The 20000 GPD Brackish water RO plant is an excellent option for businesses requiring quickly and efficiently purified water. This plant has features that ensure high-quality drinking water production, including high efficiency and reliability and an easy-to-use and maintained design. The plant’s sleek and modern design makes it an attractive addition to any facility. Additionally, the plant comes with a one-year warranty for added protection.
As more brackish water RO and NF systems are being designed and operated on high salinity brackish feed water sources, it’s essential to consider the impact of increased feed TDS on the planning of the RO/NF. Issues such as hydraulic design, feed pressure requirements, and permeate quality should be considered. Hybrid RO/NF membrane system designs, the utilization of ERDs, and the impact of higher salinities on the rejection of ions are all discussed. Systems with improved hydraulic flux designs can reduce fouling and cleaning rates, improve energy efficiency, and enhance permeate quality. While systems with feed-side or interstage energy recovery devices can be more energy-efficient, the payback period must be reviewed.
The industry has yet to address increased system salt passage with higher feed TDS widely and increased concentrate TDS at higher recoveries. Historically, the salt passage was calculated based on temperature, membrane type, membrane age, and the composition of ionic species in the feed water. Improved calculations for salt passage consider the three theoretical mechanisms of salt passage: convection, diffusion, and charge repulsion. The combined effects of feed ionic strength and membrane surface charge play a crucial role in the rate of salt passage. RO system design projection programs must account for the high TDS effect on membrane salt rejection. Two case studies with high-feed TDS feeds are presented, which review how well design correlates with actual operations.
For this paper, high TDS brackish feed waters are identified as having feed TDS up to 12,000 ppm and can be treated by brackish water NF and RO membranes with feed pressures up to 450 to 600 psi. As feed TDS increases over 12,000 ppm TDS, higher pressure seawater RO membranes rated up to 1000 to 1200 psi tend to accommodate the higher feed pressures required to overcome the higher osmotic pressures generated. The basic steps and design parameters to address in designing an RO/NF are defining the target permeate quality, the amount of feed water to be processed, and the percent recovery of feed water as permeate. Other factors to consider include the feed water source quality, feed water-specific ions, temperature range, age of the system, and operating energy expense.
High TDS feedwater systems lend themselves to designing hybrid RO systems due to the hydraulic flux imbalance created by the enormous pressure differential from the feed end to the concentrate end. A hybrid RO/NF system uses a unique set of RO/NF membranes from one stage to another or can use a different set of membrane types within a scene. The final membrane selection is based on the permeate quality required, the optimal feed pressure and energy requirement, and whether an interstage energy recovery device or booster pump is desired. Table 1 reflects the design opportunities available to the design engineer.