteria were immobilized in gel carriers, and the growth of nitrite-oxidizing bacteria was suppressed by heat-shock treatment. For the following anammox process, in order to maintain the anammox biomass in the reactor, a novel process using anammox bacteria entrapped in gel carriers was also developed. The nitritation performance was stable, and the average nitrogen loading and nitritation rates were 3.0 and 1.7 kg Nm(-3)d(-1), respectively. In the nitritation process, nitrate production was completely suppressed. For the anammox process, the startup time was about two months. Stable nitrogen removal was achieved, and an average nitrogen conversion rate of 5.0 kg Nm(-3)d(-1) was obtained. Since the anammox bacteria were entrapped in gel carriers, stable nitrogen removal performance was attained even at an influent suspended solids concentration of 1500 mg L(-1).

Stability of autotrophic nitrogen removal system under four non-steady operations.

Stable nitrogen removal from the digester supernatant for sludge via the nitritation-anammox process under steady operations of ammonium concentration and flow rate has been often reported. In this study, the effects of four non-steady operations, intentional fluctuations of influent concentration from 890 to 650 mg-N/L and hydraulic load of the 10% increase, temporally shutdown for 3-d and maximum capacity of each reactor, were evaluated in the nitritation-anammox process treating digester supernatant for sludge. No serious effects were observed in the anammox reactor because the aeration-control system in the nitritation reactor responded and controlled the nitritation efficiency satisfactorily against intentional fluctuations and temporally shutdown. Finally, the maximum capacity of each reactor was evaluated, and the nitritation rate was found to be 2.3 kg-N/m(3)/d at a DO of 4.0mg/L, and the nitrogen-conversion rate was 9.0 kg-N/m(3)/d.

More than 30% energy saving seawater desalination system by combining with sewage reclamation.

Abstract Although seawater reverse osmosis (RO) system has been applied commonly in the world, there are still remaining two key issues for further expansion; (1) High energy consumption and (2) Marine environmental impact attributing to high salt concentration of brine water. Herein, new seawater RO system that enables us to overcome the issues has been proposed. The key feature of this system is to reduce salt concentration of seawater by dilution using the water derived from wastewater treatment or reclamation system to achieve the extreme energy reduction of high pressure pump and to make salt concentration of brine water to the same level as the seawater. In order to demonstrate this system, a demo plant designed “water plaza” was built up and operated in Kitakyushu, Japan, where 1,500 m3/d of sewage and 500 m3/d of seawater are used as raw water, and product water is supplied and used as a boiler feed raw water in the Shin-Kokura Thermal Power Plant of Kyushu Electric Co., Inc. During the plant oper...