Derwent's Reverse Osmosis UK-manufactured plants are used to produce high-quality demineralised water, especially where the client looks to minimise the use of chemicals which are the regenerants associated with the more conventional demineralised ion exchange process (see Demineralisation).
R O Plant is used extensively in the food and beverage industry (especially the brewing industry), pharmaceutical and the electronics industries.
Derwent Water Services uses a computerised programme for studying the water chemistry so as to select the most suitable membrane configuration and in order to provide a plant which gives a low water-rejection rate.
Further help is provided to the client to make use of, often by further treatment, of the reject water.
The standard Derwent range of R O units utilises the most modern membrane technology and consists of a modular design comprising of:
- Skid-mounted epoxy-coated steel base
- Spiral-wound membranes in high-pressure GRP vessels
- Multi-stage high-pressure stainless steel feed pump
- Control panel
- Pressure and flow gauges for feed, reject and permeate
- Water quality indicator on conductivity alarm
R O plants are normally provided with additional pre-treatment forms - typically with softening to prevent scaling of the membrane, carbon filtration to remove chlorine and cartridge filters to remove particulate solids.
Nano-filtration and ultra-filtration plants are similar to the standard membrane technologies used in R O but use different types of membranes with different porosity characteristics. This use of different membranes provides a more specialised approach to water pre-treatment.
Membrane systems are finding increasing use in effluent treatment where suspended solids levels have been reduced but where it is then required to further concentrate the dissolved material to aid its recovery, or to recover water, or to concentrate the waste into a more suitable volume.