(Abstract)

Sewage treatment technology has changed according to occasional social circumstances and requirements, allowing development of different techniques. Along with improvement of treatment and purification functions, water treatment technology has been enhanced on energy conservation, cost reduction and maintainability. Sludge treatment technology has also been developed such as responses to low-concentration sludge, increased sludge volume, promoted recycling of sludge, effective use of sludge as biomass, energy conservation, reduced greenhouse gas and energy creation. Looking back over these past 20 years on sewage treatment technology, this paper describes its transition divided into water treatment technology and sludge treatment technology, in light of the sewerage issues and the circumstances surrounding sewerage. It also introduces TAKUMA's main developed techniques over these 20 years to respond to them.

(Abstract)

Global efforts are underway to assist developing countries, develop mercury control techniques, reclaim the environment, and work on other issues toward putting the Minamata Convention on Mercury into effect as early as possible (in around 2016). When the said convention has taken effect, mercury emissions from incineration plants for municipal refuse will be regulated, which will require a mercury control technique. As a solution to this, we determined the concentration of mercury in flue gas from incineration plants for municipal refuse and conducted verification tests to find a technique for reliable removal of mercury from it and reduction of maintenance and operation cost. The tests revealed that when mercury has flown into a bag filter, it is first adsorbed by fly ash on the filter cloth, and then desorbs from the fly ash and goes out to the downstream side of the bag filter over time. By cleaning the filter cloth when mercury is detected in the flue at the bag filter exit and then adding activated carbon, it is possible to flick the fly ash that has adsorbed mercury and allow the activated carbon to adsorb the mercury desorbed from the fly ash, allowing possible control of the amount of mercury to be discharged downstream.

(Abstract)

A fly ash circulation system is designed to reduce the usage of chemicals by injecting slaked lime containing fly ashes collected by a bag filter into the bag filter again and making effective use of unreacting slaked lime in the fly ashes. The paper reports the operation results of the fly ash circulation system installed at Ecopark-Anan, general waste incineration facilities, in March 2014. It was found out that the usage of chemicals had been reduced by 40 to 50% in removal of HCl and SOx during fly ash circulation in actual operation of this facility. It was also confirmed that controllability was stabilized by fly ash circulation.

(Abstract)

Having a high effect of cooling the fire grates, a water-cooled stoker is capable of greatly enhancing their durability and adapting to the burning materials with a high calorific value and high-temperature combustion with low air ratio. We developed the water-cooled stoker by ourselves, and we installed the first water-cooled stoker in an incinerator that disposes industrial wastes with a high LHV of 16.7 MJ/kg (4,000 kcal/kg) in Mar. 2007. With the air-cooled fire grates before remodeling, the durability was approx. 1 to 1.5 years, but improved close to 5 times longer by replacing them with the water-cooled fire grates. In addition to the above, the water-cooled stoker has been installed in several industrial waste incinerator facilities with a high heat load, allowing each plant to continue stable operation. The water-cooled stoker has been also introduced into the municipal waste incinerators for the purpose of reducing maintenance cost, starting operation from Dec. 2013.

(Abstract)

We received a construction order for the waste incineration facilities "Ecopark-Anan" from Anan City in Sep. 2010 and completed its construction in Mar. 2014. This incineration facility consists of "heat recovery facility" and "recycling facility". Heat recovery facility generates electricity and makes hot water to use at the facility. And ash is utilized as slag by melting furnace. Although the scale of this incineration facility is 48 t/day×2 systems, this facility recoveries heat energy, and generates electricity by steam turbine. Generated electricity is used in this facility and surplus electricity is sold. This paper reports the features of the heat recovery facility and its operational situation.

(Abstract)

The following reports improvement work of the Kobari Clean Center and Zushi City Environmental Center completed in 2013. Repair work of the exhaust gas treatment equipment, etc. of the Kobari Clean Center was started in May 2012 and completed in Sep. 2013 for the purpose of changing the aged exhaust gas treatment system of the facilities running from 1984 to baghouse and extending the service life of the facilities. Newly installed exhaust gas treatment equipment satisfies all the exhaust gas guarantee values and is running successfully. Key improvement work of the Zushi City Environmental Clean Center was started in Dec. 2011 and completed in Mar. 2014 for the purpose of recovering the degraded functions of the facilities running from 1981, inhibiting emissions of greenhouse gas (CO2 reduction) and extending the service life of the facilities. Taken as CO2 reduction measures were employment of a highefficiency motor, change to an inverter control system, and introduction of an automatic combustion controller allowing low air ratio operation. These measures have reduced in-plant electric power consumption and achieved CO2 reduction rate of 13.1% compared with before improvement work. Either work was conducted while running the incinerator. Various contrivances were made in the construction methods, procedures and processes. Both facilities satisfy expected performance and continue successful operation to date after completion.

(Abstract)

In the "Breakthrough by Dynamic Approach in Sewage High Technology Project" (B-DASH Project) by the Ministry of Land, Infrastructure, Transport and Tourism of Japan, we conducted a "full-scale demonstration on high-efficiency nitrogen removal technology by fixed bed type anammox process" as the 2012-2013 project in consortium sonsisting of Kumamoto City and Japan Sewage Works Agency, Takuma. This project is a study entrusted by the National Institute for Land and Infrastructure Management (NILIM) of the Ministry of Land, Infrastructure, Transport and Tourism. An anammox demonstration plant was continuously operated at a water treatment volume of 50 m3/day for the purpose of removing nitrogen from anaerobic digester liquid at a sewage treatment plant, successfully demonstrating average treatment performance of 80% or more as a nitrogen removal efficiency during stable operation. Even during the inflow load fluctuation time when a raw water concentration was temporarily fluctuated, nitrogen removal performance almost equal to stable operation was obtained. Based on these results, the NILIM designed a guideline for introducing a technology for high efficient nitrogen removal using the fixed bed type anammox process, which is now made public at its website for development of this technology.

(Abstract)

We constructed leachate treatment facility to CLEANTEC Inc. in Jun. 2013. In this paper reports the outline, facility configuration and operational situation of this treatment facility is reported. This facility is intended to treat leachate from the landfill and have a daily treatment capacity is 220 m3/day. This includes advanced treatment equipments such as an ozonation treatment equipment for respond to high-concentration COD, a boron adsorption tower for removal boron in drain and a desalinization equipment. Starting treatment from Jul. 2013, this facility have treated 167 m3/day on the average during one year until Jul. 2014, continuing operation in which discharge water quality criteria are satisfied.