Hybrid Water Filtration Systems Combining Reverse Osmosis

Like oilfield-produced water, a process for treating high total dissolved solids (TDS) water uses forward osmosis (FO) and a charged membrane. The process uses an FO system to draw water across a membrane from the high TDS stream into a more concentrated brine stream. The extracted water is then treated to purify it. The FO system uses a charged membrane that contains resin embedded throughout the membrane. The charged membrane can selectively extract specific ions like heavy metals, boron, mercury, and nitrates from the high TDS water while rejecting other ions.

A system and method for treating water using reverse osmosis (RO) and nanofiltration membranes allows high recovery rates without additional stages or pumps. It uses a two-mode process with a concentrate accumulator. In the first mode, feedwater is pumped through the RO unit, and the concentrate is stored at low pressure. In the second mode, the concentrate is drained while still pumping feedwater and recycled permeate through the RO unit. This maintains constant flow rates and pressures to achieve high recovery without requiring extra stages or pumps.

High recovery desalination system that combines nanofiltration (NF), reverse osmosis (RO), and forward osmosis (FO) to purify water from saline sources like seawater. The system uses an NF membrane to pretreat the feedwater and improve recovery. The NF permeate then goes through RO for final desalination. The reject from both NF and RO is sent through FO to concentrate the brine before disposal.

Hybrid electrochemical and membrane-based water treatment systems can effectively remove silica from water with varying concentrations to produce ultra-pure water. The systems involve a sequence of treatment steps, including bulk demineralization through electrodialysis reversal, high recovery reverse osmosis, and final polishing by electrodeionization. The specific treatment steps and configurations are tailored based on the silica level in the feed water to optimize removal efficiency and economics.

A hybrid system combining electrodialysis (ED) and reverse osmosis (RO) to desalinate brackish water. It applies a low electric potential across the saline water in the ED cell to separate it into concentrated brine and dilute water. The RO chamber then processes the brine to remove more salt. Using the RO only on the concentrated brine avoids the high energy cost of treating the full feedwater volume.

A system to treat seawater and produce water for injection into an oil-bearing reservoir. The system uses reverse osmosis (RO) and nanofiltration (NF) membranes to treat seawater, with the NF permeate blended with RO permeate to produce an injection of water with a salinity and hardness suitable for the reservoir. The system can adjust the blending ratio and treatment process to maintain consistent salinity and hardness despite changes in the feed seawater quality.

Purifying water efficiently using a combination of nanofiltration and reverse osmosis membranes. The process involves passing a feed solution through a nanofiltration membrane to remove solute and yield a concentrated solution. This concentrated solution is then passed through a reverse osmosis membrane to extract water. Using a nanofiltration membrane first, higher solute levels can be achieved in the concentrate without excessive pressure. Monovalent ions can be added to boost osmotic pressure. The nanofiltration concentrate can also be recycled through additional membranes for further concentration.

Process for efficiently filtering industrial and commercial wastewater streams to clean laundry waste streams/industrial waste streams, and/or oily waste streams. It uses a two-step filtration process: 1) ceramic microfiltration (CMF) to remove oil/grease and particulates, and 2) reverse osmosis (RO) with a special high-temperature/low fouling membrane to further purify the water. The CMF prefiltration prevents fouling of the RO membrane.