pH Control in Reverse Osmosis Systems

A method for desalinating produced water to produce high quality water suitable for reuse and disposal options beyond oil and gas applications. The method involves reducing the pH of produced water to 5-6 before desalination to convert carbonate ions into CO2 that can be stripped out. This reduces the saturation of calcium and magnesium carbonate, allowing desalination without scaling issues. It eliminates the need for expensive lime softening prior to desalination.

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Membrane biofouling is one of the most persistent challenges faced by desalination plants, particularly those utilizing reverse osmosis (RO) technology. Addressing this issue crucial to reduce maintenance costs, improve efficiency, and extend lifespan membranes. This study introduces SpectroMarine, an advanced optical water quality sensor that provides real-time data on organic content biomass levels, enabling operators take proactive measures for key parameters such as chlorophyll, total carbon oxidization agent prevent biofouling. The combines fluorescence absorption spectroscopy with Internet Things (IoT) integration, offering immediate analytics actionable insights. Field tests demonstrated significant potential reducing operational energy consumption, optimizing chemical use according quality, ultimately enhancing plant performance. paper discusses sensor’s design, application, outcomes, providing a roadmap revolutionizing monitoring in plants.

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ABSTRACT The lack of safe drinking water infrastructures in off-grid communities is a significant risk to sustainable development, especially for low- and middle-income countries (LMICs). Photovoltaic-powered reverse osmosis (PVRO) has emerged as promising method due its performance, scalability, consistency, the robust global supply chain components. However, reliability issues like biofouling can quickly reduce shorten membrane lifetime, hinder adoption settings. Ultraviolet light-emitting diodes (UV-LEDs) ranging from 200 285 nm wavelengths have been shown number microorganisms by damaging their DNA, but there are mixed results about use mitigating systems. Herein, we aim provide preliminary assessment challenges associated with using UV-LEDs pre-treatment measure PVRO systems whether it curb feedwater, thereby For experimental evaluation, bacterial feedwater was prepared Escherichia coli ATCC 11229. Batch experiments Petri dishes 275 UV-LED radiometer showed non-uniform illumination target region, indicating need optimizing reactor design consistent dosage. Optical density measur... Read More

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Wastewater concentration device and method that can stably perform wastewater concentration treatment by adjusting the pH of water supplied to an osmotic pressure-assisted reverse osmosis device. The device has an osmotic pressure-assisted reverse osmosis system with a primary chamber and secondary chamber separated by a membrane. A water supply system feeds water to the primary chamber. It has an ion exchange device to treat the water and adjust its pH. This allows concentrating wastewater with high or low pH using osmotic reverse osmosis, avoiding the need for high pressures. The ion exchange removes components that contribute to the high/low pH, then hydrogen/hydroxide ions are released through ion exchange. This reduces the pH of high pH wastewater and raises the pH of low pH wastewater, making it suitable for osmotic reverse osmosis concentration

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Cost-reducing and efficiency-increasing reverse osmosis pH adjustment method to reduce chemicals waste and energy consumption in reverse osmosis water filtration systems. The method involves dynamically adjusting the frequency of adding acid to the concentrated water stream based on pH measurements. This prevents over-addition of acid in later stages where scaling is lower, and under-addition in earlier stages where scaling is higher. By optimizing acid dosing based on the actual scaling risk, it reduces acid consumption and prevents pH overshoot.

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Device to maintain pH of reverse osmosis system effluent without dosing chemicals excessively. It uses floating balls in the secondary reverse osmosis production pool, filters on the overflow pipe and external water supply pipe, and a dosing pipe for the secondary reverse osmosis membrane group. The floating balls raise the water level to counteract pH drop from CO2 dissolution. Filters prevent CO2-rich air from entering the production pool. The dosing pipe allows adjusting pH by adding chemicals only to the secondary reverse osmosis feed.

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A method to improve the quality of permeate water produced by a reverse osmosis (RO) system when treating decarboxylated water. The method involves adjusting the pH of the RO feed water in small increments based on the permeate water quality. By periodically changing the RO feed pH by a small amount and then monitoring the permeate quality, the optimal pH for the feed water can be found that results in consistently high quality permeate water.

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Reverse osmosis water treatment method that allows efficient processing of high pH, high ammonia, and high TOC water without excessive cleaning costs or membrane fouling. The method involves adjusting the pH of the feed water to 4-8, then passing it through a RO membrane. Intermittently, high pH water above 9.5 is brought into contact with the RO membrane. This periodic high pH exposure prevents fouling without constant disinfection. The high pH water can be the original feed water itself or preprocessed water. The intermittent high pH contact is done every 12 hours to once a month.

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Multi-stage reverse osmosis water treatment system that reduces energy consumption while maintaining water quality. The system uses low-pressure reverse osmosis membranes with high flux per pressure in the first stages to remove impurities like boron and silica. The water pH is adjusted in the first stage to enhance removal. This allows fewer high-pressure stages compared to traditional RO systems, reducing energy. By optimizing the membrane selection and pH adjustment, the treated water quality can still meet requirements.

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A method for producing high quality permeate in reverse osmosis systems by dynamically adjusting the pH of the feed water based on the measured quality of the permeate. The method involves fluctuating the pH of the feed water by a small range, measuring the permeate quality after a short time, and then adjusting the feed pH again based on the average permeate quality during that time. This allows stabilizing the permeate quality even with fluctuating feed water quality by dynamically optimizing the feed pH.

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Lye addition system for adjusting pH of wastewater in a sewage treatment plant. The system has separate lye metering pumps to add alkali to the wastewater at two different points in the treatment process. One pump adds lye before softening to raise pH for better reverse osmosis membrane performance. The other pump adds lye after softening to adjust final effluent pH. This allows precise pH control at each step to meet specific process requirements.

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A reverse osmosis membrane treatment method to efficiently clean and prolong the life of reverse osmosis membranes in water treatment systems while reducing cleaning chemicals and costs. The method involves treating the feed water to a pH range of 4-8, then periodically bringing highly alkaline water with pH 9.5 or above into contact with the reverse osmosis membranes. This intermittent alkaline treatment helps suppress slime formation on the membranes between cleanings.

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Automatic pH adjustment system for secondary reverse osmosis EDI water purification to improve efficiency and quality. The system uses a mixing device with inner and outer stirring mechanisms that can rotate in different directions. The inner stirring mechanism mixes the water and reagent in the tank, while the outer stirring mechanism swirls the tank contents. This allows continuous switching between different mixing methods. The mixing device is controlled by a controller to optimize pH adjustment.

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Reverse osmosis system with recirculation loop that overcomes limitations of prior art recirculating RO systems. The system uses a combined pump and energy recovery device with fixed recovery rate that avoids mixing between feed and return streams. This allows higher recovery rates and minimizes scaling on membranes compared to prior systems with separate energy recovery units. The fixed recovery rate structure enables automated pressure adjustment as salinity increases. A pressure switch actuates a valve to replenish feed water at predetermined salinity. The fixed recovery rate structure also allows using a fixed displacement pump instead of variable speed centrifugal pumps.

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Reducing the amount of pH adjuster used in a purified water production system while maintaining high water quality by dynamically adjusting the pH of the feed water to the reverse osmosis membrane. The adjustment involves increasing the pH range allowed for the feed water when the permeate quality meets a target range, and decreasing it when the permeate quality falls below the target range. This allows optimizing the pH without over-adjustment. The pH adjustment is done using acid addition before decarboxylation and alkali addition before RO.

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A reverse osmosis alkali addition control system for a power plant to maintain stable pH levels in reverse osmosis systems used in power plant water treatment. The system uses multiple pH sensors and dosing mixers between the primary and secondary reverse osmosis units. Alkali is added at the primary reverse osmosis stage to raise pH and remove carbon dioxide. The secondary reverse osmosis feed water pump has multiple pumps to provide redundancy. This allows precise pH control throughout the reverse osmosis process to prevent fluctuations.

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A system and method for chemical cleaning of reverse osmosis membranes that accurately controls pH during cleaning to improve effectiveness and reduce manual intervention. The system includes a recyclable cleaning loop, dosing pumps for acids and bases, and online pH and temperature sensors. The method involves calculating dosages based on tank volume and time to add the correct amounts of acid and base during cleaning steps to maintain target pH.

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An apparatus and method for removing boron from water using a specific pH adjustment before reverse osmosis. The method involves adjusting the pH of the water to be treated to a range of 9.0 before passing it through a low-pressure reverse osmosis membrane. This pre-treatment step greatly improves boron removal efficiency in the subsequent high-pressure reverse osmosis stage. The higher pH prevents boron inhibition on the membrane and allows more boron to be rejected. This enables boron levels to be reduced to very low concentrations.

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A self-adjusting ultrapure water treatment system that can automatically maintain the pH of the water entering the reverse osmosis process to ensure high-quality treated water. The system uses multiple pH meters and pumps to detect and adjust the pH of the raw water before reverse osmosis. It adds pH reagent chambers with metering pumps to extract alkaline solution for automatic pH adjustment when needed. This allows the system to self-regulate pH based on raw water quality instead of relying on fixed pH adjustment. The reaction tank stirs and mixes the raw water after pH adjustment for uniformity.

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Reverse osmosis membrane system with pH adjustment and calibration to stabilize water quality. The system has multiple pH and resistivity meters to measure water quality. When calibrating one meter, the system switches to using the other meter for adjustment. The difference between the two meter readings is subtracted from the control set point for the switched meter to compensate for the calibration. This prevents pH fluctuations during meter calibration.

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