- [Show abstract] [Hide abstract] ABSTRACT: Lab-scale vertical flow constructed wetlands (CWs) were used to remove phenol, bisphenol A (BPA), and 4-tert-butylphenol (4-t-BP) from synthetic young and old leachate. Removal percentages of phenolic compounds from the CWs were in the following order: phenol (88–100%) > 4-t-BP (18–100%) ≥ BPA (9–99%). In all CWs, phenol was removed almost completely from leachate. Results show that BPA and 4-t-BP were removed more efficiently from CWs planted with Phragmites australis than from unplanted CWs, from old leachate containing lower amounts of acetate and propionate as easily degradable carbon sources than from young leachate, and in the dry season mode with long retention time than in the wet season mode with short retention time. Adsorption by initial removal and subsequent biodegradation processes might be major removal processes for these phenolic compounds. The presence of plant is beneficial for enrichment of BPA-degrading and 4-t-BP-degrading bacteria and for the carbon source utilization potential of microbes in CWs.
- [Show abstract] [Hide abstract] ABSTRACT: In recent years, several strains capable of degrading 1,4-dioxane have been isolated from the genera Pseudonocardia and Rhodococcus. This study was conducted to evaluate the 1,4-dioxane degradation potential of phylogenetically diverse strains in these genera. The abilities to degrade 1,4-dioxane as a sole carbon and energy source and co-metabolically with tetrahydrofuran (THF) were evaluated for 13 Pseudonocardia and 12 Rhodococcus species. Pseudonocardia dioxanivorans JCM 13855T, which is a 1,4-dioxane degrading bacterium also known as P. dioxanivorans CB1190, and Rhodococcus aetherivorans JCM 14343T could degrade 1,4-dioxane as the sole carbon and energy source. In addition to these two strains, ten Pseudonocardia strains could degrade THF, but no Rhodococcus strains could degrade THF. Of the ten Pseudonocardia strains, Pseudonocardia acacia JCM 16707T and Pseudonocardia asaccharolytica JCM 10410T degraded 1,4-dioxane co-metabolically with THF. These results indicated that 1,4-dioxane degradation potential, including degradation for growth and by co-metabolism with THF, is possessed by selected strains of Pseudonocardia and Rhodococcus, although THF degradation potential appeared to be widely distributed in Pseudonocardia. Analysis of soluble di-iron monooxygenase (SDIMO) α-subunit genes in THF and/or 1,4-dioxane degrading strains revealed that not only THF and 1,4-dioxane monooxygenases but also propane monooxygenase-like SDIMOs can be involved in 1,4-dioxane degradation.
- [Show abstract] [Hide abstract] ABSTRACT: To improve nitrogen removal performance of wastewater treatment plants (WWTPs), it is essential to understand the behavior of nitrogen cycling communities, which comprise various microorganisms. This study characterized the quantity and diversity of nitrogen cycling genes in various processes of municipal WWTPs by employing two molecular-based methods:most probable number-polymerase chain reaction (MPN-PCR) and DNA microarray. MPN-PCR analysis revealed that gene quantities were not statistically different among processes, suggesting that conventional activated sludge processes (CAS) are similar to nitrogen removal processes in their ability to retain an adequate population of nitrogen cycling microorganisms. Furthermore, most processes in the WWTPs that were researched shared a pattern:the nirS and the bacterial amoA genes were more abundant than the nirK and archaeal amoA genes, respectively. DNA microarray analysis revealed that several kinds of nitrification and denitrification genes were detected in both CAS and anaerobic-oxic processes (AO), whereas limited genes were detected in nitrogen removal processes. Results of this study suggest that CAS maintains a diverse community of nitrogen cycling microorganisms; moreover, the microbial communities in nitrogen removal processes may be specific.
- [Show abstract] [Hide abstract] ABSTRACT: A technique for using waste activated sludge (WAS) accumulating intracellular storage materials was studied for enhancing methane production through anaerobic digestion. Model WAS samples with various contents of poly-β-hydroxyalkanoates (PHAs) were used for anaerobic digestion tests. Methane production during 32 d from WAS with PHA content of 290 mg g−1 of dry mass was higher by 30% than that from WAS with PHA content of 30 mg g−1. Kinetic models showed that PHAs have a higher biogas production rate constant and a higher biogas yield than microbial cells of WAS in anaerobic digestion. An increase of 10 mg g−1 of the PHA content in WAS increased biogas production of 2.6 mL g−1-VSadded and methane production of 2.4 mL g−1-VSadded. Results show that PHA-accumulating WAS has high potential for methane production in anaerobic digestion.
- [Show abstract] [Hide abstract] ABSTRACT: Retinoic acid receptor (RAR) antagonists are potential toxic compounds that can cause teratogenesis in vertebrates. This study was conducted to evaluate the occurrence of RAR antagonist contamination in aquatic environments and identify its potential sources in detail. To accomplish this, the RAR antagonistic activities of surface waters of two rivers (the Yodo River and the Ina River) and influents and effluents of municipal wastewater treatment plants (WWTPs) in the Kinki region of Japan were investigated using a yeast two-hybrid assay. In the investigated rivers, remarkable RAR antagonistic activities were detected relatively consistently in specific regions, although the levels varied with time, and tended to increase downstream of municipal WWTPs. Investigations of WWTPs also revealed that RAR antagonists were present at remarkably high levels in municipal wastewater, and that RAR antagonist contamination remained in effluent after activated sludge treatments. Comparison of the concentration factors that reduced 50% of the RAR agonistic activity of 10(-7) M all-trans retinoic acid (IC50) for selected river water and WWTP effluent samples revealed that the contamination levels were greater in effluent (IC50: concentration factors of 92-313) than river water (IC50: concentration factors of 10.2-68.9). These results indicate that municipal WWTPs could be an important source of RAR antagonist contamination in the receiving rivers. Fractionations with high-performance liquid chromatography directed by the bioassay indicated that there were multiple RAR antagonists in municipal wastewater. Although a trial to identify the causative compounds in municipal wastewater was not completed, multiple bioactive peaks that should be studied further were isolated. This study clarified the occurrence of novel endocrine disrupting chemicals (i.e., RAR antagonists) in the aquatic environment at the watershed level and identified their possible source for the first time, which suggests the need of further studies to identify the causative compounds and to assess possible ecological risks associated with the contamination.
- [Show abstract] [Hide abstract] ABSTRACT: A chemostat was operated to characterize degradation of bisphenol A by Sphingomonas paucimobilis FJ-4. The chemostat at 30°C was fed with a medium containing 150 mg L(-1) of BPA as the sole carbon and energy source. At the short cell retention time of 8 h, the bacterial cells were washed out from the chemostat. At long cell retention times of 12, 16, 24, and 48 h, steady-states of the bacterial growth on BPA degradation were achieved after a lag time of 16-57 h. A mathematical model was applied to evaluate the BPA degradation ability of strain FJ-4. The maximum specific degradation rate, the half saturation constant, the cell yield, and the specific decay rate were estimated respectively as 0.46 mg-BPA (mg-VSS h)(-1), 13.1 mg L(-1), 0.39 mg-VSS mg-BPA(-1), and 0.0014 h(-1).
- [Show abstract] [Hide abstract] ABSTRACT: This study investigated changes in the structure and metabolic capabilities of the bacterial community in a full-scale membrane bioreactor (MBR) treating municipal wastewater. Microbial monitoring was also conducted for a parallel-running conventional activated sludge (CAS) process treating the same influent. The mixed-liquor suspended solid concentration in the MBR reached a steady-state on day 73 after the start-up. Then the MBR maintained higher rates of removal of organic compounds and nitrogen than the CAS process did. Terminal restriction fragment length polymorphism analysis revealed that the bacterial community structure in the MBR was similar to that in the CAS process at the start-up, but it became very different from that in the CAS process in the steady state. The bacterial community structure of the MBR continued to change dynamically even after 20 months of the steady-state operation, while that of the CAS process was maintained in a stable condition. By contrast, Biolog assay revealed that the carbon source utilization potential of the MBR resembled that of the CAS process as a whole, although it declined transiently. Overall, the results indicate that the bacterial community of the MBR has flexibility in terms of its phylogenetic structure and metabolic activity to maintain the high wastewater treatment capability.
- [Show abstract] [Hide abstract] ABSTRACT: Arable farming with intensive agricultural practices causes severe damage to groundwater quality. Hence study on mechanisms of diverse nitrogenous fertilizer regimes were focused relate to nitrate movement, transformation, and accumulation in arable soils.
- [Show abstract] [Hide abstract] ABSTRACT: Biological 1,4-dioxane removal performance using newly isolated Pseudonocardia sp. D17, which can utilize 1,4-dioxane as the sole carbon source, was evaluated. A low level of influent 1,4-dioxane, at 5–50 mg/L, was treated to meet the Japanese effluent standard of 0.5 mg/L. The gel entrapment technique was used for immobilization of Pseudonocardia sp. D17 so that it is not washed out from the bioreactor under a short hydraulic retention time. Consequently, an average effluent 1,4-dioxane concentration of 0.49 mg/L was achieved at a loading rate of 0.096 kg dioxane/(m³ · d) with an influent 1,4-dioxane concentration of 50 mg/L. The startup of the bioreactor was observed at 25°C within 2 weeks. Moreover, the effluent 1,4-dioxane concentration of 0.38 mg/L on an average was confirmed at a loading rate of 0.060 kg dioxane/(m³ · d), even though the operating temperature was 15°C. The temperature effect on 1,4-dioxane removal activity was characterized on the batch experiment. The maximum 1,4-dioxane removal activity was observed at 33.9°C. Moreover, 1,4-dioxane removal activity was observed even at 7.4°C, although that was decreased to 27% compared with that at 25°C. The activation energy for 1,4-dioxane removal by Pseudonocardia sp. D17, representing the temperature dependency, was calculated as 51.9 kJ/mol.
- [Show abstract] [Hide abstract] ABSTRACT: A pilot-scale (120L) bioreactor system using a gel carrier-entrapped pure bacterial strain, Afipia sp. strain D1, capable of degrading 1,4-dioxane as a sole carbon and energy source was constructed and applied to treat real industrial wastewater containing 1,4-dioxane from a chemical factory. Although the wastewater not only contained high concentrations of 1,4-dioxane but also considerable amounts of other organic compounds (73mg-TOCL(-1) on average), the bioreactor could efficiently remove 1,4-dioxane without significant inhibitory effects. The reactor startup could be completed within approximately 1 month by increasing the 1,4-dioxane loading rate (0.09-0.47kg-dioxanem(-3)d(-1)) in a stepwise manner. Effective 1,4-dioxane removal was stably maintained for 3 months with an influent 1,4-dioxane of 570-730mgL(-1), giving an average effluent concentration and removal rate of 3.4mgL(-1) and 0.46kg-dioxanem(-3)d(-1), respectively. A 1,4-dioxane loading fluctuation between 0.14 and 0.72kg-dioxanem(-3)d(-1) did not significantly affect its removal, and more than 99% removal efficiency was constantly maintained. The Monod model could well describe the relationship between the effluent 1,4-dioxane concentration and 1,4-dioxane removal rates of the bioreactors, showing that the half-saturation constant (Ks) was 28mgL(-1).
- [Show abstract] [Hide abstract] ABSTRACT: A mathematic model was developed for describing the nitrogen and organic carbon removal via the simultaneous anaerobic ammonium oxidation (anammox) and heterotrophic denitrification (SAD) process. The model considered anammox bacteria, heterotrophic denitrifying bacteria, ammonium, nitrite, nitrate, and readily biodegradable carbon. The model parameters were calibrated by using the experimental data in the single batch reactors inoculated with anammox sludge of 190 mg-VSS/L and activated sludge of 110 or 220 mg-VSS/L for treating wastewater containing ammonium of 30 mg-N/L and nitrate of 40 mg-N/L. The rapid depletion of nitrate and acetate as the sole carbon source were observed in the reactor. Subsequently, the temporarily accumulated nitrite was removed with ammonium. The initial C/N ratio of 1.5–2.0 and the population ratio of heterotrophic denitrifying bacteria to anammox bacteria within 0.3–0.4 were suitable conditions for the batch SAD process. The sensitivity analysis of kinetic parameters revealed that the most influential parameters for the nitrogen and organic carbon removal were the half-saturation constants for nitrite of heterotrophic bacteria and anammox bacteria and the anoxic reduction factors of heterotrophic bacteria on the nitrate-reducing rate and the nitrite-reducing rate, which closely associated with nitrite accumulation in the SAD process.
- [Show abstract] [Hide abstract] ABSTRACT: For evaluating duckweed biomass as a bioresource, the specific growth rate and the chemical constituents of duckweed of four kinds were investigated. Spirodela polyrrhiza, Lemna minor, Wolffia arrhiza, and Wolffia globosa commonly showed high specific growth rates of 0.22–0.30 d−1 with initial concentrations of nitrogen >3.0 kg m−3 and phosphorus >5.0 kg m−3. All duckweeds had high sugar contents greater than 300 g kg−1 of dry mass. Especially, vegetative fronds of W. globosa showed the highest sugar content of 410 g kg−1 of dry mass. The duckweed biomass was pretreated easily by heating at 121 °C for saccharification using α-amylase and amyloglucosidase. The ethanol yield of W. globosa biomass in the simultaneous saccharification and fermentation (SSF) using the enzymes and dry yeast was 170 g kg−1 of dry mass, whereas the succinate yield in the SSF using the enzymes and Actinobacillus succinogenes was 200 g kg−1 of dry mass. The production rates of ethanol and succinate from the W. globosa biomass were estimated as 0.58 kg m−2 y−1 and 0.68 kg m−2 y−1, respectively. The biomass of duckweed, with its high growth rate and high starch content, can be an excellent renewable feedstock for the production of ethanol and succinate as building block chemicals for the replacement of petrochemicals.
- [Show abstract] [Hide abstract] ABSTRACT: A novel process by using chemical leaching followed by bacterial reductive precipitation was proposed for selenium recovery from kiln powder as a byproduct of cement manufacturing. The kiln powder at a slurry concentration of 10 w/v% with 0.25 M Na2CO3 at 28 °C produced wastewater containing about 30 mg-Se/L selenium. The wastewater was diluted four-fold and adjusted to pH 8.0 as preconditioning for bioreduction. A bacterial strain Pseudomonas stutzeri NT-I, capable of reducing selenate and selenite into insoluble elemental selenium, could recover about 90% selenium from the preconditioned wastewater containing selenium of 5 mg-Se/L when supplemented with lactate or glycerol. The selenium concentrations in the treated wastewater were low around the regulated effluent concentration of 0.1 mg-Se/L in Japan.
- [Show abstract] [Hide abstract] ABSTRACT: We examined the effect of planting an emergent aquatic plant (Phragmites australis) on nitrogen removal from sediments using a 42-d pot experiment. The experimental pot systems comprised two types of sediments planted with and without young P. australis. Total nitrogen (total N), total dissolved N, and NH4-N in the sediments decreased markedly after planting. In contrast, those levels decreased only slightly in the unplanted sediments. The decrease in total N in the P. australis-planted sediments was 7 to 20 times those in the unplanted sediments. Abundances of bacterial 16S rRNA, archaeal 16S rRNA, ammonia-oxidizing bacterial ammonia monooxygenase (amoA), ammonia-oxidizing archaeal-amoA, and denitrifying bacterial nitrite reductase (nirK) genes increased significantly in sediments after planting. Phragmites australis appears to have released oxygen and created a repeating cycle of oxidizing and reducing conditions in the sediments. These conditions should promote mineralization of organic N, nitrification, and denitrification in the sediments. Phragmites australis absorbed bioavailable nitrogen generated by microbial nitrogen metabolism. During the 42-d period after planting, 31-44% of total N was removed by microbial nitrogen cycling, and 56-69% was removed via absorption by P. australis. These results suggest that planting P. australis can increase microbial populations and their activities, and that nitrogen removal can be accelerated by the combined functions of P. australis and microorganisms in the sediment. Thus, planting P. australis has considerable potential as an effective remediation technology for eutrophic sediments.
- [Show abstract] [Hide abstract] ABSTRACT: A biological treatment system for 1,4-dioxane-containing wastewater was developed using the bacterium Afipia sp. D1, which can utilize 1,4-dioxane as the sole carbon source. Strain D1 was entrapped in a polyethylene glycol gel carrier to stably maintain it in a bioreactor, and continuous feeding tests were performed to treat model industrial wastewater containing 1,4-dioxane. 1,4-Dioxane removal activity rapidly increased soon after the start of feeding of influent with 400 mg/L 1,4-dioxane, and the volumetric removal rate reached 0.67 kg dioxane/m(3)/d on day 36 by a stepwise increase in loading. The start-up period of the 1,4-dioxane treatment reactor was approximately 1 month, and stable removal performance was subsequently achieved for more than 1 month. The average 1,4-dioxane effluent concentration and 1,4-dioxane removal efficiency were 3.6 mg/L and 99%, respectively, during stable operation. Further 1,4-dioxane degradation activity of the of the gel carrier was characterized in batch experiments with respect to temperature. The optimum temperature for 1,4-dioxane treatment was 31.7°C, and significant removal was observed at a temperature as low as 6.9°C. The apparent activation energy for 1,4-dioxane degradation was estimated to be 47.3 kJ/mol. This is the first report of the development of a 1,4-dioxane biological treatment system using gel entrapment technology. Copyright © 2015 [The Author/The Authors]. Published by Elsevier B.V. All rights reserved.
- [Show abstract] [Hide abstract] ABSTRACT: Bacillus selenatarsenatis sp. nov. strain SF-1T is a promising agent for bioremediation of environments contaminated with selenium and arsenic. Here, we report the draft genome sequence of this strain.
- [Show abstract] [Hide abstract] ABSTRACT: Sphingobium fuliginis OMI, a 4-t-butylphenol utilizing bacterium, can degrade bisphenol S BPS, which is known to be a persistent substance. In the present study, we estimated the BPS degradation pathway by the strain OMI. Additionally, the possibility of the removal of the BPS metabolites by using activated sludge was evaluated. One or two of the phenolic rings of BPS was initially hydroxylated and then, the aromatic ring was cleaved via a meta-cleavage pathway by the strain OMI. Since several metabolites remained as dead-end products, a negligible amount of DOC was removed during BPS degradation by the strain OMI. Also, activated sludge removed neither BPS nor DOC. On the other hand, the BPS metabolites, which are produced from the BPS degradation by the strain OMI, were removed by using activated sludge, through biodegradation, adsorption and/or chemical decomposition, resulting in a 39 decrease in DOC. The present study demonstrated that the initial degradation of BPS by the strain OMI could be useful for the removal of BPS by the activated sludge process.
- [Show abstract] [Hide abstract] ABSTRACT: This study elucidated the energy budget in wastewater treatment streams at Tsumori, Ichioka, and Chishima wastewater treatment plants (WWTPs) in Osaka. At Tsumori WWTP, the primary sludge produced in primary settling tanks and excess sludge produced in secondary settling tanks of the three WWTPs were collected and then digested anaerobically to biogas for cogeneration. The energy content of raw sewage at Tsumori WWTP was 4.3 kJ/L. Those at Ichioka and Chishima WWTPs were 2.1 kJ/L. The respective energy contents of primary sludge of Tsumori, Ichioka, and Chishima WWTPs were 16.3, 7.6, and 10.2 kJ/g. Those of excess sludge were 14.6, 8.3, and 9.8 kJ/g, respectively. The total calorific inflow to the three WWTPs was 1.1 × 109 kJ/d. About 40% and 30% of the total calorific energy respectively becomes primary sludge and excess sludge. The remaining 30% is consumed in the aeration tanks. About 30 - 40% the total calorific energy is recovered as biogas by anaerobic digestion, which produces electricity at 1.6 × 108 kJ/d, corresponding respectively to 47% and 33% of the electricity consumption of Tsumori WWTP and the three WWTPs.
- [Show abstract] [Hide abstract] ABSTRACT: This study investigated nitrogen removal by the simultaneous anaerobic ammonium oxidation (anammox) and heterotrophic denitrification (SAD) process in a sequencing batch reactor (SBR) inoculated with suspended activated sludge and immobilized anammox sludge at various total organic carbon/nitrate (C/N) ratios. Synthetic wastewater containing nitrate 100 mg-N L−1, ammonium 70 mg-N L−1, and acetate 50-250 mg-C L−1 was fed to the SBR. Nitrite reduced from nitrate by heterotrophic denitrification was accumulated and removed with ammonium in each cycle operation of the SBR. The SAD process removed nitrate and ammonium effectively (T-N removal, 58-94%) by the high anammox contribution (ca. 80-100%) under low C/N ratios (0.5-1.0). At high C/N ratios of 1.2-2.5, the SAD process maintained T-N removal 67-79% with predominance of heterotrophic denitrification instead of anammox reaction. Results demonstrated that the SAD process performs high nitrogen removal effectively from wastewater with widely different C/N ratios.
- [Show abstract] [Hide abstract] ABSTRACT: AimsTo clarify the polyhydroxyalkanoate (PHA) accumulation potential and the PHA-accumulating microbial community structure in activated sludge in municipal wastewater treatment plants (WWTPs) and to identify their influential factors.Methods and ResultsNine activated sludge samples were collected from municipal WWTPs employing various biological treatment processes. In acetate-fed 24-h batch experiments under aerobic and nitrogen- and phosphorus-limited conditions, polyhydroxybutyrate (PHB) content of activated sludge increased from 0–1.3 wt% to 7.9–24 wt%, with PHB yields of 0.22–0.50 C-mol 3-hydroxybutyrate (C-mol acetate)‒1. Microbial community analyses found that activated sludge samples that accumulated >20 wt% of PHB after 24-h PHA accumulation experiments had >5.0×108 copies/g-mixed liquor suspended solid of phaC genes.Conclusions Results indicated that (i) activated sludge in municipal WWTPs can accumulate up to approximately 20 wt% of PHA without enrichment processes, (ii) PHA accumulation potential of activated sludge varied depending on the operational conditions (treatment processes) of WWTPs, and (iii) phaC gene number can provide a simple indication of PHA accumulation potential.Significance and Impact of StudyThis is the first study to compare the PHA accumulation potential and PHA-accumulating microbial communities in activated sludge of various treatment processes. Our findings may be useful for enhancing the resource recovery potential of wastewater treatment systems.This article is protected by copyright. All rights reserved.
Suika, Ōsaka, Japan
- Division of Sustainable Energy and Environmental Engineering