Identification of nitrifiers and nitrification performance in drinking water biological activated carbon (BAC) filtration

In this study laboratory scale biological activated carbon (BAC) columns were operated with water taken from a surface water reservoir in Istanbul. The aim was to evaluate the efficiency of nitrification in columns packed with two different granular activated carbon grades (open superstructure/chemically activated and closed superstructure/steam activated carbon) and to examine the probable beneficial effect of pre-ozonation. The occurrence and diversity of ammonia-oxidizing bacteria were investigated using 16S rDNA and amoA gene based molecular techniques. Nearly complete removal of NH₄⁺-N was achieved by nitrification in both carbon types. The nitrification efficiency did not change in columns fed with ozonated water. However, the type of feed (either raw or ozonated) played a more important role than the type of GAC with respect to the dominance of nitrifier species in BAC columns. In biofilters ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were most closely related to Nitrosomonas spp. and Nitrospira spp. as determined by cloning and slot-blot analysis, respectively. The fraction of the AOB population in the biomass was high as detected by real-time PCR. The amoA/16S rDNA ratio varied from 28.7% to 2.1% along the depth of filters. In spite of similar removal efficiencies, BAC columns fed with ozonated water harbored different types of AOB than columns that were receiving raw water.     

Effects of mixing and silica enrichment on phytoplankton seasonal succession

During the summer of 1983, cryptophytes, diatoms, cyanophytes, and the dinoflagellate, Ceratium hirundinella were most prominant among the phytoplankton of Eau Galle Reservoir. In the open water, cryptophytes and diatoms peaked in the spring, cyanophytes were most successful in the early summer, and Ceratium was dominant from mid-July until early August. In general, the sequence of events corresponded quite closely to the model of seasonal succession developed by the Plankton Ecology Group of the International Society of Limnology. To a large extent, the same pattern held in four experimental water columns. Departures from the model involved the roles of specific nutrients in diatom and cyanophyte periodicity. Diatoms began to yield to cyanophytes in late spring despite intermittent mixing and silica enrichment. Although capable of buoyancy regulation and thus well adapted to stable water columns, cyanophytes had greater increases in biomass in mixed columns, and in those columns, were most successful during a period of intermittent mixing. Cyanophyte success varied inversely with TN : TP ratios during the period of intermittent mixing, but not subsequently. By mid-July, Ceratium dominated the phytoplankton of every column except that of a mixed column in which conditions favored cyanophytes and large diatom species.     

Sedimentation of Bacillus sphaericus in tap water and sewage water

Formulations of Bacillus sphaericus products were applied in 1-m columns of clean water and sewage water in tubes. Samples taken through valves attached to the walls of the tubes showed that spores settled as a function of application method, droplet size, particle size, and water characteristics. In a mixture of deionized and tap water, the slowest sedimentation rate was obtained with a primary powder sonicated in water with 0.1% detergent. This product and a commercial fluid product settled faster in sewage water than in clean water and after 4 weeks, most spores were found in the sediment. In clean water, most spores remained suspended during the 4 weeks but the density was highest at the bottom. Calculation of total spore numbers in the columns after 4 weeks indicated that about 90% of spores disappeared in clean water, and 95-97% disappeared in sewage water. Bioassays showed that toxicity declined in parallel with the sedimentation, but at a higher rate, indicating a loss of toxicity from the residual spores.     

Removing Selenate from Groundwater with a Vegetable Oil-Based Biobarrier

Vegetable oil–based permeable reactive biobarriers (PRBs) were evaluated as a method for remediating groundwater containing unacceptable amounts of selenate. PRBs formed by packing laboratory columns with sand coated with soybean oil were used. In an initial 24-week study a simulated groundwater containing 10 mg L⁻¹ selenate-Se was supplied to three soil columns and the selenate and selenite content of the effluent waters monitored. Two of the soil columns were effective at removing selenate and, during the final 21 weeks of the study, effluents from these columns contained almost no selenate or selenite. Almost all (95%) of the selenate removed was recovered as immobilized selenium sequestered in the solid matrix of the column. For unknown reasons, the third column failed to reduce selenate. A second study looked at the ability of PRBs to remove selenate when nitrate was present. As was done in the first study, three columns were evaluated but this time the water supplied to the columns contained 20 mg L⁻¹ nitrate-N and 10 mg L⁻¹ selenate-Se. Nitrate quickly disappeared from the effluents of these columns and during the final 23 weeks of the study, the nitrate content of the effluent water averaged less than 0.03 μg ml⁻¹ nitrate-N. Selenate was also removed by these columns but at a slower rate than observed with nitrate. In the final 6 weeks of the study, about 95% of the selenate applied to the columns was removed. In situ PRBs containing soybean oil might be used to remediate groundwater contaminated with both selenate and nitrate.     

Phytoplankton and bacterioplankton production in a reed-covered water body

Between 1996 and 1998 phytoplanktonic primary production and bacterioplankton production were measured monthly at five sampling stations in the lower Kis-Balaton reservoir. The open water area of the reservoir was rich in phytoplankton and had hypertrophic characteristics, but inside the reed stand (80% of the surface area) phytoplankton biomass and production were substantially (30–50 times) lower. The algal removal efficiency of the lower Kis-Balaton reservoir was 96%. The reservoir had a considerably smaller effect on bacterioplankton removal than on the phytoplankton. The decrease of biomass and production of bacterioplankton in the through-flowing water was approximately 60%. Inside the reed stand the biomass and the production of planktonic bacteria exceeded that of the phytoplankton by several times, suggesting that the release of biodegradable dissolved organic (humic) substances from macrophytes stimulated the metabolism of bacterioplankton. The significant reduction of phytoplankton inside the dense reed stand was primarily the result of the shading effect of the reeds. In the open water area a shading experiment demonstrated that a 1-week residence period for planktonic algae in the reed-covered area was sufficient for their complete elimination. The decomposition of planktonic algae, reed material and the lack of primary production inside the reed stand created oxygen-deficient and phosphorus-rich conditions during the vegetative period. These results suggest that reed-covered water bodies can effectively retain suspended solids and planktonic algae, but because of decomposition processes they cannot retain biologically-available phosphorus.     

Phyto (in)stabilization of elements

The effects of plants (corn, soybean, and sunflower) and fertilizer on mobility of more than 60 elements were assessed in a greenhouse experiment. Unplanted columns with the same soil served as controls. Half the columns received fertilizer and all columns were watered at the same rate. At the end of the experiment, the columns were watered to mimic a rainstorm event such that water drained from the bases of the columns, which was collected and analyzed for element content. Soil from between the roots of the plants was also collected and the water-extractable fraction determined. It was expected that (1) more mobile elements, as measured by water extraction, would be leached from the soils at a higher rate compared to less mobile elements, (2) plants would immobilize most elements, but that some would be immobilized, and (3) that this would depend on plant species. The results led to the following conclusions: plants cause metal mobility to vary over a wide range for a specific soil and do mobilize some elements (e.g., Th) while immobilizing others (e.g., U). The effects depended on plant species for some elements. Water-extractable fractions of elements do not predict mobility.     

Effect of type of granular activated carbon on DOC biodegradation in biological activated carbon filters

The purpose of this paper is to clarify the effect of the two different GAC types (steam activated or chemically activated) on DOC biodegradation in biological activated carbon (BAC) columns. For this purpose, raw water taken from a surface reservoir was fed to continuous-flow lab-scale biofiltration columns which were run for more than 18,000 bed volumes. The effect of pre-ozonation on DOC removal was also evaluated. Experimental results showed that biological activity inside the BAC columns extended the service life and the choice of filter material was crucial in BAC systems. The DOC biodegradation was higher in thermally activated carbon columns compared to the chemically activated one. The ability of GAC to better adsorb and retain organic compounds increased the chance of biodegradation. Contrary to expectations, pre-ozonation did not significantly enhance DOC biodegradation. Despite the high increase in biodegradable dissolved organic carbon (BDOC) upon ozonation, overall DOC biodegradation efficiencies did not differ from raw water. Overall, the DOC biodegradation in columns was higher than in most of the studies. This observation was primarily attributed to the low specific ultraviolet absorption (SUVA) values in raw water indicating a high biodegradability.     

Detection of Horizontal Gene Transfer by Natural Transformation in Native and Introduced Species of Bacteria in Marine and Synthetic Sediments

Both naturally occurring marine sediments and artificial sediments were used as supports for natural transformation of marine bacteria. While transformation of Pseudomonas stutzeri ZoBell suspended in artificial seawater was not detected when recipient cells and rifampin resistance DNA were loaded onto sterile sediment columns, transformation could be detected at frequencies 4 to 20 times that of spontaneous resistance when recipient cells and rifampin resistance DNA were loaded onto sterile sediment columns. Treatment of these columns with DNase I reduced transformation frequencies to levels comparable to those of spontaneous-resistance frequencies. Sediments with higher organic contents supported higher frequencies of transformation than did those with lower amounts of organic matter. Transformation was also detected when recipient cells and DNA were loaded on columns prepared from nonsterile sediments, although the frequencies of transformation were lower than when sterile sediments were used. Finally, nonsterilized sediments that were not supplemented with laboratory strains did not support detectable levels of transformation in sediment columns, but when these same sediments were transferred to filters and placed on complex media, transformation was detected at a frequency three times that for spontaneous resistance. This transformation frequency was partially reduced to levels near that for spontaneous resistance by the addition of DNase I to sediment filters. These results indicate that marine sediments facilitate the uptake and expression of exogenous DNA by transformable marine bacteria and that sediments are a more likely niche for natural transformation than the water column in the marine environment.     

Comparison of performance of C18 monolithic rod columns and conventional C18 particle-packed columns in liquid chromatographic determination of Estrogel and Ketoprofen gel

The performance of monolithic HPLC columns Chromolith (made by Merck, Germany) and conventional C18 columns Discovery (Supelco, Sigma-Aldrich, Prague, Czech Republic) was tested and the comparison for two topical preparations Ketoprofen gel and Estrogel gel was made. The composition of mobile phases - for Ketoprofen analysis a mixture of acetonitrile, water and phosphate buffer adjusted to pH 3.5 (40:58:2) and for Estrogel analysis a mixture of acetonitrile, methanol, water (23:24:53) - was usually not optimal for analyses at all types of columns. Thus an adjustment of components ratio was necessary for sufficient resolution of the compounds analysed. Various flow rates (1.0-5.0 ml/min) and mobile phases (usually increasing ratio of water content) were applied. Determination of active substances, preservatives and impurities and comparison of retention times and system suitability test parameters was accomplished. For Estrogel gel, following chromatographic conditions were found: using Chromolith Flash RP-18e monolith column, mobile phase was acetonitrile, methanol, water (13:24:63, v/v/v) and flow-rate 3.0 ml/min. Using monolith column ChromolithSpeedROD RP-18e, the mobile phase was acetonitrile, methanol, water (18:24:58, v/v/v) and flow-rate 4.0 ml/min. For the monolith column Chromolith Performance RP-18e, the mobile phase was acetonitrile, methanol, water (23:24:53, v/v/v), flow-rate 3.0ml/min. Analysis of Ketoprofen gel gave the best results using following analytical conditions: for monolith column Chromolith Flash RP-18e, mobile phase as a mixture of acetonitrile, water, phosphate buffer pH 3.5 (30:68:2, v/v/v) was used, at flow-rate 2.0 ml/min. For ChromolithSpeedROD RP-18e monolith column, acetonitrile, water, phosphate buffer pH 3.5 (35:63:2, v/v/v) was used as a mobile phase at flow-rate 3.0 ml/min. Chromolith Performance RP-18e gave the best results using mobile phase acetonitrile, water, phosphate buffer pH 3.5 (30:68:2, v/v/v) at the flow-rate 5.0 ml/min. It was proved that monolith columns, due to their porosity and low back-pressure, can save analysis time by about a factor of three with sufficient separation efficiency. Thus, for example 11 min long analysis can be performed in 4 min with comparable results.     

Virus movement in soil during saturated and unsaturated flow

Virus movement in soil during saturated and unsaturated flow was compared by adding poliovirus to sewage water and applying the water at different rates to a 250-cm-long soil column equipped with ceramic samplers at different depths. Movement of viruses during unsaturated flow of sewage through soil columns was much less than during saturated flow. Viruses did not move below the 40-cm level when sewage water was applied at less than the maximum infiltration rate; virus penetration in columns flooded with sewage was at least 160 cm. Therefore, virus movement in soils irrigated with sewage should be less than in flooded groundwater recharge basins or in saturated soil columns. Management of land treatment systems to provide unsaturated flow through the soil should minimize the depth of virus penetration. Differences in virus movement during saturated and unsaturated flow must be considered in the development of any model used to simulate virus movement in soils.     

Virus movement in soil during saturated and unsaturated flow.

Virus movement in soil during saturated and unsaturated flow was compared by adding poliovirus to sewage water and applying the water at different rates to a 250-cm-long soil column equipped with ceramic samplers at different depths. Movement of viruses during unsaturated flow of sewage through soil columns was much less than during saturated flow. Viruses did not move below the 40-cm level when sewage water was applied at less than the maximum infiltration rate; virus penetration in columns flooded with sewage was at least 160 cm. Therefore, virus movement in soils irrigated with sewage should be less than in flooded groundwater recharge basins or in saturated soil columns. Management of land treatment systems to provide unsaturated flow through the soil should minimize the depth of virus penetration. Differences in virus movement during saturated and unsaturated flow must be considered in the development of any model used to simulate virus movement in soils.     

Technical note: fate and transport of jet fuel (JP-8) in soils with selected plants

Remediation of soil and groundwater contaminated by leaking fuel storage tanks may be assisted by plants, although plant effects on abiotic and biotic removal processes remain unclear. The objectives of this study were to investigate abiotic and biotic removal of JP-8, a kerosene-based jet fuel, in soils with plants, and to determine the effects of plant-induced water movement. Loss of JP-8 in a dry-soil, control column was 25% after 5 months, primarily due to volatilization and gas-phase diffusion. By comparison, managed treatments with simulated surface spills averaged 86% mass reduction at 5 months, indicating an important contribution of biodegradation. Overall JP-8 mass reduction was similar in surface and subsurface-irrigated systems, indicating water content, not mode of water application, influences bioremediation in near-surface systems. The JP-8 concentration reductions in soil columns contaminated above a simulated watertable were 36% after 3 months and 50% after 12 months for vegetated columns compared to 26% and 34% in unplanted columns. Downward movement of JP-8 in unplanted columns was double that in planted columns. Near the groundwater table, JP-8 persists longer than near the soil surface. Plants promote upward movement of water and help draw spilled JP-8 to aerobic near-surface soil.     

Virus movement in soil columns flooded with secondary sewage effluent.

Secondary sewage effluent containing about 3 X 10(4) plaque-forming units of polio virus type 1 (LSc) per ml was passed through columns 250 cm in length packed with calcareous sand from an area in the Salt River bed used for ground-water recharge of secondary sewage effluent. Viruses were not detected in 1-ml samples extracted from the columns below the 160-cm level. However, viruses were detected in 5 of 43 100-ml samples of the column drainage water. Most of the viruses were adsorbed in the top 5 cm of soil. Virus removal was not affected by the infiltration rate, which varied between 15 and 55 cm/day. Flooding a column continuosly for 27 days with the sewage water virus mixture did not saturate the top few centimeters of soil with viruses and did not seem to affect virus movement. Flooding with deionized water caused virus desorption from the soil and increased their movement through the columns. Adding CaCl2 to the deionized water prevented most of the virus desorption. Adding a pulse of deionized water followed by sewage water started a virus front moving through the columns, but the viruses were readsorbed and none was detected in outflow samples. Drying the soil for 1 day between applying the virus and flooding with deionized water greatly reduced desorption, and drying for 5 days prevented desorption. Large reductions (99.99% or more) of virus would be expected after passage of secondary sewage effluent through 250 cm of the calcareous sand similar to that used in our laboratory columns unless heavy rains fell within 1 day after the application of sewage stopped. Such virus movement could be minimized by the proper management of flooding and drying cycles.     

Virus movement in soil columns flooded with secondary sewage effluent.

Secondary sewage effluent containing about 3 X 10(4) plaque-forming units of polio virus type 1 (LSc) per ml was passed through columns 250 cm in length packed with calcareous sand from an area in the Salt River bed used for ground-water recharge of secondary sewage effluent. Viruses were not detected in 1-ml samples extracted from the columns below the 160-cm level. However, viruses were detected in 5 of 43 100-ml samples of the column drainage water. Most of the viruses were adsorbed in the top 5 cm of soil. Virus removal was not affected by the infiltration rate, which varied between 15 and 55 cm/day. Flooding a column continuosly for 27 days with the sewage water virus mixture did not saturate the top few centimeters of soil with viruses and did not seem to affect virus movement. Flooding with deionized water caused virus desorption from the soil and increased their movement through the columns. Adding CaCl2 to the deionized water prevented most of the virus desorption. Adding a pulse of deionized water followed by sewage water started a virus front moving through the columns, but the viruses were readsorbed and none was detected in outflow samples. Drying the soil for 1 day between applying the virus and flooding with deionized water greatly reduced desorption, and drying for 5 days prevented desorption. Large reductions (99.99% or more) of virus would be expected after passage of secondary sewage effluent through 250 cm of the calcareous sand similar to that used in our laboratory columns unless heavy rains fell within 1 day after the application of sewage stopped. Such virus movement could be minimized by the proper management of flooding and drying cycles.     

Direct extraction and purification of rRNA for ecological studies.

Microgram quantities of rRNA were recovered from natural microbial communities in sediment, soil, and water with a lysozyme-hot phenol direct extraction method. Gel filtration with Sephadex G-75 spun columns readily removed humic-like contaminants without any measurable loss of rRNA and rendered RNA extracts of sufficient quality for molecular procedures.     

Water Uptake and Germination of Leguminous Seeds in Soils of Changing Matric and Osmotic Water Potential

Water uptake and germination rate of chickpea and pea seedswere compared under changing water potentials in sand and soilaggregate columns and osmotic solutions. The final water uptake and germination were the same in allcases for a given water potential, but the rates were lowerfor seeds planted in sand columns, probably due to mechanicalconstraints imposed on the swelling seed by the dense sand,since the capillary conductivity, and the diffusivity to waterof the sand were very high. The area of the seed in contact with soil is not of importanceif soil aggregates are small as compared to the seeds but increasesin importance when the seeds and the soil aggregates are ofthe same size and at low water potentials.     

Degradation of oxadiazon in a bioreactor integrated in the water closed circuit of a plant nursery

Hardy ornamental nursery stock (HONS) use fertigation as a rational supply of nutrients all along the growth cycle of plants. Nevertheless, that frequency of irrigation increases the risks of nutrient and herbicide leaching and subsequent contamination of the waste water. Therefore, systems of water treatment are required in plant nurseries. Pseudomonas fluorescens strain CG5 cells were immobilized on a ceramic support (sepiolite) contained in a 150 l-bioreactor for the biodegradation of the herbicide oxadiazon in the re-circulated leachates. Percolation and inundation operating processes were assayed in the bioreactor. The levels of oxadiazon in water samples were determined by solid phase extraction on C18 columns and gas chromatography with electron capture detection system. Fifty eight percolation cycles resulted in a significant reduction of oxadiazon up to just 5 microg l(-1) at the outlet. Similar herbicide elimination was achieved after two consecutive 68-h inundation periods. In addition, it was found that the nutrient content in the waste water at the bioreactor outlet was sufficient to support an adequate plant growth.     

不同养殖模式对亚东鲑幼鱼生长性能、血清生化指标和肌肉营养成分的影响

为了探索亚东鲑(Salmon trutta)多元化养殖模式,以初始体质量(100.05±1.12) g幼鱼作为研究对象,开展循环水和开放流水模式养殖比较,试验周期180d,分析比较其生长性能、血清生化指标和肌肉营养成分差异。结果表明:在开放流水模式下增重率、肥满度、肝体指数、特定生长率和饲料转化率均显著高于循环水模式(P<0.05),存活率二者差异不显著(P>0.05);在循环水模式下补体C₄、总蛋白和生长激素均显著低于开放流水模式(P<0.05),但溶菌酶、谷丙转氨酶和谷草转氨酶相反(P<0.05),补体C₃、碱性磷酸酶、酸性磷酸酶和球蛋白在两种模式之间差异均不显著(P>0.05);肌肉主要营养成分粗蛋白、粗脂肪含量开放流水模式高于循环水模式,氨基酸组成二者差异不显著(P>0.05),脂肪酸中油酸、α-亚麻酸、C20:1、C20:2和MUFA含量均显著低于开放流水(P<0.05),而EPA+DHA、SAFA和PUFA含量相反,二者之间差异性显著(P<0.05),矿物质镁含量循环水模式显著高于开...     

Use of cellulose-based stationary phases for chiral separation in open tubular column chromatography

Application of cellulose-based chiral stationary phases was extended to open tubular columns. These chiral materials were mixed with achiral matrix stationary phases. Compromises were found among the polarity and the ratio of achiral matrix polymers against the content of the chiral cellulose derivative in order to optimize the resolution of the investigated racemates. In GC, the high efficiency feature of open tubular columns allows fast analysis, however, compounds which express strong H-bond interaction with cellulose derivatives elute with a bad peak shape. The application of these stationary phases for open tubular SFC was more successful, because the solvation power of the mobile phase can compensate the strong interaction between the solute and the cellulose derivative. Immobilization of the stationary phases were achieved for SFC purposes. © 1992 Wiley-Liss, Inc.     

Pollution attenuation by soils receiving cattle slurry after passage of a slurry-like feed solution. Column experiments

Designing soil filtration systems or vegetated filter strips as a means of attenuating water pollution should take into account soil purging capacity. Here we report data on laboratory column trials used to investigate the capacity of a Hortic Anthrosol to attenuate contamination due to downward leaching from cattle slurry applied at the surface. The columns comprised 900 g of soil to a depth of about 20-25 cm, and had been used previously in an experiment involving passage of at least 5 pore volumes of an ion-containing cattle slurry-like feed solution. For the present experiments, the columns were first washed through with distilled water (simulating resting and rain falling after passage of the feed solution), and then received a single slurry dose equivalent to about 300 m3 ha(-1). The columns were then leached with distilled water, with monitoring of chemical oxygen demand (COD) and ion contents in outflow. The results indicated that the pollution-neutralising capacity of the soil was still high but clearly lower than in the earlier experiments with the feed solution. Furthermore, the time-course of COD showed that organic acids were leached through the column even more rapidly than chloride (often viewed as an inert tracer) enhancing the risk of heavy metals leaching and subsequent water pollution. Resting and alternate use of different soil-plant buffer zones would increase the lifespan of purging systems that use soil like the here studied one.