Cost Benefit Analysis (CBA) is being introduced to government in order to enhance the efficiency and the accountability of the public works. One of the important issues in CBA is how to estimate the value of market-less environmental goods. The Contingent Valuation Method (CVM) is used widely to estimate its value; however, there are many questions about its reliability. In this study, the reliability of CVM is addressed by considering the effect of the consideration range in an example where CVM was applied to value the political options to protect the coastal environment. The results show that people did not consider a number of factors necessary. To improve the method, a new more convenient estimation method is proposed.

View full abstract

A draft-tube-type reactor was applied to a nitrification-denitrification process. The data obtained through the continuous treatment of domestic sewage demonstrated that 97% of BUD, 88% of ammonia nitrogen, and 84% of total nitrogen in influent could be removed under the condition that HRT was kept around 10.4h Appropriate values of design parameters (the ratio of draft tube diameter to reactor diameter and effective height of the reactor) and operational parameters (BOD-SS loading rate, aerobic zone ratio, anoxic zone ratio and C/N ratio) were also clarified. In addition, sludge produced through the treatment was from 28% to 56% less than that produced throughthe treatment by conventional activated sludge processes.

View full abstract

We targeted Japanese Toilet Roll Production from recycled paper as the most typical and simple model of Biomass recycling system. To aim at caluculatetion of the life cycle energy and carbon stocks as token of biomass resources, the production plants surveyed in detail. As the result, the toilet roll manufacturinig was limitted by the location and some environmental standards about water treatments in one side, and had severe restricts to select waste paper materials, not to inferior the production's qualities in the other side. Then the result of Life Cycle Analysis for the production, the paper-owned cordon stock and biomass energy is more sensitive factors compare with the influence of fuel resources consumption.

View full abstract

A pilot scale experiment and a numerical estimation on the performance of ozone/hydrogen peroxide process for the reuse of secondary effluent, were conducted to research the methodology and effects of controlling of dissolved ozone concentration for variation of secondary effluent quality. The major findings obtained are as follows: (1) the amount of TOC and COD removals and the hydrogen peroxide concentration of effluent are stabilized by maintaining dissolved ozone concentration at a fixed level; (2) there exists an optimal dissolved ozone concentration for TOC and COD removals (the range from 0.1 to 0.3mg/L in this study); (3) numerical estimation showed that TOC removal changes by 0.6mg/L with the variation of bicarbonate concentration from 14 to 21mg/L.

View full abstract

An optimal scheme of road paving maintenance was investigated by examining the environmental loading and cost considerations of pavement operations over a 30-year life cycle. Results indicated that the application of recycled materials in pavement construction and repair reduced the effects of environmental loading over the life cycle by approximately 40%. Furthermore, it was observed that environmental loading conditions associated with the maintenance repair stage of asphalt paving comprised 50% of the total environmental loading determined for the 30-year life cycle. Conversely, costs of the maintenance repair stage were 40% of the total life cycle costs. Finally, results suggest that environmental load and cost considerations will be improved and made more efficient over a life cycle period if a regular maintenance routine of simple asphalt repairs is established.

View full abstract

The habitat of the damselfly, Mortonagrion hirosei, which was designated species by the Environment Agency in 1991, was studied at the site of the Tone Kamome Ohashi bridge project spanning the Tonegawa river. Changes of the water level and the salinity of the habitat of this species were measured with actual survey. The larvae of the damselfly were collected only from pool in a sunken place covered with dead leaves of reeds on the riverside. It was concluded that the mesh figure of a distribution of the damselfly can be used as an excellent tool for environmental impact assessment method.

View full abstract

Concrete waste recycling as aggregate used for road construction was evaluated from environmental aspects. Conelusions are as follows: 1) recycling of concrete waste as aggregate used for road construction reduces not only waste but many other environmental loads, but this is not true in case that distance between demolition site and recycled aggregate production plant is longer than distance between demolition site and landfill site; 2) reduction of light on use at preprocessing is mentioned as a method for further environmental load reductions, and as to emission reductions of CO₂, SOx and NOx, distance of transportation is important parameter.

View full abstract

In attempt to increase the usage of recycled construction waste materials, the calcinated gravel drain material (CGDM), which construction waste is calcined a coarse-grained conditions, has been developed. In this paper, it is confirmed that the CGDM can be recycled as a gravel drain material on the bases of the clogging and field piling test result.

View full abstract