Chlorophyll-a Removal Efficiency Research Articles

Effective removal of Microcystis aeruginosa and microcystins by integrated pre-oxidation and coagulation: an environmental and economical way

The frequent occurrence of cyanobacteria blooms has gained worldwide concern. The conventional pre-oxidation methods are not only less effective in removing Microcystis aeruginosa cells, but also tend to trigger secondary pollution with an inevitable release of intracellular organic matter. In this study, Fe2+/persulfate process was applied to generate sulfate radicals and simultaneously form in situ Fe (III) for integrated oxidation–coagulation, leading to a notable enhancement in M. aeruginosa removal without cell breakage and better control of microcystins. Results showed that the Fe2+/persulfate mass ratio of 1:1 and the FeSO4 dosage of 0.1 mmol/L were efficient in M. aeruginosa removal. With the optimal FeSO4 dosage, up to 90.1% of M. aeruginosa were removed intact with the cell zeta potential of − 0.814. After settling down of M. aeruginosa within 30 min, the chlorophyll-a removal efficiency reached 98.9% and microcystins decreased remarkably. Furthermore, the degradation of algal organic matters was significantly enhanced with a relatively lower residual Fe. Protein-like substances and dissolved microbial metabolites were preferentially oxidized. The cell lysis only occurred to a small number of M. aeruginosa during the Fe2+/persulfate process, preventing from the environmental risk posed. This work demonstrates that an appropriate Fe2+/persulfate ratio and FeSO4 addition is a feasible and promising method for removing M. aeruginosa in an environmental-friendly and cost-effective way.

Enhancement of simultaneous algicidal and denitrification of immobilized Acinetobacter sp. J25 with magnetic Fe3O4 nanoparticles

In this study, immobilization technique was employed to improve simultaneous algicidal and denitrification of immobilized Acinetobacter sp. J25 with magnetic Fe3O4 in eutrophic landscape water. After 7days of operation, the maximum superoxide dismutase (SOD) activity (54.43Umg-1), nitrate removal efficiency (100% (0.2127mgL-1h-1)), and chlorophyll-a removal efficiency (89.71%) were obtained from the immobilized J25 with magnetic Fe3O4. The results suggest that immobilized J25 with magnetic Fe3O4 had better nitrogen removal efficiency and algicidal activity in eutrophic landscape water. High-throughput sequencing data profiled the strain J25 that was immobilized with magnetic Fe3O4 which changed the composition of the microbial community. The results indicated a novel concept of enhancing the algicidal and denitrification property of immobilized bacteria with magnetic Fe3O4 in eutrophic landscape water.

Lessons from the “Living-Filter”: An in-reservoir floating treatment wetland for phytoplankton reduction prior to a water treatment works intake

The Living-Filter is a novel floating emergent treatment wetland design that combines a hydroponic plant-bed with curtains and baffles. Thames Water Utilities and AquaticEngineering UK designed and installed the Living-Filter in Farmoor II reservoir, Oxfordshire, UK, in July 2012. The aim is to reduce the phytoplankton biomass prior to the water treatment works intake. The plant-bed (1mH×21mW×10mL) supports plants of Phragmites australis, Phalaris arundinacea and Carex acutiformis, with a combined system of curtains and baffles that aid the water to flow through the Living-Filter. All the water treated at the water treatment works has passed through the Living-Filter. The roots and a plastic fabric increase the surface area for biofiltration processes and the rhizosphere provides refuge for zooplankton. The research attempts to answer the question: Can the Living-Filter be used as an in-reservoir pre-treatment filtration process for reducing the phytoplankton biomass onto the water treatment works? Weekly surveys were carried out from July to October 2013 at sixteen sampling sites to measure physico-chemical and biological variables. The results for the first year of study show: (1) Soluble manganese, dissolved inorganic nitrogen and nitrites were significantly lower after treatment through the Living-Filter. (2) Chlorophyll-a removal efficiency was up to 45% during the first seven weeks. (3) Zooplankton abundance was more stable within the rhizosphere than in the water column. (4) The aerial shoots of the plants developed well, but based on root development only Phalaris and Carex should be considered for future designs. This work highlights the potential of the Living-Filter for phytoplankton reduction, but it also addresses questions that will further improve the system.

Removal Characteristics of Algae for Drinking Water Treatment Plant Using Natural Coagulants

In domestic rivers, eutrophication has led to frequent algae outbreaks. In this regard, this study investigated the algae removal characteristics according to coagulant dosage, light irradiation and coagulation nuclei dose to remove algae for drinking water treatment plant. The test results according to the natural coagulant dosage showed that as the coagulant dosage increased, chlorophyll-a and turbidity decreased, and chlorophyll-a removal efficiency ranged from 79.1% to 86.9%, and turbidity removal efficiency ranged from 74.6% to 88.2%, respectively. According to the results of test on the algae removal efficiency by light irradiation, chlorophyll-a removal efficiency increased from 17.9% to 34.4% as light intensity increased from 2000 lux to 10000 lux, and with an increase of light irradiation, the floating speed of algae turned out to be faster. The test results according to coagulation nuclei dose found that turbidity removal efficiency was 82.8%, and chlorophyll-a removal efficiency was 92.0% at the kaolin dose of 20 mg/L, which suggests that even a small dose of coagulation nuclei can further improve chlorophyll-a and turbidity removal efficiency.

Bacteriological control by Raoultella sp. R11 on growth and toxins production of Microcystis aeruginosa

Microcystis aeruginosa is a cyanobacterium that can cause harmful algal blooms (HABs) in freshwater bodies. In this study, the bacterium Raoultella sp. R11 was evaluated for its ability to control the growth of M. aeruginosa. Algal growth, denitrification activity, and toxin production were measured in the presence of various concentrations of Raoultella sp. R11. The algicidal effects of Raoultella sp. R11 were studied by measuring the zeta potential (surface charge), the activity of superoxide dismutase (SOD), and the concentrations of chlorophyll-a, dissolved organic matter, and microcystin-LR in algal cultures. The results suggested that chlorophyll-a removal, which indicates algal death, was correlated with the dose of Raoultella sp. R11. The zeta potential and denitrification activity decreased in the presence of bacteria in a dose-dependent manner. SOD activity was correlated with the inoculation dosage of Raoultella sp. R11. Using a 30% (v/v) dose of bacterial culture, the removal efficiency of chlorophyll-a was as high as 94.28% after 6days. In addition, dissolved microbial metabolites and humic acid were detected in high quantities whereas low quantities of protein-like substances and fulvic acid were found. Furthermore, toxic microcystin-LR produced by the algae was eliminated at up to 92.21% efficiency. A high denitrification rate (1.57mg NO3--NL−1h−1) and chlorophyll-a removal efficiency (73.12%) were observed within 6days at an inoculation dosage of 20% (v/v) of bacterial culture. Our findings indicated that Raoultella sp. R11 has a high potential for applications in simultaneously controlling M. aeruginosa and facilitating denitrification in freshwater bodies.

Coagulation performance and floc properties of Microcystis aeruginosa in the presence of humic acid

Coagulation removal of algae in raw water could be significantly affected by humic acid (HA). A series of jar-tests were conducted to investigate the coagulation performance with polyaluminum chloride and floc properties of Microcystis aeruginosa, a unicellular cyanobacteria, in the presence of HA. Meanwhile the coagulation mechanism was explored through the measurement of zeta potential of the supernatant. The results showed that an optimal removal efficiency of chlorophyll-a (Chl-a) was obtained at pH 8.0 with a low concentration of HA (2 mg/L) and at pH 6.0 with a high concentration of HA (8 mg/L). The floc structure was more compact and bigger-sized and the calculated fractal dimension (Df) was larger at maximum coagulation efficiency. The variation of Df was consistent with that of Chl-a removal efficiency under the same coagulation conditions. Charge neutralization was inferred to be the dominant mechanism to remove algal cells with low concentration of HA, while charge neutralization, gathering and the bridging process worked together to remove algal cells with a high concentration of HA. These results provide insight on how to achieve an optimal removal efficiency of algae in the presence of different concentrations of HA in water treatment.

Treatment of landscape water (LSW) by electrocoagulation process

Abstract The aim of this study was to utilize an aluminum electrocoagulation for the removal of algae and dissolved organic matter from landscape water, which was taken from an artificial lake and mixed with NaCl stock solutions to make its final concentration in the range of 0.5−3 g/l. The removal efficiency of chlorophyll-a, UV254 and turbidity was investigated under different current densities, charge loadings, conductivities (689–4684 μs cm−1) and pH values (3–11). The comparative removal performance together with sludge production by chemical coagulation and electrocoagulation were studied. With electrocoagulation, the optimal removal efficiencies of chlorophyll-a and UV254 were 81% and 56%, respectively, and the residual turbidity and sludge production were less than 2.6 NTU and 5.1% of the total solution (after 10 min sedimentation), respectively. In comparison, for chemical coagulation the optimum removals of chlorophyll-a and UV254 were 75% and 46%, respectively, and the residual turbidity and th...

Treatment of landscape water (LSW) by electrocoagulation process

Abstract The aim of this study was to utilize an aluminum electrocoagulation for the removal of algae and dissolved organic matter from landscape water, which was taken from an artificial lake and mixed with NaCl stock solutions to make its final concentration in the range of 0.5−3 g/l. The removal efficiency of chlorophyll-a, UV254 and turbidity was investigated under different current densities, charge loadings, conductivities (689–4684 μs cm−1) and pH values (3–11). The comparative removal performance together with sludge production by chemical coagulation and electrocoagulation were studied. With electrocoagulation, the optimal removal efficiencies of chlorophyll-a and UV254 were 81% and 56%, respectively, and the residual turbidity and sludge production were less than 2.6 NTU and 5.1% of the total solution (after 10 min sedimentation), respectively. In comparison, for chemical coagulation the optimum removals of chlorophyll-a and UV254 were 75% and 46%, respectively, and the residual turbidity and the sludge production were 3.6 NTU and 9.3% of the total solution (after 10 min sedimentation), respectively. The results demonstrated that electrocoagulation was an effective process for the removal of algae and dissolved organic matter from landscape water and exhibited advantages to chemical coagulation.

Isolation and evaluation of terrestrial fungi with algicidal ability from Zijin Mountain, Nanjing, China

Approximately 60 fungal isolates from Zijin Mountain (Nanjing, China) were screened to determine their algicidal ability. The results show that 8 fungi belonging to Ascomycota and 5 belonging to Basidiomycota have algicidal ability. Of these fungi, Irpex lacteus T2b, Trametes hirsuta T24, Trametes versicolor F21a, and Bjerkandera adusta T1 showed strong algicidal ability. The order of fungal chlorophyll-a removal efficiency was as follows: T. versicolor F21a > I. lacteus T2b > B. adusta T1 > T. hirsuta T24. In particular, T. versicolor F21a completely removed algal cells within 30 h, showing the strongest algicidal ability. The results also show that all 4 fungal species degraded algal cells through direct attack. In addition, most of the tested fungi from the order Polyporales of Basidiomycota exhibited strong algicidal activity, suggesting that most fungi that belong to this order have algicidal ability. The findings of this work could direct the search for terrestrial fungi for bloom control.

Zeta potential measurement on the surface of blue-green algae particles for micro-bubble process

Any kind of blue-green alga produces metabolites of musty substances and toxins. Therefore, it is necessary to remove the blue-green algae, and processing also including nutrient removal is desired for the water quality improvement of eutrophic lakes. The purpose of this study has been to investigate the possibility of a flotation system using a hybrid technique (chemical compounds and electrostatic bridge) applied to raw water containing phytoplankton with high pH of water, and to examine the zeta potential value of phytoplankton surface and the removal efficiency for phytoplankton, ammonia, nitrogen, and phosphoric acid. The results were as follows: firstly, zeta potential of M. aeruginosa particles was observed to achieve charge neutralization on their surface by adhesion of magnesium hydroxide precipitation with increasing pH. Secondly, maximum removal efficiency concerning chlorophyll-a was observed as 84%, and this efficiency was obtained in the condition of pH > 10, and magnesium hydroxide precipitation was observed. Thirdly, in the pH condition that the maximum removal efficiency of chlorophyll-a was obtained, the removal efficiency and the amount of decrease of NH(4)-N and PO(4)-P before and after the change of pH values were observed as 6.7% (0.04 mg-P/L) and 63.6% (0.07 mg-N/L), respectively.

好気性流動床生物ろ過法による湖水中の藻類除去特性

This paper describes a pilot plant study on algae removal of a fluidized bed biofilm reactor system for lake water treatment. The system does not need backwashing because the fluidized bed suffers no clogging. Moreover, the system uses dissolved oxygen in influent water for aerobic biological treatment without aeration equipment. Thus, this system is a low energy and easy maintenance way to purify eutrophic lake water. The system was operated continuously at a flow rate of 1500 m3·d-1 for 9 months at Tsuchiura Port in Lake Kasumigaura. In this study, chlorophyll-a and dissolved oxygen in both influent and effluent water were monitored continuously. In summer (August to September) when water bloom occurred, the average removal efficiency of chlorophyll-a was 64% at the average influent chlorophyll-a concentration of 137.8 μg·l-1. During the total experimental period (9 months), the average daily amount of removed chlorophyll-a was 40.3g·d-1 at the average influent chlorophyll-a concentration of 89.5 μg·l-1. By analyzing the relationship between the removed chlorophyll-a and the consumption of dissolved oxygen, it was estimated that almost all of algae trapped in the reactor was degraded biologically.