brackish-water reverse osmosis desalination

brackish-water Reverse Osmosis

REVERSE OSMOSIS SYSTEMS DESIGNED FOR APPLICATIONS SUCH AS BORE WATER, INDUSTRIAL WATER OR RECYCLED WATER DESALINATION

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Brackish-water reverse osmosis (BWRO) is a common desalination technique in industrial water and recycled water as well as environments where bore water or any other type of ground water is in use. Brackish water salinity typically ranges from 200 mg/L to 15,000 mg/L.

1. Brackish-water reverse osmosis systems

BWRO systems are designed to treat brackish-water feeds, up to about 4,000 to 5,000 ppm (TDS). Typical operating pressure for brackish water RO systems in the range of 10 to 20 bar.

The filtered water produced by the plant’s pre-treatment system is delivered by the low-pressure pump from a filtrated water storage tank through cartridge filters and into the suction pipe of the high-pressure RO feed pumps, which pushes this water through to the RO system vessels that contain the membrane elements where the actual desalination process occurs.

Sometimes, in bore water desalination, source water extracted from the bore comes with enough quality to be treated by the RO system with no need for pre-treatment. Other times, when industrial water is recycled, pre-treatment is the most important part of the reverse osmosis technique.

Brackish-water reverse osmosis systems provide filtered and desalinated water, free of suspended solids, ideal for many industrial applications such as manufacturing of semiconductors, power generation systems, refineries, cooling towers, boiler feedwater, etc. Brackish water RO is also a source of quality drinking water.

Industrial RO systems are a critical part of many industrial and commercial processes depend on high-quality water with low corrosive risk, specially for cooling circuits and boilers. Hence industrial ro systems are commonly used as pre-treatment before other water treatment technologies and processes.

Watercore can provide standard or custom designed brackish water RO machines

Commercial and light-industrial BWRO systems

4″ diameter membranes.
Vertical or horizontal configuration
PLC controlled
Up to 100m3/day

Industrial BWRO systems

8″ diameter membranes.
Horizontal configuration
PLC controlled
From 100m3/day

2. BWRO system functionalities

2.1 Low-pressure membranes

Any Watercore RO system is designed with low-pressure membranes. This type of membranes allow the use of smaller high-pressure pumps and reduce the overall power demand and running costs. The reduction in electric power needs doesn’t compromise the system salt rejection so these type of membranes offer an optimal performance for most brackish water applications delivering high-quality filtered water.

2.2 smart control with automatic concentrate valve

Watercore reverse osmosis plants come with an automatic concentrate valve that controls and adjusts the concentrate-permeate ratio for an optimal performance. This feature is key when feedwater quality is inconsistent with different concentration of dissolved salts.

Our RO desalination units are also equipped with an industrial MODBUS communication bus for integration in complex industrial environments, can be easily controlled locally or remotely by means of a powerful HMI interface and can be programmed to send alarms and notifications by email.

Dry contacts are provided for pretreatment units or storage tanks. When needed they can can also be controlled remotely with a TCP/IP interface and can be easily programmed to send alarms and notifications by email.

5. Reverse osmosis plants with multiple options

Cartridge filters: The main purpose of the cartridge filters is to protect the RO membranes from damaging particles that have not been removed by the pre-treatment process.

Low-pressure pumps: low-pressure pumps are sized to deliver the suction pressure needed for an efficient operation of the high-pressure RO feed pump. The low-pressure pump must be sized in a way that offsets the pressure loss across the cartridge filters. Low-pressure pumps will also need to guarantee the additional pressure needed for the suction of the high-pressure RO pump.

High-pressure pumps: high-pressure pumps are designed to deliver source water to the RO membranes at pressure required for membrane separation of the fresh water from the salts, which is typically in the range between 5 and 25 bars in brackish-water systems. Variable frequency drives (VFD) are sometimes installed on the high-pressure pumps to obtain maximum pump efficiency with changing source water fluctuations in salinity and temperature.

Concentrate-flow control valve: the concentrate-flow valve is installed to control, within certain limits the product water quality and reduce membrane fouling rate by controlling flux and back pressure.

Antiscalant dosing: Membrane scaling is typically minimized by conditioning the source water with a specific class of chemicals termed antiscalants (scale inhibitors).

Pressure vessels: the concentrate-flow valve is installed to control, within certain limits the product water quality and reduce membrane fouling rate by controlling flux and back pressure.

Recirculation: In order to achieve high recovery rates for our brackish reverse osmosis plants, we use three-stage configurations for large systems or concentrate recirculation for smaller systems and pilot units. This way we can reach up to an 80% overall recovery rate while each membrane still works under its standard 10% recovery rate. Recirculation allows membranes in small units simulate concentration conditions applicable to the final element in an industrial installation with low scale hydraulics.

7. Our range of brackish-water reverse osmosis systems

Standard Technical Data *(1)	BRO-15	BRO-20	BRO-25	BRO-35	BRO-50	BRO-120	BRO-250	BRO-500
Permeate flow (m3/d)	15	20	25	35	50	120	250	500
Feed TDS	< 6000 ppm
Feed pressure	2 bar (min) – 4 bar (max)
Permeate TDS	< 200 ppm (screen-selected by user for irrigation units)
Recovery	65% – 80%
Rejection	97% – 99%
Recirculation flow	Yes
Membrane Type	Low Energy – 4″					Low Energy – 8″
Array	1/1/1	1/1/1/1	1/1/1/1/1	2/2/2/2	2/2/2/2/2	1/1	1/1	2/2
Hydraulic connections Feed Permeate Concentrate	1″ 3/4″ 3/4″	1″ 3/4″ 3/4″	1″ 3/4″ 3/4″	1″ 1″ 3/4″	1″ 1″ 3/4″	1 1/2″ 1 1/2″ 1″	2″ 2″ 1″	3″ 3″ 2″
Dimensions Width Depth Height	1400 mm 650 mm 1800mm			2400 mm 650 mm 1800mm		1400 mm 1000 mm 1800mm
Power (KW)	2,2					7,5	15	30
Power supply	50Hz, 230V (1-Phase) or 400V (3-Phases)					50Hz, 400V (3-Phases)

8. Standard and optional features in our industrial reverse osmosis systems

Features & Options	Standard	Option
25μm cartridge filtration	Standard
High pressure pump	Standard
Low pressure pump		Optional
Stainless Steel 316 piping	Standard
Auto-flushing	Standard
Antiscalant dosing system	Standard
Chlorine Sterlization (pretreatment)		Optional
Iron, Aluminium, Manganese removal (pretreatment)		Optional
Turbidity removal (pretreatment)		Optional
Skid mounted	Standard
Containerised		Optional
VFD for high pressure pump		Optional
Energy-Saving Polyamide Membranes	Standard

Download our brackish-water RO systems specifications

9. Feed water requirementes reverse osmosis

Qualified Feed Water Quality*(2)
Total dissolved solids (TDS)	< 6000 ppm
PH value	2-11
Iron	< 0.05 ppm
Aluminium	< 0.05 ppm
Manganese	< 0.05 ppm
Free Chlorine	0 ppm
Oil and grease	0 ppm
Turbidity	< 1 NTU
(TOC) Total Organic Carbon	< 2 ppm
*(2) higher values of any of these parameters will require a pre-treatment. Contact us for a personalised solutions