GPC seeks eco-friendly solutions

Aresearch team from the Gas Processing Center (GPC) at Qatar UniversityCollege of Engineering (QU-CENG) has developed a combined approach forcarbon and high salinity water (reject brine) management.Led by GPCQafco chair Prof Muftah El-Naas, the team developed and tested amodified Solvay process that does not involve the use of ammonia. Rejectbrine was mixed with 1% to 2% of calcium oxide to raise the water pH toabove 10 and then contacted with carbon dioxide (CO2)-containing gases.The CO2 reacts with sodium chloride and calcium hydroxide to formsoluble calcium chloride and insoluble sodium bicarbonate. This processhas the dual benefits of capturing CO2 and storing it in solid sodiumbicarbonate and, at the same time, reducing the salinity of the rejectbrine. In addition to mitigating the negative impact of CO2emissions, the new process can significantly reduce the salinity ofreject brine, so that it can be used for irrigation purposes or enhancedoil recovery. An important part of the new process is a novel reactorsystem that was especially developed to facilitate the direct contactbetween the CO2 gas and the high salinity brine. Prof El-Naas noted that seawater desalination is a major source of potable water in Qatar and most countries in the region. Hesaid: “It is estimated that the Gulf countries contribute in about 44%of the world production of desalinated water, amounting to about 37mncubic metres a day. A similar amount of highly concentrated reject brineis also produced daily. The management of such large quantities ofreject brine represents major economic and environmental challenges tomost desalination plants, especially those involving thermaldesalination. Conventional management methods such as disposal throughdeep well injection, land disposal and evaporation ponds have proved tobe ineffective and often lead to negative impacts on the environment.”He noted that CO2 emission is yet another environmental concern that is considered a major contributor to global warming. CO2is believed to have the greatest adverse impact on the observedgreenhouse effect, he said, adding: “CO2 emissions come predominantlyfrom the combustion of fossil fuels in power generation, industrialfacilities, buildings and transportation. A different approach forcarbon capture and storage has been proposed as a possible, reliable andenvironmentally friendly option for the containment of CO2 emissions.It involves the reaction of carbon dioxide with high salinity water suchas desalination reject brine or produced water.”  “It is worthnoting here that this new system has the potential to be used forseveral industrial applications, such as water desalination, rejectbrine management, and produced water treatment as well as natural gastreatment processes such as gas sweetening. Therefore, several Qatariindustries such as Kahramaa, Qatar Petroleum and Qatargas will beinterested in developing the technology associated with the process orthe reactor system.”