Achieving Minimal Liquid Discharge (MLD) with Advanced Membrane Systems at Maximized Volume Reduction: 5X, 20X, 40X, and 70X!

December 23rd 2019


Saltworks Technologies Inc. (Saltworks) completed a pilot on cooling tower blowdown demonstrating minimal liquid discharge (MLD) with up to 70x volume reduction using advanced membrane systems. The MLD paper presents brine management results and economics for water plant designers. Readers will learn how to concentrate brines to 130,000 mg/L total dissolved solids (TDS) with reverse osmosis membrane technology while avoiding scaling and fouling. The work is intended to inform widening use of membrane-based brine concentration systems in order to offset more expensive evaporation or disposal methods.


Pilot test results are presented for cooling tower blowdown brine at 1,800 mg/L TDS. The pilot test consisted of several methods, used to achieve multiple volume reduction factors (recovery):  5X (80%), 10X (90%), 20X (95%), 40X (97.5%), and 70X (99%). Each jump in volume reduction adds plant complexity and cost. Each step will be explained and mapped so readers can learn about the technology and investment required to take the next step in recovery improvements.


The plant consisted of a robotized chemical softening system, BrineRefine, designed for use with variable water chemistry. This system includes a real time calcium sensor and precipitation management system. The plant also consists of ultra high-pressure reverse osmosis, XtremeRO, with spiral wound membranes rated for 1,800 psi (120 bar) to achieve ultra high recoveries.

Download the Minimal Liquid Discharge (MLD) Paper

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