Recently, anammox bacteria have been applied for nitrogen elimination from wastewater. However, anammox is not effective for other kinds of pollutants. Therefore, in this study, the treatment of ...synthetic wastewater via combining anammox and biochar in a fixed-bed column was considered to improve performance. Two reactors, Reactor 1 (containing biochar and anammox bacteria) and Reactor 2 (containing biochar as a control), were run for four months. The nitrogen concentration (mg/L) and nitrogen loading rate (g-N/L/day) ranged from 100 to 500 and 5 to 20, respectively. Reactor 1 showed better performance in removing nitrogen from wastewater than Reactor 2. For Reactor 1, the optimum nitrogen removal effectiveness and nitrogen removal rate (g/L/day) were 82.3% and 8.2 (phase 1, 0–29 days), 90.9% and 12.7 (phase 2, 30–59 days), 72.3% and 13.0 (phase 3, 60–89 days), and 69.5% and 6.9 (phase 4, 90–119 days), respectively. An artificial neural network was applied for optimization. After finding the optimum performance conditions for the Reactor 1, COD (200 mg/L to 500 mg/L) was added to the influent. Adding up to 275 mg/L COD did not significantly affect N elimination, but after this point, N elimination was dramatically decreased.
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•Combined anammox-biochar was applied to treat synthetic wastewater.•Under the optimum conditions, nitrogen removal ranged from 69.5% to 90.9%.•An artificial neural network was employed to optimize ammonia removal by the current reactor.•Adding up to 275 mg/L COD did not significantly affect N elimination.•Microscope images showed that anammox bacteria could attach to the surface of the biochar.
Central air heating systems with heat pumps can use the underfloor space, rather than air ducts, for heat distribution in houses. To minimize the energy consumption, the actual thermal environment ...and energy performance of these systems must be evaluated through continuous field measurements. This study evaluates the thermal environment, operational characteristics, and energy performance of a central air heating system with a heat pump during two winters in a two-story house in Japan. In the first winter (i.e., before case), the supply air was automatically controlled at a relatively high average temperature of 45°C with low air flow rates, resulting in a non-uniform temperature distribution among the rooms and low energy efficiency. In the second winter (i.e., after case), an increase in the fan speed improved the heat distribution, with operational conditions of high air flow rates at a lower average temperature of 39°C. This led to average energy savings of 11% while maintaining thermal comfort.
The loading and removal of polycyclic aromatic hydrocarbons (PAHs) were measured and estimated in a wastewater treatment plant in a separated sewer system in a suburban area of Japan. The influent 16 ...PAHs concentration was 219 ± 210 ng L−1, whereas the effluent concentration was 43.5 ± 42.5 ng L−1 (mean ± sd). No clear diurnal or weekly fluctuation was observed. However, evaluation of long-term changes revealed PAH fluctuations continuing for more than 1 week. Half of the PAHs (63%) were biologically or chemically transformed, or vaporized in the treatment plant, while the remainder were discharged with effluent (28%) and excess sludge (9%). Measurement of the per capita loading of the treatment plant revealed values of 142 ± 53 and 28 ± 11 μg person−1day−1 (mean ± 95% confidence interval) for influent and effluent, respectively. Isomer ratio analysis revealed that the PAHs originated from a mixture of petroleum, petroleum combustion, and burning of biomass residues.
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•PAHs concentration of a wastewater treatment plant in a separated sewer system was measured.•Half of the PAHs were decomposed or vaporized and the remainder were discharged.•The loading of PAHs from household and industrial emissions in aquatic systems was not negligible.
Candidate phylum Saccharibacteria (former TM7) are abundant and widespread in nature, but little is known about their ecophysiology and detailed phylogeny. In this study phylogeny, morphology and ...ecophysiology of Saccharibacteria were investigated in activated sludge from nine wastewater treatment plants (WWTPs) from Japan and Denmark using the full-cycle 16S rRNA approach in combination with microautoradiography (MAR) and fluorescence in situ hybridization (FISH). Phylogenetic analysis showed that Saccharibacteria from all WWTPs were evenly distributed within subdivision 1 and 3 and in a distinct phylogenetic clade. Three probes were designed for the distinct saccharibacterial groups, and revealed morphotypes representing thin filaments, thick filaments and rods/cocci. MAR-FISH results showed that most probe-defined Saccharibacteria utilized glucose under aerobic-, nitrate reducing- and anaerobic conditions. Some Saccharibacteria also utilized N-acetylglucosamine, oleic acid, amino acids and butyrate, which are not predicted from available genomes so far. In addition, some filamentous Saccharibacteria exhibited β-galactosidase and lipase activities determined using a combination of enzyme-labeled fluorescence and FISH (ELF-FISH). No uptake of acetate, propionate, pyruvate, glycerol and ethanol was observed. These results indicate that Saccharibacteria is a phylogenetically diverse group and play a role in the degradation of various organic compounds as well as sugar compounds under aerobic-, nitrate reducing- and anaerobic conditions.
Candidatus Saccharibacteria in activated sludge are phylogenetically diverse and utilize oleic acid, amino acids,and N-acetylglucosamine as well as glucose as the carbon sources.
Graphical Abstract Figure.
Candidatus Saccharibacteria in activated sludge are phylogenetically diverse and utilize oleic acid, amino acids,and N-acetylglucosamine as well as glucose as the carbon sources.
Natural abundance of stable nitrogen (N) and oxygen (O) isotopes are invaluable biogeochemical tracers for assessing the N transformations in the environment. To fully exploit these tracers, the N ...and O isotope effects (
ε and
ε) associated with the respective nitrogen transformation processes must be known. However, the N and O isotope effects of anaerobic ammonium oxidation (anammox), one of the major fixed N sinks and NO
producers, are not well known. Here, we report the dual N and O isotope effects associated with anammox by three different anammox bacteria including "Ca. Scalindua japonica", a putative marine species, which were measured in continuous enrichment culture experiments. All three anammox species yielded similar N isotope effects of NH
oxidation to N
(
ε
) ranging from 30.9‰ to 32.7‰ and inverse kinetic isotope effects of NO
oxidation to NO
(
ε
= -45.3‰ to -30.1‰). In contrast,
ε
(NO
reduction to N
) were significantly different among three species, which is probably because individual anammox bacteria species might possess different types of nitrite reductase. We also report the combined O isotope effects for NO
oxidation (
E
) by anammox bacteria. These obtained dual N and O isotopic effects could provide significant insights into the contribution of anammox bacteria to the fixed N loss and NO
reoxidation (N recycling) in various natural environments.
Although the anaerobic ammonium oxidation (anammox) process has attracted attention regarding its application in ammonia wastewater treatment based on its efficiency, the physiological ...characteristics of anammox bacteria remain unclear because of the lack of pure-culture representatives. The coexistence of heterotrophic bacteria has often been observed in anammox reactors, even in those fed with synthetic inorganic nutrient medium. In this study, we recovered 37 draft genome bins from a long-term-operated anammox column reactor and predicted the metabolic pathway of coexisting bacteria, especially Patescibacteria (also known as Candidate phyla radiation). Genes related to the nitrogen cycle were not detected in Patescibacterial bins, whereas nitrite, nitrate, and nitrous oxide-related genes were identified in most of the other bacteria. The pathway predicted for Patescibacteria suggests the lack of nitrogen marker genes and its ability to utilize poly-N-acetylglucosamine produced by dominant anammox bacteria. Coexisting Patescibacteria may play an ecological role in providing lactate and formate to other coexisting bacteria, supporting growth in the anammox reactor. Patescibacteria-centric coexisting bacteria, which produce anammox substrates and scavenge organic compounds produced within the anammox reactor, might be essential for the anammox ecosystem.
Possible emission sources of PAHs in air and water environments were discussed by a comparison between the data sets of emission sources and environmental fields using five isomer ratios. The ...similarity of a pair of the datasets of different sources or environment fields for each isomer ratio was evaluated by a newly developed modified effect size d, and the mean of those for the five isomer ratios was applied as an index of similarity. From the analysis, diesel emission and/or biomass burning residues were considered to be major emission sources for almost all the datasets of environments. The pollution loading and path to the PAHs loading of coastal sediments in Hiroshima bay area were examined and it was inferred emission sources was consistently assigned by these newly developed indicators of isomer ratios. Diesel and/or biomass burning were considered to be major sources for the west side area of the bay and the biomass burning was considered to be for the east side area. Further, it was evaluated the west side area, which confronts the Hiroshima city downtown area more directly, was more similar to diesel, and the east side area, which is a bit remoted to the urban central was more similar to the biomass burning. This newly developed method would be a promising alternative application of isomer ratio analysis.
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•A new index was developed for isomer ratio analysis of PAHs.•Similarity of the ratio was numerically defined using a modified Cohen's d index.•Applying this to air and water environments, consistent tendency was obtained.
Wastewater filtration is considered the main solution to water shortages. Here, we treated synthetic wastewater by combining treatment techniques, namely, electrochemical oxidation and adsorbent ...added sequencing batch reactor (SBR). One beaker with a working value of 1500 mL was applied in this contemporary study. In the upper part of the beaker, an anode and a cathode (Ti/RuO2-IrO2) were arranged in parallel for the electrochemical oxidation process. Sodium sulfate (Na2SO4) with a concentration of 2.5 g/L was added as the electrolyte. The voltage and current were set to 7.50 V and 0.40 A, respectively. Aeration was conducted at the bottom of the beaker. Then, 15% working value of the reactor was filled by activated sludge, and 85% working value of the reactor was added with synthetic wastewater. In addition, 1.50 g/L of powdered cockleshell was added in the reactor. Response surface methodology was used for statistical analysis. In synthetic wastewater, concentrations of COD, ammonia, phenols and chromium were 2500 mg/L, 2500 mg/L, 100 mg/L and 100 mg/L, respectively. pH and reaction time (h) were considered as independent factors. A total of 2430 mg/L biochemical oxygen demand, 2500 mg/L ammonia, 90.0 mg/L phenols, and 84.0 mg/L chromium were eliminated at the optimum reaction time (72.9 min) and pH (6.5). The energy consumption value was 6.5 (kWh kg−1) at the optimum operating conditions. This study indicated that this combined treatment system exhibited high performance.
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•Electrochemical and adsorbent augmented SBR were used to treat wastewater.•At the optimum condition, elimination efficacies of COD, ammonia, phenols and Cr were 97.0%, 99.9%, 90.0%, and 84.0%.•The efficacy of contaminants elimination (COD and Cr) increases with the increase in Na2SO4 concentration, as electrolyte, to 2.5 g/L.
Nitrous oxide (N2O) production pathway in a signal-stage nitritation-anammox sequencing batch reactor (SBR) was investigated based on a multilateral approach including real-time N2O monitoring, N2O ...isotopic composition analysis, and in-situ analyses of spatial distribution of N2O production rate and microbial populations in granular biomass. N2O emission rate was high in the initial phase of the operation cycle and gradually decreased with decreasing NH4+ concentration. The average emission of N2O was 0.98 ± 0.42% and 1.35 ± 0.72% of the incoming nitrogen load and removed nitrogen, respectively. The N2O isotopic composition analysis revealed that N2O was produced via NH2OH oxidation and NO2− reduction pathways equally, although there is an unknown influence from N2O reduction and/or anammox N2O production. However, the N2O isotopomer analysis could not discriminate the relative contribution of nitrifier denitrification and heterotrophic denitrification in the NO2− reduction pathway. Various in-situ techniques (e.g. microsensor measurements and FISH (fluorescent in-situ hybridization) analysis) were therefore applied to further identify N2O producers. Microsensor measurements revealed that approximately 70% of N2O was produced in the oxic surface zone, where nitrifiers were predominantly localized. Thus, NH2OH oxidation and NO2 reduction by nitrifiers (nitrifier-denitrification) could be responsible for the N2O production in the oxic zone. The rest of N2O (ca. 30%) was produced in the anammox bacteria-dominated anoxic zone, probably suggesting that NO2− reduction by coexisting putative heterotrophic denitrifiers and some other unknown pathway(s) including the possibility of anammox process account for the anaerobic N2O production. Further study is required to identify the anaerobic N2O production pathways. Our multilateral approach can be useful to quantitatively examine the relative contributions of N2O production pathways. Good understanding of the key N2O production pathways is essential to establish a strategy to mitigate N2O emission from biological nitrogen removal processes.
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•N2O production pathways were studied by N2O isotopic, FISH, and microsensor analyses.•Ca. 70% of N2O was produced in nitrifiers-dominated oxic surface zone of granules.•The rest of N2O (30%) was produced in the anammox bacteria-dominated anoxic zone.•Overall, N2O was produced via NH2OH oxidation and NO2− reduction pathways equally.
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