Reverse Osmosis is a process that is used to remove a wide range of salts to give water a high purity –Osmosis is a natural process involving fluid flow across a semi-permeable membrane barrier. It is the process by which nutrients feed the cells in our bodies and how water gets to the leaves at the top of the trees.
, in their basic form, consist of a pressure pump, housing, and membrane. Water is forced into the housing under pressure and the pure water ( or permeate ) is collected and passed to service.
The size of the reverse osmosis system and choice of the membrane will be determined by the permeate quality required, feed water salinity, and permeate quality expected. Low energy membranes allow the unit to run at pressures around 150-200psi, and as such the pressure booster pumps required to generate the pure water are smaller, and the power consumption is reduced significantly.
is a continuous and chemical-free process of removing ionized and ionizable species from the feed water using DC power. EDI is typically used to polish reverse osmosis (RO) permeate and to replace conventional mixed bed ion exchange, which eliminates the need to store and handle hazardous chemicals like hydrochloric acid and Sodium Hydroxide which are used for regeneration of the cation and anion resin media. When the resin media is regenerating with these acids, they need to also be neutralized before entering the waste sewer system.
The size of the RO and choice of the membrane will be determined by the permeate quantity required, feed water salinity, and permeate quality expected.
Low energy membranes allow the units to run at pressures around 150-200psi, and as such the pressure booster pumps required to generate the pure water are smaller,
and the power consumption is reduced significantly.
These membranes will produce a water quality of approx. 10 micro siemens from input water of between 500-700 micro siemens.
If higher permeate quality is required a different range of membranes with higher pressure pumps can be used. RO units are normally built and used as single units
producing the quantity required during the working day.
If circumstances demand, the RO units can be duplexed with a central control panel being used to allow manual or automatic switching of the RO plant in service,
and will also allow the units to run in parallel when the demand for water is higher, thus doubling the permeate production. Also for very high purity waters,
the RO can be manufactured in “double-pass mode” – This means the permeate water from the first unit is fed as raw water into the second pass of the
RO-This already high-quality water will then be improved and very pure water is produced, typically less than 1 micro siemens.
When sizing the pre-treatment system the quantity of water available on the raw water feed side needs to be checked carefully as the RO system needs a higher
feed flow than the permeate output flow, as the recovery of the units is approx. 75% for pure water. The 25% concentrate that is rejected by the
RO can be used for any application where soft water is required such as wash water, greywater for toilet flushing, or in some cases cooling tower make-up.
The use of this water minimises any waste from the feed supply.