atg UV Technology

Anglian water Cryptosoridium outbreak - Case Study


Courtesy of atg UV Technology

Pitsford Drinking Water Site, England

In June 2008, a rabbit was located in the wash water tank at the Pitsford Drinking Water Plant of Anglian Water, leading to contamination of the treatment works with Cryptosporidum, a chlorine resistant parasitic micro-organism. The parasite was detected on June 24 and, following consultation with health and local authorities, a notice to boil drinking water was issued for more than 100,000 households and 250,000 people served by the plant. About 500,000 litres of bottled water were also distributed.

 A decision to install UV led to seven systems - including two validated UV systems from atg UV Technology - being installed by the end of the weekend following the initial discovery. A week later, all water being produced was free from Cryptosporidium.

 The UV systems, part of the atg UV Technology validated range are automatically wiped and lamp output is monitored using a specifically designed UV monitoring probes. The power of the UV lamp is adjusted automatically to ensure the correct UV dose is delivered to the water. The units are capable of being controlled locally or remotely by SCADA. The system adjusts automatically for lamp ageing and changes in the transmittance of the water to deliver a constant UV dose.

 The units were installed in line into a 24-inch main. The design avoids bends that would be detrimental to system performance. Lamps can be changed online and the automatic wipers maintain the optical path, ensuring optimum performance, protecting Anglian from future Cryptosporidium outbreaks.

Anglian Waters investment in atg UV’s world class treatment technology has now ensured that they are protected from future outbreaks of Cryptosporidium, as well as safeguarding public health against other micro-organisms such as Legionnaire’s Disease and Cholera. In recognition of their efforts, atg UV Technology were officially recognized by Anglian Water in a presentation for “making the impossible possible” during what was a stressful and challenging time for all involved.

Onsite atg UV Engineer, Karl Sparenberg, who handled Anglians transition to Ultraviolet protection at their Pitsford site, commented “our experience in the UV industry, particularly with outbreaks of Cryptosporidium allowed us to respond at an amazing speed, it’s great to receive recognition for a job well done”.

atg UV Technology has a range of UV systems that have been designed specifically for the drinking water industry, and are fully compliant with the requirements of the US EPA Ultraviolet Disinfection Guidance Manual (UVDGM - The worlds strictest validation standard).

With more than 25 years experience in the UV industry, and over 2000 successful case studies, atg UV can offer a vast range of solutions for a number of applications, including a number of UV systems specifically engineered for drinking water applications that have been independently validated to demonstrate performance under a variety of operating conditions.

In addition to third party validation, atg UV have invested in the latest CAD and CFD design software which simulates both the flow and radiation profiles of the chamber design, and carry out tests with a variety of surrogate organisms such as B. Subtilis, and T1, MS2 phage, to further increase accuracy and performance.

As micro-organisms evolve, so too does their resistance against traditional methods of treatment. atg UV has developed a range of validated systems that comply with the requirements of the US EPA 2006 Guidance Manual (worlds strictest validation standard).

The UVDGM 2006 uses the mandate of the Safe Drinking Water Act to monitor emerging contaminants, under the Unregulated Contaminant Monitoring Regulation (UCMR2). UV light is used successfully to remove Methyl-t-butyl ether (MTBE), an fuel oxygenate that causes unpleasant tastes in water. Likewise N-Nitrosodimethylamine (NDMA), a toxic and suspected carcinogen can also be removed by using UV light.

Aimed at water supplies originating from lakes, reservoirs, ground water aquifers and rivers, the purpose of the UVDGM legislation is to ensure populations are kept safe from emerging pathogens such as Giardia and Cryptosporidium, which demonstrates enhanced resistance to conventional disinfectants such as chlorine.

atg UV can offer fully validated systems that deliver a 1 - 5 log reduction of Cryptosporidium for flows up to 1000 M3/hr at 90% transmission within a single high output, small footprint, medium pressure system. For larger flows, systems are offered as packages, utilising units placed in either series or parallel configurations.

As footprint is normally a key factor, due to limited space within pipe galleries, atg UV’s market leading designs means UV systems can be installed either vertically, or horizontally. The degree of redundancy is determined by atg UV engineers working with plant designers, and a duty assist/ duty standby arrangement is typical of most major installations.

Once installed, the delivered dose is controlled by continuously measuring the inputs of flow, water transmittance and lamp intensity using a state-of-the-art SPECTRA Control panel which uses Microprocessor technology that can be easily integrated into existing systems communicating through MODBUS or PROFIBUS. Additionally the SPECTRA’s on board data logger allows engineers to download performance data to a PC or laptop for review when needed.

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