Effect of urea concentration on microbial Ca precipitation

High calcium concentrations are problematic, because they lead to clogging of pipelines, boilers and heat exchangers through scaling, or malfunctioning of aerobic and anaerobic reactors. Urea hydrolysis provides simultaneously a pH and CO2 increase, both of which are responsible of CaCO3 production. This study was carried out to determine urea concentrations between 5 and 20 mM on ureolytic mixed culture treating synthetic wastewater. The optimum urea concentration was found as 15 mM for effective calcium removal. This work showed the feasibility of urea-based microbial carbonate precipitation as an alternative Ca2+ removal technology. (C) 2012 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.