Biological fouling of UV lamp sleeves:
Observational study of the I2/APF method for the elimination of sleeve fouling.
I2 Air Fluid Innovation, Inc.
Oceanside, NY, USA
DMSI
Thornton, Ontario, Canada
Abstract
This paper reports on an observational study to determine the efficacy of the I2/APF
protocol for eliminating foulants from UV lamp sleeves (UVLS) in addition to reducing
future fouling rate. The study was requested by The Atlantic Ultraviolet Co., Hauppauge,
NY for The Queens Botanical Gardens (QBG), Queens, NY and the New York City
Department of Design and Construction (DDC) as a response to rapid fouling caused by
iron reducing bacteria (IRB) within the UV purifiers at the botanical gardens.
The Queens Botanical Garden develops, teaches and utilizes eco-friendly protocols at its
facility. Therefore UV purification was a logical choice for coolant water disinfection.
Not originally part of the 150 gpm geothermal system, the purifiers were put online to
reduce well fouling. Diffusion well fouling increases well back pressure and reduces
water flow. The purifiers were installed to inactivate IRB before introduction into the
heat pumps and injection wells. At installation, UV sleeve transmission was 100% but
the system began fouling shortly afterwards, despite mechanical wiping. Meter display
readings degraded to single digits within weeks. Visual inspection of the sleeves
indicated IRB fouling. Mechanical wiping became difficult due to buildup on the sleeve
and mechanism.
The OBG does not have an onsite HVAC mechanical staff that could maintain the
purifiers in the event of fouling and was desirous of a sleeve cleaning method that would
remove existing fouling. The requirements were;
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Effectively remove existing sleeve foulant.
A reduction in the future fouling rate.
No purifier disassembly, sleeve removal or daily wiper use.
No environmental impact or use of caustic chemicals.
No mechanical impact to purifier or geothermal system.
Minimal down time and labor needs.
After a presentation to members of the DDC and QBG, a two month study by I2 Air Fluid
Innovation, Inc was accepted. The purpose of the study was to determine whether I2
AFI’s method for heat exchanger/geothermal well maintenance protocol would be
applicable for UV purifiers.
Keywords
Ultraviolet disinfection, iron, bio-fouling, UV sleeves, geothermal, heat exchanger,
botanical gardens
Introduction and background
A geothermal heat pump is an eco-friendly cooling/heating system that pumps heat to
or from the ground. It uses the earth as a source of heating or cooling. It is designed to
take advantage of the moderate temperatures in the ground to boost efficiency and reduce
the operational costs of heating and cooling systems. Geothermal systems are cost
effective, generally returning cost of setup in reduced energy needs over 3-10 years.
Open loop systems rely on a supply well as a water source, and diffusion or injection
wells as a return site. As a means to utilize the temperature variant for facility use, a heat
exchanger is used. Supply well water chemistry and bacteriological makeup are a
concern since fouling on the plates within the exchanger reduces heat transfer. This
increases the need for auxiliary heating or cooling reflecting in higher energy needs.
Additionally, as bio-fouling occurs within the exchanger, pieces break off and cause
downstream occlusion of screens within the diffusion or injection well. This has the
effect of adding increased back pressure which slows water flow through the exchanger
reducing heat draw. This condition adds additional load on supply well pumps increasing
energy demand and reducing pump life.
Although ultraviolet disinfection is a proven, eco friendly method for reducing microbial
content within coolant water, fouling of the quartz sleeves may limit its effectiveness.
Bacteriological films, bio-film, in conjunction with minerals present a difficult
maintenance challenge. Bio-film is a polysaccharide matrix that sticks to surfaces and
protects microbial colonies from potentially disruptive or destructive water conditions
i.e., biocides, turbulence, etc. Bio-films draw in minerals that harden its composition
making them difficult to remove with mechanical or automated wiping. Their growth
extension into water flow reduces surface water velocity and allows for additional
bacterial attachment. Iron bacteria derive its energy and multiply by oxidizing dissolved
ferrous iron into insoluble ferric oxide. IRB forms a bio-film that appears as a brown
gelatinous slime that coats quartz sleeves and breaks off for downstream occlusion.
There are three identified mechanical methods that may initiate and promote fouling;
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Heat induced precipitation of metals on the sleeve surface.
Foulant settling on the upper sleeve surfaces due to fluid motion and gravitational
influence within the purifier chamber.
Low velocity zones near sleeve surfaces and around fixtures that may impede
water flow allowing for attachment.
The I2 method is a patented protocol for the reduction of microbes through the
intermittent infusion of iodinated air bubbles into a fluid. Used in the health industry and
geothermal heat exchangers, the I2 method eliminates the needs for high levels of
biocides through a novel air/iodine vapor/microbe interaction. Additionally, the bubble
stream acts as an air sparging device which helps to prevent bacterial and mineral
attachment. Used periodically, the APF protocol removes bio-film and minerals from
internal surfaces through pressurization, purging, agitation cleaning and flush, using a
proprietary cleaner prior to bubble stream introduction. It cleans interior components
including sleeves, wipers and chamber and does not expose staff and environment to
caustic chemicals.
Objective
1. To determine the effectiveness of a protocol that uses an in-situ method for the
disruption and removal of formed bio-film/mineral coatings on the UVLS.
2. To determine the reduction in fouling rate through the intermittent introduction of
iodinated air bubbles into the purifier chamber by the;
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Elimination of low velocity zones.
Removal of recently attached foulants.
Prevention of Brownian motion and gravitational effects.
Prevention of attachment of biological and inorganic foulants.
Mitigation of higher temperature zones near the sleeve surface.
Inactivation of bacteria within the purifier.
Materials and methods
Two isolated pairs of Atlantic Ultraviolet Sanitron 40 gpm purifiers in series Each
purifier has a Guardian UV intensity meter and mechanical wiper. The study was
performed under normal operating conditions and implemented during normal working
hours. The sleeve cleaning method, the APF protocol, requires an air source, drain and
water soluble APF cleaner. The iodinated bubble infusion is formed by the patented I2
Air Infuser. All infusion and drainage is done through the APF assembly attached to the
purifier drain.
The study would include the following;
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Initial testing of influent water to determine mineral and bacteriological
composition.
Selected purifiers to be subjected to the APF protocol with readings compared
before and after to determine effectiveness in removing existing films.
After cleaning, the purifier would be allowed to foul to determine rate of foul
layer formation without I2 infusion.
After cleaning, a comparison of the fouling rate in purifiers that have either I2
infusion or not.
The APF protocol consists of purifier isolation, pressurization, purging, cleaner
introduction, cleaner agitation and flush. The time allotted is 15 minute preparation, 40
minute agitation, and 5 minute flush.
The I2 bubble infusion is produced by injecting iodinated air from the I2 Air Infuser
Cartridge through diffuser tips into the purifier chamber. It was injected both constantly
and intermittently throughout the trial period and the results compared.
Three of the four purifiers were used for the study; upper front UF, upper back UB and
lower front LF. Lower back LB was not used due to a malfunctioning meter.
All services were performed by a member of I2 Air Fluid Innovation’s staff and overseen
by members of the DDC who observed and confirmed all readings.
Water composition as determined by IME test ampoules were as follows;
Iron:
5 ppm
Iron bacteria, slime producing
Positive 24 hours/high
5/19/09 Start of study
Prior APF protocol:
UB (4), UF (1), LF (3)
Note: Wipers were frozen.
APF protocol was performed on UB and UF only. LF was untouched.
A dilute, ½, strength cleaning solution was used and allowed to dwell for ½ the time
without agitation to test for component compatibility. No damage was visible.
Results:
Following the initial protocol, readings read;
UB (39), UF (37), LF (3)
Wipers were freed considerably allowing for full stroke motion.
No I2 infusion was performed
5/27/2009
APF protocol was performed on all three purifiers using a full strength solution.
Meter readings afterwards read;
UB (98), UF (100), LF (98).
No I2 infusion was performed
6/3/2009
The APF protocol was performed on LF only.
Meter readings afterwards read;
UB (46), UF (38), LF (97).
No I2 infusion was performed
6/10/2009
The APF protocol was performed on LF only.
Meter readings afterwards read;
UB (34), UF (37), LF (98).
No I2 infusion was performed
6/17/2009
The APF protocol was performed on LF only.
Meter readings afterwards read;
UB (32), UF (27), LF (98).
.
Dried air was passed through the I2 cartridge and iodinated air was introduced to the LF
purifier only at ¼ cfm @ 62 psi. Water pressure was 60 psi.
I2 cartridge at start was weighed at 2118.2 grams.
6/22/2009
No cleaning protocol was performed.
Air infused to LF only.
Meter readings read;
UB (30), UF (22), LF (93)
Thursday 7/3/2009
No cleaning was performed.
Air infused to LF only.
Meter readings read;
UB (11), UF (18), LF (87)
Thursday 7/10/2009
Prior cleaning, meters read;
UB (11), UF (14), LF (79)
Purifiers UB, UF and LF were cleaned using the APF protocol. All meters read 100 at
end of procedure.
UF and LF received infused air intermittently every 24 hours.
Thursday 7/17/2009 End of study
No cleaning protocol was performed.
All air infusion stopped.
Purifiers with iodinated air infusion read; UF (96) and LF (94)
Purifier UB without iodinated air was (57).
I2 cartridge weighed 2113.1 indicating a loss of 5.1 grams of iodine after 4 weeks.
Water composition:
Water from UB
Water from LF and UF:
Iron 5 ppm, IRB positive 24 hours
Iron 3 ppm, IRB negative 72+ hours
Monday 8/3/2009
Meter readings read;
UB (14), UF (42), LF (39).
Results
Bold APF protocol performed. Results afterwards
Italic Received iodinated air infusion. Results next protocol session
Date
5/17
5/17
5/27
6/3
6/17
6/22
7/3
7/10
7/10
7/17
8/3
UB
4
39
98
34
32
30
11
11
100
57
14
UF
1
37
100
37
27
22
18
14
100
96
42
LF
3
3
98
98
98
93
87
79
100
94
39
Note
Meter reading start of study
Meter reading after 50% APF
Meter reading after 100% APF
Infused air started to LF after APF
All purifiers APF air to UF and LF
Meter readings at end of study
Note sleeve degradation
Observations
Prior study, all meters indicated advanced fouling with single digit readings. Visual
observation of the sleeve and meter lens confirmed fouling. The foulant appeared to be a
hardened, red/brown film not removed by mechanical means. Water composition testing
presented high iron and the presence of slime forming IRB. Wiper mechanism was
frozen on all tested purifiers.
The meter lens had a red/brown stain on the leading edge to water flow. Cleaning the
lens with oxalic acid and returned into the purifier meter readings rose slightly. Lens
cleaning was always performed prior all meter readings.
After cleaning the purifiers with the APF protocol, meter readings averaged 96. This was
observed on multiple occasions and on various purifiers. The APF protocol was easy to
implement and required no disassembly of the purifier or sleeve removal. The average
procedure time was 67 minutes which included 40 minutes dwell time. The APF cleaner
removed existing biological and mineral films through agitation and chemical cleaning.
The sleeves appeared undamaged and transparent. Wiper mechanism became unfrozen
and moved freely.
Without I2 infusion, readings would decline by an average 40 to 60% within one week.
Injecting I2 air into the purifier after cleaning, sleeve fouling declined approximately 6%
to 10% a week. Observing the bubble pattern in flowing water from both distal and
mesial ends of the quartz sleeve indicated an active profusion. The bubbles rose from the
air inlet situated at the drain port, moved in a linear direction along and up the quartz
sleeve to exit into the outlet port at the distal end of the purifier.
Conclusions
The APF protocol easily cleaned the interior components and appears to be a simple to
implement method for maintaining sleeve transmissibility. The rapid cleaning allowed
for both sets of purifiers to be cleaned in one session. The cleaner is active at varying
dilutions which would allow use on larger or smaller systems. Implementation time
would vary. Without the need for removal, sleeve and gasket integrity would be
preserved. Sleeve replacement would be reduced or eliminated. Wiper use and
mechanism failure would be reduced through foulant removal.
The I2 infusion reduced fouling rate through a change in water flow pattern within the
chamber. This appeared to eliminate low velocity zones and prevent sedimentation. The
active bubbles appeared to act as a sparger, lifting existing bio-films and preventing
attachment by planktonic bacteria and insoluble minerals. The infusion maintained meter
readings long enough to allow for a monthly one hour APF protocol application.
The protocol used approximately six grams of iodine in one month’s time. It appeared to
have no physical effect on the purifiers, sleeves or interior components. Additionally, the
bubbling had no effect on the system piping, gaskets or heat pumps. The bubbling
appears to reduce the APF protocol time by presenting a reduced bio-film for removal.
Intermittent infusion appeared as beneficial as constant.
The protocol appears to have met all QBG requirements.
Acknowledgments
I2 Air Fluid wishes to thank all the members of the Queens Botanical Gardens for their
assistance and participation during the study period as well as their devotion to
uncovering eco-friendly methods. Special thanks to Peter Sansone and his staff for all
their assistance and for their trust and use of the facility geothermal/UV system. Thank
you to all the members of the NYC DDC for overseeing the implementation and result
recording during the study protocol. Thanks Alex Posner, hydrogeologist, for his
invaluable knowledge of geothermal systems and geochemistry. Lastly, thank you to the
engineers at Atlantic Ultraviolet for their participation in this study.
Bibliography
Black & Veatch and the Electric Power Research Institute Community Environmental
Center Report CR-105252 UV Disinfection for Water and Wastewater Treatment
Sehnaoui, Karim and Gehr, Ronald Fouling of UV Lamp Sleeves: Exploring
Inconsistencies in the Role of Iron.,
Contact
For additional information contact
info@i2airfluidinnovation.com USA and International
larrysmiller@rogers.com Canada
This study contains proprietary content or intellectual property and is intended for the
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Protocol and application is based upon the art and science of U.S. Patent No. 7,329,385
and is the intellectual property of the inventor(s)
.
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