JSCE published “Agenda 21/JSCE” as it's action plan for environmental protection in March 1994. To realize this plan, the role of construction sectors (Planner, Designer, Constructor), they directly concern the construction activities, is essential. As the first step, many organizations of each sector have started to establish and implement EMS. The purpose of this sub-committee is to promote the environmental protection activities through
•mutual understanding of each sector's EMS
•cooperation among three sectors by effective use of EMS

View full abstract

The wastewater reuse systems have an important role for water cycle in urbanized area. So the present status was investigated with a questionnaire survey to the operators of wastewater reuse systems, existing in 23 wards of Tokyo. The results obtained were summarized as follows: (1) 70% of individual reuse systems, wastewater was adopted originally from the view point of cost reduction and environment preservation; and in the case of individual reuse systems, (2) the wastewater reuse volume of wasterwater reuse was about 35% of whole water consumption; (3) working ratio (=treated water/system capacity) was more than 40% when the capacity was less than 60% of whole water consumption; (4) the cost for treatment was less than 600 yen par m³ when the working ratio was more than 50%.

View full abstract

The object of this study is to evaluate quantitatively environmental burdens of the night soil treatment. Energy consumption and CO₂ emission were calculated for the night soil treatment facilities and the sludge recycling/treatment center in operation. Averages of 19 facilities for night soil treatment were 1, 099MJ/kl and 74kg-CO₂/kl on energy consumption and CO₂ emission, respectively. Energy consumption and CO₂ emission of a sludge recycling/treatment center were 944MJ/kl and 63kg-CO₂/kl, respectively. The reduction effects by applying power generation and composting were accounted for 3% of total environmental burdens. The authors also examined the influence of the design variables such as the scale of facility, the constituent processes and the treatment level of the water quality on environment burdens. In addition, the authors tried to compare the night soil treatment facilities with the sludge recycling/treatment center and the sewerage treatment facility.

View full abstract

Ultra-low pressure reverse osmosis with suction filtration below 0.06MPa was applied to ground water treatment. The volume flux of 0.030m/d and the rejection of chloride ion of 90%, was achieved in this experiment. 60 days operation of the volume flux of 0.021m/d was possible without membrane cleaning. The rejection of heavy metals in this system was higher than that of chloride ion. Color substances like humic acid and micropollutants like bisphenol A were detected in the permeate of the reverse osmosis. Diffusion or penetration through defective pores other than convection would be a mechanism for the transport of these organic solutes judging from the experimental results of decrease in the rejections with low pressure operation. The decrease in ion rejection was analyzed by the solution diffusion model and by the extended Nernst Planck equations. The results showed that the selectivity of ionic species was well characterized by the extended Nernst Planck equations, though the estimated value of effective electric charge in the model was lower than that in the case of higher pressure operation.

View full abstract

A wind tunnel experiment was conducted to investigate the effects of a building on tracer gas concentration fluctuation in a wake region of a cubic model perpendicular to the wind direction. Measurements were carried out in a plume emitted from a point source on the model roof using a high-frequency-response flame ionization detector. The concentration fluctuation intensity is approximately constant at a value between 0.4 and 0.5 in a building wake. The peak-to-mean concentration ratio in a wake agrees well with that estimated from the lognormal distribution and is always about 5 times the concentration fluctuation intensity.

View full abstract

Geoenvironmental problems in the Shiroishi Plain such as land subsidence, saltwater intrusion into groundwater and the change of strength characteristics of marine clay deposit, are all related to groundwater movement. To investigate the mechanism of saltwater intrusion into groundwater in the plain, water quality, natural radioactive isotopes and environmental stable isotopes analyses were conducted, directing our attention to the vertical migration of considered cations/anions. The results suggest that the mechanism of saltation of groundwater can be explained as the mixing of groundwater with fossilized seawater in Holocene marine deposit by seasonal pumping-up of groundwater.

View full abstract

This study investigated mobilization and leaching of three natural soil constituents, inorganic colloidal matter (ICM), colloidal organic carbon (COC) and dissolved organic carbon (DOC) from a surface soil (loam) during repeated irrigation events. IMC, COC and DOC showed widely different leaching behavior and, also, behaved differently in soil with and without continuous macropores. COC contributed with only 7% to total colloid leaching. However, DOC dominated total organic carbon leaching with a contribution of 84%. Using these results, calculations on transport of a strongly sorbing Benzo (a) pyrene suggested that DOC-facilitated transport could be a dominating part of Benzo (a) pyrene transport, and potentially violate drinking water criteria indicated by IRIS of EPA.

View full abstract

Recently prompt measures have been taken to deal with the flood control and irrigation works, centering on water conservation of forest as the “Green Dam”. It should be a principal factor on river management to assess water conservation of forest quantitatively from forestal vegetation health for individual basin. The scientific characteristics of soil commonly vary depending on growing state of vegetation. The Ogouchi Dam upper-basin of the Tama River, one of principal water resources for Tokyo and its outskirts, was selected as a study area. As results, the followings were discussed; 1) results from correlative analysis between state of vegetation health by the Landsat image processing and scientific characteristics of soil by situ. site-surveying, 2) verification of relevancy to functions of forest in the river basin.

View full abstract

In order to assess PCDD/Fs emission potentials of incinerated bulky wastes, combustion experiments were carried out with refrigerators, washing machines, bed mattresses/sofas, and TVs in a small-scale batch-type combustor. High concentrations of PCDD/Fs were detected in both soot and bottom ash samples. Soot samples from refrigerators, washing machines, bed mattresses/sofas, and TVs produced PCDD/Fs concentrations of 91, 73, 52, and 12ng-TEQ/g, respectively; while 68, 9, 14, and 8ng-TEQ/g, respectively were detected in bottom ash. PCDD/Fs emission factors calculated from the amount and concentrations of bottom ash were 3.9, 0.27, 0.90, and 0.14μg-TEQ/kg of the four items, respectively.

View full abstract

The general performance of anaerobic digestiers and the diversity of wastes which they can treat have been increasing steadily as a result of new reactor design, operating conditions, or the use of specialised microbial consortia, during the last decade. This paper illustrates examples of prospects and challenges of anaerobic digestion. Anaerobic ammonium oxidation and phosphate fermentation to phosphine are new nutrient removal methods to be coupled to anaerobic digestion. Approaches to recover organic acids and biohydrogen prior to methane fermentation are attracting interest. Solid waste digestion should evolve towards integration of the concepts of energy recovery and Kyoto-agreed CO₂ reduction.

View full abstract