Piloting experience in Santa Monica for 90% recovery in brackish water desalination

In the quest for water sustainability, the City of Santa Monica embarked on an innovative journey to optimize the efficiency of its Arcadia Water Treatment Plant. Faced with the pressing need to enhance local water supply amidst limited availability, the city turned to cutting-edge reverse osmosis (RO) technologies.

This article delves into the implementation and outcomes of piloting Flow Reversal Reverse Osmosis (FR-RO) at the facility, showcasing a pioneering approach to achieving remarkable water recovery rates and contributing to the city’s ambitious sustainability objectives.

Aiming for Self Sufficiency

Santa Monica, a city home to over 90,000 residents, traditionally relies on a blend of local groundwater (75%) and imported water (25%) to meet its demand. In alignment with the Santa Monica Sustainability 2023 Plan, the goal was set to source 100% of water needs locally by 2020, a challenging feat given the constraints on additional water supplies. This backdrop set the stage for exploring alternative sources and innovative technologies to boost the Arcadia plant’s output.

A Collaborative Team to Meet Pilot Objectives

The city’s partnership with the progressive design-build team, including Walsh and Brown and Caldwell, marked a strategic move towards testing the waters of high-recovery RO solutions. The pilot aimed to determine if ROTEC’s FR-RO could sustainably achieve over 90% recovery. CCRO’s semi-batch process and FR-RO’s innovative flow reversal mechanism represented two paths to minimize scaling on membrane surfaces, a common challenge in RO operations, thereby extending the lifecycle and efficiency of the treatment process.

Key pilot objectives were comprehensive, focusing on identifying sustainable operating conditions, optimal pretreatment dosages, stability of RO concentrate for disposal, and assessing the quality and organic carbon rejection rates of RO permeate water. Additionally, a comparative analysis of life cycle costs between the two technologies was essential to guide future decisions.

Retrofit Pilot Results

The pilot testing, initiated in April 2020 and momentarily halted due to equipment issues, resumed in June with adjustments in antiscalant dosages and operational protocols. Success was defined by maintaining over 88% recovery for extended periods, with chemical cleaning intervals set based on specific performance metrics. Despite initial setbacks, the FR-RO pilot demonstrated resilience, achieving desired recovery rates and showcasing the potential for longer operational durations between maintenance needs.

The integration of FR-RO technologies at the Arcadia Water Treatment Plant heralds a significant advancement in the pursuit of water sustainability and efficiency. By retrofitting existing systems with this technology, the Arcadia plant has significantly enhanced its capacity to produce clean drinking water, efficiently converting 9 out of 10 gallons of treated water into potable water. This remarkable achievement not only maximizes the utility of scarce water resources but also underscores the project’s contribution to the community’s well-being and environmental sustainability.

This project exemplifies a forward-thinking approach to water management, aligning with the principles of the One Water approach. This holistic perspective on water resources management emphasizes the interconnectedness of all water systems, advocating for integrated, sustainable, and resilient water solutions.

FR-RO Technology – A BluePrint for Higher Recovery & Efficiency

In conclusion, the piloting of FR-RO technology at the Arcadia Water Treatment Plant represents a significant stride towards water sustainability for the City of Santa Monica. The successful demonstration of these technologies not only aligns with the city’s sustainability goals but also sets a precedent for other municipalities grappling with similar challenges. As the city moves forward with the full-scale application, the lessons learned and data gathered from this pilot project will undoubtedly serve as a valuable blueprint for achieving high-efficiency water treatment and recovery, marking a milestone in sustainable water management practices. The project stands as a testament to the tangible value of embracing innovative technologies in addressing water scarcity, showcasing the potential for such advancements to reshape industry standards and foster a more sustainable future for water treatment globally.


The following table shows the results of the FR-RO performance at the Arcadia Retrofitted Desalination Plant Pilot

Note that the method presented above is based on the assumption of steady state operation. To capture dynamics during state transitions, spatiotemporal models are required. As a rule of thumb, it takes several space times to reach steady state.

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Piloting experience of ROTEC’s flow reversal RO (FRRO) for 90 % recovery in brackish water desalination – ScienceDirect