The author leaves some expectation illustratively for the future development of ware supply engineering. First, a perspective of water supply system in future including past decades, present topics and future perspective of the works was described. Second, education of water supply engineering was described including reform of university and water supply as a training and educational field. Next, basic requirements for new water supply engineering were shown illustrating the results of micro-energy sciences, hydro-energy sciences and monetary-energy sciences. The author points out that Sanitary Engineers must continue their studies to catch up new scientific developments to apply them to our field.

View full abstract

A simple model was developed to evaluate the material budget during the decomposition process of Phragmites australis aboveground biomass, and was applied to a reed stand in Neusiedlersee, Austria, to understand nutrient cycles. The model describes the growth of each organ of Phragmites australis, the collapse of standing dead shoot, the decomposition of leaves and stalks, and nutrient uptake and release of these processes. With a longer period of aerobic decomposition of litter before the litter was transferred to the anaerobic substrate the decomposition rate increased markedly especially from spring to autumn From 33% to 48% of the annual production was decomposed in a year and the rest remained in the anaerobic substrate, depending on the period of the aerobic decomposition of the litter. Releases of nitrogen and phosphorus were high from late spring to the end of summer, but were low and stable in autumn and winter A higher proportion of phosphorus than of nitrogen is expected to remain trapped in the anaerobic layer. Compared with nutrient. release, about 4 to 6 times more nitrogen and 5 to 7 times more phosphorus are taken up during the growing season.

View full abstract

This paper formulated a model of total value of benefits resulting from a qualitative change in environmental goods based on the concepts of Compensating Variation (CV) and Equivalent Variation (EV). We showed that the total value of environmental goods can be expressed by additive separation of use value and non-use value. We also indicated that use value can be separated into a direct use value and an indirect use value. Finally, This paper showed that observable revealed preference data from the market makes respective evaluation of the use value and the non-use value possible.

View full abstract

It is necessary to build up a tool to assess scientifically the safety of the leachate from the landfill site of waste disposal. In this research, the concentrations of heavy metals analyzed by ICP were used to assess the water quality of the leachate. Multiple regression analysis was applied to the obtained data to estimate those sources of the heavy metals that effected to the water quality of river water. And we examined a past influence by investigating the content of the metals on the small particle element (φ<105μm) in the river sediment. The influence of leachate in the past seemed to be low. However, the trace of the effect on the water environment was assumed to be clear as to cadmium and lead.

View full abstract

We constructed a factor model of waste discharge and analyzed the possibility of maintaining the waste reduction effect through variable rates. We examined data from statistical materials and questionnaire survey we conducted toward cities with variable rate program. As a result, 1) we determined that in addition to variable rates, the amount of municipal waste was influenced by the number of persons per household, average income, percentage of persons employed in primary industry, amount of collected waste resources per capita, workers per capita 2) It also became dear that waste reduction through variable rates was maintained over an average of at least 10 years. Results regarding the price effect were inconclusive.

View full abstract

In this study, we examined environmental problems caused by backyard waste burning by residents, and possible solutions to this problem, based on a case study of Moriyama, Shiga Prefecture. Results revealed a significant smoke and soot problems caused by such burning in addition to a possible increase in chlorine pollution. Residents asked that any solution allow them to continue burning o n their property. However, possible corrective steps such a s restricting buming times, monitoring wind direction, extinguishing fires after burning and prohibiting burning of plastics, are likely to be difficult to put into practice due to prevalence of backyard burning Moreover, many residents bum plastic without realizing it. We thus conclude that burning by residents must be restricted.

View full abstract

We examine the validity of pulse count of snapping shrimps for sea environmental monitoring. Snapping shrimps, which make peculiar pulse sound, are found everywhere in the world. Pulse count can be achieved merely by recording their sounds for a few minutes by using a hydrophone without special biological knowledge. This method can be a useful index of the effect of water pollution on benthic animals in fixed-pint observation. If pulse counts become environment indices, we have to do discussion of population. In this paper, we quantified between the pulse counts and the population. We measured snapping shrimp's sound source and the sound source pressure level by the measurement system of sound source with four hydrophones, and we estimated the pronunciation frequency from field survey. By these results being followed relation with water temperature, we could estimate the population using the pulse counts and water temperature from field survey.

View full abstract

The effect of NH₄⁺ concentration on hydrogen production from volatile fatty acids (acetate, propionate and butyrate) by the mixed culture of photosynthetic bacteria was investigated by batch experiments. The initial NH₄⁺ concentrations in the batch cultures ranged from 0 to 12mM. The concentrations of acetate, propionate and butyrate in the medium were 1500, 500 and 1500mg/l, respectively. Hydrogen production was observed at NH₄⁺ concentrations ranging from 0 to 6mM. The hydrogen content in the produced gas (H₂ and CO₂) was 88% at NH₄⁺ concentrations of 4 and 6mM. The hydrogen conversion efficiency was between 12.6 and 42.7%. The maximum hydrogen production rate was 42.3μl/mg dry wt/h. At NH₄⁺ concentration above 8mM, no hydrogen was detected

View full abstract

Recently, environmental problems have been a part of our major topics. In a construction field, increase of discharged soil produced by excavation works and shortage of spoil bank have become serious social problems. Especially, slurry which is specified as industrial waste is mostly disposed because there is no generally acceptable improving method. Accordingly, authors have developed a new apparatus which makes it possible to dehydrate slurry efficiently and to provides improved soil with strength enough to reuse. Furthermore, experiments were carried out in order to apply this apparatus to dehydration of slurry containing cement discharged from soil improvement works. As a result, the dehydrated soil can be used effectively as earth material, and it was confirmed that this dehydration system was applicable to slurry containing cement.

View full abstract

The interchange of the expressway is now under construction on the industrial waste disposal site. It is predicted that some environmental trouble will arise. So we consider that we must evaluate safety from a standpoint of environmental geotechnics.
In this paper, we describe the pneumatic improvement method to utilize for waste sites by means of disposal system of a waste landfill gas. To discharge landfill gas, we installed the exhaled-inhaled system in the waste landfill. Judging from the results of gas distribution extent and gas concentration, the pneumatic method will be useful to environmental improvement. The high level safety of landfill gas was confirmed by becoming aerobic conditions into ground.

View full abstract

The purpose of this paper is to grasp how residents evaluate a river landscape and how some scientific information influence the evaluation. The questionnaires of residents in Nagata along the Tama River were conducted. The environment of the Tama River in Nagata has been changed for 20-30 years. The old Tama River had wide and bared gravel bars. However, there are forest and small gravel bar at Nagata in the Tama River. The remarkable findings are as follows; 1) The difference of evaluation of past river landscape and today's one are relate to age of residents. 2) The evaluation of the present river landscape of the residents in right-bank side is different from one of the residents in left-bank side. 3) In case of giving scientific information, the difference of evaluation between residents in right-bank side and in left-bank side was changed into the same evaluation. 4) The residents between the age of 40 and 70 are influenced by the information more easily than those who are under 40 years old. 5) The rate of the residents, who are able to judge about conservation, increases by the information.

View full abstract

The vegetation areas surrounding the landing strips of airports contribute for the safe operation of aircrafts, and therefore they need to be maintained well. In Japanese airports, turf grass is planted in those areas and needs to be maintained several times per year. The maintenance works are mainly to mow the grass and to dispose the cut grass. Since there are vast areas that require such maintenance, the cost is considerably high. This study, having investigated the current maintenance practices, evaluated types of flora that are suited for the vegetation areas, and it has found that Lippia nodiflora is superior to the others because of its characteristics in its low height as well as its excellent areal coverage.

View full abstract

In order to maintain the vegetation areas surrounding the landing strips of airports, grass needs to be mowed and disposed. Since the areas that require such maintenance are vast, the cost associated with the practice is also enormously high. To reduce the amount of the cost, it is suggested to introduce new types of flora that must have particular natural characteristics such as low in their height and excellent in areal coverage. For this study, Lippia nodiflora was chosen and evaluated for its applicability by follow-up surveys that monitored the intrusion of weeds to the planted area. Based on the results, this study indicates that Lippia nodiflora is effective in reducing the cost because of its advantage in rapid areal coverage.

View full abstract

Control strategies for pre-coagulation and biological filtration processes are discussed with a pilot plant treating actual municipal sewage for 7 months including the winter season. Concentrations of SS, T-ATU-BOD, T-N and T-P in the effluent are less than 3mg/L, 5mg/L, 2mgN/L and 0.2mgP/L, respectively, and transparency is greater than 100cm, under total hydraulic retention time of 3.2h in the biological filtration part. Control of recirculation ratio by ORP measurement is proposed for good operation. Control of methanol addition by on-line nitrate measurement, control of aeration by on-line DO measurement, and control of backwashing by head loss measurement are successfully operated. They prove that easy-maintenance and cost-effective treatment is attainable.

View full abstract

We investigated the blooming period and the morphology of the flowers in Camellia hiemalis for the plants grown under several controlled temperature conditions of the outdoor temperature altered by+4.5°C, +3.0°C, +1.5°C, ±0.0°C and -1.5°C. The results showed that the blooming period began earlier under cool conditions. There were a greater number of fruitful flowers under warmer conditions, with a greater number of petals and stamen, and longer pistils. Thus, the development of flower buds was encouraged but resulted in inhibited sprouting under warmer conditions. It was thought that the blooming period and morphology of the flowers of Camellia hiemalis should change under warmer conditions.

View full abstract

We conducted a survey of M town, which is one of the municipalities that reported abolishing its variable rate program because of an increase in illegal dumping. We analyzed the phenomenon of illegal dumping based on mainly residents' perceptions and behavior. Results of the survey revealed: 1) illegal dumping into rivers, which was recognized to be the most serious problem, existed prior to the introduction of the variable rate program and did not increase significantly due to variable rates; 2) other illegal dumping problems also existed prior to variable rates but grew worse following implementation of the program; 3) the problem most frequently cited by respondents was deterioration of the scenery and living environment, but the number of respondents who cited this problem was smaller than the number who indicated backyard burning was a nuisance.

View full abstract

Rise in traffic accidents, caused by population explosion of ezodeer, becomes major concerns on road maintenance in the eastern part of Hokkaido. A lot of attention to build symbiosis with wildlife is required as in road maintenance and construction of new road in order to follow a change of social situation in recent years.
This study is conducted to monitor some cross road facilities for ezodeer and to observe ecological influence on ezodeer of road construction. It is ascertained that ezodeer trails on a road bank are hardly updated but those on a road cutting are frequently updated. Ezodeers are reluctant to use wildlife underpass. Wildlife overbridge has been used by a handful of ezodeers on the other hand. It is important to consider the nature of ezodeer as mentioned above at planning ecoroad.

View full abstract