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1.
Marine algae Gelidium and algal composite material were investigated for the continuous removal of Cu(II) from aqueous solution in a packed bed column. The biosorption behaviour was studied during one sorption–desorption cycle of Cu(II) in the flow through column fed with 50 and 25 mg l−1 of Cu(II) in aqueous solution, at pH 5.3, leading to a maximum uptake capacity of ≈13 and 3 mg g−1, respectively, for algae Gelidium and composite material. The breakthrough time decreases as the inlet copper concentration increases, for the same flow rate. The pH of the effluent decreases over the breakthrough time of copper ions, which indicates that ion exchange is one of the mechanisms involved in the biosorption process. Temperature has little influence on the metal uptake capacity and the increase of the ionic strength reduces the sorption capacity, decreasing the breakthrough time. Desorption using 0.1 M HNO3 solution was 100% effective. After two consecutive sorption–desorption cycles no changes in the uptake capacity of the composite material were observed. A mass transfer model including film and intraparticle resistances, and the equilibrium relationship, for adsorption and desorption, was successfully applied for the simulation of the biosorption column performance. 相似文献
2.
Thomas R. Clark Henry L. Ehrlich 《Journal of industrial microbiology & biotechnology》1992,9(3-4):213-218
Summary Copper contained in a solid industrial waste produced in a silicone manufacturing process was leached with spent iron medium from aThiobacillus ferrooxidans culture. Most effective leaching was observed in a continuously fed, dual reactor system. Spent iron medium was generated by growingT. ferrooxidans in 0.9 K iron medium at pH 1.5 in the first reactor, and was transferred to a second reactor in which it leached the copper from the waste. Leaching was effective at a pulp density of the waste material as high as 20%. In experiments run at a pulp density of 2.5%, the spent iron medium was most efficient in leaching copper when it was first diluted 100-fold with a mineral salts solution at pH 1.5. Removal of the copper from the waste appeared to involve its displacement by acid, dissolved mineral salts, and ferric iron. Potentials for practical application of this process are discussed. 相似文献
3.
Net growth of ice algae in response to changes in overlying snow cover was studied after manipulating snow thickness on land-fast,
Arctic sea ice. Parallel laboratory experiments measured the effect of changing irradiance on growth rate of the ice diatom,
Nitzschia frigida. After complete removal of thick snow (≥9 cm), in situ ice algae biomass declined (over 7–12 days), while removal of thin
snow layers (4–5 cm), or partial snow removal, increased net algal growth. Ice bottom ablation sometimes followed snow removal,
but did not always result in net loss of algae. Similarly, in laboratory experiments, small increases in irradiance increased
algal growth rate, while greater light shifts suppressed growth for 3–6 days. However, N. frigida could acclimate to relatively high irradiance (110 μmol photons m2 s−1). The results suggest that algal loss following removal of a thick snow layer was due to the combination of photoinhibition
and bottom ablation. The smaller relative increase in irradiance after removal of thin or partial snow layers allowed algae
to maintain high specific-growth rates that compensated for loss from physical mechanisms. Thus, the response of ice algae
to snow loss depends both on the amount of change in snow depth and algal photophysiology. The complex response of ice algae
growth and export loss to frequently changing snow fields may contribute to horizontal and temporal patchiness of ecologically
and biogeochemically important variables in sea ice and should be considered in predictions of how climate change will affect
Arctic marine ecosystems. 相似文献
4.
Selective feeding on large algae by copepods involves remotedetection of individual particles and subsequent active captureresponses In this study we use radiotracer experiments to quantifythe clearance rates of five coexisting freshwater copepods andto investigate the relative merits of the chemoreception andmechanoreception hypotheses of remote detection Tropocyclopsand three diaptomid copepods exhibited relatively high clearancerates when feeding on low concentrations of large algae, suggestingthat most previous studies with freshwater copepods have underestimatedmaximal clearance rates and the degree of size selectivity.All five species of copepods exihibited strong selection foran intermediate-sized flagellate (25 µm Cartena) or alarge-sized nonmotile alga (80 µ.m Pediastrum) over asmall-sized flagellate (6 µ.m Chlamydomonas). The weight-specificclearance rate for Tropocylops prasmus feeding on motile Cartena(271 ml mg1 h1) was about twice that of threediaptomid copepods and more than an order-of-magnitude higherthan the estimate for Epischura lacustris feeding on its preferredalga, Pediastrum Assuming that distance chemoreception (smell)is important in remote detection, we predicted that the additionof high concentrations of algal odors would obscureany chemical gradients emanating from individual algal cellsand would thereby hinder the remote detection and active captureof large algae Contrary to this hypothesis, the addition ofamino acids, sucrose, and algal extracts had no effect on theclearance rates and selectivity of Diaptomus birgei. These results,together with recent cinematographic studies (Vanderploeg etal.,1990), suggest that mechanoreception is the primary mechanismfor the remote detection of large particles by diaptomid copepods.A raptorial cyclopoid, Tropocyclops prasinus, exhibited strongpreferences for motile algae, whereas a suspension-feeding calanoid,D birgei, did not select between motile and nonmotile cells.Motility appears to be an important factor in algal detectionfor small cyclopoid copepods but not for suspension-feedingdiaptomids 相似文献
5.
Pectin-rich fruit wastes as biosorbents for heavy metal removal: equilibrium and kinetics 总被引:7,自引:0,他引:7
Biosorption can be used as a cost effective and efficient technique for the removal of toxic heavy metals from wastewater. Waste materials from industries such as food processing and agriculture may act as biosorbents. This study investigates the removal of cadmium by fruit wastes (derived from several citrus fruits, apples and grapes). Citrus peels were identified as the most promising biosorbent due to high metal uptake in conjunction with physical stability. Uptake was rapid with equilibrium reached after 30-80 min depending on the particle size (0.18-0.9 mm). Sorption kinetics followed a second-order model. Sorption equilibrium isotherms could be described by the Langmuir model in some cases, whereas in others an S-shaped isotherm was observed, that did not follow the Langmuir isotherm model. The metal uptake increased with pH, with uptake capacities ranging between 0.5 and 0.9 meq/g of dry peel. Due to their low cost, good uptake capacity, and rapid kinetics, citrus peels are a promising biosorbent material warranting further study. 相似文献
6.
Edward W. Wilde John R. Benemann Joseph C. Weissman David M. Tillett 《Journal of applied phycology》1991,3(2):159-167
A process providing a beneficial use for waste heat and excess nutrients in the cooling waters of nuclear reactors and fossil-fueled power generating plants has been developed. The process involves the cultivation of selected strains of thermotolerant microalgae in heated discharge waters and the subsequent harvesting of the algal biomass for nutrient removal, recovery of energy and fertilizer, and extraction of high value products. The design of such a process is presented for a large cooling reservoir receiving a discharge of 1091?1 d?1 of secondary cooling water containing 100 μg 1?1 of available P and 400 μg 1?1 of available N. Based on this nutrient load, with a 1% P content in the algal biomass and a productivity of 10 g m?2 d ?1, a 100 ha region would be needed for the process. Hydraulic barriers (submerged plastic curtains) would isolate the 100 ha algal production area “cultivation zone” in the influent end of the reservoir to create a hydraulic and thermal environment conductive to the selective growth of filamentous, thermotolerant, nitrogen-fixing, blue-green algae. The algal culture would be inoculated into the thermal plume and harvested near the distal barrier of the cultivation zone with rotating, backwashed, fine mesh screens (“microstrainers”). A portion of the harvested biomass would be recycled to the inoculation site to maintain a dense culture. This process could mitigate both thermal and nutrient loadings on receiving bodies of water. 相似文献
7.
Equilibrium and kinetics studies of heavy metal ions biosorption on green algae waste biomass 总被引:2,自引:0,他引:2
The biosorption of Pb(II), Cd(II), and Co(II), respectively, from aqueous solution on green algae waste biomass was investigated. The green algae waste biomass was obtained from marine green algae after extraction of oil, and was used as low-cost biosorbent. Batch shaking experiments were performed to examine the effects of initial solution pH, contact time and temperature. The equilibrium biosorption data were analyzed using two isotherm models (Langmuir and Freundlich) and two kinetics models (pseudo-first order and pseudo-second order). The results indicate that Langmuir model provide best correlation of experimental data, and the pseudo-second order kinetic equation could best describe the biosorption kinetics of considered heavy metals. 相似文献
8.
Dr. Saleh M. Okla 《Facies》1992,27(1):217-223
Summary Late Permian bioclastic calcarenite beds of the middle Khuff Formation were sampled for their algal constituents near the
city of Unayzah, Quassim district in central Saudia Arabia. The algal flora includes two species of udoteacean algae (Succodium difficile andSuccodium sp.), the dasycladacean algaMizzia velebitana and two species of red algae (Gymnocodium bellerophontis, Permocalculus plumosus).
Other algal floral remains found forming isolated single layers which have generally been named algal microfacies. These include
a phylloid microfacies, an oncoid microfacies and algal stromatolites. The Khuff Formation is well-known for its accumulation
of non-associated gas and particularly for its oil accumulation in eastern Saudi Arabia and the Arabian Gulf states. 相似文献
9.
R J Chróst J Owczarek K Matusiak 《Acta microbiologica Polonica. Series B: Microbiologia applicata》1975,7(4):231-236
Studies were conducted to determine the role of bacteria and algae in the degradation of urea in industrial waste waters. The microflora accompanying algae in continuous cultures on waste waters from the nitrogen fertilizers industry was found to include bacteria capable of intensive degradation of urea. Urea hydrolyzing bacteria are with time eliminated from the algal culture. This elimination can be attributed to algal metabolites which inhibit the development of sensitive bacteria. The Chlorella vulgaris strain used in the treatment of wast waters from the nitrogen fertilizers industry did not hydrolyse urea. 相似文献
10.
F. B. Dilek H. M. Taplamacioglu E. Tarlan 《Applied microbiology and biotechnology》1999,52(4):585-591
A mixed culture of algae was used to treat pulping mill effluent in terms of removing both colour and adsorbably organic
halides (AOX). The removal of AOX from pulping effluent increased with increasing initial colour value of the effluent. However,
for the total mill effluent (composed of both pulping and bleaching effluents), AOX removal was found to be independent of
initial colour value, and was around 70%. Up to 80% removal of colour from pulping effluent was achieved within 30 days under
continuous lighting conditions. It was found that algae reduced the colour of pulping effluent of relatively low initial colour
more efficiently than that of high initial colour. Under simulated field lighting conditions, up to 60% colour removal from
pulping effluent was observed after 60 days of exposure, whereas for the total mill effluent it was up to 64% after 45 days.
Total organic carbon and lignin (UVA280) were also removed to a significant extent, suggesting that the mechanism of colour removal might not be transformation of
the coloured lignin molecules to non-coloured ones. Analysis of alkaline extraction of the algal biomass and material balance
findings indicated that the main colour removal mechanism was metabolism rather than adsorption. The experimental results
were also analysed using multiple regression techniques and a mathematical model was developed to express the removal of colour
from pulping effluents in terms of initial colour value, exposure time and lighting periods as well as interactions between
these variables.
Received: 12 January 1999 / Revision received: 25 March 1999 / Accepted: 26 March 1999 相似文献
11.
Copper adsorption kinetics of cultured algal cells and freshwater phytoplankton with emphasis on cell surface characteristics 总被引:1,自引:0,他引:1
Comparative studies were carried out on the adsorption of copper by a range of laboratory-cultured algae and freshwater phytoplankton
samples. The level of surface mucilage associated with the cultured algae ranged from high (Anabaena spiroides, Eudorina elegans) to moderate (Anabaena cylindrica, Microcystis aeruginosa) to complete absence (Chlorella vulgaris, Asterionella formosa, Aulacoseira varians, Ceratium hirundinella). With laboratory cultures, the rapid uptake, EDTA release and quantitative similarity between living and dead (glutaraldehyde-fixed)
algae were consistent with physical binding of Cu at the cell surface. The higher Cu adsorption per unit surface area and
longer adsorption time of mucilaginous algae in the time-course study, and the relatively high level of Cu bound to mucilage
found by X-ray microanalysis suggest that mucilage played an important role in metal binding. For all species examined, Cu
adsorption kinetics (external Cu concentrations 1 to 1000 mg L−1) showed a clear fit to the Freundlich, but not the Langmuir isotherm, indicating a monolayer adsorption model with heterogenous
binding sites. The Freundlich adsorption capacity constant (Kf) was higher in mucilaginous (3.96–12.62) compared to nonmucilaginous (0.36–3.63) species, but binding intensity (Freundlich
constant 1/n) did not differ between the two cell types. The results suggest that mucilaginous algal species may have potential as biosorbents
for treatment of industrial effluents containing heavy metals. Investigation of the Cu adsorption behavior of four mixed phytoplankton
samples also revealed a good fit to the Freundlich, but not the Langmuir, isotherm. Freundlich constants were in the range
2.3–3.2 for samples dominated by Chlorophyta, Bacillariophyta and Cyanophyta, but recorded a value of 7.4 in the sample dominated
by Dinophyta. Comparison with data from laboratory monocultures suggested that the adsorption kinetics of mixed environmental
phytoplankton samples cannot be predicted simply in terms of the major algal species. 相似文献
12.
In this study, the effects of ammonium nitrogen concentration, algae biomass concentration, and light conditions (wavelength and intensity) on the ammonium removal efficiency of algae-bacteria consortia from wastewater were investigated. The results indicated that ammonium concentration and light intensity had a significant impact on nitrification. It was found that the highest ammonia concentration (430 mg N/L) in the influent resulted in the highest ammonia removal rate of 108 ± 3.6 mg N/L/days, which was two times higher than the influent with low ammonia concentration (40 mg N/L). At the lowest light intensity of 1000 Lux, algae biomass concentration, light wavelength, and light cycle did not show a significant effect on the performance of algal–bacterial consortium. Furthermore, the ammonia removal rate was approximately 83 ± 1.0 mg N/L/days, which was up to 40% faster than at the light intensity of 2500 Lux. It was concluded that the algae-bacteria consortia can effectively remove nitrogen from wastewater and the removal performance can be stabilized and enhanced using the low light intensity of 1000 Lux that is also a cost-effective strategy. 相似文献
13.
Abubakar Hamisu Mijinyawa Geeta Durga 《International journal of phytoremediation》2019,21(11):1122-1129
AbstractAdsorption of dyes onto natural materials like polysaccharides is considered a green chemistry approach for remediation of wastewater. In this work, the polysaccharide isolated from the corm of Colocasia esculenta (L.) Schott or taro tuber (CEM) was utilized for removing methylene blue (MB) from aqueous solution by batch adsorption method. The CEM adsorbent was characterized by FTIR spectroscopy, Brunauer–Emmett–Teller (BET), and scanning electron microscopy (SEM). The solution pH and adsorbent dose have been found to have a significant positive correlation with the adsorptive removal efficiency of CEM for MB dye. The removal efficiency of CEM was found to be 72.35% under the optimum conditions; 20?mg/L initial concentration of dye, 120?mg of adsorbent dose, solution pH 8.5, 311.2?K temperature and 80?min contact time. The adsorption of MB onto CEM followed best the Freundlich isotherm and pseudo-second-order kinetics. The adsorption was thermodynamically favorable and was endothermic in nature. The desorption/adsorption data justifiably indicated the reuse capability of CEM adsorbent for MB adsorption. Hence, CEM may be regarded as an eco-friendly and cost-effective natural adsorbent for MB dye removal from aqueous solution. 相似文献
14.
The occurrence of significant co-extraction of buffer anions by the ion exchanger Aliquat 336 is unavoidable when high levels of system buffering is required. The co-extraction will result in inaccurate equilibrium and mass-transfer characterization of such a system unless its occurrence is taken into account, making process design and control difficult. A study of the equilibrium of phenylalanine extraction using Aliquat 336, a system where high levels of hydroxyl co-extraction occurs, was used as a model case to develop a method of accounting for co-extraction in mass-transfer modeling. Analysis of the equilibrium between bulk-aqueous-phase chloride and phenylalanine concentrations during mass transfer in a stirred-transfer cell showed there to be linear equilibrium relationships between the two parameters for a given extraction system of the form C(Cl,t) = alpha(C(A,t) - C(A,0)) for forward extraction and C(Cl,t) = epsilon C(A,t) + C(Cl,0) for backward extraction. The constants of proportionality of these relationships, or the "co-extraction constants," alpha and epsilon, were shown to be related to the selectivity of Aliquat 336 for the phenylalanine anion by the relationships alpha = -(1/S + 1) and epsilon; = -(1/S(-1) + 1). The linear equilibrium relationships were used to develop two-film theory mass-transfer models for both forward and backward extraction that account for co-extraction. These showed much higher accuracy in modeling stirred-transfer-cell data than the equivalent models which ignored co-extraction. 相似文献
15.
16.
Phosphate concentration of the growth medium was found to affect the growth rate and agar yield of a clone of Gelidium robustum grown in the laboratory. To study differences in growth we used phosphate concentrations from 0 to 200 µM. To determine the effect of phosphate on agar yield and its properties we used concentrations from 0 to 20 µM. Growth rates generally increased with increasing phosphate concentration, with the highest growth rate (21% d–1) obtained at 150 µM. Agar yield as percentage of fresh weight was highest (10%) in the algae grown with low phosphate concentrations, but agar yield as percentage of dry weight was highest(43%) at 20 µM of phosphate. Gel strength increased with phosphate concentration with a maximum of 160 g m–2 for 0.75% gels for the cultures at 20 µM. Melting and gelling temperatures of the gels were also affected by phosphate concentration of the growth medium. Starch yield was highest in algae grown in low phosphate concentrations. 相似文献
17.
Marianne Kreusch Elisa Poltronieri Fernanda Bouvie Dbora T. Pereira Deonir Batista Fernanda Ramlov Marcelo Maraschin Zenilda L. Bouzon Carmen Simioni 《Journal of phycology》2019,55(6):1394-1400
Spore settlement and development are bottlenecks for resilience of habitat‐forming macroalgal species. These processes are directly related to temperature, a global stressor protagonist of ocean warming. The toxic effects of local pollutants such as copper may be worsened under a global warming scenario. Therefore, in this paper, we investigated the effects of increased temperature combined with elevated concentrations of copper on the viability, photosynthetic pigments, and ultrastructure of Gelidium floridanum tetraspores. Tetraspores were cultivated on slides with sterilized seawater or seawater enriched with CuCl2, and incubated under 24°C or 30°C for 24 h. Tetraspores cultivated with copper 3.0 μM under 30°C had lower viability. Both temperature and copper had a significant effect on phycocyanin and phycoerythrin concentrations. Samples cultivated with copper under 30°C presented a heavily altered cellular structure, with vesicles throughout the cytoplasm, chloroplasts with altered structure and cells with degenerated cytoplasm and cell walls. Our findings show that temperature and copper significantly affect the viability, photosynthetic pigments, and ultrastructure of G. floridanum tetraspores, presenting an additive interaction for the physiology of this seaweed's early stages. 相似文献
18.
19.
Cultivating algae on nitrogen (N) and phosphorus (P) in animal manure effluents presents an alternative to the current practice of land application. The objective of this study was to determine values for productivity, nutrient content, and nutrient recovery using filamentous green algae grown in outdoor raceways at different loading rates of raw and anaerobically digested dairy manure effluent. Algal turf scrubber raceways (30m(2) each) were operated in central Maryland for approximately 270 days each year (roughly April 1-December 31) from 2003 to 2006. Algal biomass was harvested every 4-12 days from the raceways after daily additions of manure effluent corresponding to loading rates of 0.3 to 2.5g total N (TN) and 0.08 to 0.42g total P (TP) m(-2)d(-1). Mean algal productivity values increased from approximately 2.5g DW m(-2)d(-1) at the lowest loading rate (0.3g TN m(-2)d(-1)) to 25g DW m(-2)d(-1) at the highest loading rate (2.5g TN m(-2)d(-1)). Mean N and P contents in the dried biomass increased 1.5-2.0-fold with increasing loading rate up to maximums of 7% N and 1% P (dry weight basis). Although variable, algal N and P accounted for roughly 70-90% of input N and P at loading rates below 1g TN, 0.15g TP m(-2)d(-1). N and P recovery rates decreased to 50-80% at higher loading rates. There were no significant differences in algal productivity, algal N and P content, or N and P recovery values from raceways with carbon dioxide supplementation compared to values from raceways without added carbon dioxide. Projected annual operational costs are very high on a per animal basis ($780 per cow). However, within the context of reducing nutrient inputs in sensitive watersheds such as the Chesapeake Bay, projected operational costs of $11 per kgN are well below the costs cited for upgrading existing water treatment plants. 相似文献
20.
The modification of flows in lotic ecosystems can have dramatic effects on abiotic and biotic processes and change the structure of basal trophic levels. In high-gradient streams, most of the biota are benthic, and decreased flow may homogenize and reduce benthic current velocity, potentially changing stream ecosystem function. Grazing by macroinvertebrates is an important component of stream function because grazers regulate energy flow from primary producers to higher trophic levels. We conducted an experiment to examine how macroinvertebrate grazers facilitated or removed algal biomass across a gradient of benthic current velocity (0–40 cm s?1). We chose three grazers (Drunella coloradensis, Cinygmula spp., and Epeorus deceptivus) from a montane stream and conducted our experiment using 24 artificial stream channels that had three treatments: no grazers (control), single-grazer, and combined-grazer treatments. In the absence of grazers, algal biomass increased with benthic current velocity. Grazer treatments differed from the control in that more algal biomass was removed at higher velocities, whereas algal accrual was largely facilitated at low velocities. The transition from facilitation to removal ranged from 4.5 to 5.9 cm s?1 for individual grazer treatments and occurred at 11.7 cm s?1 for the combined-grazer treatment. Our data suggest that velocity plays a significant role in the facilitation and removal of algae by macroinvertebrate grazers. Additionally, the patterns revealed here could have general implications for algal accrual in systems where flow is reduced. 相似文献