Microwave-powered system keeps the lid on the running costs of ultraviolet disinfection
31 August 2004, News release from Simon Hartley
Ultraviolet technology has an established reputation for providing effluent disinfection solutions. However, conventional systems tend to have certain disadvantages, in particular the limited lamp life and expensive spares costs.
Other problems include: inflexibility in dose application, low efficiency and high associated energy costs, poor reliability of control equipment, significant footprint and head loss.
Simon-Hartley have introduced a novel microwave technology that offers a real commercial solution which overcomes these limitations. In addition, the retrofit capability allows the potential benefit to be fully realised at existing installations.
The key benefits of this method are: significant capital and operational savings, reduced maintenance requirements, smaller footprint, intensity benefits for a given input power, increased reliability of all major elements, and retrofit capability.
Andrew Best, Business Manager of the Process Systems Group at Simon-Hartley, goes on to explain some key features and benefits: "The lamps in our microwave-powered UV disinfection system have a level of reliability never seen before in UV disinfection. They do not fade and last in excess of 24,000 hours. As a result, we are also more environmentally friendly. In comparison with our competitors, we use one-third of the number of lamps, which in turn last three times as long. And that means fewer old lamps containing mercury for disposal.
"The cool running low-pressure lamps are subject to less stress, and avoid fouling or baking of residues onto the sleeve. The latter is a persistent problem in conditions of low flow or high solids afflicting medium-pressure lamps that generate far greater heat.
"Our new UV lamps are unaffected by cold conditions and operate instantly on switch-on, a real improvement on conventional systems that can demand a 20-minute wait.
"If anything, the unit overdoses, so is exceptionally thorough and effective in its intensity of disinfection. Last but not least, having a more compact power supply and fewer lamps than other systems, the Simon-Hartley system has a smaller footprint, a decisive advantage where space is at a premium. "
How ultraviolet disinfection works
Shortwave UV light - of a wavelength between 200 and 280, optimally at 253.7, nanometres (nm) - works by destroying the DNA structure of micro-organisms (bacteria, viruses, protozoa, algae and yeast) and thereby preventing their multiplication and regrowth. The Simon-Hartley UV disinfection system comprises a series of high-intensity, low-pressure lamps enclosed in 100mm outside diameter, high-purity quartz sleeves. Effluent or water is passed through the chamber and subjected to UV rays shining through the quartz tube.
Success story at Rockcliffe
On the north shore of the Solway Firth in Dumfries & Galloway, Rockcliffe beach was suffering from problems in meeting bacterial limits in the Bathing Water Regulations during the Summer season, May - September. The ideal solution proved to be a Simon-Hartley microwave-powered Quay UV system, initially supplied on a trial basis for the local treatment works.
The equipment comprises a microwave unit powering four lamps, each with a 1kW power input. The reaction chamber is 400mm diameter and 1m long.
Typical values (per 100ml) from samples taken at the site by the Scottish Environmental Protection Agency (SEPA) were as follows :-
Pre-disinfection: ThC 125000, FS > 20000.
Post-disinfection: ThC 300, FS < 100.
ThC = thermotolerant coliforms. FS = faecal streptococci.
Accordingly, Scottish Water, impressed by the benefits of the system, went on to purchase the installation. They particularly appreciated the constant-output, long-lasting lamps, since plant maintenance at any remote site such as Rockcliffe can prove a major headache.
Now, transformed by Simon-Hartley's new Quay UV disinfection system, the water at Rockcliffe is clean for bathing.
A complete process package from Ashbrook Simon-Hartley
This ground-breaking, microwave-powered, UV disinfection technology available now from Simon-Hartley is undergoing similarly successful field trials at wastewater treatment sites all over the UK, proving its exceptional efficiency and cost-effectiveness to a wide audience of industry experts.
Based upon their years of accumulated experience and technical expertise on site, Simon-Hartley provide the complete process package for the new system, encompassing specialist advice, design, installation, commissioning and servicing.
For further information please email Simon Hartley