Utilisation of oxygen from water electrolysis – Assessment for wastewater treatment and aquaculture.

• Modelling of oxygen mass transfer from single bubbles to the water. • By 20% increase in mass transfer coefficient by replacing air bubbles with oxygen. • Using oxygen in activated sludge offsets energy usage of water electrolysis by 30% • Replacing air with oxygen in aquaculture provides 14 times higher energy efficiency. One strategy to cut down the cost of hydrogen production by electrolysis is effective utilization of the byproduct oxygen. The oxygen can be used to replace the air in the aeration of wastewater in the activated sludge process, or in the aquaculture industry. To determine the benefit of replacing air with oxygen in the aeration process, an analytical simulation of a single bubble rising in stagnant water and a comparison with literature is established. Our results show up to 30 % energy return can be obtained by using oxygen in wastewater treatment by the activated process. The greater benefit of replacing air with pure oxygen in industries requiring higher dissolved oxygen such as the aquaculture industry is also presented. [ABSTRACT FROM AUTHOR]