In the entire operation system of industrial reverse osmosis equipment, the recovery rate is arguably the most critical control indicator—it directly affects the capacity conversion rate, wastewater discharge, and the service life of the membrane modules. In reality, many operators blindly pursue high recovery rates, especially when dealing with highly mineralized brackish water sources, often neglecting the potential danger of supersaturated salt crystallization at the concentration end. This leads to stubborn scaling on the membrane surface, a precipitous drop in flux, and rapid deterioration of desalination performance, resulting in snowballing costs for subsequent cleaning agents and membrane replacements. The Xi'an DIEN Water Treatment Technology Team solemnly reminds everyone: the recovery rate is not a fixed, universally applicable figure. It is essential to incorporate multi-dimensional water quality data, such as total dissolved solids, calcium and magnesium hardness, and active silica concentration, into a comprehensive analysis and meticulously adjust the operating curve to ensure stable output throughout the entire lifespan of the equipment.
Industrial Reverse Osmosis Equipment
When using municipal tap water as the water source, the recovery rate of industrial reverse osmosis equipment can typically be set within the common range of 70% to 75%. However, once switched to a high-salt brackish water scenario, the baseline salinity of the feed water jumps significantly. If the recovery rate is still aggressively increased, the risk of scaling will rise exponentially. Industry experts recommend anchoring the recovery rate between 55% and 65%, and simultaneously optimizing auxiliary parameters such as the pretreatment stage, precise antiscalant dosing strategy, and minimum concentrate flushing velocity to fundamentally curb membrane deposition caused by concentration polarization. Many users habitually rely solely on manual valves to artificially increase the permeate ratio, ignoring the minimum crossflow velocity that must be maintained on the concentrate side. While this may seem like sufficient output water in the short term, it leads to several times the cost in the long run due to frequent disassembly, cleaning, and membrane replacement. DIEN Water Treatment can conduct parameter simulation calculations based on the complete water quality test report provided by the customer, and tailor a feasible operating strategy.
Here is a typical case from a mining area in Northwest China. A company had been using local brackish groundwater as its production water source for an extended period, with the raw water containing a measured total dissolved solids (TDS) level as high as 2200 mg/L. The industrial reverse osmosis (RO) equipment they had previously purchased, operating under conventional tap water conditions with a recovery rate capped at 75%, resulted in thick scale buildup on the membrane elements within a quarter of operation. Water production decreased weekly, necessitating shutdowns for chemical cleaning every two months or so, effectively paralyzing the factory's water supply.
After collecting water samples from multiple locations and reviewing operational records, DIEN's engineers devised a systematic modification plan: the recovery rate was proactively reduced to 62%, and the concentrate recirculation ratio was redistributed to ensure sufficient rinsing velocity across the membrane surface; an ion exchange softening module was added at the front end to reduce influent hardness; a scale inhibitor type more suitable for high-salt conditions was replaced, and its concentration was fine-tuned; simultaneously, online conductivity and transmembrane pressure differential dual-channel monitoring probes were installed, and an automatic alarm threshold for exceeding pressure differential limits was set. The PLC control program was updated synchronously to achieve fully automated intelligent control.
After modification, commissioning, and acceptance, the entire system entered a stable state, with the permeate desalination rate firmly maintained above 97% (click to learn: common causes and repair methods for decreased desalination rate in reverse osmosis equipment). The rate of increase in membrane module pressure differential slowed significantly, and the chemical cleaning interval was extended from three months to ten months or even longer. The quality of the water supplied to the workshop production line fully met standards. The project manager remarked, "Previously, we were completely clueless about the parameter logic for brackish water, only knowing to push the recovery rate as high as possible, resulting in frequent equipment malfunctions. The DIEN team meticulously recalibrated the entire parameter set using our real water quality data. We no longer need to shut down the machine every few days, the machines run smoothly, consumable costs have been significantly reduced, and their technical expertise and follow-up response are reassuring."
When dealing with highly mineralized brackish water sources, it's crucial to avoid blindly pursuing high recovery rates. The underlying water quality is the foundation for all parameter settings. Xi'an DIEN Water Treatment has accumulated extensive first-hand experience in brackish water purification, providing clients with full-chain support from water quality analysis and system parameter derivation to equipment customization, installation, commissioning, and long-term operation and maintenance. Companies with similar operating conditions requiring optimization are welcome to contact us for consultation.
