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A New Treatment Strategy for Inactivating Algae in Ballast Water Based on Multi-Trial Injections of Chlorine.

Sun J, Wang J, Pan X, Yuan H - Int J Mol Sci (2015)

Bottom Line: Ships' ballast water can carry aquatic organisms into foreign ecosystems.In addition to other substantial approaches, a new strategy for inactivating algae is proposed based on the developed ballast water treatment system.The different experimental parameters are studied including the injection times and doses of electrolytic products.

View Article: PubMed Central - PubMed

Affiliation: College of Marine Engineering, Dalian Maritime University, Dalian 116026, China. golden_sun@dlmu.edu.cn.

ABSTRACT
Ships' ballast water can carry aquatic organisms into foreign ecosystems. In our previous studies, a concept using ion exchange membrane electrolysis to treat ballast water has been proven. In addition to other substantial approaches, a new strategy for inactivating algae is proposed based on the developed ballast water treatment system. In the new strategy, the means of multi-trial injection with small doses of electrolytic products is applied for inactivating algae. To demonstrate the performance of the new strategy, contrast experiments between new strategies and routine processes were conducted. Four algae species including Chlorella vulgaris, Platymonas subcordiformis, Prorocentrum micans and Karenia mikimotoi were chosen as samples. The different experimental parameters are studied including the injection times and doses of electrolytic products. Compared with the conventional one trial injection method, mortality rate time (MRT) and available chlorine concentration can be saved up to about 84% and 40%, respectively, under the application of the new strategy. The proposed new approach has great potential in practical ballast water treatment. Furthermore, the strategy is also helpful for deep insight of mechanism of algal tolerance.

No MeSH data available.


Schematic diagram of the ballast water treatment system. E1—electrolyzer; TK1—low concentration lye tank; TK2—high concentration lye tank; TK3—seawater tank; TK4—gas-liquid separator tank; TK5—Erlenmeyer flask; P1 P2—seawater pump; A–I—stop valve, a,c—inlet, b,d—outlet.
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ijms-16-13158-f006: Schematic diagram of the ballast water treatment system. E1—electrolyzer; TK1—low concentration lye tank; TK2—high concentration lye tank; TK3—seawater tank; TK4—gas-liquid separator tank; TK5—Erlenmeyer flask; P1 P2—seawater pump; A–I—stop valve, a,c—inlet, b,d—outlet.

Mentions: Based on the above-mentioned principle of ion exchange membrane electrolysis, a new ballast water treatment system is presented in this paper. The schematic diagram of the presented ion-exchange membrane electrolysis system is shown in Figure 6. It is mainly composed of 14 parts which are: electrolyzers, magnetic drive pumps, magnetic circulation pumps, water storage tanks, cathode gas-liquid separator tanks, brine circulation tanks, anode gas-liquid separation tanks, glass rotor flowmeters, U-shaped pressure gauges, temperature control instruments, high frequency direct current (DC) power supplies, electric heaters, pressure gauges and thermometers, respectively. The details of the components in the treatment system were shown in Table 2. Seawater will be pumped in the electrolyzer from the bottom of electrolytic anode compartment (position c in Figure 6). The solution containing a low concentration of NaOH is pumped in the electrolyzer from the bottom of the cathode compartment (position a in Figure 6). After electrolysis, the available chlorine solution flows from the top of the anode compartment (position d in Figure 6) to the ballast water tank. The chlorine solution is used for ballast water treatment. The product of electrolytic cathode (high concentration NaOH) outflows from the top of the cathode compartment (position b in Figure 6) to the high concentration lye tank. The concentration of NaOH solution used in the experiments was 15%, the flowrate of the low concentration NaOH solution was 40 L/h, the temperature at which the electrolysis took place was 75 °C. The Erlenmeyer flasks (500 mL/each) were used to simulate the ballast water tank, where the experiments of the microalgae treatments were conducted. Inactivation algal experiments are carried out when the electrolyzer is under the optimum operating condition. Referring to experiment results, the current density of 1.5 KA/m2 is found to be the best while the system is working under mentioned parameters. In addition, corresponding current 300 A, current efficiency 80%, cell voltage 4.27 V, available chlorine concentration 800 mg/L are also applied.


A New Treatment Strategy for Inactivating Algae in Ballast Water Based on Multi-Trial Injections of Chlorine.

Sun J, Wang J, Pan X, Yuan H - Int J Mol Sci (2015)

Schematic diagram of the ballast water treatment system. E1—electrolyzer; TK1—low concentration lye tank; TK2—high concentration lye tank; TK3—seawater tank; TK4—gas-liquid separator tank; TK5—Erlenmeyer flask; P1 P2—seawater pump; A–I—stop valve, a,c—inlet, b,d—outlet.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4490490&req=5

ijms-16-13158-f006: Schematic diagram of the ballast water treatment system. E1—electrolyzer; TK1—low concentration lye tank; TK2—high concentration lye tank; TK3—seawater tank; TK4—gas-liquid separator tank; TK5—Erlenmeyer flask; P1 P2—seawater pump; A–I—stop valve, a,c—inlet, b,d—outlet.
Mentions: Based on the above-mentioned principle of ion exchange membrane electrolysis, a new ballast water treatment system is presented in this paper. The schematic diagram of the presented ion-exchange membrane electrolysis system is shown in Figure 6. It is mainly composed of 14 parts which are: electrolyzers, magnetic drive pumps, magnetic circulation pumps, water storage tanks, cathode gas-liquid separator tanks, brine circulation tanks, anode gas-liquid separation tanks, glass rotor flowmeters, U-shaped pressure gauges, temperature control instruments, high frequency direct current (DC) power supplies, electric heaters, pressure gauges and thermometers, respectively. The details of the components in the treatment system were shown in Table 2. Seawater will be pumped in the electrolyzer from the bottom of electrolytic anode compartment (position c in Figure 6). The solution containing a low concentration of NaOH is pumped in the electrolyzer from the bottom of the cathode compartment (position a in Figure 6). After electrolysis, the available chlorine solution flows from the top of the anode compartment (position d in Figure 6) to the ballast water tank. The chlorine solution is used for ballast water treatment. The product of electrolytic cathode (high concentration NaOH) outflows from the top of the cathode compartment (position b in Figure 6) to the high concentration lye tank. The concentration of NaOH solution used in the experiments was 15%, the flowrate of the low concentration NaOH solution was 40 L/h, the temperature at which the electrolysis took place was 75 °C. The Erlenmeyer flasks (500 mL/each) were used to simulate the ballast water tank, where the experiments of the microalgae treatments were conducted. Inactivation algal experiments are carried out when the electrolyzer is under the optimum operating condition. Referring to experiment results, the current density of 1.5 KA/m2 is found to be the best while the system is working under mentioned parameters. In addition, corresponding current 300 A, current efficiency 80%, cell voltage 4.27 V, available chlorine concentration 800 mg/L are also applied.

Bottom Line: Ships' ballast water can carry aquatic organisms into foreign ecosystems.In addition to other substantial approaches, a new strategy for inactivating algae is proposed based on the developed ballast water treatment system.The different experimental parameters are studied including the injection times and doses of electrolytic products.

View Article: PubMed Central - PubMed

Affiliation: College of Marine Engineering, Dalian Maritime University, Dalian 116026, China. golden_sun@dlmu.edu.cn.

ABSTRACT
Ships' ballast water can carry aquatic organisms into foreign ecosystems. In our previous studies, a concept using ion exchange membrane electrolysis to treat ballast water has been proven. In addition to other substantial approaches, a new strategy for inactivating algae is proposed based on the developed ballast water treatment system. In the new strategy, the means of multi-trial injection with small doses of electrolytic products is applied for inactivating algae. To demonstrate the performance of the new strategy, contrast experiments between new strategies and routine processes were conducted. Four algae species including Chlorella vulgaris, Platymonas subcordiformis, Prorocentrum micans and Karenia mikimotoi were chosen as samples. The different experimental parameters are studied including the injection times and doses of electrolytic products. Compared with the conventional one trial injection method, mortality rate time (MRT) and available chlorine concentration can be saved up to about 84% and 40%, respectively, under the application of the new strategy. The proposed new approach has great potential in practical ballast water treatment. Furthermore, the strategy is also helpful for deep insight of mechanism of algal tolerance.

No MeSH data available.