The objective of this research is to find correlations between traffic-related contaminants in the roadside soils and their ecotoxicity. The study was conducted in Moscow in the vicinity of a highway ...of 125 000 vehicles per day. The topsoils (0–3 cm depth) were sampled perpendicular to the road at 1-, 6-, 10-, 18- and 50-m distances from the roadbed. Total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAH), heavy metals (HM) in total and phyto-available forms, and deicing salts (DS) were determined. A battery of soil-contacting organisms was tested: phytotoxicity of rye (H. vulgare L.) and garden cress (L. sativum L.); E. foetida earthworm growth rate and mortality; basal and substrate-induced respiration activity, nitrogen fixation and the denitrification activity of the soil microbial complex. To determine the possible risk to aquatic ecosystems, the algal toxicity test (S. quadricauda) was provided. Correlations between "chemical" data and intensity of "biological" effects were analyzed.
Concentrations of most contaminants declined to the background values with distance from the road increase. However, the toxicity of roadside soils was obtained for all examined organisms within the whole 50 m zone. Live organisms exhibited different sensitivities to roadside soils pollution. The intensity of inhibition effects decreased in order: higher plants > earthworms and microorganisms > algae. The risk for aquatic ecosystems was assessed as low. Higher plants toxicity correlated with TPH, PAH, some HM, and DS; earthworm toxicity correlated with TPH, some PAH, HM, and DS; microorganism toxicity correlated with TPH and DS; algae had no observed correlations with contaminants. TPH and DS were general ecotoxicants affecting all organisms. Higher plants may be considered the PAH indicators and earthworms as HM indicators. A set of higher plants and earthworms may be recommended as the reduced test-battery of relevant organisms for cost-effective assessment of the toxicity of roadside soils.
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•Pollution and toxicity of soils were determined within the 50 m roadside zone of a highway.•Higher plants exhibited the highest toxicity among the battery of bioassays.•TPH and DS affected all the test-organisms excluding algae.•PAH strongly affected toxicity of higher plants and HM – earthworms.•Low toxicity risk from soil pollution was assessed for groundwaters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Hydroponic growing systems and the application of natural biostimulant substances are becoming very attractive option for crop cultivation due to their economic relevance since they allow reduction ...in the use of fertilizer and increase the yield. In order to perform a hydroponic co-cultivation system of microalgae (
Chlorella vulgaris
or
Scenedesmus quadricauda
) and tomato plants, grown in Hoagland nutrient solution, their mutual effect and the influence of a natural biostimulant obtained by alkaline extraction from a digestate of agro-livestock residues (DHL) were evaluated. The results showed that the co-cultivation system positively affected the growth of both tomato plants and microalgae. The best option, aimed to a mutual benefit for both cultures, resulted to be the co-cultivation system of tomato plants and
S. quadricauda
in the presence of DHL, positively affecting the growth of tomato plants along with a great increase in microalgal biomass.
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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
In this study, algal cathodic compartments were integrated to generate oxygen in microbial fuel cells. Chlorella vulgaris and Scenedesmus quadricauda were grown under three NH4+–N concentrations (50, ...300, and 900 mg L−1) in the catholyte. With 50 mg L−1 of NH4+–N, the highest maximum power densities of 16.72 and 5.96 mW m−2 were obtained with Chlorella vulgaris and Scenedesmus quadricauda, respectively. Under this condition, dissolved oxygen reached 19.27 and 9.87 mg L−1 for Chlorella vulgaris and Scenedesmus quadricauda respectively, along with 100% removal of NH4+–N within 210 h. Both cultures showed inhibition under higher concentrations of NH4+–N, resulting in decreased photoautotrophic growth that generates oxygen for the cathodic reaction. Under all concentrations, Chlorella vulgaris displayed better tolerance to ammonium. From the results, it can be summarized that 50 mg L−1 of NH4+–N in wastewater is suitable as a microalgal cultivation medium in a cathodic compartment.
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•Chlorella vulgaris showed better growth in ammonium than Scenedesmus quadricauda.•Low NH4+–N concentrations performed better as the catholyte algal growth medium.•Within 210 h, NH4+–N removal efficiency of 100% was achieved with 50 mg L−1.•Power density reached 16.72 mW m−2 with Chlorella under 50 mg L−1 of NH4+–N.•High NH4+–N concentrations decreased the algal growth and dissolved oxygen.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The sensitivity of individual organisms towards toxic agents is an important indicator of environmental pollution. However, organism-specific quantification of sensitivity towards pollutants remains ...a challenge. In this study, we determined the sensitivity of Chlorella vulgaris (C. vulgaris) and Scenedesmus quadricauda (S. quadricauda) towards three ionic liquids (ILs), 1-alkyl-3-methyl-imidazolium chlorides CnmimCl (n = 4,6,8). We kept all external parameters constant to identify the biotic parameters responsible for discrepancies in species sensitivity, and used flow cytometry to determine four conventional endpoints to characterise cell viability and cell vitality. Our results demonstrate that after exposure to the ILs, cell proliferation was inhibited in both species. At the same time, the cell size, complexity and membrane permeability of both algae also increased. However, while Chl a synthesis by S. quadricauda was inhibited, that of C. vulgaris was enhanced. S. quadricauda has evolved a metabolic defense that can counteract the decreased esterase activity that has been shown to occur in the presence of ILs. While it is likely that S. quadricauda was less sensitive than C. vulgaris to the ILs because of this metabolic defense, this alga may also exhibit better membrane resistance towards ILs.
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•Scenedesmus quadricauda is less sensitive than Chlorella vulgaris against the ILs.•Cell size is not a determining factor in microalgal sensitivity.•Membrane resistance or metabolic defense is the possible reasons.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The upsurge in the concerning issues like global warming, environmental pollution and depletion of fossil fuel resources led to the thrust on third generation biofuels. Algal research has gained a ...lot of importance in the recent years. Effective utilization of algal biomass in a single step is necessary as it can produce Bio-oil (BO), gases and in addition to a variety of valuable products, along with nutrient recovery. Hydrothermal liquefaction technology does not require the energy intensive drying steps and is an attractive approach for the conversion of algae to liquid fuels. This study investigates direct hydrothermal liquefaction (HTL) of microalgae (Algal biomass) to produce bio-oil using a high-pressure batch reactor under subcritical water conditions. Three different micro algae samples namely, Chlorella vulgaris, Botryococcus braunii and Scenedesmus quadricauda have been examined under hydrothermal liquefaction with different water concentrations (1:6, 1:7, 1:8, 1:9 & 1:10 ratio) at certain temperature range (200–320 °C), pressure (60 bars) and reaction time (30 min). Through liquefaction, the highest BO yield achieved with S. quadricauda was 18 wt% at 1:9 ratio. The chemical components of the obtained bio-oil were analyzed via gas chromatography and the results indicated that the algal BO was composed of furan, phenol, acid, and ester derivatives. Moreover, it was found that by increasing the temperatures, the BO yields increased. This was due to the polymerization reactions that converted the small biomass components into heavier molecules. FTIR spectra showed high percentage of Aliphatic, Phenolic, alcoholic, Carboxylic and Hydroxyl groups for solid residues.
•Replacement of organic solvent with eco friendly solvent (water)•Optimization of reaction temperatures for effective yields•Optimization of solvent biomass ratio•Conversion of biomass to bio oil
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The fast development of urbanization emits huge amount of domestic wastewater, of which the high contents of chemical oxygen demand(COD), NH4-N, total nitrogen and phosphorous lead to the difficulty ...in their complete removal and the recycling of the water. To solve this problem, the simulated domestic sewage treatment efficiency was investigated via scenedesmus quadricauda and chlorella pyrenoidosa in terms of COD, NH4-N, total nitrogen (TN), and total phosphorous (TP). The influence of the dosage of the two microalgae (100 mg/L and 200 mg/L) on wastewater treatment and the relationship of the indexes COD, NH4-N, TN, and TP with handling time were examined. The surface morphology and chemistry before and after water treatment were characterized through SEM and FTIR, respectively. Scenedesmus quadricauda and chlorella pyrenoidosa show significant removal efficiency towards COD, with removal rates of 77.92% and 80.43%, respectively. Chlorella pyrenoidosa shows better NH4-N (58.34%) and TP (51.09%) removal efficiency than scenedesmus quadricauda for NH4-N (43.66%) and TP (41.52%). Scenedesmus quadricauda shows better TN removal efficiency (78.33%) than chlorella pyrenoidosa (76.67%). The results might provide fundamental and technical support for the application of algal microorganism.
•Four fold increment of intracellular level of ABA during nitrogen starved condition.•ABA supplemented S. quadricauda exhibits 2.1 fold more biomass in nitrogen starved condition.•The total lipid ...yield sustains at low concentration of ABA.•Stress hormone ABA prevents cell denaturation and helps to cope-up the nitrogen starvation.
Scenedesmus quadricauda, accumulated more lipid but with a drastic reduction in biomass yield during nitrogen starvation. Abscisic acid (ABA) being a stress responsible hormone, its effect on growth and biomass with sustainable lipid yield during nitrogen depletion was studied. The result revealed that the ABA level shoots up at 24h (27.21pmol/L) during the onset of nitrogen starvation followed by a sharp decline. The external supplemented ABA showed a positive effect on growth pattern (38×106cells/ml) at a lower concentration. The dry biomass yield is also increasing up to 2.1 fold compared to nitrogen deficient S. quadricauda. The lipid content sustains in 1 and 2μM concentration of ABA under nitrogen-deficient condition. The fatty acid composition of ABA treated S. quadricauda cultures with respect to nitrogen-starved cells showed 11.17% increment in saturated fatty acid content, the desired lipid composition for biofuel application.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•2.27-Fold more lipid accumulation of S. quadricauda under nitrogen starved condition.•SGR of 0.33day−1 and 0.47 doubling per day under N+ condition.•Reduced SGR of 0.14day−1 with a doubling time of ...0.20 under N− condition.•Under nitrogen depleted condition about 25-fold reduction of biomass yield.•Increased L/B ratio (1.11) under nitrogen starved condition.
The experimental results revealed that the 2.27-fold lipid yield was enhanced in nitrogen-depleted condition (226mg/L) when compared to nitrogen rich condition (99.33mg/L). Since specific growth rate (SGR) is the single most criteria to decide the biomass yield of microalgae, SGR was analyzed. SGR of 0.33day−1 was observed with 0.47 doubling per day under nitrogen rich condition. However, low growth rate of 0.14day−1 with a doubling of 0.20 per day was recorded under nitrogen depleted condition. In accordance with SGR, the dry biomass yield was ranged from 0.055±0.005 to 1.394±0.010g/L in the presence of nitrogen, indicating the essentiality of major nutrient in the growth medium. The enhanced lipid accumulation under nitrogen starved condition by Scenedesmus quadricauda was perhaps achieved by adopting adverse environmental condition and possible increment in cell size in terms of length/breadth ratio (1.11).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this study, we integrated physicochemical and biological strategies for the robust treatment of piggery effluent in which high levels of organic constituents, inorganic nutrients, color, and salts ...remained. Piggery effluent that was stabilized in an anaerobic digester was sequentially coagulated, micro-filtered, and air-stripped prior to biological treatment with mixotrophic algal species that showed tolerance to high salinity (up to 4.8% as Cl−). The algae treatment was conducted with continuous O2 supplementation instead of using the combination of high lighting and CO2 injection. The microalga Scenedesmus quadricauda employed as a bio-agent was capable of assimilating both nitrogen (222 mg N g cell−1 d−1) and phosphorus (9.3 mg P g cell−1 d−1) and utilizing dissolved organics (2053 mg COD g cell−1 d−1) as a carbon source in a single treatment process under the heterotrophic growth conditions. The heterotrophic growth of S. quadricauda proceeded rapidly by directly incorporating organic substrate in the oxidative assimilation process, which coincided with the high productivity of algal biomass, accounting for 2.4 g cell L−1 d−1. The algae-treated wastewater was subsequently ozonated to comply with discharge permits that limit color in the effluent, which also resulted in improved biodegradability of residual organics. The integrated treatment scheme proposed in this study also achieved 89% removal of COD, 88% removal of TN, and 60% removal of TP. The advantage of using the hybrid configuration suggests that this would be a promising strategy in full-scale treatment facilities for piggery effluent.
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•A multi-strategic approach was successful in treating refractory piggery wastewater.•A substantial removal of TSS was achieved over a broad range of coagulant doses.•The robust bioremediation with Scenedesmus quadricauda was demonstrated at the high salinity.•The heterotrophic algal growth resulted in the simultaneous removal of TN/TP & TOC.•A greater reliability for compliance with color goals was achieved by ozonation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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