Technical informationTECHNOLOGY

VOL.22 NO.1 (published in Jun-2014)

VOL.22 NO.1 (published in Jun-2014)
Biomass Gasification Technology - Thermal Gasification and Biological Gasification
Munechika ITO*,Takashi KAWANO*
(*Energy & Engineering Development Dept.)


Takuma has been building thermal recovery and power generation plants firing various biomass, it has accumulated knowledge and technologies concerning the nature and combustion of numerous biomass sources. Biomass is utilized not only for thermal energy by combustion but also for thermal gasification and biological gasification (methane fermentation). By converting biomass into gas, we can expect the increasing of energy efficiency and method for utilization. In this article, focusing on the technology for biomass gasification we introduce the technology of thermal gasification and biological gasification and our past achievement.

Nantan Clean Center - Operational Report of Biomass Equipment
(*Environmental Engineering Dept. Ⅱ)


Takuma delivered a general waste treatment facility to Nantan integrated administration of a large region work association at the end of August 2013 (the order had been received in September 2010). This facility comprises a combined system efficient raw fuel recovery facility combining general waste and methane fermentation, and a recycle center. In the efficient raw fuel recovery facility, the waste is fermented, excluding bulky waste of combustibility, by mechanically separating the waste so as to generate methane gas or biogas. The biogas is collected and used as the fuel for a gas engine to generate electric power. Of the generated power, residual power excluding the power necessary for operating the methane fermentation facility and the power generation facility is sold to outside by using the feed-in tariff (FIT) system. In addition, fermentation unsuitable materials, mainly plastic, which are removed by mechanical separation and fermentation residue are burned in an incinerator near the facilities, so that the exhaust gas generated by the incinerator is recovered for effective use of residual heat.

Full-scale Demonstration on High-Efficiency Nitrogen Removal Technology by Fixed Bed Type Anammox Process ; Part 2
Keita TAKAKI*,Taro KURUSU*,Naoki IRIE*,Kenichi SHISHIDA*
(*Sewerage Engineering Dept.)


"Full-scale Demonstration on High-Efficiency Nitrogen Removal Technology by Fixed Bed Type Anammox Process" for "Breakthrough by Dynamic Approach in Sewage High Technology Project (B-DASH project)" implemented by the Ministry of Land,Infrastructure, Transport and Tourism of Japan, was conducted by consortium consisting of Kumamoto City and the Japan Sewage Works Agency, Takuma. In this project, an anammox demonstration plant that removed ammonium nitrogen from the digester liquid at a sewage treatment plant was constructed, and the nitrogen removal performance of the plant was demonstrated. During the demonstration operation period in 2012, the demonstration plant continuously treated 50m3/day of the digester liquid with a total inorganic nitrogen concentration of 318 to 437 mg-N/L, attaining an average nitrogen removal rate of 82%.

Report on Demonstration Test for Removing Nutrient Salts by High-rate Moving-bed Sand Filtration
Masanobu FUKUZAWA*1,Tomoyuki DOI*1,Naoya WADA*2,
Taketoshi KUSAKABE*2,Yoshihisa SHIMIZU*2
(*1Sewerage Engineering Dept.
*2Research Center for Environmental Quality Management, Kyoto University


Takuma has developed a technique for removing nutrient salts by moving-bed sand filtration. A sand filter used for this technique is equipment suitable for quick introduction in that it can remove nutrient salts if it is used with chemicals addition equipment. To examine the performance of this high-rate moving-bed sand filter to remove nitrogen, phosphorus, and suspended solid (SS) from raw water with a high concentration of these substances, demonstration tests were conducted at a sewage treatment plant from February 2013 through March 2014. The filter used for the demonstration tests was designed to save space by increasing the filtration rate. The filter was continuously operated for a long time at a filtration rate of as high as 450 to 600 m/day in the nitrogen removal test (denitrification sand filtration). As a result, stable water quality close to a targeted control value was obtained in terms of the NO3-N concentration of the filtered water. The SS concentration was about 0.5 mg/L. This demonstrated that the filter was capable of simultaneously eliminating nitrogen and SS at a high level. It could also stably remove nitrogen at a filtration rate of 700 m/day when the flow fluctuated. In phosphorus removal (coagulation filtration) test, the relationship between the additive molar ratio of the coagulant to the PO4-P concentration of raw water (Al/P) was analyzed. The filter could also continuously filter raw water with a high concentration of suspended solid, capturing four to five times as much SS as the conventional fixed-bed sand filter.

Construction Work to Extend Life of Step Grate Stoker Furnaces at Kyoto City Toba Water Environment Preservation Center
(*Sewerage Engineering Dept.)


This construction work for extending the life of the step grate stoker furnaces was intended to renew facilities for drying and incinerating sewage sludge, which are decrepit after 20 years of operation, so that the facilities would continue operating with stability and over a long time. The facilities were withdrawn and updated during a period from October 2008 to February 2014. Every precaution was made to shorten the shutdown period of the two step grate stoker furnace at the Center. After the life extension construction work, it was confirmed that the drying/ incineration facilities satisfied the reference values of exhaust gas measurement and dissolution test of main incineration ash and that the facilities stably operated. It was also ascertained that emissions of N2O, which was generated during the incineration process, of this incineration facility was about 1/10 compared with that in the conventional fluidized bed incinerator when it incinerates sewage sludge at 850℃, prescribed by ministerial ordinance.

Report on Demonstration Test of Technique for Lowering Water Content of Sludge by Using Rotating-Drum Type Thickener
(*Sewage Engineering Dept.)


Takuma conducted, as a project for 2013, "Research for demonstration of technology of system that generates electric power from biomass in sewer" for the "Breakthrough by Dynamic Approach in Sewage High Technology (B-DASH) Project" of the Japanese Ministry of Land, Infrastructure, Transport and Tourism, in cooperation with Wakayama City, Japan Sewage Works Agency, Kyoto University and Nishihara Environment Co., Ltd. This project employed the Inside Double Coagulation Type Centrifugal Dehydrator as technology for reducing water content of dewatered sludge. Takuma's Rotating-Drum type thickener was used in the preceding stage of the dehydrator. Construction of a demonstration plant was started from August 2013. In a subsequent operation test, it was confirmed that the thickener maintained a sludge concentration of 4% or more and the dehydrator could obtain a water content of dehydrated cake of 70% or more, achieving the initial performance target.

The Demonstration Study of Power Generation System with Sewage Sludge Incineration
(*Sewerge Engineering Dept.)


This study has been conducted as B-DASH Project (Breakthrough by Dynamic Approach in Sewage High Technology Project), entrusted by National Institute for Land and Infrastructure Management, Japan. To carry out this study, industry-university-government consortium has been formed. As a result of performance test, it is confirmed that reduction of N2O emissions from sludge incineration by high temperature combustion, stable heat recovery at the waste heat boiler, and power generation more than planned value.