
Takahiro FujiokaNagasaki University · Graduate School of Integrated Science and Technology
Takahiro Fujioka
B.Eng., M.Eng., M.Sc., PhD
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106
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Introduction
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May 2015 - present
December 2013 - May 2015
Publications
Publications (106)
Determining the reliability of nanofiltration (NF) membranes for the removal of contaminants of emerging concern, including polyfluoroalkyl substances (PFASs), pharmaceuticals, and personal care products (PPCPs), is important for ensuring drinking water safety. This study aimed to clarify the factors that influence the removal of nine major PFASs d...
Photobiological treatment of reverse osmosis concentrate (ROC) using brackish diatoms is a green and sustainable technology that can enhance water recovery by removing dissolved silica from ROC while producing beneficial biomass. This study aimed to determine the optimum conditions for the photobiological treatment of ROC obtained from a full-scale...
Advanced drinking water treatment process using nanofiltration (NF) membranes has gained attention recently because it removes many challenging constituents in contaminated surface waters, such as dissolved organics and heavy metals. However, much literature has reported high variations and uncertainties of NF membranes for removing nitrogen compou...
The sudden occurrence of odor in drinking water is one of the significant challenges for drinking water utilities. The concentrations of 2-methylisoborneol (2-MIB)-producing cyanobacteria, Pseudanabaena sp., can be a surrogate...
RO treatment was utilized as a pretreatment method to remove interfering substances in high-matrix water samples for NDMA measurements.
Correction for ‘Validation of a novel direct-injection chemiluminescence-based method for N -nitrosamine analysis in advanced-treated recycled water, drinking water, and wastewater’ by Shannon L. Roback et al. , Environ. Sci.: Water Res. Technol. , 2020, 6 , 1106–1115, DOI: 10.1039/C9EW00943D.
Ensuring the microbiological safety of drinking water is critical to protect public health. This study aimed to evaluate the reliability of real-time bacteriological counter coupled with an online dialysis membrane-based pre-treatment system for continuously monitoring bacterial cell counts in sand filter effluents of a full-scale drinking water tr...
Water contamination by oil spills causes severe damage to the environment and human health. Oil adsorbents should be buoyant, for effective oil-contact, and regenerable. In this study, diatomaceous-earth (DE)-incorporated magnetic alginate (Alg)-based beads, chemically modified to include phthalic or maleic anhydride (denoted as Alg/DE/Fe3O4-PA and...
Achieving high water recovery using reverse osmosis membranes is challenging during water recycling because the increased concentrations of organics and inorganics in wastewater can cause rapid membrane fouling, necessitating frequent cleaning using chemical agents. This study evaluated the potential of membrane distillation to purify reverse osmos...
The ultraviolet (UV)-based advanced oxidation process (AOP) is a powerful technology for removing pathogenic microorganisms and contaminants of emerging concern (CECs) from water. AOP in potable water reuse has been predominantly based on traditional low-pressure mercury (LP-Hg) lamps at 254 nm wavelength, supplemented by hydrogen peroxide addition...
Direct nanofiltration (NF) of secondary treated effluent can significantly simplify water recycling, especially for small scale operations. This study evaluated the performance of a novel flat-sheet submerged NF membrane module at low water flux to minimize membrane fouling. The separation performance of the NF system was assessed by periodically m...
Urine has been considered as an ideal nutrient source for microalgae cultivation thanks to its composition containing the high concentrations of nitrogen and phosphorus. Herein, the microalgae growth in urine was evaluated in a lab-scale membrane photobioreactor (MPBR) system. This work aimed to validate the influence of low biomass retention times...
Advanced oxidation processes (AOPs) play a vital role in attenuating contaminants of emerging concern (CECs) during potable water reuse. AOPs are conventionally performed by irradiating with a 254-nm low-pressure (LP) mercury-vapor (Hg) ultraviolet (UV) lamp along with chemical treatment. Compared with UV-C light treatment (200–280 nm), vacuum-UV (...
N-nitrosamines are contaminants of emerging concern, and controlling these chemicals in potable water and recycled water for potable reuse has become important for protecting public health. This study aimed to evaluate the influence of the alkyl chain lengths of N-nitrosamine precursors (secondary and tertiary amines) on the formation of N-nitrosam...
It has been recently confirmed that photoexcited ketones such as acetone promote the chemiluminescence (CL) reaction of luminol and its analog, L-012. Using this finding, a selective determination method for acetone was developed herein based on HPLC separation, online UV irradiation, and subsequent luminol CL detection. Various conditions, includi...
The frequent analysis of the 2-methylisoborneol (2-MIB)-generating algae, Pseudanabaena sp., for predicting odor occurrence in drinking water sources is a major challenge for many drinking water utilities. This study aims...
Continuous monitoring of bromate ions, a disinfection by-product of the ozonation of wastewater, may improve the safety of recycled water for potable use. A recently developed elemental analyzer can determine...
The advanced oxidation process (AOP), using conventional low-pressure mercury (LP Hg)-vapor UV lamps, forms a critical barrier for pathogens and contaminants of emerging concern (CECs) in potable water reuse. In recent years, UV-light-emitting diode (UV-LED) has attracted considerable attention as an alternative UV source because it has a long life...
Membrane fouling is a major challenge toward achieving direct nanofiltration (NF) treatment of surface water. This study aimed to evaluate the potential of the novel submerged flat-sheet NF membrane module to achieve low fouling propensity and high separation performance during the direct filtration of surface water. Laboratory-scale NF tests showe...
Palm oil industry is one of the most important agriculture sectors in Malaysia. However, this industry produces a huge amount of palm oil mill effluent (POME) which contains impurities that will pollute the environment. Hence, POME has to be treated before it can be safely discharged to the environment. This study aims to evaluate the effectiveness...
The online monitoring of bacterial content during drinking water and wastewater treatment processes is an important strategy for enhancing the quality of treated waters. Although real-time bacteriological counting techniques enable online monitoring of bacterial counts, the autofluorescence of background organic constituents in the waters (e.g., hu...
Controlling membrane fouling and disinfection by-products (DBPs) is an ongoing challenge in achieving sustainable membrane-based seawater desalination. This study assessed the efficacy of a new disinfectant, stabilized hypobromite, for controlling biofouling and DBP formation during reverse osmosis (RO) membrane treatment of seawater. Accelerated c...
Removing N-nitrosodimethylamine (NDMA), a regulated carcinogenic chemical, with a reverse osmosis (RO) membrane is a key challenge for enhancing the safety of reused potable water. This study aimed to achieve high rejection of NDMA and salts by plugging the nanopores in an RO membrane with linear-chain amines, amides, and epoxides. Plugging with am...
Pre-concentration of wastewater using a forward osmosis (FO) membrane prior to processing by an anaerobic digester can enhance biogas production. However, biofouling caused by microbes in wastewater remains a challenge. The study aimed to evaluate the efficacy of chloramination in mitigating the biofouling of an FO membrane during a single-pass con...
The attenuation of pathogenic microorganisms in potable water reuse is critical to ensure recycled water safety. Thus, this study sought to identify bacterial communities capable of passing through a commercial reverse osmosis (RO) membrane as well as to characterize the passage of these bacteria through the membranes. Three-quarters of the bacteri...
Advanced wastewater treatment using a reverse osmosis (RO) membrane is a key separation process for ensuring the removal of chemical hazards so that treated wastewater can be used for potable purposes. This study systematically assesses the effects of heat modification conditions of three commercial RO membranes on the removal of a challenging chem...
N-Nitrosamines are water contaminants of public health concern due to their carcinogenicity at low concentrations. These compounds can form in wastewater and drinking water when chloramination is utilized for disinfection. Monitoring of N-nitrosamines by current analytical techniques is difficult, time-consuming, and expensive. Therefore, a simpler...
Real-time bacteriological counting technology is capable of providing an online profile of bacterial removal during the wastewater treatment process, and can enhance the safety of recycled water for potable water reuse. However, autofluorescence emanating from dissolved organic compounds present in treated wastewater interferes with the analysis. I...
The safety of recycled water for potable water reuse can be enhanced by improving the reliability of reverse osmosis (RO) treatment for the removal of trace organic chemicals. This study assessed the mechanisms underlying the variable rejection of a carcinogenic N-nitrosamine, namely N-nitrosodimethylamine (NDMA), caused by RO membrane fouling. Fou...
The efficacy of a baffled osmotic membrane bioreactor-microfiltration (OMBR-MF) hybrid system equipped with thin film forward osmosis membrane for wastewater treatment was evaluated at laboratory scale. The novel OMBR-MF hybrid system involved baffles, that separate oxic and anoxic zones in the aerobic reactor for simultaneous nitrification and den...
Attenuation of trace organic chemicals (TOrCs), including pesticides, by reverse osmosis (RO) membrane treatment is critical for ensuring public health protection in potable water reuse. This study aimed to elucidate the mechanisms underlying the poor rejection of small pesticides by polyamide-based RO membranes. Rejection of the selected TOrCs (fo...
N-nitrosodimethylamine (NDMA) is a disinfection by-product (DBP) that has been classified as a probable human carcinogen in multiple risk assessments. NDMA presence in drinking water is widespread and dependent on source water, disinfectant type, precursors, and water treatment strategies. The objectives of this study were to investigate NDMA forma...
Chloramination is a conventional and successful pre-disinfection approach to control biological fouling for reverse osmosis (RO) treatment in water reuse. This study aimed to evaluate the possibility of using a new disinfectant-stabilized hypobromite-in controlling membrane fouling and the formation of a particular carcinogenic disinfection byprodu...
Public confidence in the safety of recycled water for potable water reuse can be improved by providing assurance regarding high removal of trace organic chemicals (TOrCs) by reverse osmosis (RO) treatment. This pilot-scale study assessed the effectiveness of a surrogate indicator-N-Nitrosodimethlyamine (NDMA)-for ensuring a high level of TOrC remov...
This study elucidates the impact of draw solution chemistry (in terms of pH and draw solute species) and membrane fouling on water flux and the rejection of trace organic contaminants by forward osmosis. The results show that draw solution chemistry could induce a notable impact on both water flux and TrOCs rejection. In addition, the impact was fu...
The safety of recycled water for potable water reuse can be enhanced by improving the removal of pathogenic microorganisms through reverse osmosis (RO) membrane. The present study aimed to identify the causes of the passage of particles through intact RO membrane elements using stable 0.5 µm fluorescent (FL) microspheres as bacteria-sized surrogate...
Microbiological risks associated with drinking water can be minimized by providing enhanced integrity monitoring of bacterial removal by water treatment processes. This study aimed to evaluate the efficacy of real-time bacteriological counters for continuously assessing the performance of a full-scale sand filter to remove bacteria. Over the course...
Safety of potable reuse can be enhanced by improved water quality monitoring techniques for assessing water treatment processes. This study evaluated the efficacy of online bacterial counting for continuous monitoring of reverse osmosis (RO) membranes to remove bacteria using real-time bacteriological commercial counters and an on-site pilot-scale...
Nowadays due to urbanization and industrialization, several pollutants and its derivatives are discharged into water environment. Most of the pollution is caused by organics, nutrients, and contaminants with low concentration but is highly toxic to human and aquatic environment. Especially, there are several micropollutants and its derivatives that...
For the protection of public health, robust quality assurance and quality control are critical elements in wastewater treatment for potable water reuse. Reverse osmosis (RO) membrane technology is a powerful wastewater treatment process that results in the removal of most contaminants. However, the efficacy of using conventional RO membranes for th...
Reliable and adequate removal of small and uncharged trace organic chemicals (TOrCs), particularly N-nitrosodimethylamine (NDMA) that is carcinogenic and known to occur in treated effluent, is essential for implementing direct potable water use. This study provides new insights to explain the low rejection of NDMA and other N-nitrosamines by revers...
Water quality and reliability during potable reuse can often depend on the performance of the reverse osmosis (RO) membrane treatment for the attenuation of microbial contaminants. This pilot-scale study aimed to assess bacterial passage through intact RO membrane element and O-ring seal using stable fluorescent microspheres as bacterial surrogates...
This book discusses major technological advances in the treatment and re-use of wastewater. Its focus is on both novel treatment strategies and the modifications and adaptions of conventional processes to optimize the treatment of a complex variety of pollutants, including organic matter, chemicals and micropollutants in different water resources,...
Pre-concentration is essential for energy and resource recovery from municipal wastewater. The potential of forward osmosis (FO) membranes to pre-concentrate wastewater for subsequent biogas production has been demonstrated, although biofouling has also emerged as a prominent challenge. This study, using a cellulose triacetate FO membrane, shows th...
Public health protection and cost effectiveness of potable reuse can be improved by providing reliable water quality assurance for removal of trace organic compounds (TOrCs) by reverse osmosis (RO) membrane. This study evaluated the effectiveness of online monitoring of N-nitrosodimethlyamine (NDMA) removal by RO system to ensure the removal of low...
Coagulation using Moringa oleifera (MO), a natural coagulant, is an attractive approach in drinking water treatment to break away from conventional chemical coagulation using aluminium or iron salts. This study aimed to evaluate the effect of pre-filtered MO coagulation pretreatment on the fouling mitigation in microfiltration (MF) process. MF trea...
Rigorous monitoring of microbial water quality is essential to ensure the safety of recycled water after advanced treatment for indirect and direct potable reuse. This study evaluated real-time bacterial monitoring for assessing reverse osmosis (RO) treatment for removal of bacteria. A strategy was employed to monitor bacterial counts on-line and i...
A new membrane fouling control technique using ozonated water flushing was evaluated for direct nanofiltration (NF) of secondary wastewater effluent using a ceramic NF membrane. Experiments were conducted at a permeate flux of 44 L/m²h to evaluate the ozonated water flushing technique for fouling mitigation. Surface flushing with clean water did no...
The polyamide skin layer of reverse osmosis (RO) membranes was characterised using advanced and complementary analytical techniques to investigate the mechanisms underlying the permeation of contaminants of emerging concern in potable water reuse – N-nitrosodimethylamine (NDMA) and N-nitrosomethylethylamine (NMEA). This study used five RO membrane...
The security of recycled water quality in potable reuse can be enhanced by improving the credibility of reverse osmosis (RO) treatment for the removal of trace organic chemicals (TOrCs). This study evaluated the potential of online monitoring of N-nitrosodimethylamine (NDMA) before and after RO treatment as a surrogate indicator for TOrC removal by...
This study proposed a new approach to apply the steric pore-flow model to predict the rejection of eight N-nitrosamines and seven VOCs that are of great concern in potable water reuse through an RO membrane. In this approach, solute rejection is predicted by estimating the free-volume hole-size. The free-volume hole-radius was determined with pure...
Direct potable reuse is becoming a feasible option to cope with water shortages. It requires more stringent water quality assurance than indirect potable reuse. Thus, the development of a high-rejection reverse osmosis (RO) membrane for the removal of one of the most challenging chemicals in potable reuse - N-nitrosodimethylamine (NDMA) - ensures f...
Direct potable reuse requires stringent water quality assurance to protect public health. This study developed an online analytical technique—high-performance liquid chromatography followed by photochemical reaction and chemiluminescence detection (HPLC-PR-CL)—for determination of the concentration of N-nitrosodimethylamine (NDMA) and three other N...
The effectiveness of hypochlorite cleaning for fouling mitigation of a prototype chlorine-resistant nanofiltration (NF) membrane was assessed for direct filtration of a secondary treated effluent. The chlorine resistance and separation performance of the prototype NF membrane were also compared to commercial NF and reverse osmosis membranes. The pr...
The ultraviolet (UV)-based advanced oxidation process (AOP) is a powerful technology commonly utilised in recent potable water reuse (PR) schemes. The AOP involves the generation of highly reactive free radicals (e.g. hydroxyl, HO•) and is primarily applied for the removal of two target trace organic chemicals—N-nitrosodimethylamine (NDMA) and 1,4-...
The impact of fouling substances on the rejection of four N-nitrosamines by a reverse osmosis (RO) membrane was evaluated via a systematic characterisation of individual organic fractions in a secondary wastewater effluent and the deployment of a novel high-performance liquid chromatography-photochemical reaction-chemiluminescence (HPLC-PR-CL) anal...
A novel method for the determination of secondary amines at the nanomolar level was developed. The method is based on the nitrosation reaction of secondary amines, with the generated N-nitrosamines being measured using an HPLC separation, photochemical reaction, and chemiluminescence detection system. The efficient nitrosation of secondary amines w...
A fast and reliable analytical technique was evaluated and validated for determination of N-nitrosodimethylamine (NDMA) formation and rejection by reverse osmosis (RO) membranes in potable water reuse applications. The analytical instrument used in this study is high-performance liquid chromatography (HPLC), photochemical reaction (PR) and chemilum...
The degradation of four pharmaceuticals, carbamazepine (CBZ), diclofenac (DCF), sulfamethoxazole (SMX) and trimethoprim (TMP) by ozonation was studied under a range of experimental conditions, including ozone dosage and concentration of target compounds. The concentration profile of the pharmaceuticals and detection of any by-products formed was ca...
High-pressure membrane separation processes including reverse osmosis (RO) and nanofiltration (NF) have been widely used for drinking water purification and water recycling as well as for the removal of trace organic contaminants (TrOCs). Rejection of TrOCs by NF/RO membranes is governed mainly by size exclusion, electrostatic repulsion and hydroph...
This study evaluated the performance of a side-stream ceramic nanofiltration membrane bioreactor (NF-MBR) system with respect to basic water quality parameters as well as trace organic contaminant (TrOC) removal efficiency. The results show a stable biological performance of the continuous NF-MBR system with high effluent quality (total organic car...
The aim of this study was to provide further insights to the rejection mechanisms of trace organic chemicals (TrOCs) by nanofiltration (NF). The separation mechanisms of TrOCs by an NF membrane were elucidated by assessing the role of molecular properties and the impact of caustic cleaning on their rejection. All charged TrOCs were rejected by the...
Reverse osmosis (RO) has been employed as a key separation process in many industrial applications. In recent years, the use of positron annihilation spectroscopy (PAS) including positron annihilation lifetime spectroscopy (PALS) and Doppler broadening of annihilation radiation to characterise the internal structure of the skin layer of thin film c...
The effects of heat treatment on membrane fouling resistance and the rejection of small and neutral solutes by reverse osmosis (RO) membranes were elucidated. RO membrane modification by heat treatment reduced fouling and improved boron rejection. However, heat treatment also caused a decrease in the water permeability of RO membranes. Significant...
Backwashing using ozonated water was investigated to control fouling during direct sewer mining using a ceramic microfiltration (MF) membrane. Primarily treated municipal wastewater was filtered and backwashing was performed using RO filtered tap water in this study. Direct MF filtration in the dead-end filtration mode using the ceramic MF membrane...
A protocol to validate the rejection of organic chemicals of potential health risk by low pressure reverse osmosis (LPRO) membranes was developed for decision making support regarding the monitoring level required for potable water reuse. Ten organic chemicals were selected for evaluation, based on their recorded usage, the scarcity of rejection da...
The rejection of 41 trace organic chemicals (TrOCs) by a ceramic nanofiltration (NF) membrane was examined and compared with that by two polyamide-based NF membranes – namely NF90 and NF270. Rejection behaviours of TrOCs by the ceramic and polymeric NF membranes were mostly similar but there were several notable differences. The rejection of neutra...
N-nitrosamines and boron are small solutes of particular concern during water recycling applications. Here, we evaluated the rejection of seven N-nitrosamines and boron under a range of operating conditions and feed solution characteristics. The evaluation was conducted using a pilot-scale reverse osmosis (RO) system to appropriately simulate hydro...
The rejection behaviours of 41 trace organic chemicals (TrOCs) by a hollow fibre cellulose triacetate (CTA) reverse osmosis (RO) membrane for potable water reuse were evaluated. Results reported here suggest that the rejection behaviours of TrOCs by the CTA RO membrane are mostly similar to those previously reported for the polyamide (PA) RO membra...
This study aims to evaluate the performance of ozone treatment for removing N-nitrosamines from reverse osmosis (RO) concentrate in water recycling applications. In the absence of any N-nitrosamine precursors, the destruction efficiency of N-nitrosamines was dependent on their molecular weight or the length of the alkyl chain in their molecular str...
This study demonstrates the feasibility of producing NaOH from coal seam gas (CSG) brine by membrane electrolysis. Membrane electrolysis of NaHCO3, Na2CO3, and NaCl, which are the three dominating sources of sodium in CSG brine, were evaluated and compared. Overall, the current efficiency did not change significantly when different brine solutions...
A mathematical model was developed based on the irreversible thermodynamic principle and hydrodynamic calculation to predict the rejection of N-nitrosamines by spiral-wound reverse osmosis (RO) membrane systems. The developed model is able to accurately describe the rejection of N-nitrosamines under a range of permeate flux and system recovery cond...
The use of heat treatment to improve solute rejection and fouling resistance of a polyamide reverse osmosis (RO) membrane was investigated in this study. Heat treatment was carried out by immersing the membrane samples in Milli-Q water at 70 degrees C for a specific duration. Heat treatment (24 h) reduced the pure water permeability from 4.1 to 2.8...
Abstract Free-volume hole-radii of the active skin layer of one seawater and two low pressure reverse osmosis (RO) membranes – namely SWC5, ESPAB, and ESPA2 respectively – were evaluated using positron annihilation lifetime spectroscopy (PALS) with a slow positron beam. The results were related to the rejection of boric acid and eight N-nitrosamine...