CMS’s technology increases the operating efficiency of membrane-based water treatment.
Electrical Impedance Spectroscopy is used to provide real-time surveillance of membrane conditions.
Benefits include reduced energy use and chemical consumption, and an increase in membrane life.
Sustaining high recovery rates and minimising the deleterious impacts of membrane fouling are the principal operational challenges for reverse osmosis (RO) systems. The consequences of fouling include the deterioration of a membrane’s ability to remove impurities and an increase in power required to produce clean water. In order to remove fouling, RO plants periodically apply an aggressive chemical treatment that reduces membrane life, adds to cost and creates waste that requires disposal. CMS’s products and services reduce the incidence of fouling in RO systems.
CMS’s core technology is an application of Electrical Impedance Spectroscopy (EIS). EIS utilises an alternating current to probe materials or devices to depth scales ranging from the atomic to macroscopic dimensions: roughly from a billionth of a metre up to that visible to the naked eye. As applied to membranes, the technology allows the condition of the critical layer adjacent to the membrane, where fouling is first initiated, to be delineated. Understanding the condition of this layer allows the plant’s operating parameters to be adjusted to run membranes at the recovery rate that delivers the most produced water at the lowest fouling rate.
Following laboratory development, an industrial trial was completed at the Bedok NEWater Plant in Singapore. A second industrial trial is currently underway at Veolia Water Australia’s Fairfield Water Treatment Plant.
Data is captured either by modified standard modules (CMS eModule) or through the installation of a small integrated flow-cell, flow management system and impedance spectrometer that run in parallel to the membranes which are under surveillance (referred to as the CMS Replicator).
Introduction to Reverse Osmosis and Critical Flux
Reverse Osmosis (RO) is widely employed in water treatment plants to produce high-quality water. RO offers numerous advantages including a small footprint with modular construction, process stability and an ability to produce permeate with excellent water quality. Despite the widespread use of RO systems, fouling remains a major obstacle that limits their applications.
Critical flux is the highest flux where no or negligible fouling occurs, a concept first proposed in 1995 for porous membranes. Above this threshold, fouling rapidly sets in. CMS’s EIS technology allows commercial identification of critical flux in real-time. The following video helps illustrate the RO water treatment process and the operation of a common RO membrane module, known as a ‘spiral wound module’.
Finding the Optimum Recovery Rate
Every RO plant has its own performance characteristics that determine the specific operational settings that will deliver maximum permeate volume for the lowest cost. The risk of fouling often prevents plant operators from running their facilities at their optimum configurations.
CMS’s system removes this limitation. The figure below shows the increase in Permeate Flow / Power (kL/kW) produced by the increase in recovery rate for a commercial RO waste water facility.
Over this data range an 8% increase in Recovery Rate has produced an average 8% increase in permeate volume produced per kW of power. Incorporating profit margin, the corresponding increase in net revenue was greater than 8%.
CMS Membrane Surveillance and Optimisation
CMS captures and analyses proprietary data relating to membrane fouling conditions and provides clients with real-time actionable information to improve the economic performance of water treatment plants.
In combination with existing performance data, including feed and permeate flow, trans-membrane pressure and salt-rejection, CMS provides water treatment plant operators with the information necessary to adjust flux, cross-flow and chemical usage in order to minimise fouling and maximise plant efficiency.
CMS provides its clients with critical operational insights that lead to:
A reduction in energy consumption
A reduction in cleaning (CIP) frequency
A reduction in chemical consumption
A reduction in descalant consumption
An increase in average membrane life
CMS’s service is applicable to any spiral-wound or flat-bed membrane-based water treatment plant, wherever located, including:
Reverse osmosis waste water treatment plants
Reverse osmosis desalination plants
Micro, ultra and nano filtration water treatment plants
The CMS technology is the product of over two decade’s research and development in Australia and Singapore lead by CMS Technical Director, Prof. Hans Coster.
CMS has developed technology that for the first time allows the condition of membranes to be accurately monitored during normal operations.