Tsuyoshi Imai

Tsuyoshi Imai
Yamaguchi University · Graduate School of Science and Engineering

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236
Publications
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Introduction
Skills and Expertise

Publications

Publications (236)
Article
The disadvantages of the air–cathode single-chamber microbial fuel cell (AC-SCMFC) performance can be caused by numerous factors, and retention time (RT) is one such factor. It is difficult to conclude the ideal RT run for the specific tests under the same conditions. To determine the optimum RT for various types of microbial fuel cell (MFC), an AC...
Article
Microplastic pollution in small-scale river sediments remains mostly unknown. This study explored microplastics in the sediments of four small-scale Japanese rivers in Yamaguchi Prefecture: the Awano, Ayaragi, Asa, and Majime. Sediment samples (n = 23) were collected from the selected stations. Density separation and wet peroxidation methods were a...
Article
Digital soil mapping using hyperscale modeling of topographic parameters is a promising approach to capture the multiscale relationship between soil properties and the landscape. Hyperscale analysis sampled and calculated topographic parameters at more than one resolution. This study aims to develop prediction models for estimating the soil particl...
Article
Full-text available
Extreme halophiles offer the advantage to save on the costs of sterilization and water for biohydrogen production from lignocellulosic waste after the pretreatment process with their ability to withstand extreme salt concentrations. This study identifies the dominant hydrogen-producing genera and species among the acclimatized, extremely halotolera...
Article
Full-text available
BACKGROUND AND OBJECTIVES: Fixed-bed column has been considered an industrially feasible technique for phosphate removal from water. Besides the adsorption capacity, the effectiveness of an adsorbent is also determined by its reusability efficiency. In this study, phosphate removal by a synthesized amorphous zirconium (hydr)oxide/MgFe layered doubl...
Conference Paper
Full-text available
Freshwater microplastics pollution has been a recent focus. River freshwater microplastics pollution are vital towards freshwater ecosystems as well as have been the prominent source-to-sink conduits to export MPs into the marine realm. Wastewater treatment plants (WWTPs) have been identified as one of the major point-sources. To date, sources-to-s...
Article
Although different treatment techniques have been developed to eliminate phosphorus contamination, including for wastewater treatment, treated water often fails to meet quality regulations. Amorphous-ZrO2/Mg-Fe layered double hydroxide (LDH) composites with different molar ratios (Zr:Fe = 1.5–2) were prepared in two-stage synthesis by the combinati...
Chapter
Extremely halotolerant hydrogen-producing bacteria were investigated, owing to their ability to live in high salinity conditions. Based on this characteristic, it was hypothesized that extremely halophilic hydrogen-producing bacteria can tolerate high concentrations of Na⁺ ions. To test this hypothesis, we investigated the characteristics of extrem...
Article
Rivers are vital for understanding freshwater microplastics pollution, along with the conduits from land-sources to marine-sinks. In this study, we investigated microplastics in the small-scale Awano and Ayaragi rivers, which flow into the Sea of Japan (SJ), and the Asa and Majime rivers, which flow into the Seto Inland Sea (SIS) in Yamaguchi Prefe...
Article
This study aimed at screening salt-tolerant phosphorus (P) accumulating organisms (PAOs) and investigating the P release and uptake of the organisms in saline wastewater. Batch experiments were conducted over 98 days in solutions with a salinity of 3.5% and P concentrations of 1, 5, 10, and 20 mg-P/L. The P-uptake ability of microorganisms increase...
Article
Mapping flood physical vulnerability is spatially limited because it requires input data such as building structures and materials, which are unavailable on large spatial scales. In this study, we propose a new method for qualitatively evaluating the flood vulnerability of residential areas in the context of the exposure and resilience to flood haz...
Article
An air-water interface generator is a proposed apparatus aiming to enhance oxygen transfer by increasing the contact area between air and water. It has been proved that this apparatus could increase the volumetric oxygen transfer coefficient in laboratory scale. Therefore, it is important to study about upscaling in order to apply this apparatus in...
Conference Paper
Full-text available
Marine microplastics pollution has been a global emerging threat. Rivers have been identified as the major transporting pathways of microplastics from land sources into marine environments. This study investigated microplastics in the two rivers i.e. Awano River (AR) and Majime River (MR) which are flowing into the Sea of Japan (SJ) and the Seto In...
Article
Full-text available
The optimum conditions for biohydrogen production from glucose with extremely halophilic bacteria from Samut Sakhon salt pan, Thailand were identified. The extremely halophilic bacteria's ability to produce hydrogen in nearly saturated NaCl concentration provides a potential benefit of cutting the cost of water and sterilization in dark fermentatio...
Article
Full-text available
Marine microplastics pollution has been an emerging global threat. This study investigated microplastics pollution in the ‘Seto Inland Sea (SIS)’ and ‘Sea of Japan (SJ)’ surrounded Yamaguchi prefecture areas in Japan. The density separation method was applied to extract microplastics from sea surface sediment and water samples. Polymeric compounds...
Article
The final objective of this study is to develop highly conductive concrete which effectively mitigates the concentration of hydrogen sulfide (H2S) in sewer pipe. In the first part of this study, using electricity-producing bacteria (EPB) isolated from sewage sludge from a municipal wastewater treatment plant, the influence of inoculation of these E...
Conference Paper
Marine microplastics pollution has been the global cause of concern currently. This study investigated marine microplastics pollution in the selected areas of Yamaguchi prefecture, Japan. Density separation methods were used to extract microplastics from sediment and water samples. Polymeric compounds were identified through ATR-FTIR analysis. The...
Conference Paper
Marine microplastics pollution has been the emerging global threat currently. This study investigated microplastics pollution in the Seto Inland Sea and the Sea of Japan surrounding Yamaguchi prefecture areas in Japan. Density separation methods were used to extract microplastics from sea surface sediment and water samples. Polymeric compositions w...
Article
The sulfate-reducing bacteria (SRB) consortium (Desulfovibrio sp. Desulfitibacter sp. Dethiosulfatibacter sp. and Clostridium sp.) was investigated for sulfate removal and biohythane production from rubber sheet wastewater (RSW). The RSW at COD/SO42− ratio of 13 and pH 6 was suitable for sulfate reduction and biohythane production. Hydrogen yield,...
Article
In this current study, an apparatus called air-water interface generator was investigated for oxygen transfer enhancement by increasing a contact area between air and water. The effect of this apparatus and its optimal installation condition were investigated. The total volumetric oxygen transfer coefficient (kLaT) in this study was divided into vo...
Article
Batch and continuous modes for bio-hydrogen production by co-digesting cassava starch wastewater with buffalo dung were investigated. Response surface methodology with central composite design was used to optimize the bio-hydrogen production conditions. A hydrogen production potential of 1787 mL H 2 /L was achieved under optimal conditions of 2.84...
Article
The objective of this study was to develop a new technology to mitigate the concentration of hydrogen sulfide in sewer pipe by using conductive concrete. Experimental results showed that the concentration of hydrogen sulfide significantly decreased by using conductive concrete, and the effectiveness lasted during 66 days experiment. Also found was...
Article
For appropriate evaluation of environmental odours, it is necessary to develop a reliable odour measurement scale. Odour intensity reflects people’s perception of odours and contributes to effective odour management. In this study, Japanese conventional six-point odour intensity scale was reconsidered to ensure equal intervals between odour intensi...
Conference Paper
Full-text available
This research aims calculate the potency of rainwater harvesting as an alternative source of freshwater on the rural areas of wetlands of Indonesia on dry season (May-October), under the effect of climatic event such as El Nino. The study area is the area of ex-Mega Rice Project areas of Central Kalimantan, Indonesia. Daily rainfall data 1990-2004...
Article
Full-text available
With tap water as a physical solvent to absorb CO2 from different concentrations of mixed gases (containing CO2 and N2), an apparatus outfitted with a water-film generator was used to enhance the CO2 dissolution rate as well as the contact between the liquid and gas phases. The operational pressure in the absorption tank, induced gas pressure, init...
Article
Residual Chlorella sp. biomass obtained after anaerobic solid-state fermentation was used to produce bio-hythane. The residual biomass was pretreated using acid, thermal, and acid-thermal methods before their respective hydrolysates were used in dark fermentation followed by the methanogenesis of anaerobic digestion to produce hydrogen and methane,...
Article
This research uses tap water to absorb carbon dioxide from mixed gas (N2 and CO2) in an absorption apparatus coupled with a water-film-forming-unit (WFFU). The objective is to assess the benefits of using a WFFU to enhance CO2 removal efficiency at low pressure conditions. Based on our results, the WFFU significantly improves CO2 capture at 0.30 MP...
Article
Extremely halotolerant hydrogen-producing bacteria were investigated, owing to their ability to live in high-salinity conditions. Based on this characteristic, it was hypothesized that extremely halotolerant hydrogen-producing bacteria can tolerate high concentrations of Na⁺ ions. To test this hypothesis, we investigated the characteristics of extr...
Article
The recent development of Structure‐from‐Motion (SfM) and Multi‐View Stereo (MVS) photogrammetry techniques has enabled semi‐automatic high‐resolution bathymetry using aerial images taken by consumer‐grade digital cameras mounted on unmanned aerial vehicles (UAVs). However, the applicability of these techniques is sometimes limited by sun and sky r...
Article
A previous study by the present authors identified nutrients necessary for hydrogen production, which was enhanced by using casamino acids (CAAs) as a nitrogen source. However, CAAs are costly; accordingly, using algal waste substrates with different nutrient compositions was speculated to serve as an alternative strategy for increasing hydrogen pr...
Article
Full-text available
The effect of glycerol waste (GW) concentration was studied in anaerobic co-digestion with canned sardine wastewater (CSW), has been examined using the 1-stage mesophilic (P1), 1-stage thermophilic (P2) and 2-stage mesophilic (P3) process. P3 process was the best process, could improve the biogas production (bio-hythane) in the case of canned sardi...
Article
The ability of Clostridium butyricum RAK25832 to use casamino acids as a nitrogen source was investigated. Strain RAK25832 showed the capacity to utilize different types of carbon sources. With glucose as a carbon source (10 g/L), the preferred final concentration of casamino acids was 26.67 g/L, with a cumulative hydrogen production, production ra...
Article
The applicability of EmporeTM styrene-divinylbenzene reverse-phase sulfonated (SDB-RPS) passive sampler disks for integrative sampling of organic chemicals in river water was investigated to evaluate toxicity levels via bioassay using larval medaka (Oryzias latipes). Those disks were deployed for periods of 1, 2, 3, 7, and 10 days (PS different per...
Article
This paper presents the results from using a physical absorption process to absorb gaseous CO2 mixed with N2 using water by producing tiny bubbles via a liquid-film-forming device (LFFD) that improves the solubility of CO2 in water. The influence of various parameters—pressure, initial CO2 concentration, gas-to-liquid ratios, and temperature—on the...
Article
Full-text available
This study aimed to enhance hydrogen production from sugarcane syrup by biogas sparging. Two-stage continuous stirred tank reactor (CSTR) and upflow anaerobic sludge blanket (UASB) reactor were used to produce hydrogen and methane, respectively. Biogas produced from the UASB was used to sparge into the CSTR. Results indicated that sparging with bio...
Article
Full-text available
River toxicity based on acute toxicity to Medaka fish and chemical concentrations measured using a gas chromatography–mass spectrometry simultaneous analysis database were investigated. Between June 2012 and January 2014, 21 samples were collected from three rivers in Japan that have most of their catchments in residential areas. Toxicity tends to...
Article
Dili is the capital city of Timor-Leste and has the highest population comparing to other cities. The quality of fresh water streams in Dili was evaluated using the larval himedaka acute toxicity assay combined with active sampling. Ten liters of grab water samples were collected from the Fatuhada, Campo Alor, Caicoli, and Kuluhun streams, filtered...
Chapter
There is increasing concern that conventional disinfection methods present several disadvantages, namely hazardous by-products (chlorine, ozone), high cost, complicated setup and high maintenance (UV, membrane, advanced oxidation process). Latest technologies of water disinfection must be developed from exploiting the advantages of conventional met...
Article
This study investigated the effect of combined treatments using pressurized carbon dioxide (PCD) and sodium hypochlorite (NaOCl) on the inactivation of Enterococcus sp. in artificial seawater. Bacterial inactivation was conducted in a liquid-film-forming apparatus with various pressure conditions, CO2 supply rates, and chlorine dosages. Combined PC...
Article
Thermophilic solid-state anaerobic digestion (SS-AD) of biomass from palm oil mill industry, including empty fruit bunches (EFB), oil palm fronds (OPF) and oil palm trunks (OPT) were investigated under different feedstock-to-inoculum ratios (F:I), carbon-to-nitrogen ratios (C:N) and total solids contents (TS). The optimal condition for biogas produ...
Article
Full-text available
In empirical approach, the satellite-derived bathymetry (SDB) is usually derived from a linear regression. However, the depth variable in surface reflectance has a more complex relation. In this paper, a methodology was introduced using a nonlinear regression of Random Forest (RF) algorithm for SDB in shallow coral reef water. Worldview-2 satellite...
Article
Aeration is an important factor in aquaculture systems due to the vital conditions for all organisms that live in water and utilize aerobic respiration. Generally, mechanical surface aerators are widely used in Thailand due to their advantage for increasing DO and for their horizontal mixing of aquaculture ponds with large-surface areas. However, t...
Article
Full-text available
Wood-inhabiting resupinate polypore fungi are abundant and widely distributed in tropical forests of Thailand. In our survey, Ceriporia cystidiata and Macrohyporia dictyopora were found in Thailand for the first time. Identification was based on morphological characteristics and DNA sequences of internal transcribed spacers and large subunit (LSU)...
Article
Full-text available
Aeration system is extensively applied in aquaculture and waste water treatment. It provides oxygen for organism living and mixing while consumes colossal amounts of energy for operating. Hence, the improvement of aeration system is not only providing enough oxygen and mixing but also concerning to the energy saving. Liquid film forming apparatus (...
Article
Full-text available
In this current study, we observed Trichoderma viride strain FRP3 capability for biodegradation of glyphosate on contaminated land in Indonesia. There were two blank plots that have been involved as representatives of indigenous fungal, that prepared as control (non-contaminated soil) and P1 (GP-contaminated soil) while the treatments were represen...
Article
Full-text available
In an attempt to find a more efficient technique for biodegradation of the recalcitrant Reactive Black 5 (RB-5) dye, a composite xylan-polyvinyl alcohol (xylan-PVOH) hydrogel was used to immobilize laccase from the white-rot fungus Trametes versicolor. Xylan was prepared from the black liquor of pulp and paper effluent, and it was esterified with c...
Article
Interest is growing in a disinfection technique for water treatment without disinfection byproducts. This study presents the result of using a liquid-film-forming apparatus at less than 1.0 MPa for disinfection of seawater. The sensitivity of Enterococcus sp. (ATCC 202155) to the pressurized carbon dioxide (CO2) was examined under various condition...
Article
Ship ballast water should be disinfected before being discharged into the ocean to avoid the dispersal of non-native species into the marine environment. This study presents the results of using pressurized carbon dioxide (CO2) at less than 1.0 MPa for inactivating Escherichia coli and Enterococcus sp. in artificial seawater (3.4% salinity). The ba...
Article
This study investigated the improvement of biogas production from solid-state anaerobic digestion (SS-AD) of oil palm biomass by optimizing of total solids (TS) contents, feedstock to inoculum (F:I) ratios and carbon to nitrogen (C:N) ratios. Highest methane yield from EFB, OPF and OPT of 358, 280 and 324 m3 CH4 ton-1 VS, respectively, was achieved...
Article
This research proposes “Eco-Environmental Diversity index (EED)”, which calculates environmental diversity of depth, velocity, bed condition, and vegetation within fish home range. To incorporate fish preference information into EED, environmental parameters are categorized to represent suitable habitat for different behavioral modes like feeding a...
Article
Full-text available
Resupinate white rot fungi were isolated from across Thailand (seven provinces) and evaluated for their ability to degrade the recalcitrant and toxic dye reactive black 5 (RB5). Seven of the 13 isolates decolorized RB5 (100 mg/L) within three days (greater than 50%). One isolate, Phanerochaete sordida PBU 0057, yielded complete decoloration within...
Article
Our previous research suggested that the entrance selection of a multiple path fishway affects migration success ratio. In this research, firstly, we prove that entrance selection affect migration success through field experiment. Secondly, we determine suitability index for air bubble condition, which were 0.27 for no bubble, 0.88 for surface bubb...
Article
Full-text available
This study involves the production of a value-added product of polyhydroxyalkanoates (PHAs) from pineapple cannery wastes by isolated bacterial strain of Bacillus sp. SV13 via batch fermentation process. Two carbon sources, glucose and sucrose, were used to investigate the potential of PHAs production compared to when the agro-industrial waste was...
Article
Recently emerging disadvantages in conventional disinfection have heightened the need for finding a new solution. Developments in the use of high pressure carbon dioxide for food preservation and sterilization have led to a renewed interest in its applicability in wastewater treatment and water disinfection. Pressurized CO2 is one of the most inves...
Article
In the palm oil mill effluent (POME) discharged during the production process of palm oil, oil is contained in the emulsion state. Currently, the open ponding system (facultative/anaerobic lagoons) is being applied as the main treatment method for POME owing to low operating costs. However, the main disadvantages of this system are the requirement...
Article
According to the cost of carbon substrate for producing biopolymer of polyhydroxyalkanoates (PHAs) still has a barrier to extend in an industrial scale. The aim of this work was to evaluate the defined PHAs media containing the agricultural raw materials of pineapple and sugarcane to produce PHAs by Bacillus strain. Batch fermentation was carried o...
Article
Enzymatic hydrolysis is an essential step in the fermentative H2 production process of lignocellulosic biomass to convert cellulose and hemicellulose into fermentable sugars. The waste from disposable wooden chopsticks (DWC) was represented as wood waste and investigated in this study. In order to optimize the condition of the enzymatic hydrolysis...
Article
Palm oil mill effluent Two-stage process Hydrogen and methane production Biohythane Microbial community a b s t r a c t A two-stage thermophilic fermentation and mesophilic methanogenic process for bio-hythane production from palm oil mill effluent (POME) was investigated. The hydrogen and methane potential from POME were 170e200 L H 2 kgCOD À1 and...
Article
Water sounds are believed to be important in triggering the upriver ascent behavior of migratory fish species. Modeling the effect of underwater sound on fish preference represents a promising technique to determine migratory paths for the comprehensive analysis of river habitat suitability. In this study, we aimed to determine the preference and w...
Article
Full-text available
A stone-embedded fish passage (SEF) allows fish to pass a barrier by reducing the velocity in the slope. The efficiency of SEFs has however not been evaluated well and the design parameters are not clear. The efficiency of SEFs for fish therefore needs to be evaluated and analyzed. In this research, we attempted to develop a simple equation to esti...
Article
Full-text available
Wastewater may contain high levels of the nutrients: nitrogen and phosphorus. Excessive release of nutrients to the environment can cause severe environmental problem such as eutrophication leading to algal blooms, oxygen deficiency, and fish kills. The forward osmosis (FO) could be a choice of treatment. FO process presents the results of using fo...
Article
Chlorination is the most common method used for disinfection of drinking water. However, growing concerns about the potential hazards of disinfection by-products have emerged many efforts to develop alternative disinfection methods. In this study, a new disinfection method was developed using low-dose chlorine in combination with a high level of wa...
Article
Full-text available
Aspergillus flavus strain KRP1 isolated from tropical forest soil was examined for its potential use in degradation of mercury contaminant in soil. This fungal strain has shown its capability to grow best in 25 ppm mercury which contaminated Potato Dextrose Agar (PDA) plate media compared with other strains. The preference pH for fungal growth was...
Article
Field investigations on wastewater quality and odor emissions at a potato starch factory were conducted from July 2007 to May 2008. Odor index of decanter effluent and separator effluent in penetration ponds ranged from 43 to 51, suggesting that anaerobic decomposition of wastewater with high concentration of organic matters especially in decanter...
Article
A modified column flotation of using tiny microbubbles ozonation (MB, diameter range: 1–16 μm, D32 = 6.59 μm) enhanced by coarse bubbles (CB, diameter range: 0.5–5 mm) was designed for the treatment of fine oil-in-water emulsions (EO, d < 16 μm, D32 = 6.3 μm) and humic acid (HA) mixture (EO/HA, d < 16 μm, D32 = 5.8 μm). Samples of EO/HA showed much...
Article
A granular calcined Mg-3-Fe LDH adsorbent was prepared by using co-precipitation method under low super saturation condition. The characteristic of the adsorbent was analyzed by powder X-ray diffraction (XRD) and scanning electron microscope (SEM). The continuous phosphate adsorption experiments were conducted in a glass fix-bed column. The results...