Novel pulp mill wastewater recovery process for CO2 and SOx utilization

Abstract

Pulping industry has a pulp mill process that emits a significant amount of carbon dioxide (CO2) and sulfur oxides (SOx). The pulp mill wastewater has a high potential for reducing pollution caused by CO2 and SOx because it contains useful mineral ions in high concentrations, such as Ca2+, Mg2+, Na+, and K+ that react with carbonate and sulfate ions. In this study, we develop a novel pulp mill wastewater recovery process for CO2 and SOx utilization. To design the CO2 and SOx capture and utilization process using pulp mill wastewater, a process model is developed based on validated experimental data. The developed process model comprises the following three steps: (1) metal ion separation of pulp mill wastewater to produce KClO4, Mg(OH)2, and Ca(OH)2; (2) SOx capture and utilization using Ca(OH)2 and SOx, utilized as desulfurization gypsum; (3) CO2 capture via generated KClO4, and the captured CO2 is utilized as carbonate using Mg(OH)2 and Ca(OH)2. Accordingly, the economic feasibility of the suggested process model is demonstrated by calculating the pay-back period in economic assessment. As a result, the desulfurization efficiency was 99% with high-purity gypsum production. In addition, ∼98.2% CO2 was captured. Furthermore, the annual profit was increased by USD 94,469, and thus, the pay-back period was determined as 8.4 y.