Research for Supporting the Emergency Water Supply Planning Based on the Liver's Adaptability to Disaster-affected Environment
Nakakubo T., Suto M, Sano S. and Otaki M.
Ochanomizu University, Tokyo, Japan
ABSTRACT
The purpose of this study is systematizing emergency water supply planning concepts where a liver's
adaptability to disaster-affected environment is included as a planning factor. Toward quantifying
the adaptability, we designed water-related living activities based on different types of quality of life (QOL)
standards for each end-use. Through the questionnaire survey, the percentages of selected activities in
each end-use and in each term were aggregated, and then we set water demand rates and disaster supplies
demand rates. The next step was estimating demands for water and disaster supplies in each term following
a water failure under a case study targeted for a scenario earthquake: Southern Ibaraki
Prefecture Earthquake. Based on the estimated results, we considered the emergency water supply plan collaborated
with preparedness of disaster supplies.
The Mechanism of Chlorine Damage Using Enhanced Green Fluorescent Protein-Expressing Escherichia coli
Mizozoe M., Otaki M. and Aikawa K.
Ochanomizu University, Tokyo, Japan
ABSTRACT
This study investigated how chlorine inactivates and damages Escherichia coli cells. E. coli
that had transformed to express enhanced green fluorescent protein (EGFP) at the cytoplasm was
treated with chlorine. Damage to the cell membrane and cell wall was analyzed by measuring the
fluorescence intensity of the leaked EGFP, then accounting for the fluorescence deterioration. At pH 7,
E. coli was lethally damaged after treatment with chlorine, but significant leakage of EGFP was not
observed. In contrast, significant leakage of EGFP was observed at pH 9, even though E. coli was not
as inactivated as it was at pH 7. Flow cytometry was used to confirm the fluorescence intensity of the
remaining EGFP inside the cells. No significant fluorescence loss was observed in the cells at pH 7.
However, at pH 9, the fluorescence intensity in the cells decreased, indicating leakage of EGFP. These
results suggest that hypochlorous acid inactivates E. coli without damaging its cell membrane and
cell wall, whereas the hypochlorite ion inactivates E. coli by damaging its cell membrane and cell wall.
It was possible to confirm the chlorine damage mechanism on E. coli by measuring the fluorescence
intensity of the leaked EGFP.
UV Resistance of E. coli
and Total Coliform in Raw and Secondary Treated Sewage
Otaki M. and Kouda M.
Ochanomizu University, Tokyo, Japan
ABSTRACT
In consideration of the changes in indicator bacteria in the environmental standard and wastewater effluent standard,
fluctuations in the concentrations of E. coli
and total coliform in raw sewage and secondary treated sewage at three
wastewater treatment plants and fluctuations in the resistance to UV disinfection were investigated. Regarding the
concentrations of E. coli
and total coliform, there were no significant fluctuations in either raw or treated sewage with
seasonal variation, water collection system, and treatment method. As a result of UV inactivation of secondary treated
water, it was found that the UV resistance of E. coli
was higher than that of total coliform. However, there was no
significant difference in UV resistance calculated using the concentration after photo-reactivation. Moreove, no
significant difference was found between seasonal variation, diurnal fluctuation, and treatment plants for these
tolerances. According to the result of similar experiments on raw sewage, the UV resistances of E. coli
and total
coliform were equivalent, and the resistances calculated using the concentration after photo-reactivation were also the
same.
Availability and public acceptability of residential rainwater use in Sri Lanka
*Takagi K., *Otaki M. and **Otaki Y. and ***Chaminda T.
*Ochanomizu University, Tokyo, Japan
**Hitotsubashi University, Tokyo, Japan
***University of Ruhuna, Galle, SriLanka
ABSTRACT
Rainwater is one of the alternative water sources that can potentially replace municipal water supply,
particularly in areas with insufficient water supply, such as developing Asian cities. In this study, we
consider both the acceptability and availability (i.e. amount) of rainwater use in Galle, situated in the
southern part of Sri Lanka. We examined the specific acceptability of each end use through a questionnaire
survey. The survey results indicated that the acceptability of non-contact and non-intake uses,
such as outdoor, toilet, and laundry uses, was high. To improve acceptability, we provided information on
quality, quantity, and cost. As a result, the acceptability of using rainwater for toilet, bath, and washing
could be significantly improved, particularly since people who considered it unacceptable tended to
change their attitude to acceptable. In addition, we estimated the availability of water rainwater harvesting
using probabilistic simulation. Finally, we found that by introducing a standard-sized water
storage tank, the toilet water demand of 90% of four-person families can be satisfied by rainwater.
Potential of rainwater utilization in households based on the distributions of catchment area and end-use water demand
*Takagi K., *Otaki M. and **Otaki Y.
*Ochanomizu University, Tokyo, Japan
**Hitotsubashi University, Tokyo, Japan
ABSTRACT
In the area where household water use exceeds the capacity of the public water supply,
rainwater is considered as one of the alternative water resources. Many researchers studied rainwater
potential to cover the specific value of water demand in households having the average catchment
area, so that the estimated potential expresses that of the average population. In this research,
the possibility of rainwater use for toilets was investigated more realistically using the probability
distributions of water demand and catchment area, and precipitation in case of Hanoi, Vietnam.
Monte Carlo simulations were conducted throughout this simulation and the distribution of the
possibility of rainwater use was estimated. The effect of household size and seasonal variations on
the potential of rainwater utilization was also assessed. These results showed that our new approach
exhibited that approximately 60% of the households failed to achieve the potential that was estimated
using the conventional approach. Therefore, our new approach should be useful to understand the
manner in which the potential of rainwater utilization differs in a given area, and it could be applied
to other areas for consideration on the rainwater use potential and the suitable tank size when the
distributions of variables and precipitation are clear.
Potential of Efficient Toilets in Hanoi, Vietnam
*Otaki Y., **Otaki M. and ***Aramaki T.
*Hitotsubashi University, Tokyo, Japan
**Ochanomizu University, Tokyo, Japan
***Toyo University, Tokyo, Japan
ABSTRACT
Many water authorities have promoted the installation of water-saving devices as an effective way of managing
residential water demand. However, there has been some controversy about the effectiveness of such
devices in studies in developed countries, and few studies have considered the use of water-saving devices
in developing countries, where a rapid increase in water demand is expected. This study focused on toilet
replacement and the residential water-saving potential in urban Hanoi, Vietnam – a country presently enjoying
remarkable economic growth and increasing water demand – using the Monte Carlo simulation, i.e.,
stochastic, approach. We surveyed the toilets of 134 households. Annual water savings were not large –
2.2 liters per person per day (1.9% of total residential consumption) – despite the assumption that all toilets
would be replaced with efficient ones within three years. Based on this study, a rebate to encourage toilet
replacement would have limited effect for saving water, contrary to experience in developed countries. Comparing
the volume of water saved, the simple analytical model, i.e. the deterministic approach, underestimated
the water-saving potential.
AOC Evaluation by Fluorescence Analysis Using Method of Dissolved Organic Matter（DOM）Fractions and Ozonation
*Tomoko JIMBO and *Masahiro OTAKI
*Ochanomizu University, Tokyo, Japan
ABSTRACT
Dissolved organic matter（DOM）contained in the Tone River as an example of resource for drinking water was
analyzed by fl uorescence intensity（ FI） and fractionation with ozonation. The fractionation into hydrophobic acid and
hydrophilic matter was conducted. And the FIs of the fractionated samples were measured as quantitative analysis of
the contained DOM. As a result, any FIs in the samples had no relationship with the assimilable organic carbon（AOC）.
However, the decrease of FIs of the hydrophilic fractionated samples by ozonation（CT = approx. 0.5
mg min L-1）had highly correlation with AOC. The wavelength used for measuring these FIs were 250 nm/435 nm and
335 nm/435 nm as excitation/emission which were correspondent with the existence of a fulvic acid or humic acid-like
substance. Especially those correlation were observed in case of AOC determined by the Pseudomonas fl uorescens P17
strain and not by the Aquaspirillum sp. NOX strain. It was suspected that the correlation between AOC and the
decrease of FI by ozonation was based on the correspondence of biodegradable organic matter for P17 strain with
ozone reactive matter.
Combined Methods for Quantifying End-Uses of Residential Indoor Water Consumption
*Yurina Otaki,**Masahiro Otaki,***Toshiya Aramaki
*Hitotsubashi University, Tokyo, Japan
**Ochanomizu University, Tokyo, Japan
***Toyo University, Tokyo, Japan
ABSTRACT
This study aims to develop a suitable tool for understanding the end-uses of indoor water consumption (e.g., toilet, kitchen, bathroom, clothes washing) in developing countries. Both direct metering and questionnaire survey were conducted for each end-use in the surrounding areas of Hanoi, Vietnam. We measured the detailed end-uses of residential indoor water, the disaggregation of total consumption of individual household into a number of end-uses, and conducted a detailed questionnaire survey on water use behaviour. A tablet-based questionnaire was used and it proved effective in terms of usability and data collection. The results suggest that the combination of direct metering, questionnaire survey, and toilet tank and shower flow rate measurement is the best method for understanding residential indoor water use.
Bactericidal and virucidal mechanisms in the alkaline disinfection of compost using calcium lime and ash
Hijikata, N., Tezuka, R., Kazama, S., *Otaki, M., Ushijima, K., Ito, R., Okabe, S., Sano, D., Funamizu, N.
*Ochanomizu University, Tokyo, Japan
ABSTRACT
In the present study, the bactericidal and virucidal mechanisms in the alkaline disinfection of compost with calcium lime and ash were investigated. Two indicator microorganisms, Escherichia coli and MS2 coliphage, were used as surrogates for enteric pathogens. The alkaline-treated compost with calcium oxide (CaO) or ash resulted primarily in damage to the outer membrane and enzyme activities of E. coli. The alkaline treatment of compost also led to the infectivity loss of the coliphage because of the partial capsid damage and RNA exteriorization due to a raised pH, which is proportional to the amount of alkaline agents added. These results indicate that the alkaline treatment of compost using calcium oxide and ash is effective and can contribute to the safe usage of compost from a mixing type dry toilet.
Inhibition of Algal Growth in Water Purification Process by UV Irradiation and observation of Damage Level on Algal Cell
*Yoshimi MORIYA, *Masahiro OTAKI
*Ochanomizu University, Tokyo, Japan
ABSTRACT
Rapid algal growth in the water purification process often causes problems such as turbidity leak. We investigated
whether the application of ultraviolet （UV） radiation （254 nm） was effective in controlling algal growth. The objective
of this study is to investigate the effect of UV irradiation on some isolated algae at a conventional UV dose （50-200
mJ cm-2） or a high UV dose （500-1000 mJ cm-2）. Three algae that obstruct water purification, that is, diatoms of
Cyclotella, green algae of Dictyosphaerium, and flagellate of Cryptomonas, were selected and cultivated. As a result, it
was observed that the cell concentration was reduced or maintained during one week after conventional UV dose
irradiation in all algae. Dictyosphaerium exhibited higher resistance or faster growth compared with Cyclotella and
Cryptomonas. Moreover, it was observed that algal cells exposed to a high UV dose were simultaneously broken, and
the cell number was reduced in the cases of Cryptomonas and Dictyosphaerium. On the other hand, for Cyclotella, the
cell content was changed but the shape of the cell was not. In conclusion, a conventional UV dose inhibited algal
growth and a high UV dose injured cellular contents directly and induced cytolysis in some algal species.
Advocating Water Literacy
*Yurina OTAKI, **Osamu SAKURA and ***Masahiro OTAKI
*Hitotsubashi University, Tokyo, Japan
**The university of Tokyo, Tokyo, Japan
***Ochanomizu University, Tokyo, Japan
ABSTRACT
Current water use in our daily life is by no means sustainable, and the environmental and social problems come to the surface. To improve the current situation and to develop sustainably both for human beings and the global environment, we have to think out a new paradigm. As the centerpiece of the new paradigm, we advocate the concept of water literacy. Water literacy was defined as the ability to feel familiar with water, get actively involved in water and face the issue of water as one’s own issue. Water literacy was divided into three categories: practical, living, and social water literacy. Water literacy enables us to re-evaluate local water systems and water usage. Furthermore, water literacy educates those citizens who are able to associate daily life with social issue, and contributes to the recovery of a variety of relations between water and humans.
Quantitative analysis of the inactivation mechanisms of Escherichia coli by a newly developed method using propidium monoazide
*Shinobu KAZAMA, **Masahiro OTAKI
*New lndustry Crealion Hatchery Center, Tohoku University, Miyagi,Japan
**Ochanomizu University, Tokyo, Japan
ABSTRACT
The present study investigates a newly developed method using propidium monoazide (PMA) to detect damage on the outer membrane of bacteria. ln order to verify this method，Escherichia coli were disinfbcted by ultraviolet，chlorine and sawdust treatments assuming a composting toilet.The inactivation mechanisms were investigated by multiple detection methods focused on which parts and/or functions were damaged. The differences in detection principles among three kinds of growth media and the polymerase chain reaction (PCR)method were used as methods to investigate the damage caused by disinfection. ln addition，damage to the outer membrane was distinguished using PMA as pretreatment following PCR or conventional cultivation media，Tryptic Soy Agar (TSA)，called PMA-PCR and PMA-TSA，respectively. As a result，it was indicated that chlorination caused outer membrane damage，and that ultraviolet treatment did not.
Sawdust treatment at high temperatufe damaged the outer membranes ffectively.lt was confirmed that PMA-TSA，a newly developed method，could detect damage on the outer membrane ofEscherichia coli more sensitively and quantitatively than PMA-PCR.
Water Demand Management: A Strategic Approach towards a Sustainable Urban Water System in Hanoi
*Pham Ngoc BA, *Toshiya ARAMAKI, **Masahiro OTAKI, ***Yurina OTAKI
*Toyo University, Tokyo, Japan
**Ochanomizu University, Tokyo, Japan
***University of Tokyo, Tokyo, Japan
ABSTRACT
Rapid urbanization and population growth, coupled with climate change, have created major challenges on urban planners and water professionals in Hanoi City to find out effective measures to sustain the growing water demand of the city. This study investigates the recent trends in residential water use, as well as the principal factors and challenges that affect the water demand of the city. A series of micro-component surveys have been conducted for a better understanding of water usage, and potential of water saving and demand management at household levels. Consequently, a range of effective water demand management (WDM) interventions, including water metering, reduction of water loss, promotion of using water-wise appliances, reforming water tariff structure to promote responsible uses, and utilization of rainwater, have been proposed as strategic approaches towards a sustainable urban water use system for the city in the future. Prospects and constraints likely to be faced while implementing these WDM interventions are also discussed in this paper.
Micro-component survey of residential water consumption in Hanoi
*Yurina Otaki, **Masahiro Otaki, ***P. N. Bao, ****T. T. V. Nga, and ***Toshiya Aramaki
*University of Tokyo, Tokyo, Japan
**Ochanomizu University, Tokyo, Japan
***Toyo University, Tokyo, Japan
****Hanoi University of Civil Engineering, Hanoi,Vietnam
ABSTRACT
Daily total water consumption per capita has been used as a basic unit for the future planning of water supply for domestic use. However, for innovative water utilization designs that consider various scenarios, including the effects of policy direction and global warming, and more strategic and efficient water use, it is absolutely essential to consider water usage divided by residential activities, such as toilet flushing, cooking, clothes washing, and bathing. We collected microcomponent data by direct measurement from each household outlet, and developed small accumulative meters. Measurements were conducted at 56 households for 2 months in Hanoi, Vietnam, and the average consumption was 18.6 L/p/d for toilet, 16.2 L/p/d for laundry, 10.4 L/p/d for bath, and 15.7 L/p/d for kitchen. We then analyzed the representative values and the distribution of water consumption for every usage from social and economic perspectives. In addition, we compared the results in Hanoi with those in Chiang Mai, Thailand, where we investigated water consumption a few years ago, and their value seemed similar except for bathroom use, but the substance was different. One distinct outcome of our investigation was the recognition of the cultural and methodological challenges to end-use assessment of water consumption in modernizing Asian communities.
Inactivation Mechanisms of E. coli in the Sawdust Used in Composting Toilet
Shinobu KAZAMA, Masahiro OTAKI
Department of Human Environmental Science, Ochanomizu University, Japan
ABSTRACT
A composting toilet, using sawdust as a matrix, has the potential to trap pathogens that might occasionally be contained in human feces. High temperature, low water content and high pH conditions are effective in reducing the pathogen content. However, it is not clear which parts or functions of pathogens are damaged under these conditions. Therefore, the present study investigates the inactivation mechanisms of pathogenic bacteria in a composting toilet, focusing on which parts and/or functions were damaged. Escherichia coli (E. coli) was used as a model of pathogenic bacteria, and its inactivation mechanisms were estimated by multiple detection methods. Differences in detection principles among the 3 types of growth media and the polymerase chain reaction method (PCR) were used as a method to investigate the damages caused by each. In addition, damage to the outer membrane was distinguished by using a propidium monoazide (PMA) treatment. The results indicated that E. coli was rapidly inactivated due to metabolic function and slight outer membrane damage under high pH conditions. In dry conditions, E. coli was inactivated by damage to metabolic function and slight outer membrane damage. High temperature treatment damaged the outer membranes effectively, and inactivated them rapidly.
Comparison of residential indoor water consumption patterns in Chiang Mai and Khon Kaen, Thailand
*Yurina Otaki, **Masahiro Otaki, ***Haruka Sugihara, ****Lada Mathurasa, *****Petch Pengchai, and ******Toshiya Aramaki
*University of Tokyo, Tokyo, Japan
**Ochanomizu University, Tokyo, Japan
***IBM Business Consulting service, Tokyo, Japan
****Chulalongkorn University, Bangkok, Thailand
*****Mahasarakham University, Maha Sarakham, Thailand
******Toyo University, Tokyo, Japan
ABSTRACT
Knowledge of the various microcomponents of residential water consumption can play an essential role in setting effective water supply plans and policies. However, there are insufficient data regarding the microcomponents of domestic water use (toilet, laundry, bath, and kitchen) in developing countries. This study measured the microcomponents of residential water use in Chiang Mai and Khon Kaen, Thailand, using a small accumulative water meter attached directly to each household tap. In addition, residents were surveyed to obtain information about income, home bathing facilities, and laundering methods.
Results showed water consumption per capita for every use to be distributed lognormaly in Chiang Mai and Khon Kaen. Water consumption for toilet use was higher in Chiang Mai than in Khon Kaen, but the study found little difference between the two cities in other microcomponents of residential water consumption. In this research, historical differences in the cities’ water resources appeared to have no effect on residential water consumption.
Mechanisms for the Inactivation of Bacteria and Viruses in Sawdust Used in Composting Toilet
Shinobu KAZAMA, Masahiro OTAKI
Department of Human Environmental Science, Ochanomizu University, Japan
ABSTRACT
A composting toilet, using sawdust as a matrix, has the potential to trap pathogens that might occasionally be contained in human feces. Therefore, care must be taken when handling the sawdust. High temperature and low water content conditions are effective for reducing pathogen content. However, it is not clear whether these effective conditions can cause lethal damage to these pathogens or not. Therefore, the present study investigates the inactivation mechanisms of pathogens in a composting toilet, using E. coli as a model of pathogenic bacteria and Qβ as a model of pathogenic viruses. Escherichia coli was rapidly and lethally inactivated under high pH conditions. In dry conditions, they were inactivated lethally but not rapidly. High temperature treatment was unable to inactivate them lethally. For Qβ, the capsid was mainly damaged under high temperature and dry conditions, whereas high pH conditions primarily damaged nucleic acids. Therefore, raising the pH was an effective way to rapidly and lethally reduce both pathogenic bacteria and viruses.
A fate model of pathogenic viruses in a composting toilet based on coliphage inactivation
*Kazama S., **Tameike N., ***Nakagawa N. and *Otaki M.
*Department of Human Environmental Science, Ochanomizu University, 2-1-1 Bunkyo-ku Otsuka Tokyo 112-8610, Japan
**INAX Co. 1-23-6, Yoshino-cho Kita-ku Satiama 331-0811, Japan
***Department of Civil and Environmental Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa Hachioji City, Tokyo 192-0397, Japan
ABSTRACT
A composting toilet using sawdust as a matrix has the potential to trap pathogens that might occasionally be contained in human feces. Therefore, care should be taken when handling the sawdust. It should also be noted that pathogenic viruses tend to have stronger tolerance than pathogenic bacteria. The fates of several species of coliphages, T4, , Q and MS2, in sawdust were investigated as a viral model. The fates of coliphages were significantly different among them, and they changed in response to temperature and the water content of the sawdust. As the results, T4 coliphage had the strongest tolerance and Q had the weakest one in sawdust. It was estimated the days required to decrease virus to a safe level based on a risk assessment. According to the rates of Q and T4, 15 days and 167 days were required respectively for a safe level of infection risk based on actually operated composting toilet condition. Thus, it was significantly different depending on the species and sawdust conditions
Detection of active Escherichia coli after irradiation by pulsed UV light using a Qβ phage
*M. B. Said, **Kazama S., **Otaki M. and ***A. Hassen
*Water Treatment and Recycling Laboratory (LTRE), Water Research and Technologies Centre (CERTE), BP 273, 8020 Borj-Cedria, Tunis, Tunisia
**
Department of Human and Environment Sciences Ochanomizu University, 2-1-1 Otsuka, Bunkyo-Ku, Tokyo 112-8610,Japan
ABSTRACT
The infectivity rates of Qβ phage is used as a bio-indicator of the physiological state of host cells and for the detection of active Escherichia coli irradiated by an increasing number of pulsed ultra-violet (UV) light. Indeed, the combination of a conventional method used to measure colony-forming ability of tested bacteria after exposure to an increase number of pulsed UV light, and the simulation of phage adsorption kinetic, can reveal the existence of active bacteria which lose the cultivability in usual culture media, but keep viability and phage susceptibility.
Detection of viable but non cultivable Escherichia coli after UV irradiation using a lytic Qβ phage
*M. B. Said, **Otaki M. and ***A. Hassen
*Water Treatment and Recycling Laboratory (LTRE), Water Research and Technologies Centre (CERTE), BP 273, 8020 Borj-Cedria, Tunis, Tunisia
**
Department of Human and Environment Sciences Ochanomizu University, 2-1-1 Otsuka, Bunkyo-Ku, Tokyo 112-8610,Japan
ABSTRACT
In order to qualify the germicidal efficacy of ultraviolet (UV) disinfection system, we generally determine the reduction of viable bacteria after UV-C irradiation. However, the simple count of viable and cultivable bacteria in usual media cannot reflect whether or not the UV dose applied to disinfect water is sufficient to inactivate bacteria. Indeed, there is a bacterial mix in the UV-treated water: dead bacteria, viable and cultivable bacteria and viable but noncultivable bacteria (VBNC). The third type of bacteria can constitute a potential risk for public health. In fact, VBNC bacteria can be active and cause diseases. Consequently, the combination of a conventional method used to measure colony-forming ability after UV disinfection and the determination of adsorption constants of a lytic Qβ phage in relation to irradiated host cells by an increased UV dose (Escherichia coli ATCC 13965) allows the detection of active bacteria, which lose their cultivability in usual growth media, but keep the phage susceptibility.
Influence of water-related appliances on projected domestic water use in Tokyo
*Nakagawa, N., **M. Otaki, ***T. Aramaki and *A. Kawamura
*Dept. of Civil and Environmental Engineering, Tokyo Metropolitan University, Tokyo, Japan
**
Dept. of Human and Environment Sciences, Ochanomizu University, Tokyo,Japan
***Dept. of Regional Development Studies, Toyo University, Tokyo, Japan
ABSTRACT
In this study, the amount of domestic water use was quantified by estimating the usage rates of various water-related appliances. Tokyo Metropolis was selected as a case study because it was relatively easy to obtain detailed data from Tokyo Waterworks Bureau. In the analysis, the calculations for domestic water use reproduced actual usage figures from 1998 to 2006. From the maximum domestic water use per capita in 1997 the projected reduction was estimated to be 9% by 2025 and 10% by 2050. In addition, our results indicate that water use for both bath and toilet is expected to remain high in the future. We performed a simulation assuming that a 6 L-type toilet is installed by all consumers, with the results suggesting that domestic water use per capita per day could reduce to around 200 L. It was therefore concluded that the replacement of a conventional toilet with a water-saving-type toilet is one of the most effective solutions for reducing domestic water use.
Environmental and economic life cycle assessment for sewage sludge treatment processes in Japan
*Hong J, **Otaki and *M, Jolliet O.
*Department of Environmental Health Science, School of Public Health, University of Michigan, 109 South Observatory, Ann Arbor, MI 48109, USA.
** Graduate School of Humanities and Science, Ochanomizu University, 2-2-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
ABSTRACT
Life cycle assessment for sewage sludge treatment was carried out by estimating the environmental and economic impacts of the six alternative scenarios most often used in Japan: dewatering, composting, drying, incineration, incinerated ash melting and dewatered sludge melting, each with or without digestion. Three end-of-life treatments were also studied: landfilling, agricultural application and building material application. The results demonstrate that sewage sludge digestion can reduce the environmental load and cost through reduced dry matter volume. The global warming potential (GWP) generated from incineration and melting processes can be significantly reduced through the reuse of waste heat for electricity and/or heat generation. Equipment production in scenarios except dewatering has an important effect on GWP, whereas the contribution of construction is negligible. In addition, the results show that the dewatering scenario has the highest impact on land use and cost, the drying scenario has the highest impact on GWP and acidification, and the incinerated ash melting scenario has the highest impact on human toxicity due to re-emissions of heavy metals from incinerated ash in the melting unit process. On the contrary, the dewatering, composting and incineration scenarios generate the lowest impact on human toxicity, land use and acidification, respectively, and the incinerated ash melting scenario has the lowest impact on GWP and cost. Heavy metals released from atmospheric effluents generated the highest human toxicity impact, with the effect of dioxin emissions being significantly lower. This study proved that the dewatered sludge melting scenario is an environmentally optimal and economically affordable method.
Attempt to Establish an Industrial Water Consumption Distribution Model
Otaki Y*., Otaki M**., and Yamada T.**
*Center for Research and Development of Higher Education, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 133-0033, Japan
** Graduate School of Humanities and Science, Ochanomizu University, 2-2-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
ABSTRACT
The need for both global and regional assessment of water consumption has been increasing. This paper aimed to understand industrial water consumption both globally and regionally, and create the 1°*1° global map. From the analysis of data in Japan and China, it was determined that industrial water consumption correlated well with urban area which can obtain from GIS data. Based on this knowledge, industrial water consumption was distributed to the 1°*1° global map, and this calculation was named urban area model.
Micro-components survey of residential indoor water consumption in Chiang Mai
Otaki Y*., Otaki M**., P. Pengchai***, Ohta Y**. and Aramaki T.****
*Center for Research and Development of Higher Education, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 133-0033, Japan
** Graduate School of Humanities and Science, Ochanomizu University, 2-2-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
***Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand
****Department of Urban Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656, Japan
ABSTRACT
The direct measurement of the micro-components of water consumption (i.e., consumption by each residential activity, such as toilet-, laundry-, bath-, and kitchen-use), both in the dry season and in the rainy season, was conducted in Chiang Mai, Thailand. It was expected that rainfall differences between the dry and rainy season would influence awareness for water resources so that water consumption in the dry season would be smaller than that in the rainy season. In addition, it was examined whether the differences in water resources such as public waterworks or non-public waterworks (i.e., community waterworks, mountainous water and groundwater), affected the amount of water use. A small-sized accumulative water meter was developed for measurement. This survey provides important information for water demand estimations and water supply planning in middle-developed countries where water consumption is expected to increase in future.
Relationship between the results of in vitro receptor binding assay to human estrogen receptor α and in vivo uterotrophic assay: Comparative study with 65 selected chemicals
Akahori Y*., Nakai M**, Yamasaki K.***, Takatsuki M.**, Shimohigashi Y.****, and Ohtaki M.*
*Department of Human Environmental Science, Ochanomizu University, 2-1-1, Otsuka, Bunkyo-ku, Tokyo, 112-8610, Japan
** Chemicals Assessment Center, Chemicals Evaluation and Research Institute, Japan (CERI) 1600, Shimo-Takano, Sugito-machi, Kitakatsushika-gun, Saimata 345-0043, Japan
***Chemicals Assessment Center, Chemicals Evaluation and Research Institute, Japan (CERI) 3-822 Ishii-machi, Hita, Oita, 877-0061, Japan
****
Department of Chemistry, Faculty and Graduate School of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
ABSTRACT
For screening chemicals possessing endocrine disrupting potencies, the uterotrophic assay has been placed in a higher level in the OECD testing framework than the ER binding assay to detect ER-mediated activities. However, there are no studies that can demonstrate a clear relationship between these assays. In order to clarify the relationship between the in vitro ER binding and in vivo uterotrophic assays and to determine meaningful binding potency from the ER binding assay, we compared the results from these assays for 65 chemicals spanning a variety of chemicals classes. Under the quantitative comparison between logRBAs (relative binding affinities) and logLEDs (lowest effective doses), the log RBA was well correlated with both logLEDs of estrogenic and anti-estrogenic compounds at r2 = 0.67 (n = 28) and 0.79 (n = 23), respectively. The RBA of 0.00233% was found to be the lowest ER binding potency to elicit estrogenic or anti-estrogenic activities in the uterotrophic assay, accordingly this value is considered as the detection limit of estrogenic or anti-estrogenic activities in the uterotrophic assay. The usage of this value as cutoff provided the best concordance rate (82%). These findings are useful in a tiered approach for identifying chemicals that have potential to induce ER-mediated effects in vivo.
systems and urban sanitation: A historical comparison of Tokyo and Singapore
*Otaki Y., *Sakura O. and **Otaki M.
*Interfaculty Initiatives in Information Studies, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 133-0033, Japan
**Graduate School of Humanities and Science, Ochanomizu University, 2-1-1 Otsuka, Bunkyo, Tokyo 122-8610, Japan
ABSTRACT
The importance of a water supply and sewage treatment for urban sanitation is recognized in the modern world. Their contributions to public health have not, however, been well demonstrated by historical data, especially in Asian cities. In this research, we focused on the Asian cities of Tokyo and Singapore, which both developed significantly in the 20th century. We analysed their development processes statistically to determine what the key elements for the protection of urban sanitation have been. Although both cities constructed modern water supply systems at almost same time (Tokyo in 1898 and Singapore in 1878), and similarly modern wastewater treatment systems (Tokyo in 1922 and Singapore in 1913), the prevalence of water-borne diseases in Tokyo was more serious than it was in Singapore, in spite of Singapore's high infant mortality rate. The main reason for this was the differences in the systems of night-soil transport. We found that the water supply system in itself was not enough to resolve all urban sanitation problems, and appropriate night-soil removal was also crucial. In addition, historical trends and water consumption vary by city, so the appropriate technology and system are also different according to the unique characteristics and needs of each.
Effects of wastewater disinfection on waterborne bacteria and viruses
Blatchley III, E.R., Gong, W.-L., Alleman, J.E., Rose, J.B., Huffman, D.E., Otaki, M., Lisle, J.T.
ABSTRACT
Wastewater disinfection is practiced with the goal of reducing risks of human exposure to pathogenic microorganisms. In most circumstances, the efficacy of a wastewater disinfection process is regulated and monitored based on measurements of the responses of indicator bacteria. However, inactivation of indicator bacteria does not guarantee an acceptable degree of inactivation among other waterborne microorganisms (e.g., microbial pathogens). Undisinfected effluent samples from several municipal wastewater treatment facilities were collected for analysis. Facilities were selected to provide a broad spectrum of effluent quality, particularly as related to nitrogenous compounds. Samples were subjected to bench-scale chlorination and dechlorination and UV irradiation under conditions that allowed compliance with relevant discharge regulations and such that disinfectant exposures could be accurately quantified. Disinfected samples were subjected to a battery of assays to assess the immediate and long-term effects of wastewater disinfection on waterborne bacteria and viruses. In general, (viable) bacterial populations showed an immediate decline as a result of disinfectant exposure; however, incubation of disinfected samples under conditions that were designed to mimic the conditions in a receiving stream resulted in substantial recovery of the total bacterial community. The bacterial groups that are commonly used as indicators do not provide an accurate representation of the response of the bacterial community to disinfectant exposure and subsequent recovery in the environment. UV irradiation and chlorination/dechlorination both accomplished measurable inactivation of indigenous phage; however, the extent of inactivation was fairly modest under the conditions of disinfection used in this study. UV irradiation was consistently more effective as a virucide than chlorination/dechlorination under the conditions of application, based on measurements of virus (phage) diversity and concentration. Taken together, and when considered in conjunction with previously published research, the results of these experiments illustrate several important limitations of common disinfection processes as applied in the treatment of municipal wastewaters. In general, it is not clear that conventional disinfection processes, as commonly implemented, are effective for control of the risks of disease transmission, particularly those associated with viral pathogens. Microbial quality in receiving streams may not be substantially improved by the application of these disinfection processes; under some circumstances, an argument can be made that disinfection may actually yield a decrease in effluent and receiving water quality. Decisions regarding the need for effluent disinfection must account for site-specific characteristics, but it is not clear that disinfection of municipal wastewater effluents is necessary or beneficial for all facilities. When direct human contact or ingestion of municipal wastewater effluents is likely, disinfection may be necessary. Under these circumstances, UV irradiation appears to be superior to chlorination in terms of microbial quality and chemistry and toxicology. This advantage is particularly evident in effluents that contain appreciable quantities of ammonia-nitrogen or organic nitrogen.
Surface water quality and information about the environment surrounding Inle Lake in Myanmar
*Akaishi F., **Satake M., *Otaki M. and **Tominaga N.
*Division of Life Science, Graduate School of Humanity and Sciences, Ochanomizu University, 2-1-1 Otsuka, Bunkyo, Japan
**Institute of Environmental Science for Human Life, Ochanomizu University, Bunkyo, Japan
ABSTRACT
Inle Lake is the second largest lake in Myanmar and one of the nine key sites for sightseeing there. An analysis of its water quality has not been published before. The objective of this study is to reveal the current situation and find any major problems with the lake. For this purpose, the natural and cultural environments were examined. Some physical and chemical aspects of the surface water were assayed in situ for 2 days in November 2004. The principal ions were analyzed in our laboratory. The main cation and anion species in the lake surface water are Ca2+ and HCO3-. Its high calcium content can be attributed to the limestone of Shan Plateau around the lake. The alkalinity of the lake water was 3829-4114 acid-neutralizing capacity (ANC) (pH 7.8-8.0); it can be attenuated by Ca2+. The concentrations of PO4-P, NO2-N, and NO3 -N were relatively high; these could originate from domestic and agriculture uses. The trophic state is eutropic. The concentrations of coliform bacteria indicated that the lake water was unfit to drink, but some people use it for drinking anyway. The bacteria could enter the lake through the direct latrine system used there. The thermal type of the lake is presumed to be warm polymictic. More extensive studies are needed because the lake is thought to be the most changing site in Myanmar as a result of both the tourism boom and increasing agricultural activity.
Field survey of a sustainable sanitation system in a residential house
Nakagawa N., Otaki M. Miura S. Hamasuna H. and Ishizaki K.
Department of Human Environmental Sciences, Ochanomizu University, 2-1-1, Otsuka, Bunkyo-Ku, Tokyo 112-8610, Japan
ABSTRACT
Sustainable sanitation is an approach for more ecological and sustainable water resources management. In this paper, we proposed one of the new integrated waste treatment systems: an "sustainable sanitation system" that includes separation of the black water from water system by a non-flushing toilet (bio-toilet), and a gray water treatment based on a biological and ecological concept. Sustainable sanitation system also converts the domestic waste to soil conditioners and fertilizers, for farmland use. As one of the case studies, Environmentally Symbiotic Housing in which people actually live using the bio-toilet for the black water treatment and the household wastewater treatment facility for the gray water was introduced. The availability of this system was investigated by analyzing the sawdust used in the bio-toilet and the quality of the effluent in the household wastewater treatment facility. As the result, the water content of the sawdust did not exceed 60% in any of the sampling points and the BOD and COD of the effluent of the household wastewater treatment facility were below 10 and 20 mg/L respectively, due to the low loading. Compared to the pollution load on the water environment created by the conventional system, it was found that the effluent of the house has a lower load than the tertiary treatment and the volume of the water consumption is 75% of the conventional system.
Application of microbial risk assessment on a residentially-operated Bio-toilet
*Nakagawa N., *Otaki M. **Hana Oe and ***K. Ishizaki
*Dept. of Human Environmental Sciences, Ochanomizu Univ., 2-1-1 Otsuka, Bunkyo-ku 112-8610 Tokyo, Japan
**Graduate School of Frontier Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku 113-0033 Tokyo, Japan
***Research Institute for a Sustainable Future, Waseda University, 513 Tsurumaki-chou, Shinjuku-Ku, Tokyo 169-8050, Japan
ABSTRACT
The Sustainable Sanitation System is a new wastewater treatment system that incorporates a non-flushing toilet (Bio-toilet) that converts excreta into a reusable resource (as fertilizer or humus for organic agriculture) and reduces the pollution load to environments of the rivers, the lakes, and the sea. However, the risk of exposure to pathogens should be considered, because excrement is stored in the Bio-toilet. The aim of the present work is to analyze the health risk of dealing with the matrix (excreta and urine mixed with sawdust) of the Bio-toilet. Therefore, the fate of pathogenic viruses was investigated using coliphages as a virus index, and the modeling of the die-off rate in matrix was introduced. Then the microbial risk assessment was applied to a Bio-toilet that was actually used in a residential house; the infection risks of rotavirus and enterovirus as reference pathogens were calculated. According to the lab-scale experiment using coliphages for investing the die-off rate of viruses in the Bio-toilet, Qβ had a higher die-off, which was greatly influenced by the water content and temperature. On the other hand, T4 showed a lower rate and was independent of water content. Therefore, these two phages' data were used as critical examples, such as viruses having high or low possibilities of remaining in the Bio-toilet during the risk assessment analysis. As the result of the risk assessment, the storage time required for an acceptable infectious risk level has wide variations in both rotavirus and enterovirus cases depending on the phage that was used. These were 0-260 days' and 0-160 days' difference, respectively.
Association of Photosynthesis and Photocatalytic Inhibition of Algal Growth by TiO2
Hong j. and Otaki M.
Department of Human Environmental Sciences, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo, 112-8610, Japan
ABSTRACT
The relationship of photosynthesis and photocatalytic inhibition of algal growth (Chroococcus sp.) by TiO2 was investigated by an ATP assay under ultraviolet (UV) and fluorescent light (FL) irradiations. The adverse effects of what on Chroococcus sp. growth in the TiO2+FL+UV run are larger than those in the TiO2+UV run. The difference is considered to be caused by oxygen generated by Chroococcus sp. under FL irradiation. A rate equation for the relationship of light irradiation intensity to rate of decrease in the Chroococcus sp. population on the basis of the Langmuir-Hinshelwood model has been proposed. The experimental data are in good agreement with the proposed model. In this study, the optimum FL intensity is 0.51 mW/cm2. © 2006 The Society for Biotechnology, Japan.
Learning from the future: What shifting trends in developed countries may imply for urban water systems in developing countries
*M. Bengtsson, **T. Aramaki, ***M. Otaki and ***Y. Otaki
*Hydrology and Water Resources Engineering, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8505 Tokyo, Japan
**Asian Institute of Technology, PO Box 4, Klong Luang, Pathumthani 12120, Thailand
***Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
****University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
ABSTRACT
This study, which is based on reports and articles from various parts of the world, discusses the future development of urban water systems in developing countries. The starting point is the growing need for water and water infrastructure in these countries. Based on an analysis of shifting trends in the water sector in developed countries it is argued that the new infrastructure being constructed runs the risk of soon becoming inefficient and outdated. The first trend is the improvements in domestic water use efficiency; the second is the new sustainability agenda, which places new demands on the water systems. Cities in the developing world have the opportunity to promote domestic efficiency at early stages by laying a strong emphasis on demand management, and to construct more sustainable systems by including sustainability criteria early in the development process.
Photodecolorization of azo dyes by extracellular metabolites under fluorescent light and influence of operational parameters
Hong J., Emori H. and Otaki M.
Department of Human Environmental Sciences, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
ABSTRACT
The contribution of extracellular metabolites (EM) to the decolorant activity of newly isolated photosynthetic bacteria was observed. The decolorization process was considered to occur by two paths: photochemical decolorization by EM and photobiological decolorization by photosynthetic bacteria. In addition, the decolorization of several azo dyes by EM under black light and fluorescent light irradiation was investigated. It was found that EM were capable of decolorizing the azo dyes directly under visible light irradiation, and the overall dye decolorization followed first-order decay kinetics. Moreover, the decolorization reaction is a nonenzymatic reaction and the unknown metabolite with the decolorizing ability had an apparent molecular weight lower than 3 kDa as determined by ultrafiltration. In addition, its decolorization activity was stable even after heating sterilization at 121°C for 10 min. Furthermore, the decolorization rate increased with increasing optical intensity, temperature and EM concentration, and decreased with increasing initial dye concentration. Decolorization of dye was best at pH 8. © 2005, The Society for Biotechnology.
Controlling algal growth in photo-dependent decolorant sludge by photocatalysis
Hong J., Ma H. and Otaki M.
Department of Human Environmental Sciences, Ochanomizu University, 2-1-1 Otsuka, Bunky-ku, Tokyo 112-8610, Japan
ABSTRACT
In the treatment of synthetic dye wastewater by photosynthetic bacteria under optical irradiation, excessive algal growth and adhesion on the walls of the reactor are serious problems. The adverse effects of excessive algal growth on photosynthetic bacterial activity are significantly greater than those of the decreased optical irradiation of the solution. In this report, we investigated the effects of photocatalysis on the growth of algae (Chroococcus sp.) and photosynthetic bacteria. The different sensitivities of Chroococcus sp. and photosynthetic bacteria to photocatalysis were observed by an ATP assay. Moreover, from microscopy findings, some algae were damaged by TiO2 with UV. We suggested that some algae suffered from membrane damage and consequently cell substances were released, resulting in the increase of dissolved material following treatment using TiO2 with UV.
Determination of naturally occurring noroviruses in coastal seawater by alkaline elution after acid rinse using negatively charged membrane
*Katayama H., **Tanaka A., **Otaki M. and *Ohgaki S.
*Dep. of Urban Eng., The Univ. of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
**Dept. of Human Environmental Sciences, Ochanomizu University, 2-1-1 Otsuka, Bunky-ku, Tokyo 112-8610, Japan
ABSTRACT
A new procedure for concentrating viruses from seawater using a negatively charged membrane eluting with alkaline solution (NaOH, pH 10.5) after acid rinse (H2SO4, pH 3.0) was applied to determine naturally occurring enteric viruses in seawater in Tokyo bay. The levels of total coliforms and fecal coliforms ranged from 40 to 68000 (cfu/100ml) and from 2 to 32000 (cfu/100ml), respectively. The F-specific phages were not detected from 5 ml of 53 samples out of 61 tested. The levels of indicator microbes were not found to be related to the tide in Tokyo bay. Enteroviruses were not detected by cell culture RT-PCR, but detected by direct RT-PCR from approximately 10% of the samples. Noroviruses were found positive from approx. 31% of the winter samples (n=29), whereas only 3% from the summer samples (n=32). These results of direct RT-PCR were equivalent to determination of Norwalk viruses occuring in 50 ml of seawater. These results suggested that the levels of noroviruses in Tokyo bay were higher in winter than those of enteroviruses The virus concentration method used was proved to be useful for determination of naturally occurring viruses in seawater, especially when applied prior to PCR detection of nonculturable viruses.
Inactivation differences of microorganisms by low pressure UV and pulsed xenon lamps
M. Otaki*, A. Okuda*, K. Tajima*, T. Iwasaki*, S. Kinoshita** and S. Ohgaki***
*Graduate School of Humanities and Science, Ochanomizu Univ., 2-1-1, Otsuka, Bunkyo-ku, Tokyo, 112-8610, Japan.
** Iwasaki denki co., 1-1 Ichiriyama-cho, Gyouda, Saitama, 361-8505, Japan
***Dep. of Urban Eng., The Univ. of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
ABSTRACT
UV disinfection has been applied to water treatment in recent years with low-pressure and
medium-pressure UV lamps mainly used as the light source. In general, UV disinfection is considered to be inefficient with water of high turbidity because of inhibition of light enetration. Additionally, photoreactivation may be a problem that should be considered in case a disinfected water is discharged to the environment where sunlight causes reactivation. Recently, other types of lamps have been proposed including a flush-type lamp (such as a pulsed-xenon lamp) that emits high energy and wide wavelength intermittently. In this study, the difference between inactivation efficiencies by low-pressure UV (LPUV) and pulsed-xenon (PXe) lamps was investigated using two coliphage types and three strains of Escherichia coli.
PXe had a suppressive effect on photoreactivation rate of the E. coli strains even though there was no significant effect on inactivation rate and maximum survival ratio after photoreactivation. PXe also had a benefit when applied to high turbidity waters as no tailing phenomena were observed in the low survival ratio area although it was observed in LPUV inactivation. This efficiency difference was considered to be due to the difference in irradiated wavelength of both lamps.
Continuous treatment of azo acid dyes by photo-dependent denitrifying sludge
*Hong J., *Otaki M., **J.D. Rouse and **Furukawa K.
*Department of Environmental Engineering of Ochanomizu University,2-1-1 Otsuka,Bunky-ku,Tokyo 112-8610,Japan
**
Department of Civil and Environmental Engineering,Kumamoto University,2-39-1 Kurokami,Kumamoto 860-8555,Japan
ABSTRACT
Simultaneous removals of dye and nitrate by photo-dependent denitryfying sludge(PDDS) have been demonstrated in a continuous-flow bench-scale reactor. The best C/N for the degradation of azo dyes by PDDS was 1.5. The specific removal rate of azo dye AB92 decreased with a decrease in hydraulic retention time and increased with a decrease in solids retention time. The degradation rate of TOC decreased with a decrease in hydraulic retention time. AB92, which has nitro and hydroxyl substitutions in non-para positions, was uniquely degraded. During continuous flow treatment experiments using PDDS, complete degradation of azo dyes AB92 and AO20 at influent concentrations of 40 mg/L and 30 mg/L, respectively, was achieved with an HRT of 16.
Pretreatment processes for membrane filtration of raw water containing manganese
*Takizawa S., **Fu L., ***Pradhan N., ****Ike T., *****Otaki M. and *Ohgaki S.
*Dept. of Urban Engineering, Graduate School of Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
**Tsinghua Unisplendour Environmental Technology Ltd., Tsinghua University, Beijing 100084, China
***Department of Water Supply and Sewage, Panipokhari, Maharajgunj, Kathmandu, Nepal
****Environmental Plant Engineering Department, Mitsubishi Heavy Industries, LTD., 1-8-1 Sachiura, Kanazawa-ku, Yokohama-city 236-8515, Japan
*****Graduate School of Humanities and Sciences, Ochanomizu Univ., 2-1-1, Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
ABSTRACT
Experimental studies on chemical and biological pretreatments in membrane filtration processes were carried out to removal manganese contained in raw water and to prevent membrane fouling due to manganese. Two types of the pretreatment reactors, i.e. the fluidised-bed and fixed-bed configurations, were compared in the biological pretreatment experiments. New synthetic media (tubular polypropylene, I.D. 3 mm, O.D. 4 mm, length 5 mm) were used in all three experiments as a manganese-oxidising catalyst. The chemical pretreatment using sodium hypochlorite was effective in manganese removal and controlling membrane fouling; more than 0.8 mg-Cl2/L of chlorine dose was necessary to bring the manganese concentration from 0.4 mg/L in raw water to less than 0.05 mg/L. The biological pretreatment for manganese removal required a long start-up period of more than 40 days. The fixed-bed biological pretreatment was superior in manganese removal and in control of membrane fouling to the fluidised-bed biological pretreatment, which showed wash-out of the attached bacteria resulting in membrane fouling. The linear velocity and the empty-bed retention time required for the treatment of 0.14 mg-Mn/L in the fixed-bed biological pretreatment was 206 m/d and 8.0 minutes, respectively.
Direct and indirect inactivation of microcystis aeruginosa by UV-radiation
*Alam M.Z.B., **Otaki M., *Furumai H. and *Ohgaki S.
*Dept. of Urban Engineering, Graduate School of Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
**Department of Humanities and Science, Ochanomizu University, 2-1-1, Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
ABSTRACT
Excessive algal growth in drinking water sources like lakes and reservoirs is responsible for filter-clogging, undesirable taste and odor, disinfection-by-product formation and toxin generation. Although various methods are currently being used to control algal bloom, their successes are limited. Some water utilities routinely use copper sulfate to control excessive algal growth. But there is a growing concern against its use mainly because it is non-specific to target algae and kills many non-target species. In this study, the scope of using UV-radiation to control algal growth was assessed using Microcystis aeruginosa as test species. A UV-dose of 75 mW s cm−2 was found to be lethal to M. aeruginosa. A smaller dose of 37 mW s cm−2 prevented growth for about 7 days. It was found that UV-radiation may increase the specific gravity of the cells and thus may adversely affect the ability of the cells to remain in suspension. Three days after a UV-dose of 75 mW s cm−2, almost all the cells settled to the bottom of the incubation tubes, whereas all the unirradiated cells remained in suspension. It was also observed that UV-radiation on algal extracellular products has a significant residual effect and can contribute to algal growth control. The extent of residual effect depends on the UV-dose and can continue even for 7 days. UV-radiation was found to produce H2O2 in the μM level concentration. But at such level, H2O2 itself is not likely to cause the residual effect that was found in this study.
AQUEOUS MICROORGANISMS INACTIVATION BY PHOTOCATALYTIC REACTION
M. OTAKI, *T. HIRATA and **S. OHGAKI
Graduate School of Humanities and Science, Ochanomizu Univ., 2-1-1, Otsuka, Bunkyo-ku, Tokyo, 112-8610, Japan.
*College of Environ. Health, Azabu Univ, 1-17-71, Fuchinobe, Sagamihara, Kanagawa, 229-8501, Japan.
**Dep. of Urban Eng., The Univ. of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
ABSTRACT
Photocatalysis by TiO2 is a new technology which can treat water without adding any chemicals. In this research, the disinfections of three microorganisms such as bacteriophage Qｧ, E.coli and Cryptosporidium parvum was investigated. An immobilized TiO2 reactor was used and UV lamp and Black light (BL) lamp were used as light source. The intensity of each lamp was set up to equalize the photocatalysis efficiency determined by the decomposition rate of Methylene Blue. The additive effect of TiO2 to inactivation didn't appear in E.coli experiments with UV and BL irradiation and in Qｧ experiment with UV. In these three cases, light irradiation owned high germicidal effect and the addition of inactivation by photocatalysis was relatively too small to be significant. In Qｧ experiment with BL and in Cryptosporidium experiment with UV and BL, the additive effect by TiO2 could be seen clearly because these microorganisms were resistant to light irradiation in these cases. In spite of setting the equal photocatalysis efficiency in both lamps reactors, UV photocatalytic inactivation of Cryptosporidium was much faster than BL. It is assumed that UV and photocatalysis were enhanced each other.
VIRUS REMOVAL IN MEMBRANE SEPARATION PROCESS
Masahiro OTAKI, Kazuyoshi YANO* and Shinichiro OHGAKI
Dep. of Urban Eng., The Univ. of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
*Metropolitan Res. Lab. of Public Health, 3-24-1, Hyakunin-cho, Shinjuku-ku, Tokyo 169, Japan
ABSTRACT
Recently, the membrane technology is considered as alternatives of conventional water purification. To study the fate of virus in membrane process, indigenous coliphages in pilot scale membrane processes located in eastern part of Tokyo Metropolitan area has been surveyed for 6 months. This plant used river water as resource and had two microfiltration membrane processes which had different pore size (0.2 μm and 0.1 μm) and one ultrafiltration process which had 13,000 nominal molecular weight cut off. To detect indigenous coliphages, E.coli K12 F+(A/λ) and E.coli C were used as host bacteria. E.coli K12 F+(A/λ) can detect both DNA and RNA phages and E.coli C can only DNA phage. The resource water contained E.coli K12 phages at 200～1500 PFU/100mL and the removal ratio of these DNA and RNA phages was lower than that of DNA phage by E.coli C in both of MF membrane processes through 6 months. It is thought to be caused by difference of phage size, because DNA phage is bigger than RNA phage in general. The removal ratio of E.coli K12 and E.coli C phages were reached to 100% in UF membrane process. According to the comparison of the concentration of phages in solution and eluted from suspended solid in resource and drain, it is thought that most of phages concentrated in drain were absorbed in suspended solid. To make certain the removal ratio in UF and NF (nanofiltration) processes, high concentration of coliphage Ｑβ and poliomyelitis virus vaccine were fed into these processes. The removal ratio of coliphage Ｑβ in UF and NF processes are 10-8.3 and 10-6.3 respectively, and the ratio of poliomyelitis virus vaccine in UF and NF are <10-6.7 and <10-7.3 respectively.
CONTROL AND MODELING OF MEMBRANE FOULING DUE TO MICROORGANISM GROWTH BY UV PRETREATMENT
M. OTAKI*, S. TAKIZAWA** and S. OHGAKI*
*Department of Urban Eng., The Univ. of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
**Environmental Engineering Program, SERD, Asian Institute of Technology, P.O. Box 4, Klongluang, Pathumthani 12120, Thailand
ABSTRACT
Control of membrane-fouling is an important topic for extending continuous running time and reducing the frequency of chemical cleaning in membrane processes. Since the microorganism contribution to membrane fouling was considered to be significant, UV was thought to be effective to control membrane fouling. In this study, a pilot plant scale MF-membrane system (flow rate = 5 m3d-1) was operated in order to investigate the effect of UV pretreatment. As the experimental results, it was found that UV irradiation prevented the membrane fouling by control the microorganism concentration in the feed. And the continuous running time of membrane was extended 6 times longer than that of a process without UV pretreatment. In order to know how UV pretreatment prevented fouling, we also investigated the residual bactericidal effect which persists in water even after UV irradiation. However, the residual bactericidal effect wasn't observed in our experiment, therefore inhibition of microorganism growth by the residual effect in the membrane module could be ignored. We developed the theoretical model of microorganism growth on membrane as a membrane fouling material. This model can explain the observed membrane fouling due to microorganism growth.
Photoreactivation Following UV Disinfection and UV with Photocatalyst Reactor
M. OTAKI*, K. KASHIMADA**, J. ISHIWATA***, S. AKAIDA****, S. OHGAKI*
*Department of Urban Eng., The Univ. of Tokyo
**Ebara co.
***Tokyo Metro. Govern.,
****Kagoshima Prf. Govern.,
ABSTRACT
Recently, UV disinfection process is thought to be an alternative disinfection process. The application to real sewage treatment have been realized in several cases. Even though this technology has many advantages, it also has some defects. One of them is the photoreactivation which happens under visible light irradiation following UV inactivation. There are three main objects in this research. First is to compare the photoreactivation after different type of UV light which are emitted from low pressure mercury UV lamp (conventional one) and medium pressure UV lamp (invented recently). Second is to investigate the effect of irradiated UV dose and irradiated visible light intensity to photoreactivation rate. Third is to investigate the inhibition effect of photocatalysis to photoreactivation.
By using bioindicator methods, intensity of different UV lamp was standardized as germicidal UV intensity and they can be compared. It is observed that the difference of photoreactivation effect after both UV lamps was negligible. The photoreactivation rate was independent on the irradiated UV dose in both UV lamp cases. On the other hand, the photoreactivation rate has liner relationship with visible light intensity. The inhibition effect of photocatalysis to photoreactivation was observed. The contact efficiency of target bacteria to photocatalyst was the key of this effect.
KEY WORDS
photoreactivation, low pressure mercury UV lamp, medium pressure mercury UV lamp, germicidal UV intensity, photoreactivation rate, photocatalysis.
Photocatalytic inactivation of phage Qβ by immobilized titanium dioxide mediated photocatalyst
Lee S., Nishida K., Otaki M. and Ohgaki S.
Department of Urban Eng., The Univ. of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
**Environmental Engineering Program, SERD, Asian Institute of Technology, P.O. Box 4, Klongluang, Pathumthani 12120, Thailand
ABSTRACT
Photocatalytic inactivation of virus by immobilized TiO2 was investigated using RNA phage QB as a model. TiO2-coated tiles, developed for interior sterilisation, were used as immobilized phoocatalyst. 2.2 log QB was inactivated by immobilized TiO2 mediated photocatalysis by 1h irradiation with near UV black light at an intensity of 3.6×10−3W/cm2. Experiments with a slurry TiO2 reactor were also performed as a reference for the inactivation kinetics study. Photocatalytic QB inactivation was expressed by first-order kinetics as the initial concentration of the phage QB varied. The inactivation rate constant was proportional to the light intensity in the range of 3–8×10−3W/cm2 of black light with immobilized TiO2 photocatalyst. Broth introduced with phage into the reaction solution inhibited Inactivation. No noticeable difference in inactivation was observed between germicidal lamp irradiation with and without immobilized TiO2.
Decomposition of Organo-Chlorine Compounds by Medium and Low Pressure UV Lamps
M. OTAKI, S. OHGAKI, K. Yamamoto, N. Kamiko
Department of Urban Eng., The Univ. of Tokyo
ABSTRACT
Recently, UV disinfection process is thought to be an alternative disinfection process. The application to real sewage treatment have been realized in several cases. Even though this technology has many advantages, it also has some defects. One of them is the photoreactivation which happens under visible light irradiation following UV inactivation. There are three main objects in this research. First is to compare the photoreactivation after different type of UV light which are emitted from low pressure mercury UV lamp (conventional one) and medium pressure UV lamp (invented recently). Second is to investigate the effect of irradiated UV dose and irradiated visible light intensity to photoreactivation rate. Third is to investigate the inhibition effect of photocatalysis to photoreactivation.
By using bioindicator methods, intensity of different UV lamp was standardized as germicidal UV intensity and they can be compared. It is observed that the difference of photoreactivation effect after both UV lamps was negligible. The photoreactivation rate was independent on the irradiated UV dose in both UV lamp cases. On the other hand, the photoreactivation rate has liner relationship with visible light intensity. The inhibition effect of photocatalysis to hotoreactivation was observed. The contact efficiency of target bacteria to photocatalyst was the key of this effect.
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