A Berson InLine UV disinfection system installed on one of Aruba's drinking water storage tanks Drinking water treatmentFollowing the desalination process the water passes through five UV systems before being transported to a number of large storage tanks situated at elevated locations around the island. The five UV units are the last step in the treatment process prior to distribution. Each UV unit disinfects 400m³ of water per hour, rising to 600m³/h during peak flow conditions. No chlorine is used at any stage of water the treatment process. The UV systems are controlled by Berson's ECtronic+ and UVtronic+ microprocessors -- allowing the units to be linked to control systems.
Two of the storage tanks situated around the island are also fitted with UV systems, which provide an additional disinfection step prior to distribution. One of these UV-fitted storage tanks is situated in the harbour and supplies cruise ships with UV treated drinking water. It is expected that all the tanks will eventually be fitted with UV systems.
Commenting on the installations, Project Manager Mr Ruiz says, "Chlorine was originally considered as an alternative to UV but was rejected after concerns over costs and safety. W.E.B. also has an anti-chemical policy."
Wastewater treatment
Aruba is currently served by two wastewater treatment plants (WWTPs), one at Parkietenbos on the west coast and another Zeewijk on the east of the island. The Parkietenbos WWTP processes wastewater brought in by septic tank trucks from the whole of the island, while the Zeewijk WWTP treats wastewater from San Nicolas, Aruba's second largest city, located in the south of the island.
Both WWTPs use UV as a final treatment step prior to discharge, following various filtration and treatment steps including grit and fat removal, screening, SBR (sequencing batch reactor) biological treatment and tertiary disc-type filtration. The Berson InLine+ UV system at Parkietenbos treats up to 75m³/hour while that at Zeewijk treats up to 200m³/hour.
The quality of the final effluent from both sites is so good that some of the wastewater is used to irrigate two golf courses on the island.
Strong interest in UV for other applications
Commenting on the UV installations, Berson's Managing Director Andrew Clark says, "Since we delivered the UV systems to W.E.B. there has been a lot of interest in our non-chemical water treatment technology from other industry sectors on the island. In particular, a lot of businesses are interested in using UV-treated wastewater for hosing down their buildings. It is very dusty on Aruba, so keeping the exterior of buildings clean is actually a bit of a problem -- using desalinated potable water is expensive and wasteful, so high quality effluent is a viable alternative."
Berson is currently one of the few non-German UV system suppliers capable of providing a complete range of UV systems with capacities between 10 and 10,000 m³/hour, certified to the latest German DVGW*** norm, W294, Part 1, 2 & 3 -- the highest standard currently possible in the world. The systems are also fully validated in accordance with the USEPA UV Disinfection Guidance Manual (UVDGM).
* Biochemical oxygen demand
** Total suspended solids
*** DVGW (German Technical and Scientific Association for Gas and Water) is the body responsible for industry self-regulation in the German water and gas and water supply industry and its technical rules are the basis for safety and reliability.###