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1.
Immobilization appears to be one of the best techniques to separate physically micro-algal cells from their culture medium
for the purpose of algal tertiary wastewater treatment. High operation costs and other drawbacks of large-scale physico-chemical
methods of harvest led to a comparative study of biotreatment systems. Before treatment began, Scenedesmus bicellularis cells were conditioned (starved) under four different sets of conditions: 1) non-immobilized cells with air bubbling (NCA);
2) cells immobilized in alginate beads (CBW) and 3) cells immobilized on alginate screens (CSW), all conditioned in synthetic
culture medium depleted in N and P; 4) cells immobilized on alginate screens but conditioned in air at 100% relative humidity
(CSA). Starvation was started under a light:dark photoperiod of 16:8 h. Starved cells were then used to treat wastewater for
a 2-h period. The performance of each system was evaluated by determination of residual NH4-N and phosphate ions and by growth (dry weight, total chlorophyll, cell count, protein content). We then tested the capacity
of microalgae immobilized on screens to eliminate N and P from a secondary municipal wastewater effluent and examined the
influence of temperature and starvation. The quality of treated effluents was improved considerably with the system using
CSA or CSW model. For CSA model, the protein content was 22.4 pg cell-1 compared to 12.9, 9.5, 9.1 pg cell-1 for NCA, CBW and CSW models, respectively. The CBW and CSW models were efficient for chlorophyll synthesis. The residual
ammonium content in natural wastewater after 2 h of treatment with CSA model was 39% at 6±2 °C and reached 100% removal at
18±2 °C. With the first 2 h, the removal of orthophosphate was inferior (53%) at 6±2 °C, but 88 to 100% at 18±2 °C depending
on starvation times. Long starvation times (72 or 96 h) caused damage to cells and uptake of nutrients was lower than with
54 h starvation. This work demonstrates that by using immobilization on screens, removal of nutrients from wastewater was
higher than with conventional biological tertiary wastewater treatments (free cells or bead-shaped alginate particles). 相似文献
2.
3.
Valentino M. Kaya Jacques Goulet Joël de la Noüe Gaston Picard 《Enzyme and microbial technology》1996,18(8):550-554
A method of accelerating the removal of ammonium and phosphate by the unicellular microalga Scenedesmus bicellularis is presented for municipal tertiary wastewater treatment using immobilized cells to obtain a high quality of effluents. Microalgal cells grown in defined medium were harvested by centrifugation and stored at 4°C in the dark for 8 months before immobilization. The concentrated cell suspension was then immobilized in alginate films supported on polypropylene screens. Immobilized cells were incubated in a water-saturated air stream enriched with CO2 at 750, 1,000, or 1,500 ppm for 3 h periods followed by 2 h periods without enrichment. The quantitative effects of these three CO2 enrichments on nutrient uptake from secondary municipal wastewater effluent were compared to a control laboratory air at 320 ppm under the same conditions of illumination, photoperiod, and humidity. The exposure cycle of 48-h nutrient deprivation in air with CO2 enrichment followed by 2 h of nutrient uptake from wastewater was repeated three times with a residual NH4---N content dropping to 0% after 105 min for the 1,500 ppm CO2 treatment and to 34% of the initial level after 120 min for the control treatment. Complete PO4---P removal required more than 2 h. The chlorophyll a contents obtained with 1,000 and 1,500 ppm CO2 enrichments were comparable. This study establishes that intermittent CO2 enrichment during nutrient deprivation of immobilized microalgal cells in a water-saturated air stream may accelerate tertiary wastewater treatment. 相似文献
4.
Narges Zamani Masoud Noshadi Seifollah Amin Ali Niazi Younes Ghasemi 《Journal of applied phycology》2012,24(4):649-656
Microalgae play an important role during the tertiary treatment of municipal wastewater. Cell immobilization techniques have been developed in order to improve the quality of the treated wastewater and avoid wash out of the biomass. Since cell immobilization method may affect the nutrient removal efficiency, ten strains of microalgae were immobilized in sodium alginate gel in different-diameter circular screens, and orthophosphate removal efficiency from municipal wastewater was studied. Results indicate that the alginate immobilization screen size and contact surface with wastewater affects the microalgae synthesis activity and thus orthophosphate removal efficiency. Increasing the contact surface by making smaller alginate screens will increase the cation exchange rate and reduce the orthophosphate concentration in the medium. Among all microalgae treatments, Scenedesmus rubescens MCCS 018, Chlamydomonas sp. MCCS 026, and Chroococcus dispersus MCCS 006 had the highest PO 4 3- -P removal efficiency of 68.8%, 71.9%, and 72.3% within 12?days. 相似文献
5.
Scendesmus sp. isolated from municipal wastewater, entrapped in calcium alginate as algal sheets was employed to remove inorganic nutrients (N and P) from artificial and real domestic secondary effluents in parallel-plate bioreactor after starvation. The key factors affecting the removal efficiency (NH4+-N and PO4(3-)-P), system stability and reuse efficiency of screens were studied and discussed. It has been shown that cell density in the mixture of algal gel was the key factor compared with the thickness of the gel and the cell density of the reactor. A complete removal of NH4+-N and PO4(3-)-P was achieved within 4h of treatment in parallel bioreactors with the optimal cell density in the mixture of algal (2 x 10(8) algae mL(-1)) and 3mm gel sheets after second cycle. Nine cycles of wastewater treatment in 21 days were accomplished, holding higher removal efficiency. NH(4)(+)-N removal efficiency was 99.1% after 105 min, 100% after 135 min, PO4(3-)-P removal efficiency was 100% after 15 min in domestic secondary effluents. Immobilized Scendesmus sp. is shown to have great potentialities for removal of inorganic nitrogen and phosphorus from treated effluents. 相似文献
6.
The ciliate Tetrahymena thermophila was starved for orthophosphate in a synthetic medium at pH 7.5. These cells did not utilize phosphorylcholine, final concentration 1 mM, as a phosphate source for cell growth and multiplication. If the phosphorylcholine solution, however, was incubated for 24 h at pH 5.5 with extracellular, "spent" medium from a culture in early stationary phase of growth, then it promoted culture growth readily at pH 7.5. It was shown that the spent medium in the same concentration did not stimulate growth in itself. It is concluded that extracellular digestion of phosphorylcholine enabled the cells to grow and multiply in a nutrient medium having organic phosphate compounds as the only phosphate source. It is argued that the phosphatases in the spent medium are of lysosomal origin. 相似文献
7.
Jan Vymazal 《Hydrobiologia》1988,166(3):225-237
The results of experiments on the efficiency of periphyton communities for nutrient removal from polluted streams in a continuous flow-through are given. The artifical stream (5 m × 0.7 m × 0.5 m) was made of wood, with silon (a kind of nylon) screens, as a substratum for periphyton growth. The elimination of nutrients was monitored by ammonium, nitrite, nitrate and orthophosphate analyses. In addition, the elimination of organics and the decrease in trophic state were determined. During two field experiments a marked elimination of nitrogen and phosphorus was demonstrated. The maximum efficiency of ammonium and orthophosphate removal was 80% and 70%, respectively. Organic removal reached 35% (C.O.D.Mn-Kubel) and 54% (B.O.D.5). Inorganic and organic nutrient elimination caused significant changes in periphyton community structure in the outflow portion of the through, evaluated by the saprobic index and the similarity coefficient. The experiments confirmed that periphyton communities are a useful means of nutrient removal from polluted streams. 相似文献
8.
Ruiz J Alvarez P Arbib Z Garrido C Barragán J Perales JA 《International journal of phytoremediation》2011,13(9):884-896
This study evaluates the feasibility of removing nutrients by the microalgae Chlorella vulgaris, using urban wastewater as culture medium, namely the effluent subjected to secondary biological treatment in a wastewater treatment plant (WWTP). For this, laboratory experiments were performed in batch cultures to study the effect of initial nitrogen and phosphorus concentrations on growth and reduction of nutrient performance of C. vulgaris. The microalga was cultivated in enriched wastewater containing different phosphorus (1.3-143.5 mg x L(-1) P.PO4(3-)), ammonium (5.8-226.8 mg x L(-1) N-NH4+) and nitrate (1.5-198.3 mg x L(-1) N-NO3-) concentrations. The nutrient removal and growth kinetics have been studied: maximum productivity of 0.95 g SS x L(-1) x day(-1), minimum yield factor for cells on substrate (Y) of 11.51 g cells x g nitrogen(-1) and 0.04 g cells x g phosphorus(-1) were observed. The results suggested that C. vulgaris has a high potential to reduce nutrients in secondary WWTP effluents. 相似文献
9.
为了探究固定化微绿球藻(Nannochloropsis oculata)去除污水中NH4+-N、PO43--P的效果,采用海藻酸钠固定化包埋技术进行实验。开展了固定化藻球大小、藻细胞包埋密度、藻球投放质量及充气培养条件对NH4+-N、PO43--P去除效果的单因子试验研究。结果表明,固定化藻球大小、藻细胞包埋密度、藻球投放质量和充气培养条件对NH4+-N、PO43--P的去除效果影响显著(P0.05)。藻球直径3.5 mm时生长速率(K)值最大(0.3320.002),同时NH4+-N、PO43--P去除率效果最佳,分别为(75.083.83)%和(80.803.81)%;藻细胞包埋密度100104 cells/ball时K值最大(0.3300.033),而NH4+-N、PO43--P去除率则以藻细胞包埋密度300104 cells/ball组为佳,分别达(87.200.43)%和(82.581.72)%,但考虑单位藻细胞去除率,包埋密度以100104 cells/ball为宜;随着藻球用量的增加K值下降,10 g/L组K值最大(0.3010.02)、50 g/L组K值最小(0.1930.01),投放量30和50 g/L时NH4+-N去除率较高分别为(84.120.78)%和(84.630.45)%,30 g/L组PO43--P去除率最高达(77.131.43)%。综合考虑,藻球投放量选用30 g/L为宜;充气条件培养K值、NH4+-N和PO43--P去除率显著(P0.05)高于不充气,K值分别为(0.3060.006)和(0.1770.010);NH4+-N去除率分别为(85.930.45)%和(49.320.45)%;PO43--P去除率分别为(66.665.00)%和(46.292.12)%。研究优化了微绿球藻固定化条件:固定化微绿球藻应进行充气培养,藻球规格3.5 mm、藻细胞包埋密度100104 cells/ball、藻球投放量30 g/L。 相似文献
10.
The removal and biodegradation of nonylphenol (NP) by alginate-immobilized cells of Chlorella vulgaris were compared with their respective free cultures. The effects of four cell densities of 10(4) per algal bead were investigated, as were the four algal bead concentrations, with regard to the removal and biodegradation of NP. Although immobilization significantly decreased the growth rate and NP's biodegradation efficiency of C. vulgaris, NP removal over a short period was enhanced. The NP removal mechanism by immobilized cells was similar to that by free cells, including adsorption onto alginate matrix and algal cells, absorption within cells and cellular biodegradation. The optimal cell density and bead concentration for the removal and biodegradation of NP was 50-100×10(4) cells algal bead(-1) and 2-4 beads ml(-1) of wastewater, respectively. These results demonstrated that immobilized C. vulgaris cells under optimal biomass and photoautotrophic conditions are effective in removing NP from contaminated water. 相似文献
11.
Removal of nitrogen and phosphorus from wastewater using microalgae immobilized on twin layers: an experimental study 总被引:2,自引:0,他引:2
Removal of nitrogen and phosphorus from wastewater by two green microalgae (Chlorella vulgaris and Scenedesmus rubescens) was investigated using a novel method of algal cell immobilization, the twin-layer system. In the twin-layer system, microalgae
are immobilized by self-adhesion on a wet, microporous, ultrathin substrate (the substrate layer). Subtending the substrate
layer, a second layer, consisting of a macroporous fibrous tissue (the source layer), provides the growth medium. Twin-layers
effectively separate microalgae from the bulk of their growth medium, yet allow diffusion of nutrients. In the twin-layer
system, algae remain 100% immobilized, which compares favourably with gel entrapment methods for cell immobilization. Both
microalgae removed nitrate efficiently from municipal wastewater. Using secondary, synthetic wastewater, the two algae also
removed phosphate, ammonium and nitrate to less than 10% of their initial concentration within 9 days. It is concluded that
immobilization of C. vulgaris and S. rubescens on twin-layers is an effective means to reduce nitrogen and phosphorus levels in wastewater. 相似文献
12.
Katsuya Abe Tomohiro Bito Asumi Sato Nobuhiro Aburai 《Journal of applied phycology》2014,26(1):341-347
Application of a laboratory-scale photobioreactor containing a biofilter composed of the aerial microalga Trentepohlia aurea to the removal of ammonium from synthetic wastewater was assessed to determine whether the system could be applied to water purification and the treatment of eutrophic water. The removal efficiency of the photobioreactor was tested after ten biofilter sheets (total dry weight cells: 50 mg) were cycled in nitrogen-free Bold’s basal (BB) medium for 72 h (pretreatment cycle). The ammonium removal ability was significantly enhanced when the photobioreactor was operated after performing the pretreatment cycle using nitrogen-free BB medium supplemented with magnesium. Moreover, the illumination conditions during the treatment were shown to affect the nitrogen removal ability, and this ability was strongly dependent on the concentrations of organic compounds (e.g., α-ketoglutarate and pyruvate) for assimilating the nitrogen source in the T. aurea biofilter. 相似文献
13.
The effect of reduced nutritional levels (particularly nitrogen source) for immobilized K. fragilis type yeast were studied using a trickle flow, "differential" plug flow type reactor with cells immobilized by adsorption onto an absorbant packing matrix. Minimizing nutrient levels in a feed stream to an immobilized cell reactor (ICR) might have the benefits of reducing cell growth and clogging problems in the ICR, reducing feed preparation costs, as well as reducing effluent disposal costs. In this study step changes in test feed medium nutrient compositions were introduced to the ICR, followed by a return to a basal medium. Gas evolution rates were monitored and logged on a continuous basis, and effluent cell density was used as an indicator of cell growth rate of the immobilized cell mass. Startup of the reactor using a YEP medium showed a rapid buildup of cells in the reactor during the initial 110 h operation. The population density then stabilized at 1.6 x 10(11) cells/g sponge. A defined medium containing a complex mix of essential nutrients with an inorganic nitrogen source (ammonium sulfate) was able to maintain 90% of the productivity in the ICR as compared to the YEP medium, but proved unable to promote growth of the immobilized cell mass during startup. Experiments on reduced ammonium sulfate in the defined medium, and reduced yeast extract and peptone in YEP medium indicated that stable productivity could be maintained for extended periods (80 h) in the complete absence of any nutrients besides a few salts (potassium phosphate and magnesium sulfate). It was found that productivity rates dropped by 35-65% from maximal values as nitrogenous nutrients were eliminated from the test mediums, while growth rates (as determined by shed cell density from the reactor) dropped by 75-95%. Thus, nutritional deficiencies largely decoupled growth and productivity of the immobilized yeast which suggests productivity is both growth- and non-growth-associated for the immobilized cells. A yeast extract concentration of 0.375 g/L with or without 1 g/L ammonium sulfate was determined to be the minimum level which gave a sustained increase in productivity rates as compared to the nutritionally deficient salt medium. This represents a 94% reduction in complex nitrogenous nutrient levels compared to standard YEP batch medium (3 g/L YE and 3.5 g/L peptone). 相似文献
14.
Olguín EJ 《Biotechnology advances》2003,22(1-2):81-91
Phycoremediation applied to the removal of nutrients from animal wastewater and other high organic content wastewater is a field with a great potential and demand considering that surface and underground water bodies in several regions of the world are suffering of eutrophication. However, the development of more efficient nutrient removal algal systems requires further research in key areas. Algae growth rate controls directly and indirectly the nitrogen and phosphorus removal efficiency. Thus, maximum algae productivity is required for effective nutrient removal and must be considered as a key area of research. Likewise, low harvesting costs are also required for a cost-effective nutrient removal system. The use of filamentous microalgae with a high autoflocculation capacity and the use of immobilized cells have been investigated in this respect. Another key area of research is the use of algae strains with special attributes such as tolerance to extreme temperature, chemical composition with predominance of high added value products, a quick sedimentation behavior, or a capacity for growing mixotrophically. Finally, to combine most of the achievements from key areas and to design integrated recycling systems (IRS) should be an ultimate and rewarding goal. 相似文献
15.
Effect of carbon source on biological nutrient removal in a sequencing batch reactor 总被引:1,自引:0,他引:1
Sequencing batch operation was used for nutrient (COD, NH4-N, NO3-N, PO4-P) removal from synthetic wastewater by using different carbon sources. Operation consisted of anaerobic, anoxic, oxic, anoxic and oxic (An/Ax/Ox/Ax/Ox) phases with durations of 2/1/4.5/1.5/1.5 h. Glucose, acetate and a mixture of glucose/acetate were used as carbon source to yield a COD/N/P ratio of 100/5/1.5 in the feed. Sludge age was kept constant at 10 days. COD, NH4-N, NO3-N and PO4-P removal efficiencies were maximum at the levels of 96%, 87%, 81% and 90% respectively, when a mixture (50/50) of glucose and acetate was used. 相似文献
16.
To investigate the coupled technology for advanced wastewater treatment and microalgal biomass production, a photo-membrane bioreactor was constructed. The microalga Scenedesmus sp. LX1 was cultured in the bioreactor using liquor prepared from the effluent of an electronic device factory. The algal cell growth, nitrate nitrogen removal, orthophosphate phosphorus removal were investigated. When cultured with batch operation, the average specific growth rate was about 0.09 d−1, and low nitrogen (N), phosphorus (P) concentrations in the liquor were achieved. However, under continuous operation with an inflow of 60 L h−1, the average specific growth rate was only 0.02 d−1, and removal rates of 100% for orthophosphate P and 46% for nitrate N were achieved. With the inflow of 120 L h−1, the accumulated metal ions in the bioreactor adversely affected the algal cells. The algal cells were much easier to settle, and the removal efficiency for N and P decreased. 相似文献
17.
Adaptation of anaerobic ammonium-oxidising consortium to synthetic coke-ovens wastewater 总被引:7,自引:0,他引:7
A consortium with autotrophic anaerobic ammonium oxidising (AAAO) activity was developed from municipal sludge, and its ability to remove high ammonium concentrations in a toxic wastewater such as coke ovens wastewater is presented here. The enriched AAAO consortium was acclimatised to a synthetic coke ovens wastewater to establish anaerobic ammonium oxidation (AAO) activity. Phenol was the main carbon component of the synthetic wastewater whereby it was added stepwise from 50+/-10 to 550+/-10 mg l(-1) into an anammox enrichment medium. Ammonium-N removal was initially impaired; however, it gradually recovered. After 15 months of further selection and enrichment, the ammonium removal rate reached 62+/-2 mg NH(4)(+)-N l(-1) day(-1), i.e. 1.5 times the rate in the original AAAO reactor. The new consortium demonstrated higher ammonium and nitrite removal rates, even under phenol perturbation (up to 330+/-10 mg l(-1)). It is therefore concluded that the AAO activity in the consortium was resistant to high phenol and has potential for treating coke-ovens wastewater. 相似文献
18.
19.
This research studied the effects of inorganic nutrient removal by free and immobilized Scenedesmus bijugatus cells, measured by algal growth (i.e., the chlorophyll a concentration) and the efficiency of the uptake of inorganic nutrients by the cells (uptake rate (b) and removal percentage) in water samples from the organically polluted Pinang River estuary (PRE). Water samples from the PRE were collected during low and high tide. S. bijugatus cells had a higher growth rate when incubated in low tide PRE water samples compared to high tide PRE water samples, with a growth rate of 0.29 µgml?1d?1 and 0.06 µgml?1d?1 for free and immobilized cells, respectively. S. bijugatus was able to more efficiently remove nitrogen, especially ammonium (81–94%), compared to phosphate (62–88%) from both low and high tide water samples. S. bijugatus cells in low tide PRE water samples recorded highest phosphate (0.36 mgL?1d?1 and 0.25 mgL?1d?1 for free and immobilized cells, respectively) and ammonium uptake rates (0.44 mgL?1d?1 and 0.29 mgL?1d?1 for free and immobilized cells respectively). Both inorganic nutrient removal and microalgal cell growth were not significantly different between free and immobilized S. bijugatus (p > 0.05). The data obtained indicated that the removal of nutrients by microalgae was affected by salinity and the immobilization technique applied may have good potential for bioremediation. 相似文献
20.
酿酒酵母X330高浓度发酵时耐酒精性能的初步研究 总被引:4,自引:0,他引:4
在完全合成培养基条件下,就渗透压保护剂和营养物质对一株产高浓度酒精的酿酒酵母X330高浓度发酵时耐酒精性能的影响进行了初步研究。结果表明,与渗透压相比,营养缺乏对酿酒酵母高浓度发酵时酒精耐受性能可能起着更为关键和重要的作用。发酵培养基中各营养元素对耐酒精性能的影响不同,由高到低的顺序是酵母抽提物>蛋白胨>硫酸镁>维生素C=磷酸二氢钾>氯化钙=硫酸铵。渗透压保护剂(甘氨酸和脯氨酸)能有效提高菌体酒精耐受性能。当甘氨酸添加浓度为20mmol/L或脯氨酸添加浓度为10mmol/L时,发酵终点酒精浓度最高,菌体于30℃在18%(V/V)酒精冲击下的存活率最大,且均高于对照组(未添加甘氨酸且未添加脯氨酸)水平,但甘氨酸的促进作用强于脯氨酸。 相似文献