Seawater bittern recovery system for CO2, SOx and NOx removal using microbubble scrubber

Abstract

In salt production, a considerable amount of seawater bittern is discharged, which contains valuable metal ions such as K+ and Mg2+. These metal ions react with sulfate and carbonate ions and can be used to isolate air pollutants. Here, this work developed a seawater bittern recovery process using a novel microbubble scrubber with the aim of CO2, SOx, and NOx reduction. The low equipment cost and compactness of the microbubble scrubber makes it highly compatible to industrial applications. In addition, it removes air pollutants using only distilled water, which is environmentally and economically desirable. To design the proposed system, a process model is developed based on the experimental results for the developed microbubble scrubber. The suggested process comprises the following four procedures: (1) metal ion separation for KOH and Mg(OH)2 production, (2) CO2 capture using the produced KOH, (3) SOx and NOx capture using the microbubble scrubber, and (4) sulfurization and carbonation using the generated Mg(OH)2. The experimental results show that 98 % and 99 % of the CO2 and SOx can be captured and utilized as CaCO3 and CaSO4, respectively. Finally, the payback period (PBP) of the proposed process is determined to be 0.5 y, confirming its economic feasibility.