In recent years “National Strategy of Biological Diversity (1993)”, “Environmental Impact Assessment Law (1997)” and “Legislation for Nature Restoration (2002)” were established and “River Law (revision 1997)” and “Coast Low (revision 1999)” were amended to add environmental consideration and conservation of environment to the purpose of the laws.
Reflecting such a situation research papers concerning ecologyical engineering are increasing in Japan Society of Civil Engineers. There were only a few papers concerning fish way in 1980s in the society and was some extension in 1990s. In 2003, there were over 60 peer-reviewed papers in the society. The field of studies has been ranging over many subjects, philosophy, gathering basic information, analyzing information, index and modeling. The subjects of research are over 30 species, such as fish, amphibian, bird, crustacean, weed, plant. Research in the field of ecological environmental research will be advanced in the future.

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These days, protection works that is intended to works as pupation place for fireflies are popular in Yamaguchi prefecture. Although a lot of such works have already been constructed, some of them have succeeded and others have failed. Follow-up survey to check the reason of success or failure of the works has not conducted yet. In this study, we conducted field surveys to investigate how fireflies utilize bank protection works in Ichinosaka River, Yoshiki River and Sawanami River.
Firstly, we tracked the climbing larvae from April to May and checked out the pupation place. Next, we established nets on the banks of the rivers from May to June and counted the number of emergence of firefly adults. From those surveys, we found that not only bank slopes but also flood planes were utilized as pupation place by fireflies. Not only the banks themselves but also lighting condition, current velocity, height of the beds and the maintenance program for those facilities were found to be important.

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This paper proposes a method to calculate water and nutrient flux between bays and major basins of large lakes in stratification period, called isotherm surface method (ISM). The data set used for this study involves water temperature time series from a fine-scale profiler, water currents from an acoustic Doppler current profiler (ADCP) and nutrient concentration distribution data by water samples of several vertical layers during 4 year-48 hour continual observations in Shiozu bay of Lake Biwa. A good agreement between the measurement and the flux by the ISM indicates that this method is appropriate. Subsequent analysis shows that this method could be used widely for estimating flux between bays and major basins of large lakes in stratification period if the Wedderburn Number is more than one.

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The structure of microbial community in the methane fermentation of solid waste was investigated by using PCR-DGGE method. The experiments were conducted for a total of 12 reactors operated, respectively, at different substrates (including cow manure, waste activated sludge and potato processing waste), different temperatures (mesophilic and thermophilic) and different HRTs. It was found that the microbial communities during the mesophilic and thermophlic condition are basically different, but there was no significant change in the both of eubacteria and archaea for the HRT ranging from 10 to 30days for the same substrate and the same temperature condition. In the thermophilic reactors acclimated with a same seed, the structure of eubateria clearly depended on the acclimated substrate, but the archaea were similar each other. The analysis of 16SrDNA seaquences indicated that the archaeal bands for thermophilic reactor were similar to that of Methanosarcina thermophila and Methanoculleus thermophilus. In the mesophilic rectors, Methanosaeta sp., Methanobrevibacter sp., Methanomicrobiacea, and Methanoculleus palmaeoli were found.

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Groundwater contamination by tetrachloroethylene (PCE) is one of the most serious environmental problems. PCE is hard to be biodegraded and suspected as carcinogenic substance. In this study, anaerobic degradation of PCE by expanded-bed granular activated carbon (GAC) bioreactor was experimentally studied. This reactor has two treatment mechanisms with the adsorption by GAC and biodegradation by attached microorganism on GAC. Continuous treatment was performed with successful results. PCE was stably removed from 2.7∼17.2mg/L in influent to less than 0.5 μ g/L in effluent under the PCE loading condition of 2.7∼15.3mgPCE/(kgGAC · d). PCE was shown to be dehalogenated to TCE and VC by attached microorganism in batch experiment. Dehalococcoides which dehalogenates PCE was shown to exist in the reactor.

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In this paper, the three dimensional numerical model is developed to predict the heat environment in an urban block in consideration of the effect of each building on wind and radiation. In this model, the time and space variations of velocity, air temperature, air humidity and surface temperature including buildings are evaluated with a horizontal resolution of about 10m. This model is applied to an ideal urban block in order to evaluate the effect of partial greening on decreasing air temperature. Numerical results on a typical summer day exhibit some fundamental knowledge about greening effects concerning with the relationship between the location of greening area and wind direction.

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In this study, the effect of anaerobic co-digestion of grass hay and sewage sludge was investigated by experiments under the mesophilic condition on the process of methane generation from mowed cuttings generated during the maintenance of green tracts of land. The results were as follows. Co-digestion using an existing digestion facility was judged to be impossible because grass hay is light and stable, and so did not keep good condition on mixing and draining of the digesting sludge liquor. Instead of a complete mixing digester, the method of circulation and sprinkling of digesting liquor on the surface of piled-up grass hay was tested. The gas generation of grass hay by co-digestion was 390 L-gas/kg-TS and 200 L-CH₄/kg-TS, and the digestion ratio was 60%.

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The saving effect of the cost required for the reduction of pollution load was estimated for the case in which a tradable emission permit system is introduced to 82 sewage treatment plants in the Tokyo bay watershed focusing on three pollutant indices: chemical oxygen demand (COD), nitrogen and phosphorus. The simulation results showed that an approximately 27% decrease in pollution reduction cost is possible on introducing a tradable emission permit system. Large cost savings can be realized 1) from the profit gained by selling emission permits after introducing advanced sewage treatment systems in the case of large-scale treatment plants and 2) by purchasing emission permits and avoiding the introduction of advanced sewage treatment systems in the case of small treatment plants.

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We manufactured a machinery device for continuous-mass-production of eco-friendly gardening pot (eco-pot) from solid fraction of the shochu-waste. Not only physico-chemical characterization of eco-pot, but also evaluation of its horticulture fertilizer effects was conducted by cultivation of “Komatsuna” vegetable. As the optimum operational conditions, twofold dilution of the raw material (the stillage waste) with tap-water, and 3 seconds of one-shot molding time duration and following 50 seconds of dehydration of time duration are experimentally turned out to be recommended. An eco-pot was evaluated to have a more significant fertilized effect upon long-term crop vegetables like fruits, rather than short-term leaf vegetables.

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Sulfur oxidation and sulfate reduction activities in the activated sludges of six municipal weastwater treatment plants were investigated. A high correlations were recognized between sulfate reduction and sulfur oxidation activities. When the concentrations of acetate and propionate in influent of aeration tank were high, both activities of sulfate reduction and sulfur oxidation were high. The microorganisms community change was analyzed using two activated sludges in which the growth of filamentous bacteria was observed. It was a tendency that when Desulfonema spp. grew in the flocs, the filament length of Thiothrix eikelboomii increasd.

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In this study, the effect of discharge on water quality were investigated at Miharu Dam's inflow river, named Otakine river. The relation between AGP (Algal Growth Potential) and water quality was also investigated. From the survey result, the effect of the inflow nutrients load during normal discharge (on fine days) and high discharge (on rainy days) on the algal growth was examined. The following results were obtained: 1) The contribution ratio of the inflow nutrients load during high discharge for algal growth is 11-97% (average 59%). This is higher than at normal discharge. Thus, counter-measuring the inflow nutrients load during high discharge is necessary in order to suppress algal growth in enclosed water areas. 2) The contribution ratio of inflow BAP (Bioavailable Phosphorus) load for algal growth is high, 23-74% (average 46%). Thus, counter-measuring the inflow BAP load is necessary in order to suppress algal growth in enclosed water areas.

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This study was done to investigate and experiment the effects of phosphorus in the Fine-Grained Soil on the eutrophication of closed water areas. The characteristics of Fine-Grained Soil were investigated, such as eutrophication potential (content and release amount of nutrients), transfer characteristics and the amount of biologically available phosphorus. The following results were obtained: 1) The amount of phosphorus contained in the Fine-Grained Soil is about 1.4-2.1 times the total sampled soil. The amount of released phosphorus in the Fine-Grained Soil is about 1.0-2.3 times the total sampled soil. 2) The amount of phosphorus contained in the Fine-Grained Soil is about 1.8-7.1 times the total sampled bottom sediment. Bottom sediment of small diameter released more phosphorus. 3) The smaller the diameter of the soil, the slower the sinking velocity. Therefore soil erosion and transfer in the river will easily occur. 4) The smaller the diameter of the soil, the higher the biologically available phosphorus percentage. The biologically available phosphorus percentage of the Fine-Grained Soil is about 30 %.

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Water supply systems of small municipalities usually have lots of facilities that are sparsely distributed over large areas and have to be inspected periodically. Unless efficient strategies are used, inspection costs of such water supply systems will be considerably high. In this study, a method for planning cost-effective patrol routes is developed. The minimum total patrol time with the constraint of daily working time was examined by using genetic algorithm. Since some of the facilities are sometimes located in undeveloped areas where access roads are likely to be damaged by natural disasters, the use of automatic analyzers for some facilities are investigated considering costs of analyzers and patrolling as well as reliability for natural disasters.

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