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ALVIM - Alfa
✔✔✔✔ biofilm early detection
✔✔✔✔ antifouling water treatment
monitoring
© ALVIM Clean Tech www.alvimcleantech.com 1/15
Summary
1- Industrial biofilm & biofouling...............................................................3
Biofilm life cycle.................................................................................3
Biofilm detection methods...................................................................5
2- The ALVIM system..............................................................................6
ALVIM System architecture.................................................................9
The probe........................................................................................10
The server.......................................................................................10
3- Applications......................................................................................12
Automated biocide dosing.................................................................12
Process optimization.........................................................................13
Legionella........................................................................................13
4- Summarizing.....................................................................................14
5- R&D.................................................................................................15
Contacts..........................................................................................15
Illustrations summary
Biofilm formation cycle..............................................................................3
SEM images of progressive covering of ALVIM probe by early stage biofilm.....4
Effectiveness of cleaning treatments on different phases of biofilm
development............................................................................................4
Sensitivity comparison among different biofilm detection methods.................5
Correlation between ALVIM signal and biofilm growth rate.............................6
Repeated biofilm growth followed by Cleaning In Place.................................7
Threshold mode - correlation between ALVIM signal and bacterial covering.....7
Measuring mode - correlation between ALVIM signal and bacterial covering... .8
Scheme of ALVIM monitoring system
Basic software version (A) and Server version (B)........................................9
ALVIM probe..........................................................................................10
Early phase of biofilm growth...................................................................12
ALVIM-triggered chlorinations inside the seawater pipeline of a reserve-
osmosis desalination plant.......................................................................12
© ALVIM Clean Tech www.alvimcleantech.com 2/15
1- Industrial biofilm &
biofouling
Microbial biofilm, the most important component of (micro) biofouling,
represents a serious technological issue, particularly where water is a criticalprocess element.
For instance, in an heat exchanger system, a major component of any power
plant, a 20 microns-thick biofilm can cause a 30% decrease in thermalefficiency. The biofilm can increase inorganic fouling, producing sticky
substances which increase particles adhesion, and paves the way to bigger
organisms settlement, the usually called macrofouling, which can constrictwater flux (thus increasing energy consumption in order to compensate for the
reduced pipeline diameter). These problems can eventually lead to pipeline
blockages and plant stopping.
Besides, biofilm is responsible for microbially-induced corrosion (MIC), which
accounts for multi-billion dollars worth of damage in industrial facilities all over
the world.
Biofilm life cycle
Since late '70s, extensiveresearches have been undertaken
on biofilm complex biological and
biochemical structure, but manyaspects of its formation are still
under study. Nevertheless,
considering a liquid environment,it is possible to divide the biofilm
life-cycle in three different
phases:
1. attachment-colonization.
In this phase first bacteria
(known as pioneers) attachto the surface coming from
the bulk fluid;
2. growth. Pioneer bacteriastart multiplying in a sessile phase and spread, covering the available
surface. Bacteria-formed colonies grow into complex three-dimensional
structures (see illustration 1.2, on the right), covered by extra-cellularpolymers (EPS), which shelter them from outside attacks (such as
biocides or antibiotics).
© ALVIM Clean Tech www.alvimcleantech.com 3/15
Illustration 1.1: Biofilm formation cycle
3. detachment. The biofilm reaches, eventually, a pseudo-equilibrium
condition, where outmost layers tend to detach under liquid flowmechanical stress, and float away. This further increase the likelihood of
biofilm formation in other plant sections with respect to the simple
presence of planktonic bacteria.
Let us remark how difficult and expensive can be, both in terms of biocide
concentration and contact time, to deal with a biofilm in phase 3, with respectto a phase 1-2 biofilm. As a matter of fact, since the first growth of the EPS
matrix, the biofilm resistance to
external agents can increase bythree order of magnitude
(x1000). This means that, when
a cleaning treatments (e.g. abiocide) is applied:
•••• if the biofilm is in its early
phase (Illustration 1.3, onthe left), it can be
completely removed;
•••• if it is a mature one(Illustration 1.3, on the
right), it is much more
difficult to completelydestroy it.
In the first case, after the
© ALVIM Clean Tech www.alvimcleantech.com 4/15
Illustration 1.2: SEM images of progressive covering of ALVIM probe by early stage biofilm
Illustration 1.3: Effectiveness of cleaning treatments on
different phases of biofilm development
cleaning treatment, biofilm will need a longer time to grow again, while in the
second case, since there will be still alive bacteria, it will regrow quickly.
It is often very difficult to foresee the environmental conditions under which
the biofilm starts to grow (phases 1 and 2, as described above), which turnsout to be the best time to apply water treatments. Those conditions usually
depend on many different factors, such as temperature, season, pH, chemical
composition, dissolved oxygen, etc.
The above presented considerations justify the massive industrial interest on
realizing sensors and technologies able to early detect biofilm formation and
monitor its very first growth. These technologies can be efficiently applied inmany industrial fields, from power plant heat exchangers to cooling water
towers, from nuclear plants to reverse osmosys desalination.
Biofilm detection methods
Many biofilm detection methods have been proposed so far, but in order to be
effective in industrial environments and for continuous monitoring applications,
we shall describe two main approaches:
•••• indirect methods based on (usually thermal or mechanical) efficiency
measures;
•••• direct methods based on detection of the electrochemical activity usuallyassociated with biofilm growth;
© ALVIM Clean Tech www.alvimcleantech.com 5/15
Illustration 1.4: Sensitivity comparison among different biofilm
detection methods
The first approach bases the biofilm covering estimate on measuring the
variation of several (electrical or thermal) parameters induced by probefouling. This kind of approach is not suitable for less than 30/40 microns thick
coverings, therefore allows only the detection of mature biofilms (see
illustration 1.4, above).
Moreover, most sensors based on this approach are not capable of
discriminating between biofilm and other kinds of fouling, such as inorganic
scaling.
On the other hand, it is very important to act as early as possible aginst
biofilm, possibly in the very first stages of growth, with suitable water
treatment (chemicals, thermal, UV, ..), in order to find the optimal trade-offbetween efficacy, costs and plant protection.
2- The ALVIM system
The ALVIM system is based on a
sophisticated biofilm electrochemical
signal measuring technique.
As a matter of fact, it is
experimentally assessed that
natural biofilm, both in fresh and inseawater, affects the kinetics of
oxygen reduction on the underlying
metal surface, and can therefore bemeasured by electrochemical
methods.
Illustration 2.1 clearly shows thecorrelation between ALVIM probe
signal (red solid line) and increasing
biofilm growth on the probe itself,evaluated by laboratory tests 1.
The ALVIM technology allows for an
effective and reliable early stagebiofilm detection. Biofilm growth
monitoring is proven to be stable
and highly sensitive (down to 1% ofthe probe surface covering). Illustration 2.2, for instance, shows ALVIM-based
biofilm monitoring in a CIP (Cleaning in Place) real-time application.
Let us note that there are few existing sensors (some of them available on themarket) based on the same phenomenon, such as e.g. the CESI patented
1 DAPI staining and epifluorescent microscopy analysis
© ALVIM Clean Tech www.alvimcleantech.com 6/15
Illustration 2.1: Correlation between ALVIM signal
and biofilm growth rate
BIOX probe
(originallydeveloped by some
of the same
inventors involved inthe ALVIM Project).
These sensors
already proved theirusefulness in
industrial
applications frompower (and nuclear)
plant to drink
bottling plant.However, if
compared with
these sensors,ALVIM (patent
pending) exhibits
significant technological innovations, such as distributed approach, completelydigital management, real-time monitoring, data accessibility from remote,
high sensitivity, precision and flexibility.
The proposed technology has been implemented by coupling advanced analog
signal conditioning with digital, microprocessor-driven, electronic stage.
ALVIM sensor architecture allows for two main functional modes:
A) Threshold mode:
sensor is programmedto raise a digital alarm
when biofilm covering
exceeds a chosenthreshold (Illustration
2.3). This mode is the
best one for industrialapplications, since it
allows to easily obtain a
clear and preciseindication about the
reaching of a given
biofilm covering level.
© ALVIM Clean Tech www.alvimcleantech.com 7/15
Illustration 2.2: Repeated biofilm growth followed by Cleaning In Place
400
500
600
700
800
900
1000
1100
1200
0 5 10 15 20 25 30 35
Time (Days)
Bio
-Ele
ctr
och
em
ical S
ign
al (m
V)
Illustration 2.3: Threshold mode - correlation between ALVIM signal
and bacterial covering
B) Measuring mode:
sensor provides as outputa digital signal which is
proportional to biofilm
growth stadium(percentage of surface
covering) (Illustration
2.4). This mode makes itpossible to follow the
whole bacterial covering
development, from 1% to100% of surface covering.
The above-describedfunctional modes are
implemented directly at
sensor (probe) level, byswitching among different
electrochemical configurations and settings. This approach allows for a simple
and flexible use of the ALVIM probes, considering different applications, suchas:
1. analysis and characterization of biofouling growth in terms of frequency
and intensity in industrial cooling water systems;
2. assessing and comparative evaluation of different chemical biocides or
water treatments;
3. real-time, continuous monitoring of water treatment systems (e.g. forredundant equipment control);
4. automatic and/or remote control and optimization of industrial water
treatment.
The possibility of connecting multiple probes at the same time, even on a
spatially distributed approach, is granted by the underlying ALVIM technology
architecture, which includes an entire family of devices, from probes toacquisition cards, to gsm/gprs modems. These features make feasible several
advanced applications, such as:
• • • • distributed water treatment systems, realized subdividing the systeminto several interconnected devices, installed in different plant sections,
depending on their likelihood of developing biofilm and on the overall
plant geometry;
• • • • remote-operated water treatment systems based on a multiple sensor
net collecting real-time continuous data on biofilm growth;
• • • • seamless integration of several sensors, beside early stage biofilm probe,
in order to integrate and enhance industrial water-based plant
assessment and characterization.
© ALVIM Clean Tech www.alvimcleantech.com 8/15
Illustration 2.4: Measuring mode - correlation between ALVIM signal
and bacterial covering
ALVIM System architecture
Illustration 2.5 shows the overall ALVIM monitoring system architecture: data
collected by probes are sent (via cable or wireless communication) to a remote
PC or server for storage and further processing. With the basic software is justpossible to store & view the data (basic features) on a single PC, while in the
server version collected data can be accessed and visualized by different
remote clients via a safe protocol. It is therefore possible to remotely monitora plant and, if necessary, to set alarm thresholds and to control complex
industrial water based systems.
© ALVIM Clean Tech www.alvimcleantech.com 9/15
A
B
Illustration 2.5: Scheme of ALVIM monitoring system
Basic software version (A) and Server version (B)
The probe
ALVIM probe allows a real-time measurement of biofilm growth rate and of its
possible decrease due to biocide injection in the plant.
The sensor is rapidlyinsertable in any
industrial plant thanks
to a simple threadedlock, and is connected
just to one cable,
which is in charge oftransporting data and
powering the sensor.
The sensor has nomoving part, and its
response is not
affected bytemperature
variations.
The sensor (composed by a sensitive element and an electronic device) isbased on an innovative electrochemical technology and detects the biofilm
covering since its very-early phase (surface covering >= 1%).
ALVIM, besides revealing and monitoring biofilm growth, is sensitive tooxidizing substances (as many biocides are). This allows a real-time monitoring
of biocides application, providing additional information on disinfection plant
functionality.
The server
Data acquired by sensors are collected by a PC (basic software / serverless
version) or an external server and stored in a database (server version).While with the basic software is just possible to store & view the data (basic
features) on a single pc, with the server it is possible to access the data from
different clients, and to automatically carry out different operations on fieldacquired data, particularly:
•••• acquisition of the electrochemical signal generated by one or more ALVIM
probes on a programmable time basis;•••• advanced data view / filtering;
•••• local transmission of acquired data via different kinds of bus (RS485,
RS232, 4-20 mA, etc.);•••• alarms generation;
•••• control of biocides application;
•••• remote transmission of acquired data via GSM/GPRS;•••• field apparatus diagnostic;
•••• automated alarm signaling to operators in charge of plant maintenance,
in response to programmed events (programmed biofilm level reached,
© ALVIM Clean Tech www.alvimcleantech.com 10/15
Illustration 2.6: ALVIM probe
failure in biocide application system, etc.);
•••• real-time analysis of signal trend for biofilm prevention or signaling ofabnormalities on plant behavior;
•••• automated report generation for water treatment responsibles.
© ALVIM Clean Tech www.alvimcleantech.com 11/15
3- Applications
Automated biocide dosing
The most common approach tobiofilm prevention in industrial
plants consists in treating process
waters with chemicals (biocides) inorder to contrast biofilm
contamination.
These chemicals, usually chlorinecompounds (e.g. Clorine dioxide),
present several environmental
risks, and their extreme toxicitymakes them dangerous for
operators.
In absence of a reliable measure ofbiofilm presence, chlorine is
normally applied in an "heuristic"
way. This approach can, sometimes, lead to an insufficient tratment or to achlorine "overdose", causing in turn an insufficient biofilm protection or a
waste of chemicals, with consequent environmental and economical damage.
It must be observed that biocides effect on biofilm is strongly influenced by itsgrowth stage. During its early development stage, biofilm is highly vulnerable
to biocides (mainly due to the absence of EPS matrix, which acts as a "shelter"
for bacteria), while in moreadvanced stages biofilm
develop a stronger
resistance to toxics,requiring higher
concentration of biocides
to achieve the requiredeffect.
Illustration 3.2 shows an
example of the ALVIMsystem employment for
pipelines chemical cleaning
triggering. As soon as theALVIM sensor detects
biofilm growth inside the
water line (more than 1%of the surface covered by
© ALVIM Clean Tech www.alvimcleantech.com 12/15
Illustration 3.1: Early phase of biofilm growth
Illustration 3.2: ALVIM-triggered chlorinations inside the seawater
pipeline of a reserve-osmosis desalination plant
bacteria2), the system can automatically send a signal which will start the pipe
cleaning treatment.
Process optimization
The capability of a precise, real-time monitoring of biofilm growth since its
early stages is very important for an effective water treatment with biocides.
Main advantages of a monitoring system can be summarized as follow:
✔✔✔✔ evaluation of disinfection system effectiveness and in particular of
different biocides in use;
✔✔✔✔ timely alert in case of malfunctioning of disinfection system;
✔✔✔✔ automated biocides dosing in function of the real needs.
Legionella
Biofilm is known to represent the ideal environment for the survival of bacterialcolonies potentially very dangerous to human health, as, for example,
Legionella pneumophila. These bacteria are known to proliferate in cooling
systems with direct air/water exchange (cooling towers, air conditioners, etc.)and can pass to the air during spraying.
In the air, dangerous bacterial colonies can travel for kilometers, representing
a possible hazard.
It is therefore important to contrast biofilm formation, to minimize the risk of
dangerous bacterial contamination.
2 This percentage can be set/changed to reduce ALVIM sensitivity
© ALVIM Clean Tech www.alvimcleantech.com 13/15
4- SummarizingReal-time, precise indications on biofilm presence and growth in water piping
systems are assuming increasing importance.
In absence of these indications, industry have to rely on "spot" monitoring of
planktonic bacteria and on heuristic water treatment with biocides. These
treatments are often carried out without taking into account the dinamicbehavior of the system, which is influenced by several variables (temperature,
seasons, etc.).
The consequences are a less efficient water treatment, growth of costs andenvironmental hazard.
Biofilm control can be greatly improved by using ALVIM technology, which in
particular:
•••• encourages the "wise" use of biocides, reducing environmental impact
and staff exposure;
•••• minimizes sanitary risks linked with the growth of uncontrolled microbialfauna;
•••• allows for a modulation of biocide treatment on effective system needs;
•••• assures a 24/7 monitoring;
•••• provides an indirect control of employed biocides effectiveness and
disinfection systems efficiency;
•••• partially or completely automates the process of treatment, minimizingthe in-situ personnel intervention;
•••• enables remote monitoring and control of treatment systems.
© ALVIM Clean Tech www.alvimcleantech.com 14/15
5- R&DThe activity of ALVIM project is in full swing, with the aim of exploring the
potential of this technology and facilitating its application in the industry.Among the issues on which the R&D is targeting:
•••• eco-toxicity biosensors in liquid environment (fresh water /sea water) for
real-time monitoring, both in industrial and natural environment;•••• sensors for monitoring sulfate-reducing bacteria biofilms, for petroleum-
related applications;
•••• systems for the evaluation/measurement of water bacterialcontamination;
•••• electrochemical detection of heavy metals contamination for
civil/industrial applications.
Contacts
For further information please contact:
Dr. Giovanni Pavanello
ALVIM Clean Tech
Office Phone: +39 0108566345
giovanni.pavanello@alvimcleantech.com
http://www.alvimcleantech.com
© ALVIM Clean Tech www.alvimcleantech.com 15/15
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