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A Study on Wastewater Treatment by Electrochemical Treatment with Various Electrode Interval

전극 간격에 따른 전기화학적 처리를 통한 폐수처리에 관한 연구

  • Song, Ju Yeong (Division of Civil, Environmental and Chemical Engineering, Changwon Nat. Univ.)
  • 송주영 (창원대학교 토목환경화공융합공학부)
  • Received : 2019.05.13
  • Accepted : 2019.06.25
  • Published : 2019.06.30

Abstract

A new wastewater treatment system was developed to remove nitrate nitrogen and phosphorus in synthetic wastewater through electrochemical treatment. Higher removal efficiencies of nitrate nitrogen were obtained as the current density increased. Higher nitrate removal efficiencies were obtained when the switching interval was 1 min. The total phosphorus removal rate according to the current density was found to be over 90% without being greatly affected by the change in current density and interval, and the total removal rate increased with increasing switching time (1 min interval). On the other hand, COD was not treated by electrochemical treatment, but rather increased as the electrode eluted. Also, the consumption rate of the electrode was smaller as the switching interval was shorter. Finally, removal efficiencies of 98.1% of nitrate and 90% of phosphorus were obtained through electrochemical treatment (current density $50mA/cm^2$, switching interval 1 min, flow rate 540 mL/min).

전기화학적 처리를 통해 합성폐수 내의 질산성 질소, 인을 제거하는 새로운 폐수처리 공정 시스템 개발을 위한 연구를 수행하였다. 전류밀도에 따른 제거율은 전류밀도가 높아질수록 질산성 질소의 높은 제거효율을 얻었고, 전극 스위칭시간에 따른 $NO_3^-$ 제거율은 스위칭 간격이 1 min일 때 높은 질산성 질소 제거효율을 얻었다. 전류밀도에 따른 총인 제거율은 전류밀도와 간격의 변화에 크게 영향을 받지 않으면서 90%이상 처리되는 것으로 나타났고, 스위칭시간(1 min간격)의 증가에 따른 총인 제거율은 증가한 것으로 나타났다. 반면 COD의 경우는 전기화학적 처리를 통해서는 처리되지 않는 것으로 나타났으며 오히려 전극이 용출되면서 증가하는 결과를 얻었다. 또한, 전극의 소모율은 스위칭 간격이 짧을수록 적은 것으로 나타났다. 최종적으로 전기화학적 처리(전류밀도 $50mA/cm^2$, 스위칭 간격 1 min, 유량 540 mL/min)를 통해 질소 98.1%, 인 90% 이상의 제거 효율을 얻을 수 있었다.

Keywords

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Fig 1. Schematic diagram of experimental apparatus.

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Fig. 2. Nitrate removal efficiency in synthetic wastewater solution. Applied density=20, 30, 40, 50, 60, 70 mA/cm2, eletrolysis time=1h, pH=8.5 at room temperature.

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Fig. 3. Phosphorus removal efficiency by applied current density 20, 30, 40, 50, 60, 70 mA/cm2, eletrolysis time=1h, pH=8.5 at room temperature.

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Fig. 4. COD concentration variation by current density, applied density=20, 30, 40, 50, 60, 70 mA/cm2, eletrolysis time=1h, pH=8.5 at room temperature.

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Fig. 5. Nitrate removal efficiency of synthetic wastewater solution by switching time and electrode interval, eletrolysis time=1h, pH=8.5 at room temperature.

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Fig. 6. Phosphorous removal efficiency of Zinc electrode plate in synthetic wastewater solution by switching time eletrolysis time=1h, pH=8.5 at room temperature.

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Fig. 7. COD concentration variation by switching time applied density= 50 mA/cm2, eletrolysis time=1h, pH=8.5 at room temperature.

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Fig. 8. Zinc electrode plate mass change by switching time at electrode interval of 2 cm , applied density=60 mA/cm2, eletrolysis time=1h, pH=8.5 at room temperature.

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