Lithium Extraction Water Treatment: How RO Enables the DLE Supply Chain

Direct Lithium Extraction is advancing from laboratory to commercial scale across Western Canada, with multiple projects targeting brine and produced water streams. Advanced RO plays a critical but often underappreciated role in making DLE processes work at scale. This post draws on GWTS’s experience from a $1.5M demonstration-scale DLE project in Calgary (June 2022 – November 2024).

Why DLE Needs RO

Direct Lithium Extraction technologies — whether ion exchange resin-based, adsorption-based, or membrane-based — selectively extract lithium ions from brine solutions. The challenge is that natural brines and produced water streams contain lithium at relatively low concentrations (50–300 mg/L Li), mixed with much higher concentrations of competing ions (Na, K, Mg, Ca, B) and total dissolved solids that can exceed 300,000 mg/L in concentrated oilfield brines.

Advanced RO serves two key functions in DLE process trains:

• Pre-concentration: High-recovery RO reduces the volume of brine requiring DLE processing, increasing lithium concentration and reducing the size and cost of the DLE system
• Post-DLE water management: Producing high-purity water streams for lithium product re-dissolution, washing, and process chemistry preparation

Water Chemistry Challenges at the RO-DLE Interface

The produced water and formation brine streams targeted for DLE are among the most challenging feedwaters for RO: ultra-high TDS, complex scaling chemistry, and variable composition. Key design considerations for RO systems integrated with DLE:

• Scaling risk from Ca, Mg, Ba, Sr, B compounds at high recovery — requires detailed geochemical modelling and aggressive antiscalant protocols
• Silica scaling potential increases significantly above 40°C — temperature management and silica-specific antiscalants required
• Boron rejection at high pH may be required if boron interferes with downstream DLE chemistry
• Consistent permeate TDS (<500 mg/L) critical for DLE selectivity and product purity

Lessons from the GWTS DLE Demonstration Project

GWTS served as Owner’s Representative on a $1.5M demonstration-scale Advanced RO + DLE system for a clean energy technology client, running from June 2022 to November 2024 in Calgary. At demonstration scale, the most significant operational challenge was managing the interaction between RO concentrate composition and DLE selectivity. As RO recovery increased above 70%, the concentration of competing ions (particularly Mg and B) became high enough to affect DLE adsorption kinetics. This drove the decision to operate RO at 65–70% recovery rather than the originally designed 80%, accepting lower volume reduction in exchange for better DLE performance.

The project successfully demonstrated the integrated process flow and generated the performance dataset required for the client’s commercial scale-up planning. The full two-year operational period was critical for observing seasonal feedwater composition variability and its impact on both RO fouling rates and DLE selectivity.