Biomineralization of Hypersaline Produced Water Using Microbially Induced Calcite Precipitation

Abstract:

Reusing produced water (PW) as the subsequent hydraulic fracturing fluid is currently the most economic and dominant practice in oil and gas industry. However, prior to the reuse, high Ca²⁺ present in PW needs to be removed in order to minimize the potential for well clogging and formation damage. In this study, microbially induced calcite precipitation (MICP), as an emerging biomineralization technique mediated by ureolytic bacteria, was employed to remove Ca²⁺ and toxic contaminants from hypersaline PW for the first time. Batch and continuous studies have demonstrated the feasibility of MICP for Ca²⁺ removal from hypersaline PW under low urea and nutrient conditions. Throughout the operation of the continuous biofiltration system with biochar as the media, high removal efficiencies of Ca²⁺ (~96%), organic contaminants (~100%) and heavy metals (~100% for As, Cd, Mn and Ni, 92.2% for Ba, 94.2% for Sr) were achieved when PW co-treated with synthetic domestic wastewater (SDW) under the condition of PW:SDW = 1:1 & urea 4 g/L. Moreover, the combination of the MICP and ammonia recovery could significantly reduce the acute toxicity of PW towards Vibrio fischeri by 75%. Furthermore, metagenomic sequencing analysis showed that a stable ureolytic bacterial consortium (containing Sporosarcina and Arthrobacter) was constructed in the continuous biofiltration system under hypersaline conditions, which may play a crucial role during the biomineralization process. This research provides a novel insight into the biomineralization of calcium and heavy metals from hypersaline PW. Considering the low cost and excellent treatment performance, the proposed process has the potential to be used for large-scale applications for hypersaline PW treatment.