Shigehisa Iwai

Estimation of size distribution of small aerosol particles by light-scattering measurement

The size distributions of very small aerosol particles (0.5 < α < 1.9) were determined by means of polarization ratio and/or dissymmetry factor measurements. The values of the polarization ratio and dissymmetry factor were calculated for various size distributions assuming a logarithmic normal distribution. The experiments were performed with linoleic acid, triphenylphosphate (TPP), and stearic acid aerosols, and the estimated values of geometric mean size and standard deviation were confirmed with the values obtained from electronmicroscopic observations.

MULTI-SPECIES OF PLANKTONS AND NUTRIENTS MODEL OF LAKE EUTROPHICATION - A SIMULATION STUDY IN LAKE BIWA -

ABSTRACT The main objectives of this study are to construct a dynamic eutrophication model of Lake Biwa which is the largest one in Japan and to obtain an quantitative relationship between the amount of nutrients and biomass of various species of planktons. This will provide basic information for the future management of water quality to prevent the further deterioration toward a dangerous direction of eutrophication. The lake is devided into two parts geographically and the larger one consists of two layers taking into account the thermal stratification during summer season. The major elements involved in the model are three types of phytoplanktons, zooplankton and nutrients (nitrogen and phosphorus) in both organic and inorganic forms. The particular feature of the study is that lots of experimental and field works have been done for identification of the model structure and parameters under the sponsorship of the Japan Society of Civil Engineers and the Ministry of Construction (Lake Biwa Office).

The producing mechanism, separative and fuel characteristics of municipal refuse☆

Abstract The mechanism of municipal refuse production was investigated by examining the close correlation between products and wastes. Consequently, effects of the variation of the constituents of municipal refuse on its characteristics for the recovery of valuable materials by means of is mechanical sorting, as well as for recovering its thermal energy, regarded as fuel, were studied. An estimation method of the average constituents of municipal refuse was proposed on the basis of national statistical data of production, export, import and re-use in Japan. An investigation was next carried out, at a pilot plant at Kyoto, into the efficiency of mechanical refuse sorting by utilizing several experimental systems consisting of pulverizers, shredders, wind separators and drum screens etc. Furthermore, the characteristics of thermal decomposition and combustion of the refuse as fuel were experimentally revealed after assuming its combustible portion to be a model mixture of cellulosic and plastic materials. Finally, the feasibility and troublesome points of re-usage of municipal refuse are discussed, together with points of potential difficulty.

An advanced sewage treatment process - combination of aerated submerged biological filtration and ultra-filtration with pulverized activated carbon

Abstract A new system was developed and experimentally examinned at a pilot plant, in order to achieve a stable performance and a easy maintenance of the advanced treatment by utilizing a biological process. It differs from the conventional system consisting of the processes of activated sludge, filtration and adsorption.

Reuse of drainage from an office building

Abstract The research pursued the treatment and the reuse of an office building drainage. The treatment system was composed of 4-staged aerated biological submerged filter(ASBF), moving bed filtration(MBF) with chemical coagulation and activated carbon adsorption with a standard treating capacity of 24m 3 /day. The purification characteristics of each unit was examined in detail for various pollutants such as organic compounds, viruses, etc..The ASBF was very effective to remove low molecular organic compounds, while the MBF showed high removal efficiencies of high molecularones and viruses. Moreover,the activated carbon adsorption ensured the requirement of the effluent quality for each reuse purpose. The trouble tests showed the trouble caused on the pipings and metal appliancea by the reused water were mainly attribuable to corrosion. Finally, cost analysis of the reuse system was made based on the experimental results.