Electrochemical ammonia removal and disinfection of aquaculture wastewater using batch and flow reactors incorporating PtRu/graphite anode and graphite cathode

Qing, Geletu; Anari, Zahra; Abolhassani, Mojtaba; Foster, Shelby L.; Matlock, Marty; Greenlee, Lauren F.

doi:10.1016/j.aquaeng.2021.102155

Cited by 23 publications

(19 citation statements)

References 66 publications

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“…Nitrate was not quantified during the experiments. However, our previous laboratory studies indicated that nitrogen gas rather than nitrate is the major product of ammonia oxidation in aquaculture wastewater (Qing, Anari, Abolhassani, et al, 2021). Further, as free chlorine and combined chlorine are powerful disinfecting agents, the disinfection of coliforms and E .…”

Section: Resultsmentioning

confidence: 99%

“…The current efficiency for chloride oxidation decreases at lower chloride concentrations due to the faster depletion of chloride ions at the electrode surface (Zhang et al, 2018). When the applied current density (i.e., the applied DC voltage) decreases, a significant decrease in the ammonia removal efficiency was observed (Qing, Anari, Abolhassani, et al, 2021), making the process unrealistic in terms of ammonia removal.…”

Section: Resultsmentioning

confidence: 99%

“…A detailed description of the flow cell design has been given in our previous publications (Qing, Anari, Abolhassani, et al, 2021; Qing, Anari, Foster, et al, 2021). Briefly, the flow cell consists of anode and cathode half‐cells, and in each of them, the electrode was fixed in an HDPE frame using 100% silicone sealant (Polyseamseal, Loctite) (Figure ).…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the storing and transportation of highly reactive chemical disinfectants such as chlorine gas and sodium hypochlorite are not necessary. In our previous works, we developed electrochemical flow cells for disinfection/ammonia removal from aquaculture wastewater and disinfection of irrigation water (Qing, Anari, Abolhassani, et al, 2021; Qing, Anari, Foster, et al, 2021). Using a flow cell assembled with PtRu/graphite anode and graphite cathode, ammonia was efficiently removed from aquaculture wastewater via indirect oxidation (Qing, Anari, Abolhassani, et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Microorganisms, in particular, are quickly inactivated during frozen storage (Gao et al, 2006; Semanchek & Golden, 1998). Therefore, we carried out field tests on disinfection/ammonia removal from aquaculture wastewater and disinfection of irrigation water using the electrochemical flow cells designed and tested in our previous laboratory studies (Qing, Anari, Abolhassani, et al, 2021; Qing, Anari, Foster, et al, 2021). We are reporting on two topics because both of them depend on the anodic oxidation of chloride ions to chlorine, which in turn oxidizes ammonia to nitrogen gas and inactivates pathogens.…”

Section: Introductionmentioning

confidence: 99%

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Disinfection/ammonia removal from aquaculture wastewater and disinfection of irrigation water using electrochemical flow cells: A case study in Hawaii

Qing

Foster

Anari

et al. 2021

Water Environment Research

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This field case study reports findings on disinfection/ammonia removal from aquaculture wastewater and disinfection of irrigation water carried out at an aquaculture farm and two irrigation locations in Hawaii. We used a flow cell incorporating PtRu/graphite anode and graphite cathode for the disinfection/ammonia removal from aquaculture wastewater, and a flow cell assembled with graphite plates as both anode and cathode for the disinfection of irrigation water. The removal of ammonia followed the indirect oxidation mechanism mediated by free chlorine electro‐generated at the PtRu/graphite anode. Ammonia removal rate increased with the increase in NaCl concentration, applied current density, or flow rate. The disinfection of aquaculture wastewater can be readily achieved due to the presence of highly germicidal free chlorine species. The disinfection of irrigation water was realized without the addition of chemicals. The disinfection mechanism was attributed to the formation of free chlorine from the anodic oxidation of chloride ions naturally occurring in the water sources. The disinfection efficiency decreased with increasing organic matter concentration. In addition to the flow cell approach, we also successfully demonstrated the disinfection of irrigation water by adding electrolyzed NaCl solution or purging with a mixture of air and chlorine gas, both of which were generated on‐site. Practitioner points Field case study on disinfection/ammonia removal from aquaculture wastewater and disinfection of irrigation water was carried out in Hawaii. Electrochemical flow cell assembled with PtRu/graphite anode and graphite cathode effectively removes ammonia from aquaculture wastewater. Ammonia removal proceeds via the indirect oxidation mechanism mediated by free chlorine electro‐generated at the PtRu/graphite anode. Electrochemical flow cell assembled with commercial graphite electrodes enables fast disinfection of coliform bacteria and E. coli. The primary disinfection mechanism is through chlorine species electro‐generated from chloride oxidation at the graphite anode.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%