Inactivation of marine heterotrophic bacteria in ballast water by an Electrochemical Advanced Oxidation Process

Abstract

Seawater treatment is increasingly required due to industrial activities that use substantial volumes of seawater in their processes. The shipping industry and the associated management of a ship's ballast water are currently considered a global challenge for the seas. Related to that, the suitability of an Electrochemical Advanced Oxidation Process (EAOP) with Boron Doped Diamond (BDD) electrodes has been assessed on a laboratory scale for the disinfection of seawater. This technology can produce both reactive oxygen species and chlorine species (especially in seawater) that are responsible for inactivation. The EAOP was applied in a continuous-flow regime with real seawater. Natural marine heterotrophic bacteria (MHB) were used as an indicator of disinfection efficiency. A biphasic inactivation kinetic model was fitted on experimental points, achieving 4-Log reductions at 0.019 Ah L. By assessing regrowth after treatment, results suggest that higher bacterial damages result from the EAOP when it is compared to chlorination. Furthermore, several issues lacking fundamental understanding were investigated such as recolonization capacity or bacterial community dynamics. It was concluded that, despite disinfection processes being effective, there is not only a possibility for regrowth after treatment but also a change on bacterial population diversity produced by the treatment. Finally, energy consumption was estimated and indicated that 0.264 kWh·m are needed for 4.8-Log reductions of MHB; otherwise, with 0.035 kWh·m, less disinfection efficiency can be obtained (2.2-Log red). However, with a residual oxidant in the solution, total inactivation can be achieved in three days.

Comparing the inactivating efficacy of enteric bacteria in seawater treated with different configurations of continuous flow‐through ultraviolet devices: single‐pass and recirculation

“…The disinfection efficacy that is achieved by the recirculation device was lower than the efficacy using a collimated beam reactor. However, continuous devices applying the UV dose with one single pass more adequately reproduced the results that were obtained with collimated beam reactor, 30,62 except at higher doses when a tailing appeared in disinfection profiles using the collimated beam reactor. In this sense, a laboratory-scale prototype of a single pass UV reactor is a better approach to evaluate and optimize efficacy of real-scale UV devices as ballast water treatment systems or water pretreatment for biofouling control in desalination plants or cooling water systems in power plants.…”

Current to Clean Water – Electrochemical Solutions for Groundwater, Water, and Wastewater Treatment

“…Furthermore, present chloride ions can get oxidized to Cl 2 and function as oxidizing agent in addition to . OH [287].…”

“…Marine ballast waters are well suited for the application of AEOP, since conductivity is relatively high. Furthermore, present chloride ions can get oxidized to Cl 2 and function as oxidizing agent in addition to • OH .…”

Electrocoagulation Process in the Context of Disinfection Mechanism

“…For instance, researchers [35] suggested a fresh disinfection process that employs a tubular coaxial-electrode copper ionization cell to disinfect drinking water. The acquired findings depicted that this technique eliminated 6-log of Escherichia coli during 2 min of application at running voltage of 1.5 V. Scientists [36] employed advanced electrochemical cell that was furnished with boron doped diamond electrodes to disinfect seawater. The results of this investigation proved that this advanced electrochemical cell reduces 4.8-Log of natural marine heterotrophic bacteria at energy consumption of 0.264 kWh/m 3 .…”

“…The results of this investigation proved that this advanced electrochemical cell reduces 4.8-Log of natural marine heterotrophic bacteria at energy consumption of 0.264 kWh/m 3 . The same researchers [36] implements the nanotechnology [37] to present a disinfection technology that comprise an anodic multiwall carbon nanotube filter to kill viruses and E. coli in water. They discovered that such technique diminished the number of viruses and E. coli, during 30 s at voltage of 3 V, to below detection limit [1].…”