Anaerobic digestion (AD) is one of the most efficient processes for treating agri-food waste in order to obtain renewable energy. Olive mill solid waste (OMSW) is the main residue from the two-phase ...olive oil manufacturing process; it has a high organic content and high C/N ratio, which hinders its AD, giving low methane yield. In the present study, a microalga,
Scenedesmus quadricauda
, was used as co-substrate for the AD of OMSW to compensate for its nitrogen deficiency. The robustness and the high growth rate of
S. quadricauda
make this microalga a potential source of nitrogen to co-digest with carbon-rich substrates. Different co-digestion mixtures of OMSW-microalgae and the single substrates were tested. For all co-digestion mixtures, the alkalinity value at the end of the experiment remained below 4889 ± 245 mg CaCO
3
L
−1
and pH in the range of 7.50–7.67 indicating stability and good process performance. Results showed the highest methane yield (461 mL CH
4
STP g
−1
VS added) for the co-digestion mixture 75% OMSW-25%
S. quadricauda
(C/N = 25.3), which was 104 and 23% higher than that obtained from the single microalga (C/N = 5.6) and OMSW (C/N = 31.9), respectively. No ammonia inhibition was detected despite the high protein content of the microalgae. The transference function model allowed for adequately fitting the experimental results of methane production with time in the anaerobic experiments. The highest maximum methane production rate,
R
m
, among the different co-digestion mixtures assayed was obtained for the mixture 75% OMSW-25%
S. quadricauda
with a value of 89 mL CH
4
g
−1
VS day
−1
.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Eichhornia crassipes
is an invasive, floating macrophyte and may have biocontrol functions on harmful cyanobacteria blooms.
Eichhornia
produces
N
-phenyl-2-naphthylamine (PNA), a compound which can ...inhibit algae. However, the impact of PNA on allelopathic effects of the cyanobacterium
Microcystis aeruginosa
on other phytoplankton species is not clear. In this study, we tested whether PNA can influence the allelopathic effect of
M. aeruginosa
on the green alga
Scenedesmus quadricauda
.
S. quadricauda
was more sensitive to PNA than
M. aeruginosa
, with 72 h-EC
50
values of 0.42 and 3.66 mg L
−1
, respectively. In addition, PNA significantly enhanced allelopathy by
M. aeruginosa
on
S. quadricauda
. Consequently, PNA had a greater impact on the green algae when
Microcystis
was present. In complex ecosystems with multiple species that release allelopathic substances, unintended interspecific interactions may occur, where allelopathy plays an important role under artificial or even natural contexts. It is hard to predict the competition outcomes among allelopathic organisms in these complex ecosystems, therefore a precautionary approach is required for biological control of algae.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The use of natural biostimulants is becoming an attractive option in order to reduce the use of fertilizer and increase the yield of crops. In particular, algal extracts are suitable candidates as ...they positively affect plant physiology. Among crops, lettuce often requires the use of biostimulants to improve both the quality and quantity of production. The aim of this work is to investigate the potential use of a
extract as a biostimulant in order to obtain sustainable cultivation and a reduction in the cost of chemical fertilizers in lettuce cultivation. Therefore, the effect of
extract on lettuce seedlings was explored by evaluating the physiological parameters, chlorophyll, carotenoid, and total protein contents as well as several plant enzymatic activities involved in primary and secondary metabolisms. The experiment was performed by growing plants on inert substrate (pumice) with a 16-h photoperiod, by carrying out two consecutive radical treatments, one week apart, using a concentration of the extract corresponding to 1 mg Corg L
. Lettuce plants were sampled at 1, 4, and 7 days from the first treatment and 7 days from the second treatment. The results showed that the
extract positively affected the growth of lettuce seedlings, mainly acting at the shoot level, determining an increase in dry matter, chlorophylls, carotenoids, proteins, and influencing the activities of several enzymes involved in the primary metabolism.
In this study, the extracellular polymeric substance of Scenedesmus quadricauda called EPS-S.q and its bioflocculatoin mechanism were investigated. Results showed EPS-S.q was successfully used as ...bioflocculating agent for S. quadricauda biomass harvesting and flocculation efficiency of up to 86.7% to S. quadricauda cells could be achieved in presence of Zn2+. EPS-S.q was the flocculating agent for self-flocculating microalga S. quadricauda and bioflocculation mechanism was polymer bridging. The sugar and protein mass fraction of dry EPS-S.q was sugar 56.7% and protein 41%. The infrared spectrum further indicated the presence of hydroxyl, carboxyl and amino groups. Moreover, pH decrease induced the flocculation of S. quadricauda and 78.4% of flocculation efficiency was the highest at pH 3. In addition, chemical flocculant FeCl3 was efficiently used for S. quadricauda harvesting and up to 96.8% of flocculation efficiency could be achieved for S. quadricauda culture with biomass concentration 0.21–0.39 g L−1 at pH 7.
•EPS-S.q is bioflocculating agent produced from self-flocculating Scenedesmus quadricauda.•Flocculation activity of EPS-S.q was induced by Zn2+ ion.•Polymer bridging is the proposed flocculation mechanism of EPS-S.q.•S. quadricauda flocculation was induced by pH decrease.•Ferric chloride can be efficiently used in S. quadricauda biomass harvesting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This study achieves a better operational simplicity for the phycoremediation of reverse osmosis (RO) concentrate using Scenedesmus quadricauda microalgae. Under continuous illumination with CO2 ...supplementation, algal growth in the RO concentrate resulted in a conversion of polymeric organic matter (a mixture of humic substances and polysaccharides) to biodegradable fractions and their prompt removal along with inorganic nutrients (NO3− and PO43−). The algal-induced degradation of humic-like substances which are typically refractory to microbial decomposition was demonstrated in an indirect manner. In this study, we also investigated the effects of algal treatment on the growth of Escherichia coli and removal of trace organic compounds (TOrCs) from the RO concentrate. Our results indicate that algal treatment of the RO concentrate using aeration with 10% (v/v) CO2 under continuous illumination is highly feasible as a safe and inexpensive technology to remove non- or slowly-biodegradable organic matter, reduce enteric bacteria, and attenuate TOrCs in wastewater. However, the results should not be generalized, but critically discussed, due to limitations of using the synthetic RO concentrate in evaluating the performance of wastewater remediation with microalgae.
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•S. quadricauda is capable of utilizing carbonaceous organics under aerated conditions.•Continuous light stimulated the microalga to improve the biodegradability of organics.•S. quadricauda successfully removed colored refractory organics along with N & P.•The algal treatment is also promising to reduce E. coli and trace organic chemicals.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Scientific and research work was carried out to determine the bioregulatory properties of Botryococcus, Chlorococcus, Tetradesmus Scenedesmus strains in plant growth. In the initial stages of the ...research, the influence of these microwater strains on the general germination of the seeds of the medium-ripe cotton variety "Bukhara-10" was studied, in which the international gene bank stored in the scientific laboratory "Biotechnology" of the Tashkent Institute of Chemical Technology was studied. Registered microalgae were used as main objects in our research.
In order to conquer the block of high cost and low yields which limit to realize the commercialization of microalgal biodiesel, the mixotrophic and heterotrophic cultivation of
Scenedesmus ...quadricauda
FACHB-1297 fed on xylose was separately studied employing six forms of media: phosphorus sufficient, phosphorus restricted, and phosphorus starvation were combined with nitrogen sufficient and nitrogen starvation conditions. The maximum lipid content (about 41% of dry weight) was obtained on the 5th day (heterotrophic cultivation) and 8th day (mixotrophic cultivation) under the nitrogen starved and phosphorus sufficient (N
0
&P) conditions, which was about twofold in comparison to the final lipid content on the sufficient nitrogen condition (control). Under mixotrophic and heterotrophic modes, the highest lipid production was achieved in the N
0
&P trial, with the value of 274.96 mg/L and 193.77 mg/L, respectively. Xylose utilization rate of 30–96% under heterotrophic modes was apparently higher than that of 20–50% in mixotrophic modes. In contrast, phosphorus uptake rate of 100% under mixotrophic cultivation was significantly more than that of 60–90% in heterotrophic cultivation. Furthermore, under the condition of heterotrophic cultivation using xylose as a carbon source, the phosphorus had a positive impact on microalgae cell synthesis and the lipid content enhanced with the augmentation in phosphorus concentrations. We suggested that sufficient phosphorus should be supplied for obtaining higher microalgal lipid production in the lack of nitrogen under xylose heterotrophic/mixotrophic condition. This was a highly effective way to obtain efficient microalgae lipid production.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Aquatic organisms are exposed to a wide range of salinity, which could critically affect their survival and growth. However, their survival and growth response to salinity stress remain unclear. This ...study evaluates the growth response and intracellular proline accumulation of green algae,
, isolated from brackish water, against dissolved salts stress with N and P enrichment. We tested a hypothesis that nutrient enrichment can relieve the dissolved salts stress of algae by accumulating intracellular proline, thereby improving survival and growth. Four levels of salinity (0, 3, 6, 12 psu) were experimentally manipulated with four levels of nutrient stoichiometry (N:P ratio = 2, 5, 10, 20) at constant N (1 mgN/L) or P levels (0.05 and 0.5 mgP/L). In each set of experiments, growth rate and intracellular proline content were measured in triplicate. The highest level of salinity inhibited the growth rate of
, regardless of the nutrient levels. However, with nutrient enrichment, the alga showed tolerance to dissolved salts, reflecting intracellular proline synthesis. Proline accumulation was most prominent at the highest salinity level, and its maximum value appeared at the highest N:P ratio (i.e., highest N level) in all salinity treatments, regardless of P levels. Therefore, the effects of P and N on algal response to salt stress differ.
Abstract
The paper presents data on the biotechnology of growing accumulative cultures of algae Scenedesmus quadricauda when adding organo-mineral complex drag to the culture growth medium. It is ...shown that the trace elements that make up the drug (trade name “Helavit”), at the studied concentrations, act in various ways stimulating and inhibiting the growth of algological culture. Having a different effect in the concentration range from 0.1 to 1 mg / L. The maximum positive effect is achieved with a drug concentration of 0.3 mg / l (8986 ± 120 103*cells/ ml), which can be recommended for mass cultivation of algae. A possible cause of inhibition of culture growth, at a concentration of 0.1 mg / l (6960 ± 115 103*cells/ ml), are the inhibitory effects of copper and iodine ions.
Room-temperature ionic liquids (ILs) are a class of novel green chemicals being designed to replace traditional volatile organic solvents in industrial processes. The potential effects of ILs on ...aquatic ecosystems have been poorly studied, despite the possibility of unintentional discharge into rivers and lakes, and their intentional disposal in wastewater treatment plants. We studied the effects of three imidazolium ionic liquids, 1-butyl-, 1-hexyl- and 1-octyl-3-methylimidazolium bromide, on the growth rates of two freshwater algae, Scenedesmus quadricauda and Chlamydomonas reinhardtii, in 96 h standard toxicity bioassays. Increases in alkyl chain length increased the toxicity of these ionic liquids to both S. quadricauda (EC50 values of 0.005-13.23 mg L-1) and C. reinhardtii (EC50 values of 4.07-2138 mg L-1). Bioassays were performed in both nutrient-amended media and low-nutrient groundwater to evaluate if test conditions altered IL toxicity. EC50 values for S. quadricauda were similar between nutrient media and groundwater for all ILs tested, while the presence of nutrient media appeared to partially mitigate the toxicity of ILs to C. reinhardtii (groundwater EC50 media EC50). Overall, S. quadricauda was much more sensitive than C. reinhardtii to all ILs tested, perhaps reflecting differences in cell wall structure. EC50 values suggest that ILs are more, or just as, toxic to algae than many of the solvents they are intended to replace. Results of this study show that ionic liquids can elicit a range of algal responses, suggesting that a diversity of target organisms be tested in order to predict the effects of ILs in natural environments.
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