Plainly explained in the preceding article are : the Offensive Odor Control Law, a method of measuring specified odor substances and odor removal technologies. The anticipated trend of odor control regulations is discussed with the current law , and the odor concentration, the most popular standard of measuring odor today, is described. In particular, Takuma's regenerative thermal oxidizer technology and plasma deodorization are introduced, adding an outlines of other deodorization technologies. The pretreatment and air velocity in the duct, important factors in planning deodorization epuipment, are also explained with recommendations. An overview of the future trend of deodorization equipment are concluded in this article.
The following data have been obtained from the operation of Kokubu District Shikine Cleaning Center and Clean Oshima that were built in March 2003. Kokubu plant has been operating smoothly in spite of treating various kinds of refuse including municipal waste, recycling residue, sewage sludge, night soil sludge and waste from landfill recovery. In Oshima, a continuous operation for more than 90 days has been attained. Since the temperature and the pressure in the pyrolysis drums are stable, the pyrolytic reaction is stabilized, not influenced by the fluctuation in the refuse quality. The discharged slag and metals are picked up and the slag is used effectively as asphalt mixture material. In both plants, the usual operation is performed only by the thermal energy of the refuse, without using an auxiliary fuel. The dioxins concentrations at the stack outlets were 0.0082ng-TEQ/m3N at Kokubu and 0.0017ng-TEQ/m3N at Oshima.
We have developed a carbonization technology as a means of utilizing refuse-type biomass and reducing its weight. For this study, we selected wood chip, sewage sludge and soy sauce cake as the refuse-type biomass. We have built a bench scale, externally heated, kiln-type carbonizing furnace of approximately 20kg/h capacity as converted to wood chip basis, on which we conducted the carbonizing tests.
The externally heated furnace enabled us to reduce the weight of wood chip, sewage sludge and soy sauce cake by 80%, 53.5%, and 83% dry base, respectively. Wood chip, when carbonized at 800°C for 40minutes, has become to possess the specific surface area of 395.5m2/g, indicating the possibility of its use as an absorbent of toxic substances.
Carbonizing soy sauce cake required the heat input of 181MJ/h while the heat value of the distillation gas generated by the carbonation was 218.5MJ/h, confirming that carbonation by the self-generated gas is feasible.
Carbonizing test using charcoal at the carbonizing temperature of 800°C for 110 minutes produced activated charcoal having the specific surface area of 569m2/g, suitable for use as an absorbent of toxic substances. Sewage sludge activated at 800°C for 65 minutes possessed the specific surface area of 159m2/g, while soy sauce cake activated at 800°C for 80 minutes resulted in the specific surface area of 192m2.
Recently, the communication network infrastructure has been developing and the cost of communication has come down. Since most local municipalities face financial crises, it is expected that plant operations on consignment and contracts under the Private Finance Initiative (PFI) program will increase in the future for cost reduction.
In order to respond to such situation, it is urgent that plant manufacturers strengthen the total-service organization that includes operational management, post-sale services and plant overhaul.
With this background, we developed the TIPLOS system in 2003 and started its operation last April. This system offers the total operational support using the Internet from the operation support center located on the second floor of our head office building.
The preceding article reports on this system that utilizes remote monitoring of DCS and ITV displays, and provides remote support using the data thus collected, accumulated and analyzed.
We have joined the study project "Development of resource-recycling system for the treatment of municipal sewage and waste" under the guidance of Professor Hiroshi Tsuno of Kyoto University. The project was within the scheme of the core research for evolutional science and technology promotion by the Japan Science and Technology Agency titled "System Technology for Resource Recycling and Minimum Energy Requirement." We have conducted a demonstration test of TCP30 MicroTurbine package using digester gas from the sewage sludge in order to understand its viability and long-term operational characteristics. The result has confirmed that the MicroTurbine canaoperate steadily using digester gas alone. We have tried various methods of removing siloxane from the digester gas, and have found out that activated carbon removes almost 100% of it. We have also conducted a test operation using gas without its siloxane removed, and observed its effect to the turbine and the heat-recovery unit.
With the budget reduction of ODA (Official Development Assistance), it is becoming more customary to provide an aid to developing countries in the form of transferring technology, rather than giving materials.
Therefore, more senior overseas volunteers are sent to developing countries than before.
The forgoing article reports an example of a senior overseas volunteer from JICA. In response to requests from seven small municipalities in Paraguay, one was sent there to cooperate with the local officials to study environmental protection and to formulate plans for the administration of waste disposal.