North West, UK based manufacturers and suppliers of UV water treatment systems, specialising in ultra violet water purification. Specialists in ultra violet or ultraviolet technology. Including uv water treatment systems, uk, north west, purification, sterilisation, ultra violet, arc tubes, water treatment, bespoke projects, suppliers, manufacturers, offshore, buildings, pharmaceutical, food, drinking water. Ultravoilet, voilet and ulartviolet.

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Treatment Process

Tuesday September 7, 2010

Treatment Process

EFFECT OF UVC ON DNA

DNA or deoxyribonucleic acid is a long polymer made from repeating units called nucleotides. The DNA chain is 66 to 78 x 10-10  feet wide and 10 x10-10  feet  long.

Information in the DNA is stored as a code made up from 4 chemical bases ; adenine (A) , guanine (G) , cytosine (C) and thymine (T). Human DNA consists of 3 billion bases , with more than 99% of these bases the same in all people. The largest human chromosome, chromosome number 1 is approximately 220 million bases long.

DNA 

The order or sequence of these bases determines the information available for building and maintaining an organism. DNA bases pair up with each other; A with T and C with G to form units called base pairs.  Each base pair is also attached to a sugar molecule and a phosphate molecule. Together, the base, sugar and phosphate is called a nucleotide. 

The nucleotides are arranged in 2 long strands that form a spiral or double helix. The double helix is like a twisted ladder; the base pairs forming the ladders rungs, and the alternating sugar and phosphate forming the vertical sides of the ladder. Each strand of DNA in the double helix can serve as the pattern for duplicating the patterns of the bases

The base pairs are linked together by hydrogen bonds. These bonds are responsible for all of the interactions between the complimentary base pairs, and this  link is critical for all of the functions of living organisms. 

These hydrogen bonds are ruptured by UV light in the 260nm light region, and when the cross bonds are broken , new bonds called dimers form between adjacent bases. This process is almost instantaneous, taking approximately 1 Pico second to occur. Once the cross bond is broken, normal cell function including replication, assimilation of food and respiration cease.  The organism is rendered non viable, and it poses no further infectious threat.

UV Disinfection effect on DNA

A number of research groups have shown that this phenomena can be reversed for very low doses of UV light; this makes the design of the UV system and  regular maintenance very important. Photo-repair does not occur at a normal disinfection dose.

Healthy organisms can replicate and quickly spread infection or cause product spoilage. UV light effectively prevents cell replication and routine cell functions. Equipment design needs to ensure that the delivery of UV dose is uniform, that the optical path is not blocked, and that inlet bends or baffles used to overcome poor hydraulic designs do not permit breakthrough or cause shadows.

The majority of organisms have been studied and their  susceptibility to UV, known as their D10   value has been determined. This value indicates the dose in mJcm-2   that is required to achieve a 90% (or 1 log) reduction of a challenge species. Typical UV doses can achieve 99.9999% reduction of the target species. Certain species demonstrate higher resistance to UV; molds and yeasts for example do require a higher UV dose than many common waterborne species.  Contact ETS UV Technology if you have concern about a particular nuisance organism that you are trying to ensure does not become a problem, or would like to review our research database. 

atg UV Lamp Technology

Amalgam lamps are generally incorporated into atg UV systems, as they offer unparalleled electrical efficiency, long and predictable lamp life (generally 12000 hours) , and are unaffected by changes in water temperature.  A correctly run Amalgam lamp is 38-42% efficient; so a 320watt lamp is capable of delivering 134 watts of UV at 254nm.  These lamps produce a monochromatic output at 254nm in the germicidal region.

UVC Lamps

Medium pressure lamps are most efficient when run at maximum power, which is detrimental to lamp life(3-4000 hours). Typically a medium pressure lamp will deliver 12% efficiency, with most of the output emitted as nuisance heat (which causes fouling of the quartz surfaces) and long wave UV light, (which encourages algal growth). So a 5Kw lamp will deliver 600 watts of germicidal UV light.

The same amount of germicidal light is delivered using 72% less energy when comparing Amalgam technology and the older medium pressure technology. The output of these lamps is polychromatic, and they emit the wavelengths used to effectively remove chlorine from pool water.

For a number of applications, medium pressure lamps are incorporated due to their small footprint and short arc length. e.g. Retrofits into existing small footprint facilities.  Our UV monitors can be offered as NIST traceable devices , and fit into dry ports that permit reference monitors to be inserted without breaking a water seal to validate the lamp output. In all cases the sensor technology we use is specific to germicidal UV and blind to visible light and IR.