Effect Of Inorganic Carbon Research Articles

Inorganic carbon (IC) as a key factor affecting the performance of anammox-hydroxyapatite (HAP) process at extremely low temperature (7 °C)

Based on the requirements for advanced treatment of nitrogen in wastewater and energy conservation, the anammox-hydroxyapatite (HAP) process was applied in this study. The objective was to achieve a high efficiency of nitrogen removal at a low temperature of 7 °C. As a key influencing factor, the effect of inorganic carbon (IC) on the anammox-HAP process was examined throughout the long-term operation and in batch tests. In the long-term operation, the maximum nitrogen removal rate (NRR) reached 2.10 ± 0.09 gN/L/d at a nitrogen loading rate (NLR) of 3.0 gN/L/d. An efficient and stable nitrogen removal efficiency of 82.31 ± 2.05% was obtained at an NLR of 2.0 g/L/d. The phosphorus removal efficiency ranged from 13.65 to 54.24% as the Ca/P ratio was 1.63–5.46, and the analysis by micro characterization technologies clearly showed the formation of bio-induced HAP. It was found that IC has different effects on nitrogen and phosphorus removal under insufficient and excessive conditions. A higher addition of IC increased the anammox activity and provided the alkalinity required for the formation of HAP. However, excess IC and high calcium resulted in precipitates of calcium carbonate on the sludge surface and affected the diffusion between biomass and substrate. This hindrance to substrate transfer has impaired the anammox activity and the nitrogen removal performance. In addition, it was demonstrated that excess IC competed with phosphorus for calcium, thus having a negative effect on the removal of phosphorus. The optimal range of IC/TN was determined to be 0.25–0.58, and the influence mechanism of IC on the anammox-HAP process was clarified in this study.

Inorganic carbon uptake in a freshwater diatom, Asterionella formosa (Bacillariophyceae): from ecology to genomics

ABSTRACT Inorganic carbon availability can limit primary productivity and control species composition of freshwater phytoplankton. This is despite the presence of CO2-concentrating mechanisms (CCMs) in some species that maximize inorganic carbon uptake. We investigated the effects of inorganic carbon on the seasonal distribution, growth rates and photosynthesis of a freshwater diatom, Asterionella formosa, and the nature of its CCM using genomics. In a productive lake, the frequency of A. formosa declined with CO2 concentration below air-equilibrium. In contrast, CO2 concentrations at 2.5-times air-equilibrium did not increase growth rate, cell C-quota or the ability to remove inorganic carbon. A pH-drift experiment strongly suggested that HCO3 − as well as CO2 could be used. Calculations combining hourly inorganic carbon concentrations in a lake with known CO2 and HCO3 − uptake kinetics suggested that rates of photosynthesis of A. formosa would be approximately carbon saturated and largely dependent on CO2 uptake when CO2 was at or above air-equilibrium. However, during summer carbon depletion, HCO3 − would be the major form of carbon taken up and carbon saturation will fall to around 30%. Genes encoding proteins involved in CCMs were identified in the nuclear genome of A. formosa. We found carbonic anhydrases from subclasses α, β, γ and θ, as well as solute carriers from families 4 and 26 involved in HCO3 − transport, but no periplasmic carbonic anhydrase. A model of the components of the CCM and their location in A. formosa showed that they are more similar to Phaeodactylum tricornutum than to Thalassiosira pseudonana, two marine diatoms.

Effects of inorganic carbon and light on acetate assimilation by Nannochloropsis oceanica (Eustigmatophyceae) in mixotrophic cultivation

ABSTRACT Microalgae are capable of accumulating biomass and high value-added products in mixotrophic culture. Carbon sources and light intensity have significant impacts on mixotrophic algal growth and metabolites accumulation. To investigate the underlying mechanism of interaction between metabolism of inorganic carbon and organic carbon, growth of Nannochloropsis oceanica with two different carbon sources (organic sodium acetate and inorganic sodium bicarbonate) and under three different light conditions (low, medium and high) was examined. A combination of sodium acetate and sodium bicarbonate significantly enhanced algal growth with higher acetate assimilation, when compared with single carbon sources. With increasing light intensity from low to high, the algal growth rates decreased in both autotrophic and mixotrophic cultures. Proteome and 13C metabolic flux results showed that acetate utilization via the glyoxylate (GOX) cycle was enhanced, and both the tricarboxylic acid (TCA) cycle and putative C4 pathway were stimulated in the presence of sodium acetate and sodium bicarbonate. These data suggest that sodium bicarbonate could facilitate acetate assimilation and enhance the putative C4 pathway, GOX cycle and TCA cycle in N. oceanica under mixotrophic culture conditions.

Catalytic and photocatalytic ozonation with activated carbon as technologies in the removal of aqueous micropollutants

Clopyralid degradation by different treatment processes combining olive stone activated carbon (OSAC), ozone and Solar-Simulated Radiation (SSR) were studied. Firstly, a detailed study of clopyralid adsorption onto OSAC was carried out. The fitted experimental data suggest pseudo-first order kinetics and Freundlich equilibrium isotherm models to describe the process. Secondly, the application of catalytic ozonation was explored. The combination of ozone and OSAC significantly improved the generation of hydroxyl radicals. Moreover, the catalyst showed higher stability and kept efficiency in reuse cycles, if compared to adsorption. Thirdly, the combination of O3, OSAC, and SSR was applied, and different systems were compared, focusing on pH as the main variable. At basic pH (pH = 9), the best removal rate was achieved by O3/OSAC/SSR. Finally, all systems were applied for the treatment of the target compound in an urban wastewater matrix, focusing on the effect of inorganic carbon. The presence of carbonates inhibited only the mineralization rate, not affecting the compound removal.

A novel mechanistic model for nitrogen removal in algal-bacterial photo sequencing batch reactors

A comprehensive mathematical model was constructed to evaluate the complex substrate and microbial interaction in algal-bacterial photo sequencing batch reactors (PSBR). The kinetics of metabolite, growth and endogenous respiration of ammonia oxidizing bacteria, nitrite oxidizing bacteria and heterotrophic bacteria were coupled to those of microalgae and then embedded into widely-used activated sludge model series. The impact of light intensity was considered for microalgae growth, while the effect of inorganic carbon was considered for each microorganism. The integrated model framework was assessed using experimental data from algal-bacterial consortia performing sidestream nitritation/denitritation. The validity of the model was further evaluated based on dataset from PSBR performing mainstream nitrification. The developed model could satisfactorily capture the dynamics of microbial populations and substrates under different operational conditions (i.e. feeding, carbon dosing and illuminating mode, light intensity, influent ammonium concentration), which might serve as a powerful tool for optimizing the novel algal-bacterial nitrogen removal processes.

Research on Partial Nitrification Based on Mathematical Model

The successful completion of partial nitrification is the basis of good nitrogen removal efficiency in subsequent anammox process. The effects of inorganic carbon, salinity, FA, FNA, DO and other key factors can be predicted and verified through mathematical simulation to determine the most suitable environmental conditions for the partial nitrification.

Abundant and rare microbial sub-communities in anammox granules present contrasting assemblage patterns and metabolic functions in response to inorganic carbon stresses

Nitrogen-transforming microorganisms play pivotal roles for the microbial nitrogen-cycling network in the anammox granular system. However, little is known about the effects of inorganic carbon (IC) stresses on the assemblage patterns and functional profiles of abundant and rare taxa. Herein, the community assemblage and functional traits of abundant and rare sub-communities were investigated. Results revealed that insufficient IC had adverse influences on the process performance, while anammox activity could be recovered by IC addition. Co-occurrence network analysis indicated that abundant and rare sub-communities present divergent co-occurrence patterns. Additionally, environmental filtering had different influences on the ecological adaptability of bacterial sub-communities. Furthermore, qPCR results illustrated that NH4+-N and NO2−-N consumption were regulated by abundant sub-community, while their accumulation was mediated by rare sub-community. Collectively, these findings suggest that abundant and rare sub-communities present contrasting assemblage patterns and metabolic pathways, and functional profiles dominated selection of bacterial sub-communities under IC stresses.

Start-up of the completely autotrophic nitrogen removal over nitrite process with a submerged aerated biological filter and the effect of inorganic carbon on nitrogen removal and microbial activity

Good start-up and performance are essential for the completely autotrophic nitrogen removal over nitrite (CANON) process, and inorganic carbon (IC) is also important for this process. In this study, a lab-scale submerged aerated biological filter (SABF) was adopted for the CANON process. A 16S rRNA gene high-throughput sequencing analysis showed that the phyla Proteobacteria and Planctomycetes were the dominant microorganisms and that the genus Candidatus Brocadia functioned as the nitrogen remover. The effect of IC on the nitrogen removal was analyzed. The results showed that the optimum concentration ratio of IC to nitrogen (IC/N) was 1.2, which produced the highest average ammonium nitrogen removal rate (ANR) and total nitrogen removal rate (TNR) values of 95.5% and 80.3%, respectively. The average AOB and AnAOB activities were 2.45 mg·L−1·h−1 and 3.57 mg·L−1·h−1, respectively. This research could promote the nitrogen removal ability of the CANON process with a SABF in the future.

Effects of inorganic carbon on the nitrous oxide emissions and microbial diversity of an anaerobic ammonia oxidation reactor

Inorganic carbon (IC) is important for anaerobic ammonium oxidation (anammox). In this study, the effects of the IC concentration on N2O emissions and microbial diversity in an anammox reactor were investigated. N2O emissions were positively correlated with IC concentrations, and IC concentrations in the range of 55–130 mg/L were optimal, considering the nitrogen removal rate and N2O emissions. High IC concentrations resulted in the formation of CaCO3 on the surface of anammox granules, which impacted the diffusion conditions of the substrate. Microbial community analysis indicated that high IC concentrations decreased the populations of specific bacteria, such as Achromobacter spanius strain YJART-7, Achromobacter xylosoxidans strain IHB B 6801, and Denitratisoma oestradiolicum clone 20b_15. D. oestradiolicum clone 20b_15 appeared to be the key contributor to N2O emissions. High N2O emissions may result from changes in organic carbon sources, which lead to denitrification by D. oestradiolicum clone 20b_15.

Effects of inorganic carbon and pH on growth kinetics of Synechocystis sp. PCC 6803

Growth pH and the concentration of bioavailable inorganic carbon (Cib) are two essential factors controlling the rate of photoautotrophic growth of microalgae. We developed a novel experimental strategy to determine the effects of pH and Cib independently by a pH-Stat and the use of NH4NO3 as the N source. We grew Synechocystis sp. PCC 6803 at pH values of 7.5, 8.5, and 9.5, with a stable inorganic carbon (Ci) concentration ranging from 0.08 to 3.3mM, and a light intensity of ~202μEm−2s−1. Among the pH values tested, pH8.5 supported the highest maximum specific growth rate (μmax), 2.4/day that was statistically larger than μmax values at pH7.5 and 9.5, about 2.0/day. Using the sum of dissolved CO2, carbonic acid, and bicarbonate (i.e., Cib) to fit Monod kinetics, we found the half-maximum-rate concentrations (KCib) were in a narrow range: 86μM for pH8.5, 84μM for pH7.5, and 96μM for pH9.5, values that were statistically indistinguishable. All KCib values were small, indicating that Synechocystis has a high affinity for Cib, attaining μmax by ~1mM. Analyzing the kinetics individually for each Ci species supports that bicarbonate best represented the rate of Ci uptake.

Effect of inorganic carbon on nitrogen removal and microbial communities of CANON process in a membrane bioreactor

In this study, a membrane bioreactor (MBR) was adopted for completely autotrophic nitrogen removal over nitrite (CANON) process. Inorganic carbon (IC) was step-wise decreased to analyze the IC influence on nitrogen removal and microbial communities, finally IC was elevated to study its recovery capability. The bioactivities of functional organisms were detected by batch experiments. Results showed that the bioactivity and biodiversity of aerobic ammonia-oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing bacteria (AAOB) both decreased due to the IC shortage, while nitrite-oxidizing bacteria bioactivity showed a contrary result. When the concentration ratio of IC to nitrogen (IC/N) decreased to 1.0, the nitrogen removal sharply deteriorated, which then recovered when the ratio increased to 2.5. Denaturing gradient gel electrophoresis results showed that Nitrosomonas sp. of AOB and Candidatus Brocadia fulgida of AAOB could survive in the condition of IC deficit. The prominent IC/N ratio for high-rate and stable CANON was between 1.5–2.0.

N2O production by ammonia oxidizing bacteria in an enriched nitrifying sludge linearly depends on inorganic carbon concentration

The effect of inorganic carbon (IC) on nitrous oxide (N2O) production by ammonia oxidizing bacteria (AOB) was investigated over a concentration range of 0–12 mmol C/L, encompassing typical IC levels in a wastewater treatment reactors. The AOB culture was enriched along with nitrite-oxidizing bacteria (NOB) in a sequencing batch reactor (SBR) to perform complete nitrification. Batch experiments were conducted with continuous carbon dioxide (CO2) stripping or at controlled IC concentrations. The results revealed a linear relationship between N2O production rate (N2OR) and IC concentration (R2 = 0.97) within the IC range studied, suggesting a substantial effect of IC on N2O production by AOB. Similar results were also obtained with an AOB culture treating anaerobic sludge digestion liquor. The fundamental mechanism responsible for this dependency is unclear; however, in agreement with previous studies, it was observed that the ammonia oxidation rate (AOR) was also influenced by the IC concentration, which could be well described by the Monod kinetics. These resulted in an exponential relationship between N2OR and AOR, as previously observed in experiments where AOR was altered by varying dissolved oxygen and ammonia concentrations. It is therefore possible that IC indirectly affected N2OR by causing a change in AOR. The observation in this study indicates that alkalinity (mostly contributed by IC) could be a significant factor influencing N2O production and should be taken into consideration in estimating and mitigating N2O emissions in wastewater treatment systems.

The effect of inorganic carbon on microbial interactions in a biofilm nitritation–anammox process

The overarching goal of this study was to determine the role of inorganic carbon (IC) in influencing the microbial ecology, performance and nitrogen turnover by individual microbial communities of a biofilm based combined nitritation–anammox process. IC limitation was transiently imposed by reducing the IC input from 350% to 40% of the stoichiometric requirement for 40 days. The principal impact observed during IC limitation was the overgrowth of nitrite oxidizing bacteria (NOB) at the expense of anaerobic ammonia oxidizing bacteria (AMX). On the other hand, the concentrations of ammonia oxidizing bacteria (AOB) were relatively stable during the imposition of and recovery from IC limitation. The resulting dominance of NOB, in terms of their concentration and contribution to nitrite consumption over AMX, resulted, in turn, in a decrease in overall nitrogen removal from 78 ± 2.0% before IC limitation to 46 ± 2.9% during IC limitation. Upon recovery back to non-limiting IC input, it took an inordinately long time (about 57*HRT) for the N-removal to recover back to pre-limitation conditions. Even after recovery, NOB were still persistent in the biofilm and could not be washed out to pre-limitation concentrations. The emission of nitrous oxide (N2O) and nitric oxide (NO), likely from AOB, transiently increased in concert with transient increases in ammonia and hydroxylamine concentrations during the period of IC limitation. Therefore, an unintended consequence of IC limitation in nitritation–anammox systems can be an increase in their greenhouse gas footprint, in addition to compromised process performance. Most emphasis to date on nitritation and anammox studies has been on the nitrogen cycle. The results of this study demonstrate that the differing strategies used by AOB, NOB and AMX to compete for their preferred assimilative carbon source can also significantly influence the microbial ecology, performance and carbon footprint of such processes.

Carbon limitation enhances CO2 concentrating mechanism but reduces trichome size in Arthrospira platensis (cyanobacterium)

Arthrospira species grow well under highly enriched inorganic carbon concentrations, but little is known on the effects of inorganic carbon (Ci) limitation on its physiological performance. When Arthrospira platensis D-0083 was grown in a modified medium without NaHCO3 under ambient air of 380 ppm CO2, its trichomes became disassembled while the growth and photosynthetic rates were severely reduced. Phycocyanin and allophycocyanin contents decreased but the carotenoid content increased under the Ci limitation. Compared with the cells grown in Zarrouk medium, the trichomes grown under the Ci limitation increased their photosynthetic apparent affinity for Ci by about 14 times but photochemical quenching capacity was reduced. It appeared that A. platensis increased its CO2 concentrating mechanism by inducing HCO3 − transporters and reducing the trichome size which increased filamentous surface to volume ratio.

Achieving high-rate autotrophic nitrogen removal via Canon process in a modified single bed tidal flow constructed wetland

This study attempts to explore the Complete Autotrophic Nitrogen removal Over Nitrite (Canon) process to enhance the nitrogen removal in constructed wetlands (CWs). To achieve a stable and high-rate nitrogen removal via Canon, a single stage tidal flow constructed wetland (TFCW) system was modified by adopting internal upflow recirculation, shorter unsaturated time, and creating a pre-saturated zone. It was found that reduction of recirculation reduced oxygen supply, which favored partial nitrification and anammox process but decreased the overall nitrogen conversion rate. On the contrary, increasing the recirculation cycles enhanced the overall ammonium oxidization, but partial nitrification and anammox process could no longer be maintained. The setup of a pre-saturated zone in CW was beneficial to maintaining the stability of the Canon route. The effect of inorganic carbon (IC) on Canon was tested and the results revealed that high inorganic carbon (IC) could promote both partial nitrification and anammox activities but had no substantial effect on nitrite oxidization, which provided a strong selective method to maintain the Canon pathway. By integrating the control of oxygen supply (internal recirculation and pre-saturated zone) and high influent IC concentration, this study finally achieved total inorganic nitrogen (TIN) removal of >80% under high nitrogen loading rate of 15gN/m2/d from long-term stored livestock wastewater, which was characterized as having extremely low BOD5/TN ratio of <0.2.

Effect of inorganic carbon on the completely autotrophic nitrogen removal over nitrite (CANON) process in a sequencing batch biofilm reactor

Ammonia-oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing bacteria (AnAOB) are autotrophic microorganisms. Inorganic carbon (IC) is their main carbon source. The effects of IC limitation on AOB and AnAOB in the completely autotrophic nitrogen removal over nitrite (CANON) process in a sequencing batch biofilm reactor (SBBR) were examined. The optimal IC concentration in the influent was investigated. The start-up time of the CANON process from the activated sludge in the SBBR was 80 d under controlled free ammonia (FA) conditions and sufficient IC source. The AOB and AnAOB activities were limited by an IC concentration of 50 mg− C·L−1 in the influent, whilst the nitrogen loading rate (NLR) was 200 mg-N·L−1·d−1. The experiment on recovering the influent IC showed that AOB and AnAOB activities were affected by the IC limitation, and not by the pH or FA, at 200 mg-N·L−1·d−1 NLR and 50 mg-C·L−1 IC in the CANON process. The activities were recovered by increasing the IC concentration in the influent. From an economic point of view, the optimal IC concentration in the influent was 250 mg-C·L−1 at 200 mg-N·L−1·d−1 NLR in this CANON system.

PRIMARY CARBON AND NITROGEN METABOLIC GENE EXPRESSION IN THE DIATOM THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE): DIEL PERIODICITY AND EFFECTS OF INORGANIC CARBON AND NITROGEN(1).

Diel periodicity and effects of inorganic carbon (Ci ) and NO3 (-) on the expression of 11 key genes for primary carbon and nitrogen metabolism, including potential C4 photosynthesis, in the marine diatom Thalassiosira pseudonana Hasle et Heimdal were investigated. Target gene transcripts were measured by quantitative reverse transcriptase-PCR, and some of the gene-encoded proteins were analyzed by Western blotting. The diatom was grown with a 12 h photoperiod at two different Ci concentrations maintained by air-equilibration with either 380 μL · L(-1) (near-ambient) or 100 μL · L(-1) (low) CO2 . Transcripts of the principal Ci and NO3 (-) assimilatory genes RUBISCO LSU (rbcL) and nitrate reductase displayed very strong diel oscillations with peaks at the end of the scotophase. Considerable diel periodicities were also exhibited by the β-carboxylase genes phosphoenolpyruvate carboxylase (PEPC1 and PEPC2) and phosphoenolpyruvate carboxykinase (PEPCK), and the Benson-Calvin cycle gene sedoheptulose-bisphosphatase (SBPase), with peaks during mid- to late scotophase. In accordance with the transcripts, there were substantial diel periodicities in PEPC1, PEPC2, PEPCK, and especially rbcL proteins, although they peaked during early to mid-photophase. Inorganic carbon had some transient effects on the β-carboxylase transcripts, and glycine decarboxylase P subunit was highly up-regulated by low Ci concentration, indicating increased capacity for photorespiration. Nitrogen-starved cells had reduced amounts of carbon metabolic gene transcripts, but the PEPC1, PEPC2, PEPCK, and rbcL transcripts increased rapidly when NO3 (-) was replenished. The results suggest that the β-carboxylases in T.pseudonana play key anaplerotic roles but show no clear support for C4 photosynthesis.

Effect of inorganic carbon on anaerobic ammonium oxidation enriched in sequencing batch reactor

The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon (sodium bicarbonate) on anaerobic ammonium oxidation. The enrichment of anammox bacteria was carried out in a 7.0-L sequencing batch reactor (SBR) and the effect of bicarbonate on anammox was conducted in a 3.0-L SBR. Research results, especially the biomass, showed first signs of anammox activity after 54 d cultivation with synthetic wastewater, when the pH was controlled between 7.5 and 8.3, the temperature was 35 degrees C. The anammox activity increased as the influent bicarbonate concentration increased from 1.0 to 1.5 g/L, and then, was inhibited as the bicarbonate concentration approached 2.0 g/L. However, the activity could be restored by the reduction of bicarbonate concentration to 1.0 g/L, as shown by rapid conversion of ammonium, and nitrite and nitrate production with normal stoichiometry. The optimization of the bicarbonate concentration in the reactor could increase the anammox rate up to 66.4 mgN/(L x d).

Effect of Inorganic Carbon on Ozone Self-Decomposition

The effect of inorganic carbon on ozone self-decomposition was examined in this study. Experiments were carried out under a wide concentration range of inorganic carbon of 0–30 mgC/L. First, the rate constant in the overall description model with nth order reaction on dissolved ozone was evaluated. A clear difference in the rate constants with and without inorganic carbon was observed even when the concentration of inorganic carbon was as low as 3 mgC/L; the difference with and without inorganic carbon was almost one order of magnitude. Reaction rate constant was lower with an increase of inorganic carbon concentration. The reaction rate constants were in the range from 1.4 × 10−5–1.9 × 10−4 (mg/L)−1sec.−1 under pH of 6.8–8.1 and inorganic carbon concentration of 6–30 mgC/L and converged on the order of 1.0 × 10−4 (mg/L)−1sec.−1. The difference of the second-order reaction rate constant under the practical range of pH and inorganic carbon concentration was one order of magnitude at most. Depression of ozone self-decomposition rate by inorganic carbon was also evaluated as a scavenging rate by inorganic carbon species against hydroxyl radical. Although the profile of scavenging rate constant was complex, the order of scavenging rate was 102 sec−1 at most in the practical range of pH and inorganic carbon concentration. Because the overall effect of inorganic carbon species on hydroxyl radical scavenging was evaluated qualitatively, the depression extent on ozone self-decomposition, as well as scavenging extent on hydroxyl radical by inorganic carbon is able to be analyzed qualitatively.

Modulation and adaptation of carbonic anhydrase activity in Microcystis spp. under different environmental factors

The carbonic anhydrase (CA) activities were determined in three cyanobacterial species, namely Microcystis aeruginosa Kütz., Microcystis viridis (A.Br.) Lemm, and Microcystis wesenbergii (Kom.) Kom, which were dominant in a lake (Dianchi Lake) subject to major blooms. In more detailed experiments on M. aeruginosa, the effects of inorganic carbon, pH, temperature, nitrogen/phosphorus ratio, glucose, and light intensity on CA activity were also investigated. Because of the relatively alkaline pH value of the culture media for the optimum growth of algal cells, bicarbonate ions were the main form of exogenous inorganic carbon. The results showed that the CA activity of M. aeruginosa was influenced dramatically by the concentration of bicarbonate. Consequently, it was suggested that bicarbonate ions were the main form of exogenous inorganic carbon that M. aeruginosa could utilize. Cultures grown in the dark exhibited CA activity six times higher than that of cells cultured mixotrophically with the addition of glucose. Features of eutrophic water bodies promoted an increase in CA activity, and the resulting higher CA activity would accelerate the utilization of inorganic carbon and favor the growth and blooming of Microcystis spp. in eutrophic lakes. Although the experiments were carried out under controlled experimental conditions, they could provide some basic data that would prove useful for the control of cyanobacterial blooms in nature.