Size mass distribution of water-soluble ionic species and gas conversion to sulfate and nitrate in particulate matter in southern Taiwan

A Micro-Orifice Uniform Deposition Impactor (MOUDI) and a Nano-MOUDI were employed to determine the size-segregated mass distributions of ambient particulate matter (PM) and water-soluble ionic species for particulate constituents. In addition, gas precursors, including HCl, HONO, HNO3, SO2, and NH3 gases, were analyzed by an annular denuder system. PM size mass distribution, mass concentration, and ionic species concentration were measured during the day and at night during episode and non-episode periods in winter and summer. Average total suspended particle (TSP) concentrations during episode days in winter were as high as 153 ± 33 μg/m(3), and PM mass concentrations in summer were as low as one-third of that in winter. Generally, PM concentration at night was higher than that in the daytime in southern Taiwan during the sampling periods. In winter during the episode periods, the size-segregated mass distribution of PM mass concentration was mostly in the 0.32-3.2-μm range, and the PM concentration increased significantly in the range of 0.32-3.2 μm at night. Ammonium, nitrate, and sulfate were the dominant water-soluble ionic species in PM, contributing 34-48% of TSP mass. High concentrations of ammonia (12.9-49 μg/m(3)) and SO2 (2.6-27 μg/m(3)) were observed in the gas precursors. The conversion ratio was high in the PM size range of 0.18-3.2 μm both during the day and at night in winter, and the conversion ratio of episode days was 20% higher than that of non-episode days. The conversion factor was high for both nitrogen and sulfur species at nighttime, especially on episode days.

[Effect of NH4(+) -N/NO3(-)-N ratio in applied supplementary fertilizer on nitrogen metabolism and main chemical composition of Pinellia ternata]

OBJECTIVE

To study the effect of nitrogen forms on nitrogen metabolism and main chemical composition of Pinellia ternate.

METHOD

Through the soilless cultivation experiment and based at the same nitrogen level and different NH4(+) -N/NO3(-) -N ratios, nitrate reductase (NR) activity, glutamine synthetase (GS) activity, the content of nitrate nitrogen and ammonium nitrogen in different parts of P. ternate were determined. The contents of total alkaloid, free total organic acids and guanosine in the tuber were determined. The yield of bulbil and tuber was calculated.

RESULT

The test results showed that, with the NH4(+) -N/NO3(-) -N ratio increasing, the activity of nitrate reductase decreased, the content of nitrate nitrogen in the leaves, petioles and tuber increasing initially, then decreased, and the content of nitrate nitrogen in the root decreased. Meanwhile, with the NH4(+) -N/NO3(-) -N ratio increasing, the activity of glutamine synthetase in the leaves, petioles and root increased, the activity of glutamine synthetase in the tuber increasing initially, then decreased. The contents of ammonium nitrogen in the leaves, tuber and root increased initially, then decreased, and the contents of ammonium nitrogen in the petioles increased with the NH4(+)(-N/NO3(-)-N ratio increasing. The yield of bulbil and tuber were the highest at the NH4(+)-N/NO3(-) -N ratio of 75: 25. The content of total alkaloid and guanosine in the tuber were the highest at the NH4(+)-N/NO3(-) -N ratio of 0: 100, and the contents were 0.245% and 0.0197% respectively. With the NH4(+)-N/NO3(-) -N ratio of 50: 50, the content of free total organic acids was the highest, it reached 0.7%, however, the content of free total organic acids was the lowest at the NH4(+) -N/NO3(-) -N ratio of 0: 100.

CONCLUSION

Nitrogen fertilization significant influences the nitrogen metabolism, the yield and main chemical composition of P. ternate.

N2O and NO emissions from a partial nitrification sequencing batch reactor: exploring dynamics, sources and minimization mechanisms

A sequencing batch reactor (SBR) was enriched with ammonia oxidizing bacteria (AOB) in order to treat synthetic reject wastewater (1 g NH4+ N/L). Partial nitrification was successfully achieved at a NH4+ -N to NO2- -N conversion rate of 98%. The emission dynamics of nitrous oxide (N2O) and nitric oxide (NO) were monitored during normal operation and under 3 different cycle configurations. An N2O peak was detected during the first 5 min of the cycle in all cases which corresponded to 60-80% of the total N2O emitted. When anoxic phases were introduced, N2O emissions were minimized but NO increased. Factors affecting the initial N2O peak were studied in a set of individual experiments. It was concluded that most of this N2O originated during settling due to biological reactions. Complete oxidation of NH4+ (or most likely hydroxylamine) as a result of sufficient aeration time can be a minimization strategy for N2O emissions in partial nitrification systems.

[Effects of drying-rewetting alternation on nitrogen, dynamics in a typical coastal wetland: a simulation study]

The coastal wetland, a key transitional zone between land and ocean, is a complex and sensitive ecosystem with special environmental processes and functional values. Sediment and sea water samples were taken from Chongming east intertidal flat, a typical coastal wetland in China. Sediment cores were incubated under simulated spring tides (approximately twice a month) and semi-diurnal tides (two almost equal high tides and two low tides in a lunar day), to define the responses of nitrogen to periodic alternation of drying and re-flooding. The contents of NO3(-) -N, NO2(-) -N, NH4(+) -N, dissolved organic N (DON), and the activities of nitrate reductase (Nar), nitrite reductase (Nir), and hydroxylamine reductase (Hyr) in sediments were determined during the incubation. Nitrification stood in a dominant position during the drying period with sediment moisture decreasing from 35% to 5% -7% in simulated spring tides. The NO3(-) -N and NO2(-) -N were found to be substantially converted into DON following a further exsiccation (the sediment moisture decreased from 5%-7% to 0%-3%). However, the conversion rates decreased with the increase of drying and rewetting cycles. Following the rewetting of dried sediments (from 0% -3% to 37% -45%), the contents of NO3(-) -N, NO2(-) -N, NH4(+) -N and DON increased to 1 to 3 times that of the dry sediments. Nar and Nir activities in sediments rapidly increased after the rewetting, indicating that the reduction of NO3(-) -N and NO2(-) -N were substantially enhanced. Significant positive correlations were found between Nar and Nir activities, and Hyr activities and NH4(+) -N contents during the simulated spring tides. Moreover, the decreases of NO3(-) -N and NO2(-) -N contents were observed to be significantly correlated to the increases of NH4(+) -N contents. Combined with the fact that the sediment had a high organic carbon content but a very low NO3(-) -N content, it can be concluded that the reduction of NO3(-) -N and NO2(-) -N following the rewetting was dominated by nitrate ammonification. In contrast, NO3(-) -N, NO2(-) -N, NH4(+) -N and DON contents in sediments were relatively stable during semi-diurnal tides, which were (3.0 +/- 0.3), (1.2 +/- 0.1), (133.3 +/- 4.3) and (41.1 +/- 10.6) mg x kg(-1), respectively. This indicated that semi-diurnal tides slightly affected the variations of nitrogen contents in the wetlands.

Long-term effects of Ni(II) on the performance and activity of activated sludge processes

The long-term effects of Ni(II) on substrate removal and microorganism activities were investigated by operating sequencing batch reactors (SBRs). Compared to the control system lacking Ni(II), the removal efficiencies of total organic carbon (TOC) and ammonium nitrogen (NH4(+)-N) in SBR system loading with 10mgL(-1) Ni(II) decreased drastically from 90.2±3.6 percent to 75.0±8.9 percent, and 99.2±0.6 percent to 50.8±11.5 percent, respectively. As compared to the control system, a inhibitory rate of more than 50 percent for the 2,3,5-triphenyltetrazolium chloride electron transport system (TTC-ETS) and the 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride electron transport system (INT-ETS), and 43 percent for the specific oxygen uptake rate (sOUR) were detected in SBR system loading with 20mgL(-1) Ni(II). TTC-ETS, INT-ETS, and sOUR were significantly correlated with substrate removal efficiencies, suggesting that they could all serve as effective indicators of the performance of activated sludge processes. Additionally, INT-ETS is superior to sOUR and TTC-ETS in detecting the toxic effects of Ni(II) on sludge microorganism activity.

Microfauna communities as performance indicators for an A/O Shortcut Biological Nitrogen Removal moving-bed biofilm reactor

The microfauna communities present in the mixed liquor and biofilm of an Anoxic/Oxic Shortcut Biofilm Nitrogen Removal moving-bed biofilm process were characterised in order to optimise process control through the use of bioindicators. The system operated at high ammonium concentrations, with an average of 588 ± 220 mg N-NH4(+) L(-1) in the influent, 161 ± 80 mg L(-1) in the anoxic reactor and 74 ± 71.2 mg L(-1) in the aerobic reactor. Up to 20 different taxa were identified, including ciliates (4), flagellates (11), amoebae (4) and nematodes (1). Compared to conventional wastewater treatment processes (WWTPs), this process can be defined as a flagellates-predominant system with a low diversity of ciliates. Flagellates were mainly dominant in the mixed liquor, demonstrating high tolerance to ammonium and the capacity for survival over a long time under anoxic conditions. The data obtained provide interesting values of maximum and minimum tolerance ranges to ammonium, nitrates and nitrites for the ciliate species Cyclidium glaucoma, Colpoda ecaudata, Vorticella microstoma-complex and Epistylis cf. rotans. The last of these was the only ciliate species that presented a constant and abundant population, almost exclusively in the aerobic biofilm. Epistylis cf. rotans dynamics showed a high negative correlation with ammonium variations and a positive correlation with ammonium removal efficiency. Hence, the results indicate that Epistylis cf. rotans is a good bioindicator of the nitrification process in this system. The study of protozoan communities in unexplored WWTPs sheds light on species ecology and their role under conditions that have been little studied in WWTPs, and could offer new biological management tools.

Bottle gourd rootstock-grafting affects nitrogen metabolism in NaCl-stressed watermelon leaves and enhances short-term salt tolerance

The plant growth, nitrogen absorption, and assimilation in watermelon (Citrullus lanatus [Thunb.] Mansf.) were investigated in self-grafted and grafted seedlings using the salt-tolerant bottle gourd rootstock Chaofeng Kangshengwang (Lagenaria siceraria Standl.) exposed to 100mM NaCl for 3d. The biomass and NO3(-) uptake rate were significantly increased by rootstock while these values were remarkably decreased by salt stress. However, compared with self-grafted plants, rootstock-grafted plants showed higher salt tolerance with higher biomass and NO3(-) uptake rate under salt stress. Salinity induced strong accumulation of nitrate, ammonium and protein contents and a significant decrease of nitrogen content and the activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT) in leaves of self-grafted seedlings. In contrast, salt stress caused a remarkable decrease in nitrate content and the activities of GS and GOGAT, and a significant increase of ammonium, protein, and nitrogen contents and NR activity, in leaves of rootstock-grafted seedlings. Compared with that of self-grafted seedlings, the ammonium content in leaves of rootstock-grafted seedlings was much lower under salt stress. Glutamate dehydrogenase (GDH) activity was notably enhanced in leaves of rootstock-grafted seedlings, whereas it was significantly inhibited in leaves of self-grafted seedlings, under salinity stress. Three GDH isozymes were isolated by native gel electrophoresis and their expressions were greatly enhanced in leaves of rootstock-grafted seedlings than those of self-grafted seedlings under both normal and salt-stress conditions. These results indicated that the salt tolerance of rootstock-grafted seedlings might (be enhanced) owing to the higher nitrogen absorption and the higher activities of enzymes for nitrogen assimilation induced by the rootstock. Furthermore, the detoxification of ammonium by GDH when the GS/GOGAT pathway was inhibited under salt stress might play an important role in the release of salt stress in rootstock-grafted seedlings.

Fate and toxicity of melamine in activated sludge treatment systems after a long-term sludge adaptation

Melamine is a nitrogen-rich (67% nitrogen by mass) heterocyclic aromatic compound that could significantly increase effluent total nitrogen concentrations. In this study, we investigated the degradation of melamine and its impact on activated sludge operations by employing two common activated sludge processes, namely the Modified Ludzack-Ettinger (MLE) process and the continuous stirred tank reactor (CSTR) process. Melamine was dosed continuously from day 125 in both activated sludge treatment systems at an influent concentration of 3 mg/L for about 100 days. Even after such a long period of sludge adaptation, melamine appeared not to be easily biodegradable. The average melamine removal efficiencies in the CSTR and MLE systems were 14 ± 10% and 20 ± 15%, respectively. There was no significant difference in melamine removal between the two different activated sludge processes. The long-term input of melamine resulted in a decrease in the nitrifying bacterial activities (by 82 ± 8%) and population in both systems. Short-term microtiter assay results also showed that melamine reduced activated sludge growth by 80% when supplied at a concentration of 75.6 mg/L. These results suggest that sludge adaptation plays a minimal role in melamine degradation, as the enzymes responsible for hydrolytic deamination of melamine in activated sludge are not easily induced. The insignificant biodegradation of melamine is also attributed to bacterial growth inhibition under long-term dosing conditions with melamine, resulting in a significant decrease in effluent water quality.

[Chemical characteristics of water-soluble components of aerosol particles at different altitudes of the Mount Huang in the summer]

Aerosol was collected with Anderson cascade sampler at three altitudes of the Mount Huang in the summer 2011. Samples were analyzed by the ion chromatography (IC, Metrohm). The results showed that the mean mass concentrations of all the ions were 13.21 microg x m(-1), 10.94 microg x m(-3), 9.97 microg x m(-3), at the foot, mid height and the summit of the mountain, respectively. The mass concentration of water-soluble components of aerosol decreased with altitude. The major anion and cation of aerosols were SO4(2-) and NH4+, respectively. The descending order of mass concentration of major ionic species was: SO4(2-) > NH4+ > Ca2+ > NO3- and NH4+ account for about 75% of total ionic concentrations of PM2.1 in three sampling sites. The concentration of SO4(2-) and NH4+ decreased conspicuously with altitude. The major cation and anion of coarse mode particles were Ca2+ and NO3-, respectively. The slope of the linear regression line between anion and cation of PM10 and PM2.1 approximates 1, indicating acid-base balance in aerosol particles. Aerosols over the region Mount Huang were influenced by anthropogenic source of surrounding areas to a certain extent. The result also suggested that the correlation between NH4+ and SO4(2-) was 0. 98 and these ions predominantly existed in the form of (NH4)2SO4 and NH4HSO4. Backward trajectory analysis revealed that the air mass was originated from southern coastal regions, the East China Sea, the Yellow Sea and the northern China. Due to the northern air masses go through heavily polluted areas, concentrations of water-soluble ions in these air masses were higher than that of other air masses. The concentration of K+ in northern air mass was several times higher than that in southwestern air mass.

Biomass burning in eastern Europe during spring 2006 caused high deposition of ammonium in northern Fennoscandia

High air concentrations of ammonium were detected at low and high altitude sites in Sweden, Finland and Norway during the spring 2006, coinciding with polluted air from biomass burning in eastern Europe passing over central and northern Fennoscandia. Unusually high values for throughfall deposition of ammonium were detected at one low altitude site and several high altitude sites in north Sweden. The occurrence of the high ammonium in throughfall differed between the summer months 2006, most likely related to the timing of precipitation events. The ammonia dry deposition may have contributed to unusual visible injuries on the tree vegetation in northern Fennoscandia that occurred during 2006, in combination with high ozone concentrations. It is concluded that long-range transport of ammonium from large-scale biomass burning may contribute substantially to the nitrogen load at northern latitudes.

Impacts of eutrophic freshwater inputs on water quality and phytoplankton size structure in a temperate estuary altered by a sea dike

Phytoplankton size structure and water properties in the Youngsan River estuary, which has been altered by a sea dike, were monitored over an annual cycle (2003-2004) to investigate the effects of freshwater inputs on their spatial and temporal variation. Trophic status was also evaluated using the trophic status index (TRIX). Freshwater was discharged from an artificial reservoir throughout the year, supplying nutrients (except for [Formula: see text] ) and low levels of dissolved oxygen to the estuary, which resulted in eutrophication ("greatest trophic level"). Turbidity increased, and density stratification developed in the water column. The density stratification in turn affected the reduction of dissolved oxygen concentration in the bottom water during the freshwater discharge. Chlorophyll a concentrations, dominated by nano-sized (<20 μm) particles, were generally much lower when the water column was stratified by freshwater discharge (.90-5.03 μg chl L(-1)) than when the water column was well-mixed with no freshwater inputs from the dike (3.42-47.0 μg chl L(-1)). The net-scale (>20 μm) decrease in phytoplankton biomass differed from that in tropical estuaries affected by monsoons and in other temperate estuaries. Temporal variations in water quality and phytoplankton size structure were more strongly influenced by artificial regulation of the freshwater discharge than by monsoon meteorological events. This study implies that a different paradigm than that for natural estuaries or larger estuaries with dams is required for the better understanding and management of ecosystems in estuaries altered by anthropogenic activities, such as the construction of sea dikes.

Measuring and modeling ammonium adsorption by calcareous soils

The aim of this study was assessment of ammonium (NH 4(+) ) adsorption isotherms in some agricultural calcareous soils and modeling of that by using the mechanistic exchange model. Ten surface soils (0-30 cm) were collected from areas covered with different land uses in Hamedan, western Iran. Isotherm experiments were carried out by concentrations of NH 4(+) prepared from NH4Cl salt (0, 10, 20, 30, 40, 50, 100, and 150 mg NH 4(+)  l(-1)) in presence of 0.01 M CaCl2 solution. The empirical models including simple adsorption isotherm and Freundlich equations were fitted well to the experimental data. The average amounts of adsorbed NH 4(+) in studied soils varied from 8.95 to 35.23 %. Adsorption percentage indicated positive correlation with pH, cation-exchange capacity (CEC), equivalent calcium carbonate, and clay content and had negative correlation with sand content. In order to predict and model NH 4(+) adsorption, cation-exchange model in PHREEQC program was used. The model could simulate the NH 4(+) adsorption very well in all studied soils. The values of CEC played the major role in modeling of NH 4(+) adsorption in this study indicating that cation-exchange process was the major mechanism controlling NH 4(+) adsorption in studied soils.

[Comparing microbial community of high ammonia wastewater and municipal sewage in a partial nitrification system]

Nitritation is an important part of the biological nitrogen removal process, and the performance of the process was determined by the microbial community structure. To explore the microbial adaptability to different sewage, the microbial diversity and the amount of bacteria were investigated in a high ammonia wastewater treatment process and a sewage treatment process using the clone library of bacterial 16S rDNA, the phospholipid fatty acid method (PLFA) and the quantitative PCR. The clone library results showed that there was a significantly difference in bacterial community structure of these two processes, although the dominant bacteria belong to the Proteobacteria and Bacteroidete, there were more clusters in the sewage treatment process. The PLFAs results showed that the microbial diversity index and the evenness index of the high ammonium wastewater treatment process were significantly low. The quantitative PCR results showed that amounts of ammonia oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the high ammonium wastewater treatment process were higher than these in sewage treatment process. The copy number of AOB was higher than the copy number of NOB in the high ammonia wastewater treatment process by three orders magnitude. The copy number of AOB was higher than the copy number of NOB in sewage treatment process by two orders of magnitude.

Start-up and long-term operation of the Anammox process in a fixed bed reactor (FBR) filled with novel non-woven ring carriers

A novel kind of non-woven ring carriers was used to improve a fixed bed reactor (FBR) as Anammox reactor. The improved FBR was operated for about 1 year. The Anammox activity occurred on day 39. On day 367, the maximum total nitrogen removal rate reached 9.2 kg Nm(-3)d(-1). FISH analysis showed that Anammox bacteria predominated in the mature sludge and accounted for 78% of the total bacteria. Phylogenetic analysis further showed that Candidatus Kuenenia stuttgartiensis occupied 70% of Anammox bacteria, which benefited keeping the stability of Anammox reactor. The FBR was proved to be a suitable reactor for start-up and long-term operation of Anammox process.

Removal of nitrogen from wastewater with perennial ryegrass/artificial aquatic mats biofilm combined system

To develop a cost-effective combined phytoremediation and biological process, a combined perennial ryegrass/artificial aquatic mat biofilm reactor was used to treat synthetic wastewater. Influent ammonium loading, reflux ratio, hydraulic retention time (HRT) and temperature all had significant effects on the treatment efficiency. The results indicated that the effluent concentration of ammonium increased with increasing influent ammonium loading. The reactor temperature played an important role in the nitrification process. The ammonium removal efficiency significantly decreased from 80% to 30%-50% when the reactor temperature dropped to below 10 degrees C. In addition, the optimal nitrogen removal condition was a reflux ratio of 2. The nitrate and ammonium concentration of the effluent were consistent with the HRT of the combined system. The chemical oxygen demand (COD) removal efficiency was at a high level during the whole experiment, being almost 80% after the start-up, and then mostly above 90%. The direct uptake of N by the perennial ryegrass accounted for 18.17% of the total N removal by the whole system. The perennial ryegrass absorption was a significant contributor to nitrogen removal in the combined system. The result illustrated that the combined perennial ryegrass/artificial aquatic mat biofilm reactor demonstrated good performance in ammonium, total N and COD removal.

Microbial community characterization, activity analysis and purifying efficiency in a biofilter process

The growth and metabolism of microbial communities on biologically activated carbon (BAC) play a crucial role in the purification of drinking water. To gain insight into the growth and metabolic characteristics of microbial communities and the efficiency of drinking water treatment in a BAC filter, we analyzed the heterotrophic plate count (HPC), phospholipid, dehydrogenase, metabolic function and water quality parameters during start-up and steady-state periods. In the start-up process of the filter with natural biofilm colonization, the variation in heterotrophic plate count levels was S-curved. The total phospholipid level was very low during the first 5 days and reached a maximum value after 40 days in the filter. The activity of dehydrogenase gradually increased during the first 30 days and then reached a plateau. The functional diversity of the microbial community in the filter increased, and then reached a relatively stable level by day 40. After an initial decrease, which was followed by an increase, the removal rate of NH4(+)-N and COD(Mn) became stable and was 80% and 28%, respectively, by day 40. The consumption rate of dissolved oxygen reached a steady level after 29 days, and remained at 18%. At the steady operation state, the levels of HPC, phospholipid, dehydrogenase activity and carbon source utilization had no significant differences after 6 months compared to levels measured on day 40. The filter was shown to be effective in removing NH4(+)-N, NO2(-)-N, COD(Mn), UV254, biodegradable dissolved organic carbon and trace organic pollutants from the influent. Our results suggest that understanding changes in the growth and metabolism of microorganisms in BAC filter could help to improve the efficiency of biological treatment of drinking water.

Inhibition of anaerobic ammonium oxidizing (anammox) enrichment cultures by substrates, metabolites and common wastewater constituents

Anaerobic ammonium oxidation (anammox) is an emerging technology for nitrogen removal that provides a more environmentally sustainable and cost effective alternative compared to conventional biological treatment methods. The objective of this study was to investigate the inhibitory impact of anammox substrates, metabolites and common wastewater constituents on the microbial activity of two different anammox enrichment cultures (suspended and granular), both dominated by bacteria from the genus Brocadia. Inhibition was evaluated in batch assays by comparing the N(2) production rates in the absence or presence of each compound supplied in a range of concentrations. The optimal pH was 7.5 and 7.3 for the suspended and granular enrichment cultures, respectively. Among the substrates or products, ammonium and nitrate caused low to moderate inhibition, whereas nitrite caused almost complete inhibition at concentrations higher than 15 mM. The intermediate, hydrazine, either stimulated or caused low inhibition of anammox activity up to 3mM. Of the common constituents in wastewater, hydrogen sulfide was the most severe inhibitor, with 50% inhibitory concentrations (IC(50)) as low as 0.03 mM undissociated H(2)S. Dissolved O(2) showed moderate inhibition (IC(50)=2.3-3.8 mg L(-1)). In contrast, phosphate and salinity (NaCl) posed very low inhibition. The suspended- and granular anammox enrichment cultures had similar patterns of response to the various inhibitory stresses with the exception of phosphate. The findings of this study provide comprehensive insights on the tolerance of the anammox process to a wide variety of potential inhibiting compounds.

A portable analyser for the measurement of ammonium in marine waters

A portable ammonium analyser was developed and used to measure in situ ammonium in the marine environment. The analyser incorporates an improved LED photodiode-based fluorescence detector (LPFD). This system is more sensitive and considerably smaller than previous systems and incorporates a pre-filtering subsystem enabling measurements in turbid, sediment-laden waters. Over the typical range for ammonium in marine waters (0–10 mM), the response is linear (r(2) = 0.9930) with a limit of detection (S/N ratio > 3) of 10 nM. The working range for marine waters is 0.05–10 mM. Repeatability is 0.3% (n =10) at an ammonium level of 2 mM. Results from automated operation in 15 min cycles over 16 days had good overall precision (RSD = 3%, n = 660). The system was field tested at three shallow South Florida sites. Diurnal cycles and possibly a tidal influence were expressed in the concentration variability observed.

Characterization of a new series of fluorescent probes for imaging membrane order

Visualization and quantification of lipid order is an important tool in membrane biophysics and cell biology, but the availability of environmentally sensitive fluorescent membrane probes is limited. Here, we present the characterization of the novel fluorescent dyes PY3304, PY3174 and PY3184, whose fluorescence properties are sensitive to membrane lipid order. In artificial bilayers, the fluorescence emission spectra are red-shifted between the liquid-ordered and liquid-disordered phases. Using ratiometric imaging we demonstrate that the degree of membrane order can be quantitatively determined in artificial liposomes as well as live cells and intact, live zebrafish embryos. Finally, we show that the fluorescence lifetime of the dyes is also dependent on bilayer order. These probes expand the current palate of lipid order-sensing fluorophores affording greater flexibility in the excitation/emission wavelengths and possibly new opportunities in membrane biology.

Water chemistry in the microenvironment of rainbow trout Oncorhynchus mykiss embryos is affected by development, the egg capsule and crowding

The hypothesis tested was that embryonic metabolism affects the water chemistry in the boundary layer. In addition, embryo crowding would further compound the metabolic effect on the water chemistry in the boundary layer. As development progressed, the magnitude of the boundary layer gradients for O(2) and pH, but not for NH4(+), increased. The presence of the egg capsule hindered the diffusion of O(2) into and H(+) and NH4(+) out of the embryo. The magnitude of the O(2), pH and NH4(+) boundary layer gradient was significantly increased when embryos were surrounded by either sham embryos or live embryos. The majority of this crowding effect on embryo boundary layers was due to changes in water flow rather than due to metabolism directly. These results clearly show that the microenvironment adjacent to the developing rainbow trout Oncorhynchus mykiss embryo becomes more stagnant as development progresses in the presence of the egg capsule and is further intensified with embryo crowding.

Treatment of high-ammonium anaerobic digester supernatant by aerobic granular sludge and ultrafiltration processes

Anaerobic sludge digester supernatant characterized by 569 mg TKN L(-1), high color and a COD/N ratio of 1.4 was treated in granular sequencing batch reactors (GSBRs) followed by post-denitrification (P-D) and ultrafiltration (UF) steps. The use of granular sludge allowed for the oxidation of ammonium in anaerobic digester supernatant at all investigated GSBR cycle lengths of 6, 8 and 12 h. The highest ammonium removal rate (15 mg N g(-1) VSS h(-1)) with removal efficiency of 99% was noted at 8 h. Since the GSBR effluent was characterized by a high concentration of nitrites, slowly-degradable substances and biomass, additional purification steps were applied. In P-D stage, the microbial activity of granular biomass in the GSBR effluent was implemented. The P-D was supported by external carbon source addition and the most advantageous variant comprised dosing of half of the theoretical acetate dose for nitrite reduction in the 3-h intervals. The use of the system consisting of the GSBR with 8 h, an optimal P-D variant and a UF for the treatment of anaerobic digester supernatant allowed for the 99%, 71% and 97% reductions of TKN, COD and color, respectively.

[Effects of Phyllostachys edulis expansion on soil nitrogen mineralization and its availability in evergreen broadleaf forest]

By the methods of space-time substitution and PVC tube closed-top in situ incubation, this paper studied the soil mineralized-N content, N mineralization rate, and N uptake rate in Phyllostachys edulis-broadleaf mixed forest (PBMF) formed by P. edulis expansion and its adjacent evergreen broadleaf forest (EBF) in Dagangshan Mountain of Jiangxi Province, China. There existed the same spatiotemporal variation trend of soil total mineralized-N (TMN) content between the two forests. The annual average N mineralization rate was slightly lower in PBMF than in EBF. In PBMF, soil N mineralization was dominated by ammonification; while in EBF, soil ammonification and nitrification were well-matched in rate, and soil nitrification was dominated in growth season (from April to October). The N uptake by the plants in PBMF and EBF in a year was mainly in the form of NH4+-N, but that in EBF in growth season was mainly in the form of NO3- -N. These findings indicated that the expansion of P. edulis into EBF could promote the ammonification of soil N, weakened soil nitrification and total N mineralization, and also, increased the NH4+-N uptake but decreased the NO3- -N and TMN uptake by the plants.

Adsorption of ammonium ion by coconut shell-activated carbon from aqueous solution: kinetic, isotherm, and thermodynamic studies

Ammonium ions are one of the most encountered nitrogen species in polluted water bodies. High level of ammonium ion in aqueous solution imparts unpleasant taste and odor problems, which can interfere with the life of aquatics and human population when discharged. Many chemical methods are developed and being used for removal of ammonium ion from aqueous solution. Among various techniques, adsorption was found to be the most feasible and environmentally friendly with the use of natural-activated adsorbents. Hence, in this study, coconut shell-activated carbon (CSAC) was prepared and used for the removal of ammonium ion by adsorption techniques. Ammonium chloride (analytical grade) was purchased from Merck Chemicals for adsorption studies. The CSAC was used to adsorb ammonium ions under stirring at 100 rpm, using orbital shaker in batch experiments. The concentration of ammonium ion was estimated by ammonia distillate, using a Buchi distillation unit. The influence of process parameters such as pH, temperature, and contact time was studied for adsorption of ammonium ion, and kinetic, isotherm models were validated to understand the mechanism of adsorption of ammonium ion by CSAC. Thermodynamic properties such as ∆G, ∆H, and ∆S were determined for the ammonium adsorption, using van't Hoff equation. Further, the adsorption of ammonium ion was confirmed through instrumental analyses such as SEM, XRD, and FTIR. The optimum conditions for the effective adsorption of ammonium ion onto CSAC were found to be pH 9.0, temperature 283 K, and contact time 120 min. The experimental data was best followed by pseudosecond order equation, and the adsorption isotherm model obeyed the Freundlich isotherm. This explains the ammonium ion adsorption onto CSAC which was a multilayer adsorption with intraparticle diffusion. Negative enthalpy confirmed that this adsorption process was exothermic. The instrumental analyses confirmed the adsorption of ammonium ion onto CSAC.

An operational protocol for facilitating start-up of single-stage autotrophic nitrogen-removing reactors based on process stoichiometry

Start-up and operation of single-stage nitritation-anammox sequencing batch reactors (SBRs) for completely autotrophic nitrogen removal can be challenging and far from trivial. In this study, a step-wise procedure is developed based on stoichiometric analysis of the process performance from nitrogen species measurements to systematically guide start-up and normal operation efforts (instead of trial and error). The procedure is successfully applied to laboratory-scale SBRs for start-up and maintained operation over an 8-month period. This analysis can serve as a strong decision-making tool to take appropriate actions with respect to reactor operation to accelerate start-up or ensure high-rate N removal via the nitritation-anammox pathway.

Evaluation of the individuality of white rot macro fungus for the decolorization of synthetic dye

INTRODUCTION

A biosorbent was developed by simple dried Agaricus bisporus (SDAB) and effectively used for the biosorption of cationic dyes, Crystal Violet and Brilliant Green.

MATERIALS AND METHODS

For the evaluation of the biosorbent system, all the batch equilibrium parameters like pH, biomass dose, contact time, and temperature were optimized to determine the decolorization efficiency of the biosorbent. The maximum yields of dye removal were achieved at pH 4.0 for Crystal Violet (CV) and pH 5.0 for Brilliant Green (BG), which are closer to their natural pH also.

RESULT AND DISCUSSION

Equilibrium was established at 60 and 40 min for CV and BG, respectively. Pseudo first-order, pseudo second-order, and intraparticle-diffusion kinetic models were studied at different temperatures. Isotherm models such as Freundlich, Langmuir, and Dubinin-Radushkevich were also studied. Biosorption processes were successfully described by Langmuir isotherm model and the pseudo second-order kinetic model.

CONCLUSIONS

The biosorption capacity of A. bisporus over CV and BG were found as 21.74 and 12.16 mg gm(-1). Thermodynamic parameters indicated that the CV and BG dye adsorption onto A. bisporus is spontaneous and exothermic in the single and ternary systems. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used for the surface morphology, crystalline structure of biosorbent, and dye-biosorbent interaction, respectively. This analysis of the biosorption data confirmed that these biosorption processes are ecofriendly and economical. Thus, this biomass system may be useful for the removal of contaminating cationic dyes.

Enhancement of phosphorus removal in a low temperature A(2)/O process by anaerobic phosphorus release of activated sludge

An anaerobic phosphorus release tank was introduced to an anaerobic-anoxic-aerobic (A(2)/O) process treating domestic sewage to enhance the phosphorus removal at low temperature. Phosphorus release of the activated sludge from the second sedimentation tank was evaluated at 14 °C by batch cultures, and the nutrient removal in the modified low temperature A(2)/O process was further investigated at the same temperature. The results showed that the feasible sludge retention time was 14 h for sequencing batch reaction and 12 h for continuous flow operation. The ratio of raw sewage to activated sludge from the second sedimentation tank was 1:1 in volume to meet the demand of carbon resource for the growth of phosphorus release microbes. The feasible chemical oxygen demand (COD) loading rate of the activated sludge in the phosphorus release tank was 0.015-0.02 g COD/g MLSS (mixed liquor suspended solids) and the nitrate concentration should be less than 5 mg/L. The phosphorus release was doubled when the sludge was blended intermittently and gently. The anaerobic phosphorus release of the activated sludge improved the phosphate removal remarkably, as well as the removal of NH4(+)-N and total nitrogen (TN) in the modified low temperature A(2)/O process. The effluent COD, NH4(+)-N, TN and total phosphorus could meet a stricter discharge standard.

High NH(4)(+)-N concentration wastewater treatment by shortcut nitrification-denitrification using a system of A/O inner loop fluidized bed biofilm reactors

In this experiment, a rapid mass-transfer inner loop fluidized bed biofilm reactor (ILFBBR) was employed to treat synthetic high ammonia nitrogen-containing (NH(4)(+)-N) wastewater by shortcut nitrification-denitrification. The reactor operation was stable after a short start-up period. Ammonia oxidizing bacteria (AOB) were predominant and 65% nitrite (NO(2)(-)-N/NO(x)(-)-N) levels were achieved. During the nitrification-denitrification period, the removal rates of NH(4)(+)-N and total nitrogen (TN) reached 94 and 82%, respectively. From the material balance, it was indicated that 87% of NH(4)(+)-N was removed by shortcut nitrification. The features of ILFBBR and the benefits of shortcut nitrification were combined in this experiment, and showed an excellent removal of NH(4)(+)-N from high-concentration NH(4)(+)-N wastewater.

Nitrous oxide formation during nitritation and nitrification of high-strength wastewater

The purpose of this study was to investigate the formation of nitrous oxide (N2O) in nitritation and nitrification under stable, comparable and not limiting conditions typical for treatment of high-strength wastewater. A laboratory-scale aerated chemostat was operated with reject water at different sludge retention times, achieving suppression of nitrate formation by wash-out of nitrite-oxidizing bacteria for nitritation. The N2O formation factor during stable nitritation was higher (2.90% N2O-N /NH4(-)-Nox) than during nitrification (0.74%). The positive correlation of N2O formation rates and ammonium oxidation rates was linear and thus did not contribute to changes of the N2O formation factor. The dominant factor for N2O formation during stable operation was high nitrite concentration, which was positively correlated with N2O formation rates. The highest formation factors were observed during a transition phase from nitrification to nitritation with unstable process conditions (4.81%) and during a short-term experiment with increased pH of 7 (10.28%). The results indicate that even with operational conditions that are regarded favourable for the process of nitritation N2O formation can be limited but not avoided.

Effect of pH and HNO2 concentration on the activity of ammonia-oxidizing bacteria in a partial nitritation reactor

Ammonia-oxidizing bacteria (AOB) are very sensitive to environmental conditions and wastewater treatment plant operational parameters. One of the most important factors affecting their activity is pH. Its effect is associated with: NH3/NH4(+) and HNO2/NO2(-) chemical equilibriums and biological reaction rates. The aim of this study was to quantify and model the effect of pH and free nitrous acid (FNA) concentration on the activity of AOB present in a lab-scale partial nitritation reactor. For this purpose, two sets of batch experiments were carried out using biomass from this reactor. Fluorescent in situ hybridization analysis showed that Nitrosomona eutropha and Nitrosomona europaea species were dominant in the partial nitritation reactor (>94%). The experimental results showed that FNA inhibits the AOB activity. This inhibition was properly modelled by the non-competitive inhibition function and the half inhibition constant value was determined as 1.32 mg HNO2-N L(-1). The optimal pH for these AOB was found to be in the range 7.4-7.8. The pH inhibitory effect was stronger at high pH values than at low pH values. Therefore, an asymmetric inhibition function was proposed to represent the pH effect on these bacteria. A combination of two sigmoidal functions was able to reproduce the experimental results obtained.

Caragana fabr. promotes revegetation and soil rehabilitation in saline-alkali wasteland

To determine how plantations of Caragana microphylla shrubs affect saline-alkali soil amelioration and revegetation, we investigated the vegetation and sampled soils from saline-alkali wasteland (SAW), perennial Caragana forestland (PCF), Caragana forest after fire disturbance (CFF). Results showed that with the development of Caragana Fabr., highly dominant species of Poaceae family, including Elymus dahuricus, Thermopsis lanceolata, Stipa tianschanica, died out in PCF. Moreover, Papilionaceaefamily, including Lespedeza indica, Oxytropis psammocharis, and Astragalus scaberrimus, was established both in PCF and CFF. Phytoremediation of saline-alkali wasteland (SAW) was achieved by plantation, resulting in the reduced soil pH, sodium adsorption ratio, exchangeable sodium percentage, salinity, and Na+ concentration around Caragana shrubs. Greater amounts of soil organic, total nitrogen, ammonium nitrogen, available phosphorus, and available potassium were observed in PCF topsoil than in SAW topsoil The concentration of mineralized N in PCF soil was significantly lower than that in SAW soil at all sampled depths, indicating that Caragana shrubs were just using N and therefore less measured in soils. Fire disturbance resulted in decreased soil pH and salinity, but increased organic content, total nitrogen, and ammonium nitrogen. The improved soil parameters and self-recovery of shrubs indicated that Caragana shrubs were well established after burning event.

Seasonal variations and aeration effects on water quality improvements and physiological responses of Nymphaea tetragona Georgi

Seasonal variations and aeration effects on water quality improvements and the physiological responses of Nymphaea tetragona Georgi were investigated with mesocosm experiments. Plants were hydroponically cultivated in six purifying tanks (aerated, non-aerated) and the characteristics of the plants were measured. Water quality improvements in purifying tanks were evaluated by comparing to the control tanks. The results showed that continuous aeration affected the plant morphology and physiology. The lengths of the roots, petioles and leaf limbs in aeration conditions were shorter than in non-aeration conditions. Chlorophyll and soluble protein contents of the leaf limbs in aerated tanks decreased, while peroxidase and catalase activities of roots tissues increased. In spring and summer, effects of aeration on the plants were less than in autumn. Total nitrogen (TN) and ammonia nitrogen (NH4(+)-N) in aerated tanks were lower than in non-aerated tanks, while total phosphorus (TP) and dissolved phosphorus (DP) increased in spring and summer. In autumn, effects of aeration on the plants became more significant. TN, NH4(+)-N, TP and DP became higher in aerated tanks than in non-aerated tanks in autumn. This work provided evidences for regulating aeration techniques based on seasonal variations of the plant physiology in restoring polluted stagnant water.

Characteristics of particulate constituents and gas precursors during the episode and non-episode periods

Size-segregated distribution of ambient particulate matter (PM) was determined using a micro-orifice uniform deposition impactor (MOUDI) and a nano-MOUDI in southern Taiwan. Eleven water-soluble ionic species including six anions (NO3-, SO4(2-), Cl-, F-, NO2-, Br-) and five cations (NH4+, Na+, K+, Ca2+, Mg2+) for particulate inorganic ions and five gaseous pollutants (i.e., HNO2, HNO3, HCl, SO2, NH3) were analyzed during episode and non-episode periods. The particulate mass concentration was about 30 microg/ m3 higher at night than during the day, and it reached 162 microg/m3 during the episode periods. The difference was mainly attributable to the particle size of 0.1-2.5 microm. Nitrate, sulfate, ammonium, and chloride ions were the dominant inorganic ions in PM. HONO and NH3 concentrations were high at night; in contrast, HNO3, HCl, and SO2 were high during the day. The equivalent ratio of {[NO3-] + 2 [SO4(2-)}/[NH4+] was about 0.98 and revealed a high correlation between {[NO3-] + 2[SO4(2-)]} and [NH4+] that clearly pointed to ammonium neutralization or condensation of ammonium nitrate and ammonium sulfate in PM0.32. The precursor gases and ionic species in different particle sizes did not reveal a strong correlation, which could be attributed to the complex of source emissions, atmospheric reactions and meteorological parameters in the area.

IMPLICATIONS

Size-segregated distribution and chemical compositions of atmospheric aerosols play important roles in their visibility reduction, health effects, and toxicity in urban areas. Inorganic ionic species are major constituents in particulate matter, except carbonaceous chemicals. In this work, the compositions of water-soluble ions in particulate matter and acid/base gaseous pollutants (such as HNO2, HNO3, HCl, SO2, NH3) were determined during the day and at night during episode and non-episode periods from 2006 to 2007 in southern Taiwan.

Sediment-seawater solute flux in a polluted New Zealand estuary

We investigated the sediment-seawater solute flux at five sites in the polluted Avon-Heathcote Estuary, New Zealand, to provide a point of comparison for future studies of the effects of the closure of a major wastewater outfall into the estuary. Sediments collected in winters 2007 and 2008, and summer 2008, ranked consistently in organic matter content. Microelectrode profiling and sediment-core incubations revealed (1) a dominant role of microphytes in regulating solute flux causing significant differences in the dark and light sediment O₂ consumption (R(d), R(l)), total sediment O₂ utilisation (TOU(d), TOU(l)), and inorganic nutrient flux, (2) consistent ranking of sites in solute flux, and (3) a clear solute-flux signature of the wastewater effluent. Sediment near the wastewater outfall exhibited the highest absolute R and TOU(,) the lowest ratio R(l)/R(d,) the highest dark efflux of dissolved reactive phosphorus and ammonium, and the highest dark and light uptake of nitrate+nitrite.

Response of Arabidopsis thaliana, seedlings to cadmium in relation to ammonium availability

This study explored the natural variability of Arabidopsis thaliana to find out its response to ammonium availability and characterize the tolerance capacity to cadmic stress under low, average or high nitrogen supplies. Growth was determined by different morphological traits and metabolic enzymes. Plant growth was inhibited by cadmium at low nitrogen regime. But, at average or high nitrogen conditions, plant growth seems to be no affected by cadmium. Cadmium inhibited glutamine synthetase activity and stimulated glutamate dehydrogenase one in order to tolerate cadmium stress. Cadmium enhanced proline and sugar tenor in average or high nitrogen plants parallel with activation of Rubisco. Observations show that cadmium-induced stress was alleviated by optimal ammonium availability.

Characterization of ammonium retention processes onto cactus leaves fibers using FTIR, EDX and SEM analysis

In order to reduce the impact of nitrogen pollution and to increase the agronomic value of plant wastes to be reused as organic fertilizer, we have investigated the removal of ammonium from aqueous solutions onto cactus leave fibers (CLF), and the mechanisms involved in the retention of ammonium at CLF surface. The results showed that ammonium retention onto these fibers occurred for a wide pH (6-10) and temperature ranges (20-60°C) and the biosorption potential of CLF increased with temperature from 1.4 to 2.3 mg g(-1) for initial concentration of 50 mg L(-1). The modeling studies showed that the ammonium biosorption was well described by the pseudo-second-order model, predicting therefore, chemisorption interactions-type at earlier stages and by intraparticle diffusion at later stages. Biosorption is governed by film diffusion process at higher concentrations and by particle diffusion process at higher temperatures. The surface of CLF determined by SEM revealed the presence of cracks and cavities which may allow the intraparticle diffusion and the ion exchange processes. Moreover, FTIR and EDX analysis before and after ammonium retention showed that the main mechanisms involved in the removal of ammonium were the ionic exchange by calcium ions as well as H(+) and the complexation with carboxylic, alcoholic and phenolic groups.

Nutrient fluxes via submarine groundwater discharge to the Bay of Puck, southern Baltic Sea

Submarine groundwater discharge (SGD) has been recognized as an important exchange pathway between hydrologic reservoirs due to its impact on biogeochemical cycles of the coastal ocean. This study reports nutrient concentrations and loads delivered by SGD into the Bay of Puck, the southern Baltic Sea. Measurements were carried out between September, 2009 and October, 2010 at groundwater seepage sites identified by low salinity of pore water. Groundwater fluxes, measured using seepage meters, ranged from 3 to 22 L m(-2)day(-1). Average concentrations of nutrients in groundwater samples collected were as follows: 0.4 μmol L(-1) nitrate (NO(3)), 0.8 μmol L(-1) nitrite (NO(2)), 18.2 μmol L(-1) ammonium (NH(4)) and 60.6 μmol L(-1) orthophosphate (PO(4)). Levels of NH(4) and PO(4) were significantly higher in samples from SGD sites than in seawater. Seawater and SGD samples showed similar NO(2) concentrations but SGD samples exhibited lower NO(3) levels than those observed in seawater samples. Measured seepage water fluxes and nutrient concentrations were used to calculate nutrient loads discharged into the study area while the literature groundwater flux and the measured nutrient concentrations were used to estimate nutrient loads discharged into the Bay of Puck. The estimates suggest that SGD delivers a dissolved inorganic nitrogen (DIN) load of 49.9 ± 18.0 t yr(-1) and a PO(4)(-) load of 56.3 ± 5.5tyr(-1) into the Bay of Puck. The projected estimates are significant in comparison with loads delivered to the bay from other, well-recognized sources (705 ty r(-1) and 105 ty r(-1) respectively for DIN and PO(4)). Nutrient discharge input loads were projected to the entire Baltic Sea The extrapolated values indicate SGD contributes a significant proportion of phosphate load but only an insignificant proportion of DIN load. Further studies are necessary to better understand SGD contributions to the nutrient budget in the Baltic Sea.

Characterization and tropical seasonal variation of leachate: results from landfill lysimeter studied

This study aims to characterize the leachate and to investigate the tropical climatic influence on leachate characteristics of lysimeter studies under different seasonal variations at KUET campus, Bangladesh. Three different situations of landfill were considered here as well as both the open dump lysimeter-A having a base liner and sanitary landfill lysimeter-B and C at two different types of cap liner were simulated. The leachate characteristics, leachate generation and climatic influence parameter had been continually monitored since June 2008 to May 2010, these periods cover both the dry and rainy season. The leachate generation had followed the rainfall pattern and the open dump lysimeter-A without top cover was recorded to have highest leachate generation. Moreover, the open dump lysimeter-A had lower total kjeldahl nitrogen (TKN), ammonia nitrogen (NH(4)-N) and TKN load, while both the COD concentration and load was higher compared with sanitary landfill lysimeter-B and C. In addition, sanitary landfill lysimeter-B, not only had lowest leachate generation, but also produces reasonable low COD concentration and load compared with open dump lysimeter-A. Result reveals that lysimeter operational mode had direct effect on leachate quality. Finally, it can be concluded that the knowledge of leachate quality will be useful in planning and providing remedial measures of proper liner system in sanitary landfill design and leachate treatment.

Evidence that northern pioneering pines with tuberculate mycorrhizae are unaffected by varying soil nitrogen levels

Tuberculate mycorrhizae on Pinus contorta (lodgepole pine) have previously been shown to reduce acetylene, but an outstanding question has been to what degree these structures could meet the nitrogen requirements of the tree. We compared the growth, tissue nitrogen contents, and stable nitrogen isotope ratios of P. contorta growing in gravel pits to the same species growing on adjacent intact soil. Trees growing in severely nitrogen deficient gravel pits had virtually identical growth rates and tissue nitrogen contents to those growing on intact soil that had nitrogen levels typical for the area. δ(15)N values for trees in the gravel pits were substantially lower than δ(15)N values for trees on intact soil, and isotope ratios in vegetation were lower than the isotope ratios of the soil. The form of soil nitrogen in the gravel pits was almost exclusively nitrate, while ammonium predominated in the intact soil. Discrimination against (15)N during plant uptake of soil nitrate in the highly N-deficient soil should be weak or nonexistent. Therefore, the low δ(15)N in the gravel pit trees suggests that trees growing in gravel pits were using another nitrogen source in addition to the soil. Precipitation-borne nitrogen in the study area is extremely low. In conjunction with our other work, these findings strongly suggests that P. contorta and its microbial symbionts or associates fix nitrogen in sufficient amounts to sustain vigorous tree growth on the most nitrogen-deficient soils.

Performance of intermittently aerated up-flow sludge bed reactor and sequencing batch reactor treating industrial estate wastewater: a comparative study

In this study, an innovative aerobic/anoxic sludge bed bioreactor with two feeding regimes, continuous-fed (an up-flow sludge bed reactor (USBR)) and batch fed (sequencing batch reactor (SBR)), was evaluated for the treatment of an industrial estate wastewater with low BOD(5)/COD ratio. The process performance in the two regimes was compared. Two numerical independent variables (retention/react time and aeration time) were selected to analyze, model and optimize the process. Response surface methodology with central composite design (CCD) was used with five levels of hydraulic retention time (HRT)/react time (12-36h) and aeration time (40-60min/h). In order to analyze the process, ten dependent parameters as the process responses were studied. As a result, HRT/react time showed a decreasing impact on the responses measured in both hydraulic regimes, USBR and SBR. The USBR showed better performance than the SBR in removal of total COD, slowly biodegradable COD, total nitrogen and total Kjeldahl nitrogen.

Effects of step-feed on granulation processes and nitrogen removal performances of partial nitrifying granules

Two anoxic/oxic sequencing batch reactors (A/O SBRs) were operated to investigate the effects of step-feed on granulation processes and performances of partial nitrifying granules (PNG). R1 was operated in a traditional single-feed mode, while a two-step-feed strategy was used in R2. Results showed that R1 had a faster granulation process and better performance in maintaining partial nitrification compared with R2, indicating that the step-feed mode had a negative effect of on formation of PNG. However, after full granulation, PNG in both reactors had similar properties in terms of suspended solids (MLSS), sludge volume index (SVI) and granule size. Moreover, mature granules in R2 had a higher nitrite accumulation rate than that in R1. Step-feed strategy was also observed to enhance denitrification and TN removal, as well as ammonia oxidation. It can be concluded that step-feed was unfavorable for cultivating PNG, but it significantly improved the nitrogen removal performance of PNG.

Biochemical methane potential of microalgae: influence of substrate to inoculum ratio, biomass concentration and pretreatment

The anaerobic digestion of three microalgae mixtures was evaluated at different substrate to inoculum (S/I) ratios (0.5, 1 and 3), biomass concentrations (3, 10 and 20gTS/kg) and pretreatments (thermal hydrolysis, ultrasound and biological treatment). An S/I ratio of 0.5 and 10gTS/kg resulted in the highest final methane productivities regardless of the microalgae tested (ranging from 188 to 395mL CH(4)/gVS(added)). The biological pretreatment supported negligible enhancements on CH(4) productivity, while the highest increase (46-62%) was achieved for the thermal hydrolysis. The optimum temperature of this pretreatment depended on the microalgae species. The ultrasound pretreatment brought about increases in CH(4) productivity ranging from 6% to 24% at 10,000kJ/kgTS, without further increases at higher energy inputs. The results here obtained confirmed the lack of correlation between the solubilization degree and the methane enhancement potential and pointed out that anaerobic digestion of algae after thermal pretreatment is a promising technology for renewable energy production.

Effect of biochar amendment on sorption and leaching of nitrate, ammonium, and phosphate in a sandy soil

When applied to soils, it is unclear whether and how biochar can affect soil nutrients. This has implications both to the availability of nutrients to plants or microbes, as well as to the question of whether biochar soil amendment may enhance or reduce the leaching of nutrients. In this work, a range of laboratory experiments were conducted to determine the effect of biochar amendment on sorption and leaching of nitrate, ammonium, and phosphate in a sandy soil. A total of thirteen biochars were tested in laboratory sorption experiments and most of them showed little/no ability to sorb nitrate or phosphate. However, nine biochars could remove ammonium from aqueous solution. Biochars made from Brazilian pepperwood and peanut hull at 600°C (PH600 and BP600, respectively) were used in a column leaching experiment to assess their ability to hold nutrients in a sandy soil. The BP600 biochar effectively reduced the total amount of nitrate, ammonium, and phosphate in the leachates by 34.0%, 34.7%, and 20.6%, respectively, relative to the soil alone. The PH600 biochar also reduced the leaching of nitrate and ammonium by 34% and 14%, respectively, but caused additional phosphate release from the soil columns. These results indicate that the effect of biochar on the leaching of agricultural nutrients in soils is not uniform and varies by biochar and nutrient type. Therefore, the nutrient sorption characteristics of a biochar should be studied prior to its use in a particular soil amendment project.

Measuring biomass specific ammonium, nitrite and phosphate uptake rates in aerobic granular sludge

Aerobic granular sludge (AGS) technology offers the possibility to remove organic carbon, nitrogen and phosphorus in a single reactor system. The granular structure is stratified in such a way that both aerobic and anaerobic/anoxic layers are present. Since most of the biological processes in AGS systems occur simultaneously, the measurement and estimation of the capacity of specific conversions is complicated compared to suspended biomass. The determination of the activities of different functional groups in aerobic granular sludge allows for identification of the potential metabolic capacity of the sludge and aids to analyze bioreactor performance. It allows for comparison of different sludges and enables improved understanding of the interaction and competition between different metabolic groups of microorganisms. The most appropriate experimental conditions and methods to determine specific ammonium, nitrite and phosphate uptake rates under normal operation of AGS reactors were evaluated and described in this study. Extra biomass characterization experiments determining the maximum uptake rate of these compounds on optimized conditions were performed as well to see how much spare capacity was available. The methodologies proposed may serve as an experimental frame of reference for investigating the metabolic capacities of microbial functional groups in biofilm processes.

Integrated photo-bioelectrochemical system for contaminants removal and bioenergy production

An integrated photobioelectrochemical (IPB) system was developed by installing a microbial fuel cell (MFC) inside an algal bioreactor. This system achieves the simultaneous removal from a synthetic solution of organics (in the MFC) and nutrients (in the algal bioreactor), and the production of bioenergy in electricity and algal biomass through bioelectrochemical and microbiological processes. During the one-year operation, the IPB system removed more than 92% of chemical oxygen demand, 98% of ammonium nitrogen, and 82% of phosphate and produced a maximum power density of 2.2 W/m(3) and 128 mg/L of algal biomass. The algal growth provided dissolved oxygen to the cathode reaction of the MFC, whereas electrochemical oxygen reduction on the MFC cathode buffered the pH of the algal growth medium (which was also the catholyte). The system performance was affected by illumination and dissolved oxygen. Initial energy analysis showed that the IPB system could theoretically produce enough energy to cover its consumption; however, further improvement of electricity production is desired. An analysis of the attached and suspended microbes in the cathode revealed diverse bacterial taxa typical of aquatic and soil bacterial communities with functional roles in contaminant degradation and nutrient cycling.

Is the relation between ozone and mortality confounded by chemical components of particulate matter? Analysis of 7 components in 57 US communities

Epidemiologic studies have linked tropospheric ozone pollution and human mortality. Although research has shown that this relation is not confounded by particulate matter when measured by mass, little scientific evidence exists on whether confounding exists by chemical components of the particle mixture. Using mortality and particulate matter with aerodynamic diameter ≤2.5 µm (PM(2.5)) component data from 57 US communities (2000-2005), the authors investigate whether the ozone-mortality relation is confounded by 7 components of PM(2.5): sulfate, nitrate, silicon, elemental carbon, organic carbon matter, sodium ion, and ammonium. Together, these components constitute most PM(2.5) mass in the United States. Estimates of the effect of ozone on mortality were almost identical before and after controlling for the 7 components of PM(2.5) considered (mortality increase/10-ppb ozone increase, before and after controlling: ammonium, 0.34% vs. 0.35%; elemental carbon, 0.36% vs. 0.37%; nitrate, 0.27% vs. 0.26%; organic carbon matter, 0.34% vs. 0.31%; silicon, 0.36% vs. 0.37%; sodium ion, 0.21% vs. 0.18%; and sulfate, 0.35% vs. 0.38%). Additionally, correlations were weak between ozone and each particulate component across all communities. Previous research found that the ozone-mortality relation is not confounded by particulate matter measured by mass; this national study indicates that the relation is also robust to control for specific components of PM(2.5).

Nitrification performance and microbial ecology of nitrifying bacteria in a full-scale membrane bioreactor treating TFT-LCD wastewater

This study investigated nitrification performance and nitrifying community in one full-scale membrane bioreactor (MBR) treating TFT-LCD wastewater. For the A/O MBR system treating monoethanolamine (MEA) and dimethyl sulfoxide (DMSO), no nitrification was observed, due presumably to high organic loading, high colloidal COD, low DO, and low hydraulic retention time (HRT) conditions. By including additional A/O or O/A tanks, the A/O/A/O MBR and the O/A/O MBR were able to perform successful nitrification. The real-time PCR results for quantification of nitrifying populations showed a high correlation to nitrification performance, and can be a good indicator of stable nitrification. Terminal restriction fragment length polymorphism (T-RFLP) results of functional gene, amoA, suggest that Nitrosomonas oligotropha-like AOB seemed to be important to a good nitrification in the MBR system. In the MBR system, Nitrobacter- and Nitrospira-like NOB were both abundant, but the low nitrite environment is likely to promote the growth of Nitrospira-like NOB.

Modeling the effects of conservation practices on stream health

Anthropogenic activities such as agricultural practices can have large effects on the ecological components and overall health of stream ecosystems. Therefore, having a better understanding of those effects and relationships allows for better design of mitigating strategies. The objectives of this study were to identify influential stream variables that correlate with macroinvertebrate indices using biophysical and statistical models. The models developed were later used to evaluate the impact of three agricultural management practices on stream integrity. Our study began with the development of a high-resolution watershed model for the Saginaw River watershed in Michigan for generating in-stream water quality and quantity data at stream reaches with biological sampling data. These in-stream data were then used to explain macroinvertebrate measures of stream health including family index of biological integrity (FamilyIBI), Hilsenhoff biotic index (HBI), and the number of Ephemeroptera, Plecoptera , and Trichoptera taxa (EPTtaxa). Two methods (stepwise linear regression and adaptive neuro-fuzzy inference systems (ANFIS)) were evaluated for developing predictive models for macroinvertebrate measures. The ANFIS method performed the best on average and the final models displayed the highest R(2) and lowest mean squared error (MSE) for FamilyIBI (R(2)=0.50, MSE=29.80), HBI (R(2)=0.57, MSE=0.20), and EPTtaxa (R(2)=0.54, MSE=6.60). Results suggest that nutrient concentrations have the strongest influence on all three macroinvertebrate measures. Consistently, average annual organic nitrogen showed the most significant association with EPTtaxa and HBI. Meanwhile, the best model for FamilyIBI included average annual ammonium and average seasonal organic phosphorus. The ANFIS models were then used in conjunction with the Soil and Water Assessment Tool to forecast and assess the potential effects of different best management practices (no-till, residual management, and native grass) on stream integrity. Based on the model predictions, native grass resulted in the largest improvement for all macroinvertebrate measures.

Seasonal alterations of landfill leachate composition and toxic potency in semi-arid regions

The present study investigates seasonal variations of leachate composition and its toxic potency on different species, such as the brine shrimp Artemia franciscana (formerly Artemia salina), the fairy shrimp Thamnocephalus platyurus, the estuarine rotifer Brachionus plicatilis and the microalgal flagellate Dunaliella tertiolecta. In specific, leachate regularly collected from the municipal landfill site of Aigeira (Peloponissos, Greece) during the year 2011, showed significant alterations of almost all its physicochemical parameters with time. Further analysis showed that seasonal alterations of leachate composition are related with the amount of rainfall obtained throughout the year. In fact, rainfall-related parameters, such as conductivity (Cond), nitrates (NO(3)(-)), total nitrogen (TN), ammonium (NH(4)-N), total dissolved solids (TDS) and the BOD(5)/NH(4)-N ratio could merely reflect the leachate strength and toxicity, as verified by the significant correlations occurred among each of them with the toxic endpoints, 24 h LC(50) and/or 72 h IC(50), obtained in all species tested. According to the result of the present study, it could be suggested that the aforementioned leachate parameters could be used independently, or in combination as a low-cost effective tools for estimating leachate strength and toxic potency, at least in the case of semi-arid areas such as the most of the Mediterranean countries.

Biochar and nitrogen fertilizer alters soil nitrogen dynamics and greenhouse gas fluxes from two temperate soils

Biochar (BC) application to agricultural soils could potentially sequester recalcitrant C, increase N retention, increase water holding capacity, and decrease greenhouse gas (GHG) emissions. Biochar addition to soils can alter soil N cycling and in some cases decrease extractable mineral N (NO and NH) and NO emissions. These benefits are not uniformly observed across varying soil types, N fertilization, and BC properties. To determine the effects of BC addition on N retention and GHG flux, we added two sizes (>250 and <250 µm) of oak-derived BC (10% w/w) to two soils (aridic Argiustoll and aquic Haplustoll) with and without N fertilizer and measured extractable NO and NH and GHG efflux (NO, CO, and CH) in a 123-d laboratory incubation. Biochar had no effect on NO, NH, or NO in the unfertilized treatments of either soil. Biochar decreased cumulative extractable NO in N fertilized treatments by 8% but had mixed effects on NH. Greenhouse gas efflux differed substantially between the two soils, but generally with N fertilizer BC addition decreased NO 3 to 60%, increased CO 10 to 21%, and increased CH emissions 5 to 72%. Soil pH and total treatment N (soil + fertilizer + BC) predicted soil NO flux well across these two different soils. Expressed as CO equivalents, BC significantly reduced GHG emissions only in the N-fertilized silt loam by decreasing NO flux. In unfertilized soils, CO was the dominant GHG component, and the direction of the flux was mediated by positive or negative BC effects on soil CO flux. On the basis of our data, the use of BC appears to be an effective management strategy to reduce N leaching and GHG emissions, particularly in neutral to acidic soils with high N content.

Fate of NO and NH in the treatment of eutrophic water using the floating macrophyte

Use of the floating aquatic macrophyte, , to improve eutrophic water quality is practiced on a large scale in China. Limited information is available on the relative importance of the biological NO or NH removal process during the treatment of eutrophic water using . To investigate the key process responsible for the removal of NO and NH, N-NO (9.98 atom % [at.%] N) or N-NH (10.08 at.% N) was added to obtain eutrophic water with or without the cultivation of . In the unplanted water, considerable proportions of the added N-NO (27.13 ± 4.87%) or N-NH (42.08 ± 7.22%) were assimilated by the developed algae. The growth of controlled algae development in the planted water. Furthermore, the cultivation of stimulated gaseous loss of N by microbial denitrification (8.61 ± 1.70% NO-N loss from N-NO-labeled water). Apart from N loss by denitrification, considerable proportions of the added N-NO (62.01 ± 6.93%) or N-NH (76.76 ± 6.21%) were assimilated into the macrophyte N pools. The fine root detritus of contained a proportion of N (4.37 ± 1.39% in NO-labeled water, 2.03 ± 0.52% in NH-labeled water) that will be returned to the water after decomposition. In addition to N loss via NO emission, an unaccounted proportion of N could be mainly due to gaseous loss as N by denitrification (25.00% in N-NO-labeled water with Eichhornia crassipes)