Technical informationTECHNOLOGY

VOL.10 NO.2 (published in Dec-2002)

Photo in Cover : Saitama city Omiya Nanbu sewage treatment center
VOL.10 NO.2 (published in Dec-2002)
Bacterial Chitosan Produced by Citrobacter sp. strain TKF04
Chiyo INOUE*,Katsushi WADA*,
Tomohiko HIRAO**Jin-Ho Jang***,
Hui Ching Hia***,Michihiko IKE***
and Masanori FUJITA***
(* Energy & Environmental Development Dept.
** Technology Planning & Administration Dept.
*** Department of Environmental Engineering, Graduate School of Engineering, Osaka University)


We have been studying Citrobacter sp. strain TKF04 that extra-cellularly produces a using acetic acid as sole carbon source. [1, 2] From previous studies, it has been suggested that the bioflocculant thus obtained (BF04) is a polymer structurally similar to chitin/chitosan. In this study, we have undertaken to maximize the productivity of this biopolymer by pH-stat fed batch culture. The results have proven that the production rate of the extra-cellular biopolymer (obtained by ethanol precipitation from the culture broth after cell removal) considerably depend on culture conditions such as the inoculum size, medium composition, agitation speed, etc. We have also carried out a series of analyses for characterization of its chemical structure. The biopolymer obtained by ethanol precipitation and dialysis followed by freeze-drying was qualitatively analyzed by FT-IR, LCMS, NMR, HPLC (GPC and monosaccharide analysis). According to these results, it is clear that the biopolymer is a polysaccharide mainly consisting of glucosamine units, strongly indicating that BF04 is a chitin/chitosan-like material that we termed "Bacterial Chitosan."

Laten Heat Storage Characteristics of Microcapsule Slurry under a Vacuum Condition
Masatoshi KATAYAMA*and Hideo INABA**
(* General Machinery & Engineering Division
** Department of Mechanical Engineering,School of Engineering, Okayama University)


Highly efficient utilization and storage are the two most important subjects among the energy utilization technologies. Various researches for the latent-heat technology are under way in order to solve the space and time discrepancy between supply and demand of heat. Water, the cheapest heat storage medium presents a problem as it requires large device for its sensible-heat storage. Recently, a new heat transfer medium that fulfills both functions of heat storage and heat transportation has been developed. It uses latent-heat medium enclosed in spherical microcapsules dispersed in water slurry, maintaining fluidity while the medium is in solid phase. The current study has chosen microcapsules filled with paraffin wax with the melting point of 62°C. Heat storage experiments have been conducted at boiling conditions in a heat storage unit under less than atmospheric pressure. The boiling behaviors and conditions, and the influence latent-heat medium gives to heat storage have been observed. As a result, we have arrived at a non-dimensional correlation equation representing heat storing time of the latent-heat storage medium (solid-liquid phase transition time), and another producing average heat transfer rate from the onset to completion of the phase transition.

Measuring Technology by laser and its Appliciation in Waste Incinerators (Report No.2)
Dawei Liu*,Satoshi YOSHIMOTO*,
Masaaki KURATA*and Shizuo KATAOKA**
(* Energy and Environmental Development Dept.
** Energy and Environmental Technology Division)


Recent development in high-performance laser has engendered a rapid advancement in the measuring technology using laser, particularly with the advent of high-output, variable wavelength, diode laser. This has enabled the real-time direct measuring of high-temperature gases during combustion, particularly those containing particulates, considered difficult until now. Our previous article reported on the principle of measuring by laser at the combustion stage of waste incinerator, the measuring of the gas flow inside the furnace and the mixing characteristics of the gas using LDV (Laser Doppler Velocimeter), the method of real-time measuring of O2 concentration in the gas by means of absorption spectroscopy, and the results of measurements and combustion control. In the current article, we have selected to focus on the flue gas treatment system, and discussed the principle of laser measurement, its method and the result of measuring HCl concentration in the exhaust gas from a working incinerator, with our observations

Fluidized-Bed Boiler Firing Chiken Droppings
Kenji MUKAI*Yasuhiro YOSHINAGA*,
Norishige ONO**and Masahide YAMASHITA*
(* Energy Engineering Dept
** Engineering Dept.,Takuma Plant Co., Ltd.)


The manure from cattle, pig and chicken has so far been mostly used for composting. Because the volume keeps growing, better treatment methods are called for, particularly in view of the Law of Livestock Excrement Control that will take effect in the fiscal year 2004. For the effective use of livestock manure, we have built and supplied a fluidized-bed boiler power plant for Nangoku Kosan Co., Ltd. of Miyazaki Prefecture. This unit is capable of burning chicken droppings up to roughly 90,000 ton/year, almost one-half of the total generated in that prefecture. It recovers energy in the form of steam and electric power. The preceding article describes the plant outline and the result of its test run.

Decomposition of Dioxins in Landfill Leachate by Advanced Oxidation Process on TeRRA association
Hiroto HARUKIand Kiyoshi FURUKAWA
(Plant Engineering & Construction Division Sewerage Designing Dept.)


To establish the technology of dioxin decomposition, we have set up TeRRA association, that aims to develop the better efficient leachate treatment system by using advanced oxidation process (AOP). TeRRA assosication compreses Fukuoka University, Kobe Steel Corporation., Nippon Steel Corporation, Takuma Co., Ltd., Today Engineering Co., Ltd., NKK Corporation and Maezawa Industries, Inc. TeRRA association researches three types of AOP technologies the "Ultraviolet-Falling Film (UV-FF)" which is enables to decrease dioxins in treated leachate and sludge generated post-processe such as coagulation sedimentation process and biological treatment, the"Membrane filtration with AOP"whichi enables to surely remove dioxins from treatde leachate, and the"Photocatalystic AOP"which enables to obtain higher efficiency by combining photocatalyst.

A New Film Melting Furnace, its Development and Operation
Satoshi YOSHIMOTO*and Shinji SHIBANO**
(* Energy and Environmental Development Dept.
** Mechanical Design and Engineering Dept.)


We have developed a new 4-surface film melting furnace using fossil fuels with improved melting efficiency. This new furnace keeps its internal atmosphere uniform by having its entire inside perimeter sealed with ash and having small-capacity burners at suitable locations. The testing unit of 8ton/24h size returned fuel consumption of 238~256L/ton of ash, a 20% reduction. The commercial unit with the capacity of 13 tons/24h built on the operational data of the testing unit has proven further fuel savings at 228~240L/ton of ash under stable operation.