Kensuke Fukushi

Sustainability science: Bridging the gap between science and society

These challenges are nolonger ignorable, as they have triggered fierce debates andcontroversies across all sectors and classes of society,finally infiltrating the ivory towers of academia. Yet, publicattention is captivated by the entertaining media episodeson these catastrophes and hardly any attention is paid to thecatastrophes’ underlying structures and root causes. Recentexamples include Fukushima’s nuclear power plant fiascoand the BP oil spill in the Gulf of Mexico that divertattention from the key drivers, namely, the insatiableenergy consumption in industrialized nations; the eco-nomic ideologies of safety and security that justify militaryinterventions and arms trade, which continue to increaseand spread in spite of humanitarian rhetoric and globalrecession; the continuous urbanization, with the majority ofthe world’s population now living in urban areas, thereby,perpetuating the discredits and exploits of rural areas; thesilent discounting of our children’s future through indus-trial food, resulting in more than a quarter of all children inindustrialized nations being obese or overweight, with themajority staying obese as adults (Wiek et al. 2011b).While research and education slowly recognize theimportance of shifting their efforts to such challenges andtheir root causes (Jerneck et al. 2011; Spangenberg 2011;Wiek et al. 2011a), sustainability scientists lack experienceand expertiseincontributingtofeasibleandeffectivesolutionoptions. The concept of linking knowledge to action forsustainability was initiated a decade ago (Kates et al. 2001)and has been reiterated since then (Komiyama and Takeuchi2006; van Kerkhoff and Lebel 2006); yet, too many scholarsstillbelievethatthislinkwillmiraculouslyemerge.However,it is obvious that it requires a very different type of researchand education (Sarewitz et al. 2010;Wieketal.2011a):namely, research that generates knowledge that matters topeople’s decisions and engages in arenas where powerdominates knowledge; and education that enables students tobe visionary, creative, and rigorous in developing solutionsand that leaves the protected space of the classroom to con-front the dynamics and contradictions of the real world.Against this background, the community of sustain-ability scientists is confronted with two essential questions.First, what is a reasonable mission for sustainability sci-ence, considering that research and education are valuablebut not sufficient contributions to solving sustainability

A novel application of a submerged nanofiltration membrane bioreactor (NF MBR) for wastewater treatment

Nanofiltration (NF) membrane technology has made rapid progress and then extended its application fields. It has obtained in particular the good results in the removal of organic and inorganic matters or microbes in the water and wastewater. To investigate the applicability and characteristics of NF membrane, the membrane bioreactor (MBR) using the cellulose acetate NF membrane was performed to treat synthetic wastewater. A hollow-fiber-type cellulose acetate membrane was chosen to get enough water productivity regardless of its biodegradability. As a result of the experiments, enough water productivity was obtained for 60 days without fatal fouling and membrane cleaning. This raised the applicability of cellulose acetate membrane to the MBR system. Electrolytes were not accumulated in the bioreactor, as its rejection was also low. This enabled the NF MBR to be operated under a low suction pressure and prevented from inhibition against microorganisms, whose activity might be deteriorated by high salt concentration. Nitrification and denitrification happened simultaneously and this might be achieved by the module configuration. The phosphorus was not removed with the loose NF membrane. According to AFM investigation, the cellulose acetate membrane after 71 days has larger voids because of the biodegradation.

Bioaugmented membrane bioreactor (MBR) with a GAC-packed zone for high rate textile wastewater treatment.

The long-term performance of a bioaugmented membrane bioreactor (MBR) containing a GAC-packed anaerobic zone for treatment of textile wastewater containing structurally different azo dyes was observed. A unique feeding strategy, consistent with the mode of evolution of separate waste streams in textile plants, was adopted to make the best use of the GAC-zone for dye removal. Dye was introduced through the GAC-zone while the rest of the colorless media was simultaneously fed through the aerobic zone. Preliminary experiments confirmed the importance of coupling the GAC-amended anaerobic zone to the aerobic MBR and also evidenced the efficacy of the adopted feeding strategy. Following this, the robustness of the process under gradually increasing dye-loading was tested. The respective average dye concentrations (mg/L) in the sample from GAC-zone and the membrane-permeate under dye-loadings of 0.1 and 1 g/L.d were as follows: GAC-zone (3, 105), permeate (0, 5). TOC concentration in membrane-permeate for the aforementioned loadings were 3 and 54 mg/L, respectively. Stable decoloration along with significant TOC removal during a period of over 7 months under extremely high dye-loadings demonstrated the superiority of the proposed hybrid process.

Factors governing performance of continuous fungal reactor during non-sterile operation--the case of a membrane bioreactor treating textile wastewater.

White-rot fungi, unlike bacteria in conventional activated sludge system, can degrade wide varieties of textile dyes. Their large scale implementation, however, has been impeded due to lack of appropriate reactor system that can sustain stable performance under non-sterile environment. In this study, contrary to virtually complete decoloration of an azo dye (Acid Orange II, 100 mg L(-1)) in pure culture batch test, a fungal membrane bioreactor (MBR) achieved 93% removal during long-term non-sterile operation at a hydraulic retention time (HRT) of 1 d. Through a set of novel observations made in MBR and parallel batch tests, the interrelated factors responsible for incomplete dye removal, namely, bacterial disruption, fungal morphology and enzyme washout were identified. As compared to the activity of pure fungus culture, the bacteria-contaminated disintegrated MBR-sludge demonstrated low decoloration and undetectable enzymatic activity, indicating detrimental effect of bacterial contamination. Additional observations suggested close relationship between fungal morphology and enzymatic/decoloration activity under non-sterile environment. This study also demonstrated the occurrence of enzyme washout from MBR and its HRT-specific detrimental influence on removal performance. Based on the observations, certain ways to enhance decoloration were proposed.

Bacterial Community Structure on Membrane Surface and Characteristics of Strains Isolated from Membrane Surface in Submerged Membrane Bioreactor

Abstract In order to investigate the bacterial community structure and the characteristics of bacteria on the membrane surface, a submerged membrane bioreactor treating municipal wastewater was continuously operated under two different conditions. Bacterial community structures were examined by PCR‐denaturing gradient gel electrophoresis and PCR cloning of 16S rRNA genes. Bacterial strains isolated from membrane surface were identified and their growth curve, EPS concentration and hydrophobicity were measured. The structures of bacterial communities in the suspended solids and on the membrane surface were obviously different, and γ‐Proteobacteria more selectively adhere and grow on the membrane surface than other microorganisms. Most of the membrane isolates grew slowly as compared with the strains isolated from the suspended solids. Also, the membrane isolates were higher cell surface hydrophobicities, higher EPS concentrations, and higher ratios of protein to carbohydrate within the EPSs than the isolates from suspended solids.

Survival of Salmonella spp. in a simulated acid-phase anaerobic digester treating sewage sludge

The presence of pathogenic microorganisms in municipal waste sludge may create a serious outbreak of water borne diseases if the sludge is used for agricultural purpose. An attempt to decrease the number of pathogenic microorganisms, Salmonella spp. using a simulated acid-phase anaerobic digester was tested in a laboratory-scale batch experiment. Reduction of Salmonella spp. was demonstrated in a mixture of sludge and organic acid, simulating an acid digester of a two-phase anaerobic digestion process. A high concentration of organic acid at a pH value of 5.5-6.0 prevents a decrease in Salmonella spp. concentration. Almost complete destruction of Salmonella spp. is observed within two days if the pH value is maintained below 5.5.

Detection of enteric viruses in municipal sewage sludge by a combination of the enzymatic virus elution method and RT-PCR

Pathogenic enteric viruses can be retained in municipal sewage sludge as has been reported by many researchers. Although the RT-PCR technique has been extensively employed for the virus detection from various environmental samples, the application of RT-PCR to the detection of viruses in sewage sludge has the difficulty because of inhibitory substances to the gene amplification. However, a combination of the enzymatic virus elution (EVE) method with RT-PCR made it possible to effectively detect viruses in sewage sludge. The enzymatic breakdown of sludge flocs in the EVE method enhanced the virus elution from poliovirus 1 (PV1)-inoculated sewage sludge, and the detection of PV1 was performed by RT-PCR without any inhibitions. On the contrary, the application of RT-PCR to the viral assay in the US EPA method using the 10% beef extract solution was not practical because of inhibitions to the viral gene amplification. The combination of the EVE method using lysozyme (polysaccharide-degrading enzyme), papain (protease), and chymotrypsin (protease) with RT-PCR resulted in a virus recovery efficiency of 31%, but a synergistic effect of these enzymes on the virus recovery efficiency was not observed. The EVE method using lysozyme or papain could be a promising procedure for the virus elution from sewage sludge in detecting these viruses with RT-PCR.

Degradation of azo dye acid orange 7 in a membrane bioreactor by pellets and attached growth of Coriolus versicolour

The aim of this study was to systematically compare the degradation of azo dye acid orange 7 by spongy pellets and attached biofilm of Coriolus versicolour (NBRC 9791) in a membrane bioreactor (MBR) under non-sterile conditions. Mild stirring (35 rpm) resulted in spherical (φ=0.5 cm), spongy pellets and concomitantly triggered high enzymatic activity of the fungus, allowing for excellent decolouration (>99%) of a synthetic wastewater containing the dye. However, bacterial contamination eventually damaged the fungus pellets, leading to decreased decolouration efficiency. Promotion of attached growth on a plastic support along with formation of spherical spongy pellets allowed maintenance of high enzymatic activity and decolouration/degradation for an extended period. Hydraulic retention time (HRT) could influence the level of enzymatic activity and decolouration; however, even at the shortest HRT (1 day) examined, the MBR could accomplish >95% decolouration.

Comparison of DNA damage detected by plant comet assay in roadside and non-roadside environments.

Although mixed air pollutants generated from traffic are suspected as one of the causes of DNA damage in living species, effects of the combination of these pollutants and other micro-environmental factors on urban biota have not been clarified yet. Thus, this study mainly aimed to detect the genetic damages in selected plant biomonitors, which were ginkgo (Ginkgo biloba), pohtos (Epipremnum aureum), and periwinkle (Vinca rosea), setting in roadside and non-roadside environments. Two monitoring positions were selected in the Hongo campus of the University of Tokyo, Japan. This area was categorized as the urban residential zone. Both roadside and non-roadside samples were analyzed by using comet assay protocol. Different distribution changes in DNA migration ratios of all species could be observed and further interpreted as percentages of DNA damage. For all test species, in the final stage of experiment, roadside samples showed significantly higher degrees of DNA damage than non-roadside one. Time-dependent response pattern of each species to the overall environmental stresses was performed. Increase in the percentages of DNA damage could be expressed by regression equations. In addition, ratio of percentage of DNA damage between roadside and non-roadside species (R/N ratio) was introduced in order to clarify the additional genetic effect caused by roadside air pollutants. Series of response phase of plant under stresses, including cell destabilization, damage intensification, and re-stabilization, were explained. This study might be applied as a preliminary method in urban air quality assessment for detecting the existing effects of air pollutants and micro-environmental stress in an urban ecosystem.

Nitrate removal and biofilm characteristics in methanotrophic membrane biofilm reactors with various gas supply regimes

Aerobic methanotrophs can contribute to nitrate removal from contaminated waters, wastewaters, or landfill leachate by assimilatory reduction and by producing soluble organics that can be utilized by coexisting denitrifiers. The goal of this study was to investigate nitrate removal and biofilm characteristics in membrane biofilm reactors (MBfR) with various supply regimes of oxygen and methane gas. Three MBfR configurations were developed and they achieved significantly higher nitrate removal efficiencies in terms of methane utilization (values ranging from 0.25 to 0.36molNmol(-1)CH(4)) than have previously been observed with suspended cultures. The biofilm characteristics were investigated in two MBfRs with varying modes of oxygen supply. The biofilms differed in structure, but both were dominated by Type I methanotrophs growing close to the membrane surface. Detection of the nitrite reductase genes, nirS and nirK, suggested genetic potential for denitrification was present in the mixed culture biofilms.