Efficiency of Bark, Activated Charcoal, Foam and Sand Filters in Reducing Pollutants from Greywater

Greywater is a potential resource of water that can be improved to meet the quality needed for irrigation. This study evaluated the performance of bark, activated charcoal, polyurethane foam and sand filters in removing biochemical oxygen demand (BOD₅), surfactants, phosphorus, nitrogen and microbial indicators from greywater during start-up and steady state. In column experiments, 0.6?m high filters (diameter 20?cm) were fed for 113?days with artificial greywater at a hydraulic loading rate of 0.032?m³?m^?2?day^?1 and an organic loading rate of 0.014?kg BOD₅ m^?2?day^?1. Bark and activated charcoal efficiently reduced the concentrations of organics (BOD₅), surfactants (methylene blue active substances??MBAS), total phosphorus (Tot-P) and total thermotolerant coliform numbers, while sand and foam were less efficient. Bark, activated charcoal, foam and sand reduced influent BOD₅ by 98, 97, 37 and 75?%; MBAS by >99, >99, 73 and 96?%; Tot-P by 97, 91, 36 and 78?%; and total nitrogen by 19, 98, 13 and 5?%, respectively. BOD₅ and MBAS were efficiently reduced directly from start-up by bark and activated charcoal, while foam needed 30?days to achieve about 50?% reduction in BOD₅. Bark was the most efficient filter in reducing thermotolerant faecal coliforms (2.4 log₁₀), while foam achieved the lowest reduction (0.5 log₁₀). Overall, bark and activated charcoal filters appeared to be the most suitable filters for improving greywater quality to reach irrigation quality in terms of organic matter reduction. Performance of these filters under higher and fluctuating loadings and the long-term sustainability of the filter materials need further investigation.     

Utilization of created wetlands to upgrade small municipal wastewater treatment systems

Created wetlands offer a low cost, low maintenance, and practical alternative for upgrading secondary municipal wastewater treatment systems. The removal efficiencies, effects of seasonal temperature variations, and effects of increased loading rates on contaminant removal within such a system was studied by Auburn University researchers at a created wetland site in Hurtsboro, Alabama. The 0.16 ha system consisted of a two cell wetlands planted with cattails (Typha latifolia), bulrush (Scirpus validus), arrow duck potatoes (Sagitaria latifolis), burr reeds (Spargaminum eurycarpun), water pennywort (Hydrocotyl ranunculoides), and parrotfeather (Myriophyllum brasiliense). Testing occurred from January through September of 1988 at hydraulic loading rates of 169, 289, and 345 m³ ha^?1 d^?1. The monthly average total suspended solids influent: effluent mg L^?1 concentration ratio during the study period was 135:19 while the monthly average total BOD₅ influent: effluent mg L^?1 concentration ratio was 38:8. Once the system stabilized, the monthly average total BOD₅ effluent concentration remained essentially constant over the range of average BOD₅ loading rates employed in this study. Total Kjeldahl N removal was more effective at loading rates of 2.6 kg ha^?1 d^?1. The monthly average influent: effluent TKN mg L^?1 concentration ratio was 15:4.     

How effectively does a single or continuous iron supply affect the phosphorus budget of aerated lakes?

Purpose

In lake restoration, the redox sensitivity of iron (Fe)?Cphosphorus (P) compounds has been regarded as detrimental for a sustainable increase in sedimentary P retention since developing low redox potentials release Fe-bound P. Thus, Fe salts alone have rarely been used successfully to inactivate sediment P, and there are no studies on the long-term effects of in-lake Fe applications on P retention. Here, we analyzed for how long, and how efficiently, a single and continuous Fe application can affect the P budget of lakes.

Materials and methods

Two aerated lakes in Berlin, Germany were compared: Lake Tegel (TEG) experienced a continuous Fe supply via its tributaries, while Lake Gro?-Glienicke (GGS) was treated once with Fe in the winter of 1992/1993. By controlling the operation of aerators, their effectiveness on P exchange at the sediment?Cwater interface (non-aerated vs. aerated) was directly compared in spring and autumn between 2008 and 2010. The amount of P controllable by aeration (P _control) was experimentally determined by non-aerated vs. aerated sediment cores (at 10 and 16?°C). Core stratigraphy of Fe was observed by high-resolution ??X-ray fluorescence analysis.

Results and discussion

In TEG, the mobility of Fe was limited due to its sulfidic fixation, and thus Fe only accumulated slightly at the sediment surface (Fe/P ratio, ??3). P _control corresponded to only 4?% of the P content of the lake and 18?% of P loading. Hence, aeration only slightly influenced trophy-relevant epilimnetic P. In GGS, the single Fe application still ensures a high P binding ability of sediment since Fe relocated towards the surface (Fe/P ratio, ??7). P _control corresponded to 38?% of the P content of the lake and 74?% of annual P loading. Thus, the P release is not relevant for the P supply to the epilimnion since with the lake??s overturn P is co-precipitated by the hypolimnetically accumulated Fe.

Conclusions

When external P loading is sufficiently reduced, as in GGS, amendments to Fe precipitants can increase sediment P retention in a redox-dependent manner over the long term. Thus, the redox-dependent mobility of Fe should no longer be regarded as a disadvantage of Fe-containing precipitants. To compensate for co-precipitation and complexation of Fe with sediment organic matter, a high Fe dosage (??200?g?m^?2) is needed.     

Oxygen Transfer and Industrial Wastewater Treatment Efficiency of a Vertically Moving Biofilm System

A vertically moving biofilm system (VMBS) was developed to treat wastewater. In this system, the biofilm grows on a biofilm module consisting of plastic media that is vertically and repeatedly moved up into the air and down into the water. The objectives of this study were to investigate the oxygen transfer efficiency and industrial wastewater treatment performance of the VMBS. The oxygen transfer coefficient (K _L a) depended on the movement frequency (n) of the biofilm module and was proportional to n ^1.67. K _L a values measured were within the range of 0.0001 to 0.0027 s^-1. The VMBS exhibited good carbonaceous removal when treating industrial wastewater produced in a factory manufacturing synthetic fibres. Removal efficiency of filtered chemical oxygen demand (COD) and biological oxygen demand (BOD₅) was up to 93.2 and 97.9%, respectively. The volumetric removal rates of filtered COD and BOD₅ reached 1320 g COD m^-3 day^-1 and 700 g BOD₅ m^-3 day^-1. The areal organic removal rates, based on the surface area of the biofilm substrata, were 16 g BOD₅ m^-2 day^-1 and 39 g COD m^-2 day^-1. No clogging occurred during the experiment. The mean areal biofilm mass increased with increasing the mean areal BOD₅ removal rate. The new biofilm process has such advantages as high carbonaceous oxidation, energy saving, simpleconstruction and easy operation for industrial wastewater treatment.     

Treatment of Hydroponics Wastewater Using Constructed Wetlands in Winter Conditions

Hydroponics culture generates large amounts of wastewater that are highly concentrated in nitrate and phosphorus but contains almost no organic carbon. Constructed wetlands (CWs) have been proposed to treat this type of effluent, but little is known about the performance of these systems in treating hydroponic wastewater. In addition, obtaining satisfactory winter performances from CWs operated in cold climates remains a challenge, as biological pathways are often slowed down or inhibited. The main objective of this study was to assess the effect of plant species (Typha sp., Phragmites australis, and Phalaris arundinacea) and the addition of organic carbon on nutrient removal in winter. The experimental setup consisted of 16 subsurface flow CW mesocosms (1 m², HRT of 3 days) fed with 30 L?d¹ of synthetic hydroponics wastewater, with half of the mesocosms fed with an additional source of organic carbon (sucrose). Carbon addition had a significant impact on nitrate and phosphate removal, with removal means of 4.9 g m^-2?d^-1 of NO₃-N and 0.5 g m^-2 d^-1 of PO₄-P. Planted mesocosms were generally more efficient than unplanted controls. Furthermore, we found significant differences among plant treatments for NO₃-N (highest removal with P. arundinacea) and COD (highest removal with P. australis/Typha sp.). Overall, planted wetlands with added organic carbon represent the best combination to treat hydroponics wastewater during the winter.     

Tillage system affects fertilizer-induced nitrous oxide emissions

Since the development of effective N₂O mitigation options is a key challenge for future agricultural practice, we studied the interactive effect of tillage systems on fertilizer-derived N₂O emissions and the abundance of microbial communities involved in N₂O production and reduction. Soil samples from 0–10 cm and 10–20 cm depth of reduced tillage and ploughed plots were incubated with dairy slurry (SL) and manure compost (MC) in comparison with calcium ammonium nitrate (CAN) and an unfertilized control (ZERO) for 42 days. N₂O and CO₂ fluxes, ammonium, nitrate, dissolved organic C, and functional gene abundances (16S rRNA gene, nirK, nirS, nosZ, bacterial and archaeal amoA) were regularly monitored. Averaged across all soil samples, N₂O emissions decreased in the order CAN and SL (CAN?=?748.8?±?206.3, SL?=?489.4?±?107.2 μg kg^?1) followed by MC (284.2?±?67.3 μg kg^?1) and ZERO (29.1?±?5.9 μg kg^?1). Highest cumulative N₂O emissions were found in 10–20 cm of the reduced tilled soil in CAN and SL. N₂O fluxes were assigned to ammonium as source in CAN and SL and correlated positively to bacterial amoA abundances. Additionally, nosZ abundances correlated negatively to N₂O fluxes in the organic fertilizer treatments. Soils showed a gradient in soil organic C, 16S rRNA, nirK, and nosZ with greater amounts in the 0–10 than 10–20 cm layer. Abundances of bacterial and archaeal amoA were higher in reduced tilled soil compared to ploughed soils. The study highlights that tillage system induced biophysicochemical stratification impacts net N₂O emissions within the soil profile according to N and C species added during fertilization.     

Fluid Catalytic Cracking Unit Emissions and Their Impact

A constructed wetland composed of a pond- and a marsh-type wetland was employed to remove nitrogen (N) and phosphorus (P) from effluent of a secondary wastewater treatment plant in Korea. Nutrient concentrations in inflow water and outflow water were monitored around 50 times over a 1-year period. To simulate N and P dynamics in a pond- and a marsh-type wetland, mesocosm experiments were conducted. In the field monitoring, ammonium (NH ₄ ⁺ ) decreased from 4.6 to 1.7 mg L^?1, nitrate (NO ₃ ^? ) decreased from 6.8 to 5.3 mg L^?1, total N (TN) decreased from 14.6 to 10.1 mg L^?1, and total P (TP) decreased from 1.6 to 1.1 mg L^?1. Average removal efficiencies (loading basis) for NO ₃ ^? , NH ₄ ⁺ , TN, and TP were over 70%. Of the environmental variables we considered, water temperature exhibited significant positive correlations with removal rates for the nutrients except for NH ₄ ⁺ . Results from mesocosm experiments indicated that NH ₄ ⁺ was removed similarly in both pond- and marsh-type mesocosms within 1 day, but that NO ₃ ^? was removed more efficiently in marsh-type mesocosms, which required a longer retention time (2?C4 days). Phosphorus was significantly removed similarly in both pond- and marsh-type mesocosms within 1 day. Based on the results, we infer that wetland system composed of a pond- and a marsh-type wetland consecutively can enhance nutrient removal efficiency compared with mono-type wetland. The reason is that removal of NH ₄ ⁺ and P can be maximized in the pond while NO ₃ ^? requiring longer retention time can be removed through both pond and marsh. Overall results of this study suggest that a constructed wetland composed of a pond- and a marsh-type wetland is highly effective for the removal of N and P from effluents of a secondary wastewater treatment plant.     

Influence of Three Aquatic Macrophytes on Mitigation of Nitrogen Species from Agricultural Runoff

Agricultural runoff containing nitrogen fertilizer is a major contributor to eutrophication in aquatic systems. One method of decreasing amounts of nitrogen entering rivers or lakes is the transport of runoff through vegetated drainage ditches. Vegetated drainage ditches can enhance the mitigation of nutrients from runoff; however, the efficiency of nitrogen removal can vary between plant species. The efficiency of three aquatic macrophytes, cutgrass (Leersia oryzoides), cattail (Typha latifolia), and bur-reed (Sparganium americanum), to mitigate dissolved and total nitrogen from water was investigated. Replicate mesocosms of each plant species were exposed to flowing water enriched with ammonium and nitrate for 6?h, allowed to remain stagnant for 42?h, and then flushed with non-enriched water for an additional 6?h to simulate a second storm event. After termination of the final simulated runoff, all vegetated treatments lowered total nitrogen loads exiting mesocosms by greater than 50%, significantly more than unvegetated controls, which only decreased concentrations by 26.9% (p????0.0023). L. oryzoides and T. latifolia were more efficient at lowering dissolved nitrogen, decreasing ammonium by 42?±?9% and 59?±?4% and nitrate by 67?±?6% and 64?±?7%, respectively. All treatments decreased ammonium and nitrate concentrations within mesocosms by more than 86% after 1?week. However, T. latifolia and L. oryzoides absorbed nitrogen more rapidly, lowering concentrations by greater than 98% within 48?h. By determining the nitrogen mitigation efficiency of different vegetative species, plant communities in agricultural drainage ditches can be managed to significantly increase their remediation potential.     

Simulation of seasonal changes in microbial activity of maritime antarctic peat

Seasonal variations in temperature and moisture in moss peat were monitored in the field at Signy Island, Antarctica. When simulated in intact peat cores in vitro after frozen storage, these variations caused changes on O₂-uptake which closely reproduced the results for fresh samples. Respiration rate was used as a measure of aerobic decomposer activity. Supplements of sugars indicated the predominance of microbial respiration and its dependence on the availability of dissolved organic C (DOC). Low temperatures of 0° to 1°C were not rate-limiting for respiration in vivo or in vitro, and O₂-uptake was detected at ?1°C. Repeated peaks of O₂-uptake under wet conditions resulting from simulated spring freeze-thaw cycles, and a solitary peak during an autumn simulation, suggested release of DOC substrates from frost-damaged cells. Desiccation, microfaunal predation and microaerophily were thought to contribute to respiratory declines. O₂-uptake and CO₂-evolution were equivalent in peat beneath Polytrichum sampled in autumn. Peat respiration was not generally proportional to microbial biomass, but saccharolytic yeasts were dominant during the respiratory maximum in spring and correlated with O₂-uptake in a mixed culture of indigenous microflora. Yeasts grew exponentially in freezethaw cycle simulations but percolated into the peat profile in the field. The basal O₂-uptake, which may be attributable to the decomposition of redalcitrant molecules such as cellulose, was lower in simulations of spring than autumn. Although bacterial biomass increased and diversified during summer, the ratio of fungal-to-bacterial contributions to O₂-uptake in an incubated homogenate of peat sampled in autumn was 4:1.     

Anaerobic ammonium oxidation and denitrification in a paddy soil as affected by temperature,pH, organic carbon,and substrates

Anaerobic ammonium oxidation (anammox process) widely occurs in paddy soil and may substantially contribute to permanent N removal; however, little is known about the factors controlling this process. Here, effects of temperature, pH, organic C, and substrates on potential rate of anammox and the relative contribution of anammox to total N₂ production in a paddy soil were investigated via slurry incubation combined with ¹⁵N tracer technique. Anammox occurred over a temperature range from 5 to 35 °C with an optimum rate at 25 °C (1.7 nmol N g^?1 h^?1) and a pH range from 4.8 to 10.1 with an optimum rate at pH 7.3 (1.7 nmol N g^?1 h^?1). The presence of glucose and acetate (5–100 mg C L^?1) significantly inhibited anammox activities and the ratio of anammox to total N₂ production. The response of potential rates of anammox to ammonium concentrations fitted well with Michaelis-Menten relationship showing a maximum rate (V_max) of 4.4 nmol N g^?1 h^?1 and an affinity constant (K_m) of 6.3 mg NH₄⁺-N L^?1. Whereas, nitrate addition (5–15 mg ¹⁵NO₃^?-N L^?1) significantly inhibited anammox activities and the ratio of anammox to total N₂ production. Our results provide useful information on factors controlling anammox process and its contribution to N loss in the paddy soil.     

Relationships between the denitrification capacities of soils and total,water-soluble and readily decomposable soil organic matter

The relationships between the denitrification capacities of 17 surface soils and the amounts of total organic carbon, mineralizable carbon, and water-soluble organic carbon in these soils were investigated. The soils used differed markedly in pH, texture, and organic-matter content. Denitrification capacity was assessed by determining the N evolved as N₂ and N₂O on anaerobic incubation of nitrate-treated soil at 20°C for 7 days, and mineralizable carbon was assessed by determining the C evolved as CO₂ on aerobic incubation of soil at 20°C for 7 days. The denitrification capacities of the soils studied were significantly correlated (r = 0·7771) with total organic carbon and very highly correlated (r = 0·9971) with water-soluble organic carbon or mineralizable carbon. The amount of nitrate N lost on anaerobic incubation of nitrate-treated soils for 7 days was very closely related (r = 0·99971) to the amount of N evolved as N₂ and N₂O.The work reported indicates that denitrification in soils under anaerobic conditions is controlled largely by the supply of readily decomposable organic matter and that analysis of soils for mineralizable carbon or water-soluble organic carbon provides a good index of their capacity for denitrification of nitrate.     

Effect of Flow Rate, Concentration and Transient—State Operations on the Performance of a Biofilter Treating Xylene Vapors

Biological treatment systems such as biofilters offer a potential alternative to the existing physicochemical techniques for the removal of volatile organic compounds from gaseous emissions. In this experimental work, continuous phase biofiltration of xylene vapors were performed in a laboratory scale compost biofilter that was inoculated with a xylene-acclimatized consortium. The performance was assessed by continuously monitoring the removal efficiency (RE) and elimination capacity (EC) of the biofilter at loading rates varying between 2–220 g?m^?3?h^?1. The steady-state removal efficiencies were maintained between 60% and 90% up to a loading rate of 80 g?m^?3?h^?1. The removal efficiency decreased significantly at loading rates higher than 100 g?m^?3?h^?1. The pressure drop values were consistently less and insignificant in affecting the performance of the system. The present study also focuses in evaluating the stability of biofilter during shut down, restart, and shock-loading operations. An immediate restoration of biological activity after few days of starvation indicated their capability to handle discontinuous treatment situations which is more common to industrial biofilters. The sensitiveness of the biofilm to withstand shock loads was tested by abruptly increasing/decreasing the loading rates between 9–55 g?m^?3?h^?1, where, removal efficiencies between 60–90% were achieved. These results prove the resilience of the biomass and the stability of the compost biofilter. Anew, results from kinetic analysis reveal that, steady-state xylene removal in the biofilter can be adequately represented by Michaelis–Menten type kinetics, and the kinetic constants namely, EC_max (120.4 g?m^?3?h^?1) and K _s (2.21 g?m^?3) were obtained.     

Sources of soil CO2 in calcareous grassland with woody plant encroachment

Purpose

The objective of this study is to estimate the contribution of various sources that influence soil CO₂ concentrations in calcareous grassland.

Materials and methods

The research was performed at the Podgorski Kras plain (45?°33?? N, 13?°55?? E, 400?C430?m.a.s.l.) in the sub-Mediterranean region of Slovenia (SW Slovenia), where many meadows and pastures have been abandoned. In parallel to the measurement of soil respiration R _s, soil gas was sampled for stable isotope analysis. Samples were taken biweekly at two sites, Grassland and Invaded, from July 2008 until November 2010. In addition, daily variations in concentration and stable isotope composition of soil CO₂ were determined in May 2009. The partitioning of soil CO₂ concentrations was performed using stable isotope mass balance calculation.

Results and discussion

The concentration and isotope composition of soil CO₂ exhibited similar seasonal variations at both sites. Lower ??¹³C_CO2 values, ranging from ?28.2 to ?15.2 ??, which occurred during warm periods and higher values, up to ?12.1 ??, were typical of cold winter periods, from December to March. Organic sources were estimated to constitute between 78 and 99?% of total soil CO₂ during warmer periods from May until October. This contribution was lower during the winter, ranging from 46 to 77?%. In winter, the atmospheric component to soil CO₂ dominated, constituting up to 60?%. On average, the inorganic contribution was estimated to comprise 12?% of the soil CO₂ at all sampling locations. The contribution of this source to soil CO₂ concentration, at up to 41?%, was highest in Grassland during the growing season. The inorganic source of soil CO₂ was also an important component during daily variations. The highest contribution was observed during the day, in parallel to the highest respiration rates.

Conclusions

The inorganic pool is shown to be an important part of soil CO₂ in calcareous areas and should be considered as equal to organic CO₂ as a source in soil CO₂ partitioning.     

Protozoa of a rotating biological contactor treatment plant in Mexico

A protozoological analysis of the biofilm developed on the discs of an RBC unit was performed using light microscopy; the species found belonged to 2 phyla: Sarcomastigophora with 23, and Ciliophora with 30 species. All isolates were free-living with the exception of Tritrichomonas fecalis. Most abundant species were: Euglena gracilis, Paramecium multimicronucleatum, Tetrahymena pyriformis, Polytoma uvella, Didinium nasutum, Bodo caudatus, Vorticella microstoma, Cyclidium glaucoma, Sathrophilus agitatus, Antophysa vegetans, and Urothrica farcta. Ciliates predominated over the flagellates in number and diversity. According to their locomotion most abundant species were free-swimming, followed by the attached, and crawling forms. In relation to their nutrition most frequent species were bacterivorous, saprozoic, and carnivorous. Values of the saprobic index calculated for each sampling station indicated that α-mesosaprobic conditions prevailed along the contactor with a zone of overlap with polysaprobic conditions at station IV. The RBC received an influent flow that varied from 1.5 to 13.5 L s^?1 and a soluble BOD₅ which range from 46 to 170 mg L^?1. The contactor studied showed an overall BOD₅ removal of 86% and a COD removal of 74%. DO levels influenced the values obtained for the saprobic index and the kind of protozoan populations and communities present. The biological findings (indicator species of the saprobic system), clearly reflected and agreed with the physicochemical results obtained simultaneously; the results showed that the system performed efficiently.     

Optimization of Petroleum Refinery Wastewater Treatment by Vertical Flow Constructed Wetlands Under Tropical Conditions: Plant Species Selection and Polishing by a Horizontal Flow Constructed Wetland

Typha latifolia-planted vertical subsurface flow constructed wetlands (VSSF CWs) can be used to treat petroleum refinery wastewater. This study evaluated if the removal efficiency of VSSF CWs can be improved by changing the plant species or coupling horizontal subsurface flow constructed wetlands (HSSF CWs) to the VSSF CW systems. The VSSF CWs had a removal efficiency of 76% for biological oxygen demand (BOD₅), 73% for chemical oxygen demand (COD), 70% for ammonium-N (NH₄⁺-N), 68% for nitrate-N (NO₃^?-N), 49% for phosphate (PO₄^3?-P), 68% for total suspended solids (TSS), and 89% for turbidity. The HSSF CWs planted with T. latifolia further reduced the contaminant load of the VSSF CW-treated effluent, giving an additional removal efficiency of 74, 65, 43, 65, 58, 50, and 75% for, respectively, BOD₅, COD, NH₄⁺-N, NO₃^?-N, PO₄^3?-P, TSS, and turbidity. The combined hybrid CW showed, therefore, an improved effluent quality with overall removal efficiencies of, respectively, 94% for BOD₅, 88% for COD, 84% for NH₄⁺-N, 89% for NO₃^?-N, 78% for PO₄^3?-P, 85% for TSS, and 97% for turbidity. T. latifolia strived well in the VSSF and HSSF CWs, which may have contributed to the high NH₄ ⁺-N, NO₃^?-N, and PO₄^3?-P removal efficiencies. T. latifolia-planted VSSF CWs showed a higher contaminant removal efficiency compared to the unplanted VSSF CW. T. latifolia is thus a suitable plant species for treatment of secondary refinery wastewater. Also a T. latifolia-planted hybrid CW is a viable alternative for the treatment of secondary refinery wastewater under the prevailing climatic conditions in Nigeria.     

Effect of calcium nitrate foliar spray on the calcium content,growth and freezing tolerance of Forsythia × Intermedia cultivars

Abstract

In many northern regions frost hardiness of new cultivars of woody plants and perennials is fundamental for nursery production and the greenery industry. This study was conducted to determine the effect of calcium fertilization on frost resistance of Forsythia sp. cultivars. Plants were sprayed five times at four week intervals with calcium nitrate 1?g of (Ca(NO₃)₂). 100?ml H₂O^?1 per shrub. Shoots were frozen at three temperatures: –20, –25, and –30?°C. In all cases the chlorophyll content index in the leaves, and the calcium (Ca²⁺) content in leaves and stems of forsythia cultivars were significantly higher when calcium nitrate supplementation was provided. The Ca²⁺content in the roots was not affected. The freezing temperature had a great effect on the stem frost damage of tested forsythia cultivars. The greatest damage was observed after freezing at –30?°C. However, tissue damage of plants that were sprayed with calcium nitrate was considerably less evident, and cross sections of stems looked significantly better. At the lowest temperatures (–25 and –30?°C) a positive effect of calcium fertilization on lower electrolyte leakage was observed in all tested cultivars. Fertilization with finely ground calcium nitrate increased stem freezing tolerance of forsythia tested cultivars, especially new ones which have stems that are more susceptible to frost damage.     

Heterogeneous Atmospheric Nitrogen Deposition Effects Upon the Nitrate Concentration of Stream Waters in a Forested Mountain Area

Nitrogen compounds generated by anthropogenic combustion deposits in forest watersheds and induce nitrogen saturation of the area. Because excess nitrogen is derived from atmospheric deposition, this action is expected to uniformly affect a wide area of forest soils. Geographically, heterogeneous nitrate concentration of stream water within a small area has been attributed to the tree type, geological setting and tree cut. In this article, we hypothesized that the effect of the atmospheric nitrogen deposition in the forest watershed may vary within a small area, and that such variation is induced by the degree of air mass containing a high concentration of nitrogen deposition of combustion origin. We measured major ion concentrations, including nitrate, nitrite oxygen and nitrogen stable isotope of nitrate sampled at 24 water streams in the Chichibu region, which is 50?C100 km from the Tokyo metropolitan area. The nitrate concentration showed a wide range (25.6?C237 ??mol L^?1) within 300 km², which was explained sufficiently by the air mass advection path and its contact with the mountain??s surface. The nitrate concentration showed a significant positive correlation with chloride (r?=?0.73; p?<?0.001). As chloride originates outside of the Chichibu region, the positive correlation between two ions showed that the nitrate concentration of the stream water was affected by the nitrogen compound from the Tokyo Metropolitan area as a form of atmospheric deposition. Between the nitrate concentration and the stable isotope ratio of oxygen of nitrate, there was a positive correlation until nitrate concentration of 100 ??mol L^?1. When the nitrate is over 100 ??mol L^?1, ??¹⁸O shows a stable value of ca. 5.7??. This indicates that the nitrification proceeds when the nitrate concentration was low to middle, but the reaction slowed when the nitrate concentration became high. Oxygen stable isotope of nitrate along with a set of nitrate concentrations can be used as a good indicator of nitrogen saturation.     

Hydrogenated Vegetable Oil Industry Wastewater Treatment using UASB Reactor System with Recourse to Energy Recovery

The investigation was carried out on laboratory scale to assess the feasibility of upflow anaerobic sludge blanket reactor system as a pretreatment for hydrogenated vegetable oil industry wastewater with recourse to energy recovery. The reactor system operated at 35°C, resulted in COD removal efficiency in the range 98.9–80.1% at organic loading varying in the range 1.33–10 kgCOD/m³ day. The specific methane yield varied from 0.295–0.345 m³CH₄/kgCOD_r. Hydraulic retention time, substrate concentrations, pH, and temperature were also varied to study the influence of operating parameters on reactor performance. The methane content decreased with increase in substrate loading rate, and varied from 53–66.7% under varying operating conditions. Impulse loading studies in terms of hydraulic, organic, and pH though resulted in destabilization of the reactor; however, the reactor rapidly achieved stable performance after steady operation.     

Impacts of Corbicula fluminea on Oxygen Uptake and Nutrient Fluxes across the Sediment–Water Interface

Corbicula fluminea (Asian clam) can assemble in high densities and dominate benthic communities. To evaluate the influence of this clam on sediment oxygen uptake and nutrient fluxes across the sediment–water interface, a microcosm study was conducted using a continuous-flow cultivation system with sediment, lake water, and C. fluminea specimens from Taihu Lake, China. C. fluminea destroyed the initial sediment surface, enhanced O₂ penetration into the sediment partially, and increased the sediment water content, the volume of oxic sediment, and total microbial activity. Sediment O₂ uptake was significantly stimulated by C. fluminea. Linear regression results for O₂ uptake versus clam biomass ranged from 21.9 to 9.47 μmol h^?1 g^?1?DW (dry weight). The release of soluble reactive phosphorus, ammonium, and nitrate from the sediment was also increased by the clams. The increase in the amount of soluble reactive phosphorus and ammonium released into the overlying water was 0.042?~?0.091 and 2.77?~?3.03 μmol h^?1 g^?1?DW, respectively, and this increase was attributed to increased diffusion, enhanced advection between the pore water and the overlying water, and the excretions from C. fluminea. Enhanced nitrification was suggested as the reason for the increase in nitrate release (2.95?~?4.13 μmol h^?1 g^?1?DW) to the overlying water.     

Efficiency of Mesocosm-Scale Constructed Wetland Systems for Treatment of Sanitary Wastewater Under Tropical Conditions

Subsurface-flow constructed wetlands technology (SSFW) has been used successfully for treating sanitary wastewater throughout North America and Europe. However, treatment wetland technologies have not been used extensively in the tropics. To advance tropical studies, a pilot-scale SSFW was constructed on the campus of the University of the Atlantic in Barranquilla, Colombia. The systems performance was monitored from January to July of 2009. The treatment system consisted of a 760-L septic tank followed by three mesocsom-scale subsurface-flow constructed wetlands in parallel arrangement. Clarified wastewater was batch loaded to each unit at a rate of 53 L/m²/day to affect a hydraulic retention time of approximately 3 days. One of the treatment units served as a non-planted control (gravel only), while the other two treatment units were planted with either Eriochloa aristata or Eleocharis mutata. The objective of this study was to evaluate the comparative efficacy of the treatment units (planted vs. unplanted), with respect to their abilities to augment treatment of septic tank effluent (sanitary wastewater). Monitored parameters included plant biomass, oxidation?Creduction potential, chemical oxygen demand (COD), temperature, dissolved oxygen, pH, ammonia?Cnitrogen (NH ₄ ⁺ ?CN) nitrate?C and nitrite?Cnitrogen (NO₃?CN, NO₂?CN), phosphates (PO ₄ ^? ), and coliform bacteria. Total biomass (dry matter) was 2.84 and 0.87 Kg/m² for E. aristata and E. mutata, respectively. Redox potential in the plant rizospheres averaged ?172 mV (±164.1) in E. aristata, 29 mV (±251.1) in E. mutata, and 32 mV (±210.5) in the unplanted control. COD removal was superior in planted vs. non-planted systems (>75% vs. 47%). Ammonia and total phosphorus removal averaged 69% and 85%, respectively, in planted systems versus 31% and 59% in the unplanted system. Removal of total and fecal coliforms averaged 96%. Results of this pilot study revealed that SSFW technology in the tropics can provide significant removal of organic matter, nutrients, and bacteria from clarified sanitary wastewater.