Mar 2019 DOI 10.14302/issn.2691-3208.ijli-19-2647
Kobayashi NaotoCorresponding author
Department of Innovative Energy Science and Engineering, Graduate school of Engineering, Chubu University, Japan
In this study, basic cultivation experiments were performed on microalgae Desmodesmus sp, then, the experiment results were deductively expanded, and the use of paddy in the off-season for farmers is advocated. As a result of the continuous culture experiments using 100 mL test tubes, 101.3 mg dry biomass was harvested in the aeration culture using the BG-11 medium. In the aeration culture with mixing CO2, the maximum harvest was obtained under the 10%-CO2 concentration. Considering about CO2 concentration, the condition of 1%-CO2 was superior in CO2 use efficiency. Based on the changes in the pH of the medium, algae such as Desmodesmus sp exchanges ions between the inside of the cell and the surrounding environment, and changes the surrounding environment in order to adapt themselves. In the proforma calculation of second crops in paddy fields, 26.4 million tons dry biomass is harvested in 120 days long of culture a year. Considering that the harvested dry biomass amount, 187 × 106 GJ power energy is obtained by burning them. This amount of energy corresponds to about 5.2% of total electricity.
Oct 2021 DOI 10.14302/issn.2641-7669.ject-21-3970
Dias Toledo Arruda-Neto JoaoCorresponding author
Linear Accelerator Laboratory, Physics Institute, University of Sao Paulo, São Paulo-SP, Brazil
Microcystins (MCs) are toxins profusely synthesized by cyanobacteria, causing livestock poisonings and endangering human health. We design and execute an experiment to investigate the attenuation (degradation) of microcystins by exposing them to gamma radiation and electron beams at doses of 0 (control), 3, 5, 10 and 15 kGy. The experimental conditions simulate microcystin contamination of aquatic environments; we thus consider (1) microcystins inside whole cells and extracellular dissolved in water, simulated by non-sonicated and sonicated cells, respectively, and (2) two acute microcystin concentrations within water. Toxicity tests of Microcystis aeruginosa detected immobilization (i.e., paralysis) of Ceriodaphniasilvestrii exposed to aqueous crude extracts of irradiated and non-irradiated M. aeruginosa (NPLJ-4 strain) at concentrations of 45 and 90 mg.L-1 (mg dry weight of freeze-dried material), and the results were analyzed using the Trimmed Spearman-Karber statistical program to obtain 48-h EC50, the average effective concentration causing immobility in 50% of organisms after 48 hours. We conclude that electron beams are effective physical agents for toxin attenuation (degradation) and reach 100% effectiveness at 5 kGy and above; their efficiency is two orders of magnitude greater than that of gamma radiation. This new body of information contributes to (1) remediating environmental water sources; (2) designing water/wastewater treatment facilities; (3) combatting chronic microcystin environmental contamination; and (4) inspiring further studies to promote the use of biomonitors (e.g., Cladocerans) to detect and evaluate microalgae contamination.