Biomineralization of hypersaline produced water using microbially induced calcite precipitation

Reusing produced water (PW) as the subsequent hydraulic fracturing fluid is currently the most economical and dominant practice in the shale oil and gas industry. However, high Ca2+ present in PW needs to be removed prior to reuse to minimize the potential for well clogging and formation damage. In this study, the 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 demonstrated the feasibility of MICP for Ca2+ removal from hypersaline PW under low urea and nutrient conditions. Throughout the continuous biofiltration operation with biochar as the media, high removal efficiencies of Ca2+ (similar to 96%), organic contaminants (similar to 100%), and heavy metals (similar to 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. Metagenomic sequencing analysis showed that a stable ureolytic bacterial consortium (containing Sporosarcina and Arthrobacter at the genus level) was constructed in the continuous biofiltration system under hypersaline conditions, which may play a crucial role during the biomineralization process. Moreover, the combination of the MICP and ammonium recovery could significantly reduce the acute toxicity of PW towards Vibrio fischeri by 72%. This research provides a novel insight into the biomineralization of Ca2+ and heavy metals from hypersaline PW through the MICP technique. Considering the low cost and excellent treatment performance, the proposed process has the potential to be used for both hydraulic fracturing reuse and desalination pretreatment on a large scale. (c) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study demonstrates the feasibility of using MICP for removing Ca2+ and toxic contaminants from hypersaline produced water (PW), achieving high removal efficiencies in batch and continuous studies. Metagenomic sequencing analysis reveals the construction of a stable ureolytic bacterial consortium in the continuous biofiltration system. The combination of MICP and ammonium recovery significantly reduces the acute toxicity of PW towards Vibrio fischeri.