“…Algae cells were counted on a compound microscope in the counting chamber after preservation in Lugol's iodine. Cell counts were carried out according to the method used by Burrini et al (7).…”
Section: Methodsmentioning
confidence: 99%
“…So, in drinking water treatment, preoxidation and/or postoxidation are often used to inactivate the algae. The chemicals such as chlorine, chlorine dioxide (2), ozone (1,6,7), potassium permanganate (8), or hydrogen peroxide (8) could be used as oxidants to treat these water quality problems. These oxidants do not physically eliminate algal cells but favor the oxidation process, thus inactivating any algae that survive the preceding treatment phases and their metabolites (7).…”
Section: Introductionmentioning
confidence: 99%
“…The chemicals such as chlorine, chlorine dioxide (2), ozone (1,6,7), potassium permanganate (8), or hydrogen peroxide (8) could be used as oxidants to treat these water quality problems. These oxidants do not physically eliminate algal cells but favor the oxidation process, thus inactivating any algae that survive the preceding treatment phases and their metabolites (7). They are not only used to control algae but also used as aids for the oxidation of natural and synthetic organics, oxidation of inorganics, color removal, and taste and odor control (9,10).…”
Algae in waters often bring about influence in drinking water supplies. In this study, an electrochemical tube employing titanium coated with RuO2 as anode was constructed for inactivation of cyanobacteria (often called bluegreen algae) Microcystis aeruginosa. Suspensions containing M. aeruginosa (2-4 x 10(9) L(-1)) were exposed to current densities ranging from 1 to 10 mA cm(-2) in a detention time of 52 min. The variations of cell density, chlorophyll-a, optical density, pH, and conductivity were examined during the treatment. After 3.5 min the population of M. aeruginosa dropped rapidly and was reduced from 3 x 10(9) to 0.6 x 10(9) L(-1) after 52 min at current densities from 5 to 10 mA cm(-2). The cell density and optical density of M. aeruginosa decreased proportionally to the current density and the detention time. Scanning electron microscopy investigation of algae revealed surface damage and apparent leakage of intracellular contents after electrochemical cycling process. Due to the damage of cells, the chlorophyll-a released from the cells was degraded by electrochemical oxidation. The removal rate of chlorophyll-a could reach 96% at the current density of 10 mA cm(-2). Electrochemical treatment caused minor variation of pH values and conductivity of the suspensions. After electrochemical cycling processes, the optical density at 680 nm of algal cell suspensions remained below 0.1 after 6 days, and it showed that cells had no potential to survive and grow. The results implicated that the inactivation of M. aeruginosa was successfully performed by the electrochemical treatment, and it made the algal cells lose ability to survive, demonstrating the potential of such an alternative process for efficient water purification.
“…Algae cells were counted on a compound microscope in the counting chamber after preservation in Lugol's iodine. Cell counts were carried out according to the method used by Burrini et al (7).…”
Section: Methodsmentioning
confidence: 99%
“…So, in drinking water treatment, preoxidation and/or postoxidation are often used to inactivate the algae. The chemicals such as chlorine, chlorine dioxide (2), ozone (1,6,7), potassium permanganate (8), or hydrogen peroxide (8) could be used as oxidants to treat these water quality problems. These oxidants do not physically eliminate algal cells but favor the oxidation process, thus inactivating any algae that survive the preceding treatment phases and their metabolites (7).…”
Section: Introductionmentioning
confidence: 99%
“…The chemicals such as chlorine, chlorine dioxide (2), ozone (1,6,7), potassium permanganate (8), or hydrogen peroxide (8) could be used as oxidants to treat these water quality problems. These oxidants do not physically eliminate algal cells but favor the oxidation process, thus inactivating any algae that survive the preceding treatment phases and their metabolites (7). They are not only used to control algae but also used as aids for the oxidation of natural and synthetic organics, oxidation of inorganics, color removal, and taste and odor control (9,10).…”
Algae in waters often bring about influence in drinking water supplies. In this study, an electrochemical tube employing titanium coated with RuO2 as anode was constructed for inactivation of cyanobacteria (often called bluegreen algae) Microcystis aeruginosa. Suspensions containing M. aeruginosa (2-4 x 10(9) L(-1)) were exposed to current densities ranging from 1 to 10 mA cm(-2) in a detention time of 52 min. The variations of cell density, chlorophyll-a, optical density, pH, and conductivity were examined during the treatment. After 3.5 min the population of M. aeruginosa dropped rapidly and was reduced from 3 x 10(9) to 0.6 x 10(9) L(-1) after 52 min at current densities from 5 to 10 mA cm(-2). The cell density and optical density of M. aeruginosa decreased proportionally to the current density and the detention time. Scanning electron microscopy investigation of algae revealed surface damage and apparent leakage of intracellular contents after electrochemical cycling process. Due to the damage of cells, the chlorophyll-a released from the cells was degraded by electrochemical oxidation. The removal rate of chlorophyll-a could reach 96% at the current density of 10 mA cm(-2). Electrochemical treatment caused minor variation of pH values and conductivity of the suspensions. After electrochemical cycling processes, the optical density at 680 nm of algal cell suspensions remained below 0.1 after 6 days, and it showed that cells had no potential to survive and grow. The results implicated that the inactivation of M. aeruginosa was successfully performed by the electrochemical treatment, and it made the algal cells lose ability to survive, demonstrating the potential of such an alternative process for efficient water purification.
“…Total coverage of the water surface with algae can restrict sunlight penetration and limit the production of oxygen and food items necessary for fish growth. Traditionally, physical and chemical treatment methods have been applied to the removal of algae from the water surface [1][2][3]. However, because of the high costs and the significant risk of environmental damage of these techniques, the development of more economical and ecologically favorable methods has attracted increasing attention.…”
The capabilities of TiO 2 -coated materials for the inactivation and removal of algae were investigated. As supports for TiO 2 , non-woven fabric and Ni foam were chosen. To evaluate the ability of noble metal cocatalyst additions to facilitate the photocatalytic algal inhibition of TiO 2 -coated materials, Pd nanoparticles were deposited on non-woven fabric-supported TiO 2 by photoelectrochemical deposition. The fabric-supported Pd/TiO 2 showed higher inhibition activity for algal growth compared to the fabricsupported TiO 2 without Pd. In addition, Ni foam-supported TiO 2 also showed high inhibition activity, both in laboratory-scale tests and open-air tests. Therefore, TiO 2 -coated materials with suitable coating methods such as the use of cocatalysts or large surface area can substantially inhibit algal growth. The ability of the TiO 2 -coated materials to inhibit algae correlated well with their activity for the photocatalytic decolorization of methylene blue, suggesting a nonspecific mechanism in the breakdown of cellular structures.
“…Treatment of drinking water source with copper sulfate is another method to inactivate HABs (Haughey et al, 2000). Preoxidation with chlorine dioxide and coagulation–flocculation and sedimentation by adding powdered activated carbon have also been used for algae inactivation (Burrini et al, 2000). However, these methods need the addition of chemicals that are harmful to the environment (Green, 2019).…”
Frequent outbreaks of harmful algal blooms (HABs) have brought adverse impacts on human health, economic viability, and recreational activities in many communities in the United States. Cyanobacteria (or blue‐green algae) blooms are the most common type of HABs in surface water. Current bactericides for controlling the blooms are disadvantageous due to the recycling difficulty. In this study, an innovative magnetic nanomaterial―γFe2O3/TiO2 nanoparticle—was used to inactivate toxic cyanobacteria species found in a lake in Southern Illinois that frequently experienced HABs. Cyanotoxin genes of mcy, nda, cyr, and sxt were used for targeting microcystin‐, nodularin‐, cylindrospermopsin‐, and saxitoxin‐producing cyanobacteria, respectively, by quantitative polymerase chain reaction (PCR) method. It was found that the concentration of chlorophyll a presents a strong correlation (R2 = 0.6024) with the gene copy obtained from 16S rRNA targeted for all cyanobacteria, but not with that from individual toxigenic cyanobacteria. The inactivation efficiencies of the nanomaterials under visible light were as high as 5‐log and 1‐log for cyanobacteria species containing mcyE/ndaF and sxtA genes, respectively, an improvement over the treatment under darkness. These nanomaterials can be recycled by their magnetic properties for reuse. Communities susceptible to HAB outbreaks are expected to benefit from the developed method for mitigating the blooms.
Practitioner points
Lab‐made γFe2O3/TiO2 nanoparticles can be used to inactivate microcystin/nodularin‐ and saxitoxin‐producing cyanobacteria species.
qPCR method can be used for targeting toxic cyanobacteria; Chl a cannot be used as a standalone indicator for HABs.
Better inactivation efficiency under visible light indicated possible application of the technology under sunlight for HAB mitigation from surface water.
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