Scenedesmus Species Research Articles

A Study on the Diversity of Planktons of Urban and Rural Ponds of Kokrajhar District, Assam, India

Due to rapid urbanization, many aquatic habitats are now under severe eutrophication because of waste contaminated soil. Therefore, it is essential to assess the status of aquatic ecosystem surrounding us. The present study was conducted for the study of diversity of planktons which are indicator of aquatic ecosystem of two urban and two rural ponds of Kokrajhar district, Assam. The present study reveals a total of 37 species of planktons of which 23 species represents phytoplankton and 14 species represent zooplankton. The most pollution-tolerant species of Euglena, Navicula, Nitzschia, Ankistrodesmus, Phacus,Pinnularia and Scenedesmus were recorded indicating the highest degree of organic pollution. This plankton study explore that water quality has reached its threshold level and therefore, it needs some corrective measures to maintain the water quality from further deterioration in the study area.

Modification of Growth Media for Scenedesmus and Nitchzer Species for Fatty Acid Methyl Esters Production in Raceway Pond

The aim of this study was to modify the growth media for Scenedesmus and Nitchzia species for fatty acid methyl esters production in raceway pond. Native Scenedesmus and Nitchzia species were cultivated in raceway pond in three different growth media (Nitrogen-sufficient, Nitrogen-deficient and Blue Green 11) media at different periods to assess their quantitative parameters (biomass concentration (g/L), biomass productivity (g/L/d), lipid content (%), and lipid productivity (mg/L/d) as well as their fatty acid methyl esters composition. The quantitative parameters were determined following standard methods and the fatty acid methyl esters composition was analysed by Gas Chromatography Mass Spectrometry (GC-MS). The results of the quantitative parameters obtained from Scenedesmus species were highest in the Blue Green 11 (control) media as compared to the experimental media. Statistically, there is significant difference (p<0.05) in the lipid content obtained from Scenedesmus species between the Blue Green 11 media and the experimental media. The biomass concentration and lipid content obtained from Nitchzia species were also found to be highest in Blue Green 11 media as compared to the other two media. However, the lipid content obtained from Nitchzia species in the three different media showed insignificant difference (p>0.05). Scenedesmus and Nitchzia species did not respond to nitrogen deficiency condition. The Gas Chromatography Mass Spectrometry analysis of the fatty acid methyl esters composition revealed the presence of similar compounds in different proportion. The dominant compound of the fatty acid methyl esters of the two species in the three different media are Hexadecanoic acid methyl ester ((palmitic acid)), 9-octadecenoic acid (Z) methyl ester ((oleic acid) and 9, 12-octadecadienoic acid methyl ester (linolenic acid) among others. The Carbon16-Carbon18 (C16-C18) chain in Scenedesmus and Nitchzia species ranges from 74.14-61.84% and 63.81-61.98% respectively. These could suggest that both species have a great potential for the production of fatty acid methyl esters in large scale cultivation.

Accessing biochemical shifts in a novel Scenedesmus strain via acetaminophen detoxification: Experiment utilizing Box-Behnken optimization and isotherm analysis

Acetaminophen's inherent solubility and hydrophilic nature facilitate its accumulation in aquatic ecosystems. Herein, Scenedesmus dimorphus IITISM-DIX1 demonstrates efficient acetaminophen removal, concurrently serving as a substrate for lipid biosynthesis. Employing Box-Behnken design, optimization of parameters like pH, light duration and concentration of acetaminophen influencing its elimination is executed. Characterization of pre- and post-algal biomass involves FE-SEM, FTIR, and BET analysis. Kinetic and adsorption analyses reveal pseudo-first-order kinetics (R2 = 0.99) and adherence to the Freundlich isotherm (R2 = 0.94). FTIR spectroscopy demonstrates subtle shifts in IR bands post-sorption, indicative of biomass involvement in adsorption processes. Biodegradation and biosorption serve as the main removal pathways, facilitated by exopolysaccharides, generating by-products such as 4-aminophenol, hydroquinone, and formic acid. The Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) values obtained for the Freundlich isotherm validate it as the optimal model, indicating heterogeneous multilayered sorption with efficiency ranging from 44% to 100%. Additionally, exposure to acetaminophen-contaminated media leads to biochemical alterations in Scenedesmus dimorphus IITISM-DIX1. The findings of this study unveil the first elucidated pathway for acetaminophen degradation by any Scenedesmus species, delivering essential knowledge about microalgae-mediated acetaminophen degradation and lipid enrichment mechanisms.

Chemotactic Interactions of Scenedesmus sp. and Azospirillum brasilense Investigated by Microfluidic Methods

The use of algae for industrial, biotechnological, and agricultural purposes is spreading globally. Scenedesmus species can play an essential role in the food industry and agriculture due to their favorable nutrient content and plant-stimulating properties. Previous research and the development of Scenedesmus-based foliar fertilizers raised several questions about the effectiveness of large-scale algal cultivation and the potential effects of algae on associative rhizobacteria. In the microbiological practice applied in agriculture, bacteria from the genus Azospirillum are one of the most studied plant growth-promoting, associative, nitrogen-fixing bacteria. Co-cultivation with Azospirillum species may be a new way of optimizing Scenedesmus culturing, but the functioning of the co-culture system still needs to be fully understood. It is known that Azospirillum brasilense can produce indole-3-acetic acid, which could stimulate algae growth as a plant hormone. However, the effect of microalgae on Azospirillum bacteria is unclear. In this study, we investigated the behavior of Azospirillum brasilense bacteria in the vicinity of Scenedesmus sp. or its supernatant using a microfluidic device consisting of physically separated but chemically coupled microchambers. Following the spatial distribution of bacteria within the device, we detected a positive chemotactic response toward the microalgae culture. To identify the metabolites responsible for this behavior, we tested the chemoeffector potential of citric acid and oxaloacetic acid, which, according to our HPLC analysis, were present in the algae supernatant in 0.074 mg/ml and 0.116 mg/ml concentrations, respectively. We found that oxaloacetic acid acts as a chemoattractant for Azospirillum brasilense.

Microalgae and co-culture for polishing pollutants of anaerobically treated agro-processing industry wastewater: the case of slaughterhouse

Anaerobically treated slaughterhouse effluent is rich in nutrients, organic matter, and cause eutrophication if discharged to the environment without proper further treatment. Moreover, phosphorus and nitrogen in agro-processing industry wastewaters are mainly removed in the tertiary treatment phase. The objective of this study is to evaluate the pollutant removal efficiency of Chlorella and Scenedesmus species as well as their co-culture treating two-phase anaerobic digester effluent through microalgae biomass production. The dimensions of the rectangular photobioreactor used to conduct the experiment are 15 cm in height, 20 cm in width, and 30 cm in length. Removal efficiencies between 86.74–93.11%, 96.74–97.47%, 91.49–92.91%, 97.94–99.46%, 89.22–94.28%, and 91.08–95.31% were attained for chemical oxygen demand, total nitrogen, nitrate, ammonium, total phosphorous, and orthophosphate by Chlorella species, Scenedesmus species, and their co-culture, respectively. The average biomass productivity and biomass yield of Chlorella species, Scenedesmus species, and their co-culture were 1.4 ± 0.1, 1.17 ± 0.12, 1.5 ± 0.13 g/L, and 0.18, 0.21, and 0.23 g/L*day, respectively. The final effluent quality in terms of chemical oxygen demand, total nitrogen, and total phosphorous attained by Chlorella species and the co-culture were below the permissible discharge limit for slaughterhouse effluent standards in the country (Ethiopia). The results of the study showed that the use of microalgae as well as their co-culture for polishing the nutrients and residual organic matter in the anaerobically treated agro-processing industry effluent offers a promising result for wastewater remediation and biomass production. In general, Chlorella and Scenedesmus species microalgae and their co-culture can be applied as an alternative for nutrient removal from anaerobically treated slaughterhouse wastewater as well as biomass production that can be used for bioenergy.Graphical

Morphological and cellular organization of green microalgae to cope with cold stress in subarctic environment

Microalgae are one of the most widely dispersed living organisms on Earth and can be found even in extreme environments. Especially in such habitats, the microalgal cell wall plays an essential role as it is the first barrier in continuous contact with the surrounding and changing environment. In cold conditions microalgae can show changes in their morphology, also known as phenotypic plasticity which is the ability of an organism to show different phenotypes when exposed to different environmental conditions. In addition, presence or absence of algaenan is thought to be responsible for increase/decrease permeability and stiffness of the cell wall. The aim of this work was to evaluate and compare how microalgae cells can modify their cell wall components and cellular morphology under low-temperature conditions (5 °C) and differ during the exponential and stationary phases. Four microalgae species were studied: Coelastrella sp. 3–4, Chlorella vulgaris sp. 13–1, Haematococcus pluvialis, and Scenedesmus sp. B2–2, which were isolated from subarctic locations.Using a histochemical approach in conjunction with light microscopy, cell features such as size, organization and cell wall ornamentation were evaluated. Staining procedures showed changes in biochemical components such as pectins and presence or absence of exopolysaccharides and lipids. Results showed that Coelastrella cultures did not grow under low-temperature conditions. However, Chlorella vulgaris, Haematococcus pluvialis and Scenedesmus species demonstrated a slower growth rate, bigger and rounded cell-shape during cold condition. Furthermore, the latter microalgal strain also showed modification in algaenan presence as one of the main components in cell wall architecture, which can be related to the permeability of cell wall. Changes in other features such as cell organization and cell wall ornamentation were investigated.

Antioxidative defense systems in two scenedesmus species exposed to copper and lead

Antioxidative defense systems in two scenedesmus species exposed to copper and lead

Multi-pollutants (organic and inorganic) removal potential of scenedesmus species on municipal sewage water and analyzed their phycoremediation mechanisms

Municipal sledge water is a combination of residential wastewater, industrial effluent, and precipitation water. The water quality parameters analyses results demonstrated that most of the parameters (pH: 5.6 ± 0.3, Turbidity: 102.31 ± 2.8 mg L−1, TH: 946.38 ± 3.7 mg L−1, BOD: 295.63 ± 5.4 mg L−1, COD: 482.41 ± 4.9 mg L−1, Ca: 278.74 ± 1.8 mg L−1, SO42−: 559.64 ± 11.4 mg L−1, Cd: 18.56 ± 1.37 mg L−1, Cr: 31.25 ± 1.49 mg L−1, Pb: 21.45 ± 1.12 mg L−1, and Zn: 48.65 ± 1.56 mg L−1) were considerably increased in quantities with slightly acidic in condition. The in-vitro phycoremediation study was carried out for two weeks with pre-identified Scenedesmus sp. Biomass in different groups of treatments (A, B, C, and D). Interestingly, most of the physicochemical parameters were significantly reduced in group C (4 × 103 cells mL−1) treated municipal sludge water in a shorter treatment period than in the other treatment groups. The phycoremediation percentage of group C were found as pH: 32.85%, EC: 52.81%, TDS: 31.32%, TH: 25.58%, BOD: 34.02%, COD: 26.47%, Ni: 58.94%, Ca: 44.75%, K: 42.74%, Mg: 39.52%, Na: 36.55%, Fe: 68%, Cl: 37.03%, SO42−: 16.77%, PO43−: 43.15%, F: 55.55%, Cd:44.88%, Cr:37.21%, Pb:43.8%, and Zn:33.17%. These findings suggest that increased biomass from Scenedesmus sp. can be used to significantly remediate municipal sludge water and that the obtained biomass and treated sludge can be used as feedstock's for bio fuel as well as bio fertilizer, respectively.

Molecular insight into cellulose degradation by the phototrophic green alga Scenedesmus.

Lignocellulose is the most abundant natural biopolymer on earth and a potential raw material for the production of fuels and chemicals. However, only some organisms such as bacteria and fungi produce enzymes that metabolize this polymer. In this work we have demonstrated the presence of cellulolytic activity in the supernatant of Scenedesmus quadricauda cultures and we identified the presence of extracellular cellulases in the genome of five Scenedesmus species. Scenedesmus is a green alga which grows in both freshwater and saltwater regions as well as in soils, showing highly flexible metabolic properties. Sequence comparison of the different identified cellulases with hydrolytic enzymes from other organisms using multisequence alignments and phylogenetic trees showed that these proteins belong to the families of glycosyl hydrolases 1, 5, 9, and 10. In addition, most of the Scenedesmus cellulases showed greater sequence similarity with those from invertebrates, fungi, bacteria, and other microalgae than with the plant homologs. Furthermore, the data obtained from the three dimensional structure showed that both, their global structure and the main amino acid residues involved in catalysis and substrate binding are well conserved. Based on our results, we propose that different species of Scenedesmus could act as biocatalysts for the hydrolysis of cellulosic biomass produced from sunlight.

Evaluation of visible-light wavelengths that reduce or oxidize the plastoquinone pool in green algae with the activated F<sub>0</sub> rise method

We recently developed a chlorophyll a fluorescence method (activated F0 rise) for estimating if a light wavelength preferably excites PSI or PSII in plants. Here, the method was tested in green microalgae: Scenedesmus quadricauda, Scenedesmus ecornis, Scenedesmus fuscus, Chlamydomonas reinhardtii, Chlorella sorokiniana, and Ettlia oleoabundans. The Scenedesmus species displayed a plant-like action spectra of F0 rise, suggesting that PSII/PSI absorption ratio is conserved from higher plants to green algae. F0 rise was weak in a strain of C. reinhardtii, C. sorokiniana, and E. oleoabundans. Interestingly, another C. reinhardtii strain exhibited a strong F0 rise. The result indicates that the same illumination can lead to different redox states of the plastoquinone pool in different algae. Flavodiiron activity enhanced the F0 rise, presumably by oxidizing the plastoquinone pool during pre-illumination. The activity of plastid terminal oxidase, in turn, diminished the F0 rise, but to a small degree.

Effects of Two Quinolone Antibiotics on Growth of Four Species of Planktonic Algae

Quinolone antibiotics, especially enrofloxacin and ciprofloxacin, are currently found to be at high levels commonly in natural waters. Studying the effects of these two quinolones on the growth of common microalgae in water is valuable for understanding the ecological effects of quinolones in the aquatic environment. Therefore, the effects of different concentrations of enrofloxacin and ciprofloxacin hydrochloride on the population growth of four species of planktonic microalgae (Chlorella vulgaris, Tetradesmus obliquus, Scenedesmus quadricauda, and Microcystis aeruginosa) were studied. The results showed that there was a significant effect-dose regression relationship between the concentration of nofantibiotic and the growth inhibitory rate of the algae population. The 96h half maximal inhibitory concentration (96h-IC50) of enrofloxacin on T. obliquus, S. quadricauda, M.aeruginosaI and C. vulgaris were 195.6, 88.8, 56.1, and 22.6 mg/L respectively, and the order of sensitivity of the four microalgae to enrofloxacin was T. obliquus＜S. quadricauda＜M. aeruginosa＜C. vulgaris. Another 96h-IC50 of ciprofloxacin hydrochloride to S. quadricauda, T. obliquus, M. aeruginosa, and C. vulgaris were 588.6, 546.3, 49.8, and 44.7 mg/L respectively. The sensitivity of the four microalgae to ciprofloxacin hydrochloride was ranked as follows: S. quadricauda＜T. obliquus＜M. aeruginosa＜C. vulgaris. Among the four species of planktonic microalgae, two species of Scenedesmus were less sensitive to the quinolone antibiotics. Therefore, these two species of Scenedesmus were more resistant to the two quinolone antibiotics, while C. vulgaris was the most sensitive to them. According to the data of IC50, the toxicity of enrofloxacin to three green microalgae was higher than that of ciprofloxacin, while the toxicity of enrofloxacin to M. aeruginosa was lower than that of ciprofloxacin. The population growth of the four planktonic microalgae was inhibited in the first 4 days after being treated by these two quinolone antibiotics, but the microalgae could gradually detoxify and restore their population growth after 96 h. Moreover, the toxicity of enrofloxacin to the four algae increased with time. The toxicity of ciprofloxacin hydrochloride to T. obliquus and S. quadricauda increased, and the toxicity to M. aeruginosa and C. vulgaris decreased. The recovery degree of ciprofloxacin hydrochloride was at least 39% higher than that of enrofloxacin. Low concentrations of enrofloxacin (<36mg/L) provoked a higher density of M. aeruginosa than that of the control group after 10 days of exposure. In this case, the algal density of M. aeruginosa could be more than 107 cells/L when the concentration of enrofloxacin was below 36mg/L.

FT-ICR MS characterization of bio-binders for road pavement from HTL of microalgae residues

Hydrothermal liquefaction (HTL) of microalgae-derived feedstocks into a bio-binder was investigated in the absence or presence of a catalyst. The resulting products of HTL of Scenedesmus species (sp.) residues present rheological properties close to those of a petroleum-derived bitumen. The chemical composition of the biobinder was analysed by two-dimensional gas chromatography (GCxGC-MS), gel permeation chromatography (GPC), and negative and positive-ion laser desorption/ionization FT-ICR MS to provide a complementary analysis of the biobinder and understanding of the role of catalysts. A detailed description of the heavy nitrogen compounds contained in the biobitumen is given.

Advanced wastewater treatment process using algal photo-bioreactor associated with dissolved-air flotation system: A pilot-scale demonstration

This research explores the feasibility of using an algal photo-bioreactor as an integrated algal-bacterial treatment system combined with a dissolved air flotation (DAF) system for the deduction of COD, BOD5, TSS, TN and TP from primary treated wastewater (PTW). Isolated algae species of Anomoeoneis, Scenedesmus, Anabaena and Spirulina at fixed hydraulic retention time (HRT) of 16 h were used to conduct batch experiments to determine optimum conditions of pH, temperature, light intensity and mixing rate on the removal rates of contaminants. The optimum removal rates were studied at neutral pH, 25 °C, light intensity of 90 μmol m−2S−1 and 100 rpm mixing rate. A scaled-up pilot plant treatment system was designed, constructed and operated to evaluate the system performance to treat (0.1 L/min) of primary treated wastewater disposed of ZENIN WWTP-Giza, Egypt. The design criteria of the algal photo-bioreactor were acquired from the batch investigations. The plant was operated for 10 continuous days and the analytical analysis was performed twice a day at a fixed time. The DAF system was used to isolate the infiltrated algae from the system for cultivation and reuse purposes. The achieved results revealed the superior COD, BOD5, TSS, TN and TP removal percent reached in average 56.4%, 61%, 59.2%, 48.3% and 51.7% at 12 pm and 49.7%, 54.9%, 52.4%, 39% and 40.57% at 12 am, respectively. All data gained from experimental studies demonstrated the efficiency of using algal photo-bioreactor combined with DAF system as an effective wastewater treatment technique.

Nutritional Profiling and Preliminary Bioactivity Screening of Five Micro-Algae Strains Cultivated in Northwest Europe.

This study aimed to map the nutritional profile and bioactivities of five microalgae that can be grown in Northwest Europe or areas with similar cultivation conditions. Next to the biochemical composition, the in vitro digestibility of carbohydrates, proteins, and lipids was studied for Chlamydomonas nivalis, Porphyridium purpureum, Chlorella vulgaris, Nannochloropsis gaditana, and Scenedesmus species biomass. These microalgae were also assessed for their ability to inhibit the angiotensin-1-converting enzyme (ACE-1, EC 3.4.15.1), which is known to play a role in the control of blood pressure in mammals. Large differences in organic matter solubility after digestion suggested that a cell disruption step is needed to unlock the majority of the nutrients from N. gaditana and Scenedesmus species biomass. Significant amounts of free glucose (16.4–25.5 g glucose/100 g dry algae) were detected after the digestion of C. nivalis, P. purpureum, and disrupted Scenedesmus. The fatty acid profiles showed major variations, with particularly high Ω-3 fatty acid levels found in N. gaditana (5.5 ± 0.5 g/100 g dry algae), while lipid digestibility ranged from 33.3 ± 6.5% (disrupted N. gaditana) to 67.1 ± 11.2% (P. purpureum). C. vulgaris and disrupted N. gaditana had the highest protein content (45–46% of dry matter), a nitrogen solubility after digestion of 65–71%, and the degree of protein hydrolysis was determined as 31% and 26%, respectively. Microalgae inhibited ACE-1 by 73.4–87.1% at physiologically relevant concentrations compared to a commercial control. These data can assist algae growers and processors in selecting the most suitable algae species for food or feed applications.

The Structural Difference of Isobaric N-Glycans of Two Microalgae Samples Reveals Taxonomic Distance.

Microalgae of the Chlorella clade are extensively investigated as an environmentally friendly source of renewable biofuels and high-value nutrients. In addition, essentially unprocessed Chlorella serves as wholesome food additive. A recent study on 80 commercial Chlorella preparations revealed an unexpected variety of protein-linked N-glycan patterns with unprecedented structural features, such as the occurrence of arabinose. Two groups of products exhibited a characteristic major N-glycan isobaric to the Man2GlcNAc2XylFuc N-glycan known from pineapple stem bromelain, but tandem mass spectrometry (MS/MS) analysis pointed at two types of N-glycan different from the bromelain structure, as well as from each other. Here we report the exact structures of these two novel N-glycan structures, elucidated by nuclear magnetic resonance spectroscopy and MS/MS, as well as on their phylogenetic context. Despite their humble size, these two N-glycans exhibited a very different design with structural features unrelated to those recently described for other Chlorella-clade strains. The major glycans of this study presented several novel structural features such as substitution by arabinose or xylose of the internal N-acetylglucosamine, as well as methylated sugars. ITS1-5.8S-ITS2 rDNA barcode analyses revealed that the xylose-containing structure derived from a product primarily comprising Scenedesmus species, and the arabinose-containing glycan type related to Chlorella species (SAG211-34 and FACHB-31) and to Auxenochlorella. This is another example where characteristic N-glycan structures distinguish phylogenetically different groups of microalgae.

A Hybrid Biological-Adsorption Approach for the Treatment of Contaminated Groundwater Using Immobilized Nanoclay-Algae Mixtures

Mixing the Scenedesmus species with nanoclay and immobilizing in sodium alginate was evaluated as a sustainable treatment method for removing nitrate, atrazine, and metals from groundwater. Gel beads containing the hybrid mixture removed 100% of 10 mg/L N nitrate and 98% of 100 µg/L atrazine from synthetic groundwater in three days. The optimal amount of nanoclay was found to be 0.30 mg per bead. The experimental data fit well into a Freundlich adsorption isotherm and followed pseudo first-order kinetics. When tested in actual groundwater, 91% of nitrate and 100% of Cr, Se, and V were eliminated in three days without need for any nutrients or carbon source. Immobilizing algal beads embedded with nanoclay is a natural, low-cost alternative for groundwater treatment. The gel beads can be reused for at least two cycles without a compromise in performance. They are water-insoluble, easy to harvest, and offer high removal efficiency.

Single nucleotide polymorphism-mismatch primer development for rapid molecular identification of selected microalgal species

Microalgae have been a great source for food, cosmetic, pharmacological, and biofuel production. The adoption of effective diagnostic assays for monitoring all stages of algal cultivation has become essential. In addition to microscopy identification, molecular assays can aid greatly in the identification and monitoring of algal species of interest. In this study the 18S ribosomal RNA (rRNA) sequences of 12 microalgal species and/or strains were used to design algal identification primers. Sequence alignment revealed five highly variable regions and multiple unique single nucleotide polymorphisms (SNPs). To design target algae specific primers, a SNP identified as unique to each microalgal species was incorporated into the 3’-terminus of forward and reverse primer pairs, respectively. To further enhance primer specificity, transverse mutation was introduced into each primer at the third base upstream of the respective SNP. The SNP-mismatch primer pairs yield size-specific amplicons, enabling the rapid molecular detection of 12 microalgae by circumventing cloning and sequencing. To verify the primer specificity, two SNP-mismatch primer pairs designed for Chlorella sorokiniana DOE1412 and wildtype species of Scenedesmus were tested in the outdoor reactor run inoculated with C. sorokiniana DOE1412. The primer pairs were able to identify C. sorokiniana DOE1412 as well as the environmental invader Scenedesmus sp. Furthermore, the “relative concentration” of two microalgae was accessed throughout the entire cultivation run. The use of SNPs primers designed in this study offers a cost-effective, easy to use alternative for routine monitoring of microalgal cultures in laboratories, in scale-ups, and in cultivation reactors, independent of the production platform.

Sustainable Production of Reclaimed Water by Constructed Wetlands for Combined Irrigation and Microalgae Cultivation Applications

Considering the increasing pressure on freshwater resources due to the constant increase in water consumption and insufficient wastewater control and treatment, recovering wastewater is a path to overcoming water scarcity. The present work describes the potential of reusing treated wastewater (reclaimed water) for irrigation and production of microalgae biomass in an integrated way, through experimental evaluation of plant and microalgae growth, and creation of an application model. First, two parallel experiments were conducted to evaluate the use of reclaimed water produced by a constructed wetland filled with a mix of solid waste: the irrigation of a set of small pots filled with soil and planted with Tagetes patula L., and the cultivation of microalgae Chlorella sp. and a mixed microalgae population with predominant species of the genus Scenedesmus sp. in shaken flasks and tubular bubble column photobioreactors. Results indicated no negative effects of using the reclaimed water on the irrigated plants and in the cultivated microalgae. The growth indicators of plants irrigated with reclaimed water were not significantly different from plants irrigated with fertilized water. The growth indicators of the microalgae cultivated with reclaimed water are within the range of published data. Second, to apply the results to a case study, the seasonal variability of irrigation needs in an academic campus was used to propose a conceptual model for wastewater recovery. The simulation results of the model point to a positive combination of using reclaimed water for the irrigation of green spaces and microalgae production, supported by a water storage strategy. Water abstraction for irrigation purposes can be reduced by 89%, and 2074 kg dry weight microalgae biomass can be produced annually. Besides the need for future work to optimize the model and to add economical evaluation criteria, the model shows the potential to be applied to non-academic communities in the perspective of smarter and greener cities.

Algal flora Saint-Petersburg water bodies

In the spring and summer of 2019, 43 lakes and ponds of Saint Petersburg were surveyed. The algal flora contains 110 species of algae of the following divisions: Cyanophyta =Cyanobacteria=Cyanoprokaryota – 18, Cryptophyta – 1, Dinophyta – 9, Euglenophyta – 11, Chlorophyta – 57 Streptophyta - 2, Ochrophyta (classes Chrysophyceae – 2, Bacillariophyceae – 10). For the majority of the found species, the saprobity mark and saprobic index were specified. The most diverse group in the water bodies of Saint Petersburg is green algae, which includes single and coenobial algae of the coccoid and monad tallom organization, which are well adapted to vegetation in the water column. In most reservoirs at spring Monoraphidium arcuatum (Korshikov) Hindák and Monoraphidium contortum (Thuret) Komárkova-Legnerova, species of genera Scenedesmus, including species of the genera Desmodesmus and Tetradesmus actively vegetate. In the reservoirs of Saint Petersburg, the leading positions are taken by euglenic algae, especially species of genera Trachelomonas (Trachelomonas hispida (Perty) F. Stein, Trachelomonas volvocina (Ehrenberg) Ehrenberg). Summer phytoplankton differs in the more vigorous development of blue-green algae-especially such species as Dolichospermum flosaquae (Brébisson ex Bornet & Flahault) P. Wacklin, L. Hoffmann & Komárek, Dolichospermum spiroides (Klebhan) Wacklin, L. Hoffmann & Komárek. The species of β- mesosaprobic dominate. There are also α-mesosaprobes and species with a wide range of existence in reservoirs with different degrees of organic content. Biological analysis of the surveyed water bodies shows that their condition is satisfactory.

Immobilized algae-based treatment of herbicide-contaminated groundwater.

Scenedesmus species, immobilized on alginate gel, was found effective in removing nitrate, atrazine, magnesium, phosphorus, zinc, oxadiazon, and triallate from groundwater in a continuous flow reactor. The laboratory-scale experiments with synthetic groundwater, made of 8.8mg/L NO3 -N and 90µg/L atrazine, were performed at a hydraulic retention time of 7days and the temperatures of 20 and 35°C. The highest uptake of nitrate and atrazine was observed at 20°C (97% and 70%, respectively). When tested in actual groundwater, 92% of nitrate, 100% of magnesium, 99.9% of phosphorus, and 92% of zinc were successfully removed at the end of 29days' treatment operations. The algal beads removed 100% of oxadiazon and triallate in the first 10days, but some of the herbicides diffused back into the solution toward the end of the treatment process. PRACTITIONER POINTS: Immobilized algae-alginate beads can remove nitrate, atrazine, oxadiazon, and triallate from groundwater in continuous flow reactor. The uptake rate of nitrate and atrazine is higher in room temperature (20°C). Same algae beads could be reused for herbicide uptake for the average of 10days. The immobilized system is a natural sustainable alternative that can be used in groundwater pump and treat.