Comparison of conventional and inverted A2/O processes: Phosphorus release and uptake behaviors

Two full-scale systems operated in parallel, a conventional A²/O system consisting of anaerobic, anoxic and oxic compartments in succession and an inverted system consisting of anoxic, anaerobic and oxic compartments without internal recycle, were compared in terms of their phosphorus removal performance, with an emphasis on phosphate (P) release behaviors, using both operational data and simulation results. The inverted system exhibited better long-term phosphorus removal performance (0.2 ± 0.3 vs. 0.7 ± 0.7 mg/L), which should be attributed to the higher P release rate (0.79 vs. 0.60 kg P/(kg MLSS·day)) in the non-aerated compartments. The P release occurred in both the anoxic and anaerobic compartments of the inverted system, resulting in more efficient P release. Although the abundances of the ‘Candidatus Accumulibacter phosphatis' population in the two systems were quite similar ((19.1 ± 3.27)% and (18.4 ± 4.15)% of the total microbe (DAPI stained particles) population in the inverted and conventional systems, respectively, by fluorescence in situ hybridization (FISH)), the high-concentration DAPI staining results show that the abundances of the whole polyphosphate accumulating organisms (PAOs) in the aerobic ends were quite different (the average ratios of the poly-P granules to total microbes (DAPI stained particles) were (45 ± 4.18)% and (35 ± 5.39)%, respectively). Both the operational data and simulation results showed that the inverted system retained more abundant PAO populations due to its special configuration, which permitted efficient P release in the non-aerated compartment and better P removal.     

Treatment of methylene blue-containing wastewater using microorganisms supported on granular activated carbon under packed column operation

We studied the feasibility of using biological granular activated carbon-packed column in treating methylene blue-containing wastewater. The granular activated carbon with immobilized microbes was packed into a column and fed with 3 liter methylene blue-containing wastewater daily. With initial 1350 mg/l of methylene blue and 1550 mg/l of chemical oxygen demand, it was observed that the colour and chemical oxygen demand removal efficiencies were 99 and 78%, respectively. The high treatment performance of the system could be due to the simultaneous adsorption and biodegradation processes and advantages of immobilized microbes compare to suspended cell system.     

Effects of light quality on initiation and development of meroplanktonic diatom blooms in a eutrophic shallow sea

We investigated the effects of light quality on resting stage cell germination and vegetative cell growth of meroplanktonic diatoms in a small port in Hakata Bay, Japan and in the laboratory. During the investigation over the year of 2006, the meroplanktonic diatom bloom first occurred in the end of May and then repeated wane and wax until October in the small port. From late April to middle May, light penetrating the water column was often strong and attenuations of all spectral lights were low. During this period, Skeletonema costatum, Thalassiosira minima, and Chaetoceros sp. appeared frequently, followed by the blooms of S. costatum and Chaetoceros sp. in late May. Thereafter, S. costatum and Chaetoceros sp. bloomed in late June but not in middle June, when pigmented flagellates bloom appeared. The attenuation of short-wavelength light such as violet and blue lights was markedly high during these diatom and flagellate blooms; all blooms disappeared within several days. Vegetative cell strains of the three diatoms under light emitting diodes (LEDs) with six different spectra (violet, blue, green, orange, red, and near-infrared) grew at a higher rate under short-wavelength light, violet and blue. On the other hand, when suspensions of bottom sediments from Hakata Bay were cultured under the same LEDs and in the dark, vegetative cells of S. costatum appeared under all LEDs except for orange and near-infrared, vegetative cells of T. minima appeared under all LEDs but not in the dark, and vegetative cells of Chaetoceros sp. appeared under violet and blue LEDs. However, vegetative cell densities of the three diatoms increased much more under violet light than under other LEDs within a short period (6 days). Our study indicates that underwater penetration by short-wavelength light, such as violet and blue, may be an important factor in the initiation and development of meroplanktonic diatom blooms.     

Habitat provisioning for aboveground predators decreases detritivores

Although provisioning of habitat by ecosystem engineers is one of the most common biological interactions, previous studies have mostly focused on facilitative or bottom-up processes. Here we show that engineering effects can indirectly strengthen top-down effects mediated by predator abundance. We conducted a small-scale manipulative field experiment and broad-scale field observations of the plant, web spider, and detrital insect system in forest understory habitats. In the field experiment, artificially increasing architectural elements enhanced the abundance of spiders by providing physical support for web building. Moreover, aerial insects derived from the detrital food web decreased in response to increased spider abundance. As artificial architecture per se did not affect aerial detritivores, these results indicate that ecosystem engineering indirectly strengthens top-down effects mediated by predators. In field observations conducted in 12 cedar forests, path analyses supported the importance of an indirect pathway originating from understory vegetation complexity to spider abundance and to aerial detritivores. The effect size of spiders on detrital insects was similar in the field experiment and in the observations. These results indicate that the engineering effects of plants cascade to detrital insects through web spiders across different scales.     

Restoration of cadmium-contaminated paddy soils by washing with ferric chloride: Cd extraction mechanism and bench-scale verification

The ability of FeCl3 to extract Cd from three paddy soils was compared with that of various irons, manganese, and zinc salts to elucidate the extraction mechanism. Manganese, zinc and iron salts (including FeCl3) extracted 4-41%, 8-44% and 24-66% of total Cd, respectively. This difference reflected the pH of the extraction solution, indicating that the primary mechanism of Cd extraction by FeCl3 is proton release coupled with hydroxide generation, as iron hydroxides are insoluble. Washing with FeCl3 led to the formation of Cd-chloride complexes, enhancing Cd extraction from the soils. FeCl3 effectively extracted Cd from all of the three soils compared to HCl that is a conventional washing chemical, when the concentrations of the two washing chemicals were between 15 and 60mM(c) (at above extraction pH 2.4), while the corresponding extraction pH of FeCl3 was slightly higher than HCl. As HCl is the strong acid of complete dissociation, if excess amount of HCl was added to soil, it is possible to give the dissolution of clay minerals in soils. In contrast, proton release from FeCl3 is controlled by the chemical equilibrium of hydroxide formation. While soil fertility properties were affected by a bench-scale soil washing with 45mM(c) FeCl3, adverse effects were not crucial and could be corrected. The bench-scale test confirmed the effectiveness of FeCl3 for removal of soil Cd. The washing had no negative effect on rice yield and lowered the Cd concentration of rice grain and rice straw in a pot experiment.     

Concentrations and their ratio of (222)Rn decay products in rainwater measured by gamma-ray spectrometry using a low-background Ge detector

The concentrations and the concentration ratios of individual short-lived (222)Rn decay products ((214)Pb and (214)Bi) in rainwater were measured at Kumatori village (34.39 degrees N, 135.35 degrees E, approximately 70 m above sea level) in Osaka, Japan, by gamma-ray spectrometry using a low-background Ge detector. The dependence of the time variations of the concentrations and their ratios on rainfall rate was investigated. It was observed that the concentrations were negatively correlated with the rainfall rate in some rainfall events, and that there was no clear correlation in other rainfall events. The changes in the dependence of the concentration on the rainfall rate occurred after the passage of a cold front during a single rainfall event. The concentration ratios showed a weak negative correlation with the rainfall rate for most of the observed rainfall events. A scavenging model was designed in this study in order to explain the observation results. Based on the relationship between the concentrations of (214)Pb and (214)Bi in the rainwater and the rainfall rate for an individual rainfall event, the increase in the environmental gamma-ray dose rate from (214)Pb and (214)Bi deposited on the ground was calculated, and the calculated increase agreed well with that observed by the in situ measurement on flat ground.     

Formation of PCDDs and PCDFs during the combustion of polyvinylidene chloride and other polymers in the presence of HCl

PVDC and three non-chlorinated polymers (PP, PET, and PA) were incinerated at 700-850 degrees C in a laboratory-scale quartz tubular furnace in the presence of HCl (ca. 500 ppm congruent with 0.8 mg/l), and the gas-phase formation of PCDD/Fs, their putative precursors and their homologue profiles were investigated. The addition of HCl had little or no apparent effect on the level of PCDD/Fs formation during PVDC combustion, and their homologue profiles were quite different from those of the three non-chlorinated polymers. With PVDC, O8CDD and particularly O8CDF were by far most prevalent, apparently as a result of the selective formation of the precursors. With each of the three non-chlorinated polymers, combustion at 800 degrees C or higher in the presence of HCl resulted in PCDD/Fs formation at levels equaling or exceeding those observed with PVDC. In trials made with one of them (PP) under the same conditions but using a large polymer sample (100 mg vs 20 mg in all other trials), the level of PCDD/Fs formation was far higher than with the smaller polymer samples, and thus demonstrated the importance of appropriate combustion conditions for polymer incineration.     

Enzymatic Degradation and Aminolysis of Microbial Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) Single Crystals

Solution-grown single crystals of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] were hydrolyzed by polyhydroxybutyrate (PHB) depolymerase from Ralstonia pickettii T1. Enzymatic degradation proceeded from the edges of lamellar crystals, yielding serrated contour and small crystal fragments. Gel permeation chromatography analysis revealed that the molecular weights of the crystals decreased during enzymatic degradation, suggesting that the enzymatic hydrolysis of chain-folding regions at the crystal surfaces occurred in addition to the enzymatic degradation at crystal laterals or edges. After P(3HB-co-4HB) single crystals were aminolysed in 20% aqueous methylamine solution to remove the folded-chain regions and enzymatic degradation by lipase from Rhizopus oryzae to remove 4HB components at crystal surfaces of single crystal aminolyzed, it was found that a small amount (up to ca. 2 mol%) of 4HB component can be incorporated into the P(3HB) mother crystal lattice irrespective of the 4HB content.     

Combination of adsorption and biodegradation processes for textile e uent treatment using a granular activated carbon-biofilm configured packed column system

The objective of this study was to investigate the feasibility of using a granular activated carbon-biofilm configured packed column system in the deeolodzation of azo dye Acid Orange 7-containing wastewater.The Acid Orange 7-degrading microbial from anaerobic sequencing batch reactor which treating the azo dye-containing wastewater for more than 200 d was immobilized on spent granular activated carbon(GAC)through attachment.The GAC-biofilm configured packed column system showed the ability to decolorize...