Desupersaturation of RO concentrate and gypsum removal via seeded precipitation in a fluidized bed crystallizer

Jin Yong Choi; Florian Kaufmann; Anditya Rahardianto; Yoram Cohen

doi:10.1016/j.watres.2020.116766

Desupersaturation of RO concentrate and gypsum removal via seeded precipitation in a fluidized bed crystallizer

Water Res. 2021 Feb 15:190:116766. doi: 10.1016/j.watres.2020.116766. Epub 2020 Dec 22.

Authors

Jin Yong Choi¹, Florian Kaufmann², Anditya Rahardianto¹, Yoram Cohen³

Affiliations

¹ Water Technology Research Center, Chemical and Biomolecular Engineering Department, Henry Samueli school of Engineering and Applied Science, 5531 Boelter Hall, University of California, Los Angeles, CA 90095-1592, USA; Institute of the Environment and Sustainability, 300 LaKretz Hall, University of California, Los Angeles, Los Angeles, CA 90095-1496.
² Water Technology Research Center, Chemical and Biomolecular Engineering Department, Henry Samueli school of Engineering and Applied Science, 5531 Boelter Hall, University of California, Los Angeles, CA 90095-1592, USA.
³ Water Technology Research Center, Chemical and Biomolecular Engineering Department, Henry Samueli school of Engineering and Applied Science, 5531 Boelter Hall, University of California, Los Angeles, CA 90095-1592, USA; Institute of the Environment and Sustainability, 300 LaKretz Hall, University of California, Los Angeles, Los Angeles, CA 90095-1496. Electronic address: yoram@ucla.edu.

PMID: 33388534
DOI: 10.1016/j.watres.2020.116766

Abstract

The feasibility of a continuous chemically-enhanced seeded precipitation (CCESP) process was evaluated for desupersaturation of primary reverse osmosis (PRO) concentrate generated from RO desalting of inland agricultural drainage (AD) water with high gypsum scaling potential. The CCESP approach, comprised of partial lime treatment (PLT) followed by gypsum seeded precipitation (GSP), was assessed via laboratory and field tests, along with model simulations. PLT effectiveness was confirmed for residual antiscalant removal from the PRO concentrate, which otherwise would suppress gypsum crystallization. GSP was carried out in a fluidized bed crystallizer (FBC) demonstrating the feasibility of continuous PRO concentrate desupersaturation with suitable solids management. FBC operation was stable, with respect to desupersaturation performance, when operating over a sequence of periodic solids purge-only mode with intermittent seeds replenishment. The study suggests that CCESP integration with primary and secondary RO desalting (i.e., PRO-CCESP-SRO) can provide for significant enhancement of product water recovery for inland water of high gypsum scaling propensity. For example, source water of high salinity (14,347 mg/L total dissolved solid) AD water, nearly saturated with respect to gypsum, could be desalted up to a recovery of 88-96% (relative to merely 66% recovery feasible via PRO desalting. Moreover, net salt harvesting of 2.6-3.6 kg per m³ RO concentrate (with concentrate recycle) can be obtained from high recovery desalting of the above PRO concentrate.

Keywords: RO desalination; concentrate treatment; fluidized bed crystallizer; gypsum precipitation; high recovery RO; membrane mineral scaling.

MeSH terms

Calcium Sulfate*
Filtration
Membranes, Artificial
Osmosis
Water
Water Purification*

Substances

Membranes, Artificial
Water
Calcium Sulfate