UK-based Hanovia is one the world's major suppliers of UV (ultraviolet) disinfection systems.

And its new, more efficient MP (medium pressure) UV technology offers water utilities and suppliers significant cost savings, reduced headlosses and more effective UV monitoring, says the company.

Hanovia recently won a contract to supply three Photon medium pressure ultraviolet (UV) disinfection systems to the prestigious NEWater factory developments at Bedok and Kranji in Singapore testifying to the technology's appeal.

Explaining the advantages of medium pressure UV systems, Hanovia says UV disinfection systems are generally split into two distinct types: low pressure (LP) and medium pressure (MP).

"LP systems have a monochromatic UV output (limited to a single wavelength at 254 nm) whereas MP systems have a polychromatic UV output (between 240 - 310 nm)," the company says.

"UV works by disrupting the DNA of micro-organisms, rendering them unable to reproduce. It is generally accepted that DNA absorbs UV most effectively at 265nm, a wavelength that MP lamps produce in abundance.

"For LP systems to be effective at destroying DNA, a large number of UV lamps are required. This has obvious cost and maintenance implications for the operator. All UV lamps have set lifespan and need replacing after a certain number of hours (normally several thousand). The more lamps there are, the greater the likelihood that the system will need to be stopped to replace those that fail.

"UV monitoring is also more difficult with a large number of lamps - UV monitors are located on the wall of the UV chamber, so if a lamp located away from the chamber wall fails, it may not be detected. In addition, a large number of lamps impedes fluid flow through the UV chamber, resulting in pressure headloss and higher pumping costs.

"For these reasons, more operators are now switching to the newer, more efficient MP technology. With a wider and more powerful UV output than LP lamps, far fewer MP lamps are required for the same level of disinfection.

"Headloss is significantly reduced and monitoring is far more effective.

Hanovia says the fact that its MP systems can operate remotely and unattended was one of the biggest factors in it winning the Singapore contract which is a joint project between the Singapore Public Utilities Board and the Ministry of Environment.The NEWater factories will recover good quality water from tertiary treated effluent for use by the island's high technology industries.

Hanovia, based in Slough, England, was established in 1924 and specialises in the manufacture of UV equipment for disinfection, deozonation, dechloramination, and dechlorination and for the enhanced removal of total organic carbon (TOC) from ultrapure applications.

Other photolysis applications include the removal of NDMA and MTBE from drinking water.