alvim - alfa - inven
TRANSCRIPT
ALVIM Clean Tech
ALVIM - Alfa
✔✔✔✔ biofilm early detection
✔✔✔✔ antifouling water treatment
monitoring
www.alvimcleantech.com
Summary
1- Industrial biofilm & biofouling...............................................................2
Biofilm life cycle.................................................................................2
Biofilm detection methods...................................................................4
2- The ALVIM system...............................................................................5
ALVIM system structure......................................................................8
The probe.........................................................................................8
The server.........................................................................................9
3- Applications......................................................................................10
Automated biocide dosing.................................................................10
Process optimization.........................................................................11
Legionella risk prevention..................................................................11
4- Summarizing.....................................................................................12
5- R&D.................................................................................................13
Contacts..........................................................................................13
Illustrations summary
Biofilm formation cycle..............................................................................2
SEM images of progressive covering of ALVIM probe by early stage biofilm.....3
Effectiveness of cleaning treatments on different phases of biofilmdevelopment............................................................................................3
Sensitivity comparison among different biofilm detection methods.................4
Correlation between ALVIM signal and biofilm growth rate.............................5
Repeated biofilm growth followed by Cleaning In Place.................................5
Threshold mode - correlation between ALVIM signal and bacterial covering.....6
Measuring mode - correlation between ALVIM signal and bacterial covering... .6
Scheme of ALVIM monitoring system
Basic software version (A) and Server version (B)........................................8
ALVIM probe............................................................................................8
Early phase of biofilm growth...................................................................10
ALVIM-triggered chlorinations inside the seawater pipeline of a reverse-
osmosis desalination plant.......................................................................10
© ALVIM Clean Tech www.alvimcleantech.com 1/13
1- Industrial biofilm &
biofouling
Microbial biofilm, the most important component of (micro) biofouling,represents a serious technological issue, particularly where water is a critical
process element.
For instance, in an heat exchanger system, a major component of any powerplant, a 20 microns-thick biofilm can cause a 30% decrease in thermal
efficiency. The biofilm can increase inorganic fouling, producing sticky
substances which increase particles adhesion, and paves the way to biggerorganisms settlement, the usually called macrofouling, which can constrict
water flux (thus increasing energy consumption in order to compensate for the
reduced pipeline diameter). These problems can eventually lead to pipelineblockages 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 overthe world.
Biofilm life cycle
Since late '70s, extensive
researches have been undertaken
on biofilm complex biological andbiochemical structure, but many
aspects of its formation are still
under study. Nevertheless,considering a liquid environment,
it is possible to divide the biofilm
life-cycle in three differentphases:
1. attachment-colonization. In this phase first bacteria (known as
pioneers) attach to the surface coming from the fluid bulk;
2. growth. Pioneer bacteria start 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 extracellular polymeric substances (EPS), which shelter them
from outside attacks (such as biocides or antibiotics).
3. detachment. The biofilm reaches, eventually, a pseudo-equilibriumcondition, where outmost layers tend to detach under liquid flow
mechanical stress, and float away. This further increase the likelihood of
biofilm formation in other plant sections with respect to the simplepresence of planktonic bacteria (free in the liquid phase).
© ALVIM Clean Tech www.alvimcleantech.com 2/13
Illustration 1.1: Biofilm formation cycle
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 by three order of
magnitude (x1000). This means that, when a cleaning treatment (e.g. abiocide) is applied:
•••• if the biofilm is in its early
phase (Illustration 1.3, on theleft), it can be completely
removed;
•••• if it is a mature one(Illustration 1.3, on the right),
it is much more difficult to
completely destroy it. In the first case, after the
cleaning treatment biofilm will
need a longer time to growagain, 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, the best time to apply water treatments). Theseconditions usually depend on many different factors, such as temperature,
season, pH, chemical composition, dissolved oxygen, etc.
© ALVIM Clean Tech www.alvimcleantech.com 3/13
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
The above presented considerations justify the massive industrial interest
towards new sensors and technologies able to early detect biofilm formationand monitor its very first growth. These technologies can be efficiently applied
in many industrial fields, from power plant heat exchangers to cooling water
towers, from nuclear plants to reverse osmosis desalination.
Biofilm detection methods
Many biofilm detection methods have been proposed so far, but we shall
describe two main approaches effective for continuous monitoring applications
in industrial environments:
•••• indirect methods based on (usually thermal or mechanical) efficiency
measures;
•••• direct methods based on detection of the electrochemical activityassociated with biofilm growth.
The first approach bases the
biofilm covering estimate onmeasuring the variation,
induced by fouling, of
several (mechanical orthermal) parameters. This
kind of approach is not
suitable for less than 30-40microns thick coverings,
therefore allows only the
detection of mature biofilms(see illustration 1.4).
Moreover, most sensors
based on this approach arenot capable of
discriminating between
biofilm and other kinds offouling, such as scaling
(inorganic deposit).
On the other hand, it is veryimportant to act as early as
possible against biofilm, possibly in the very first stages of growth, with
suitable water treatments (chemicals, thermal, UV, ..), in order to find theoptimal trade-off between efficacy, costs and plant protection.
© ALVIM Clean Tech www.alvimcleantech.com 4/13
Illustration 1.4: Sensitivity comparison among different biofilm
detection methods
2- The ALVIM systemThe ALVIM system is based on a
sophisticated biofilm electrochemicalsignal measuring technique.
As a matter of fact, it is
experimentally assessed that naturalbiofilm, both in fresh and in
seawater, affects the kinetics of
oxygen reduction on the underlyingmetal surface, therefore biofilm
growth can be measured by
electrochemical methods.
Illustration 2.1 clearly shows the
correlation between ALVIM probe
signal (red solid line) and increasingbiofilm growth on the probe itself,
evaluated by laboratory tests 1.
The ALVIM technology allows for aneffective and reliable early stage
biofilm detection. Biofilm growth
monitoring is proven to be stable andhighly sensitive (down to 1% of the
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 the
market) based on
the samephenomenon, such
as e.g. the CESI
patented BIOXprobe (originally
developed by some
of the sameinventors involved
in the ALVIM
Project). Thesesensors already
proved their
usefulness inindustrial
applications from
power plants to
1 DAPI staining and epifluorescent microscopy analysis
© ALVIM Clean Tech www.alvimcleantech.com 5/13
Illustration 2.1: Correlation between ALVIM signal
and biofilm growth rate
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)
drink bottling plants. However, if compared with these sensors, ALVIM
exhibits significant technological innovations, such as distributed approach,completely digital 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.
B) Measuring mode:
sensor provides asoutput a 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%to 100% of surface
covering.
© ALVIM Clean Tech www.alvimcleantech.com 6/13
Illustration 2.4: Measuring mode - correlation between ALVIM signal
and bacterial covering
Illustration 2.3: Threshold mode - correlation between ALVIM signal
and bacterial covering
The above-described functional modes are implemented directly at sensor
(probe) level, by switching among different electrochemical configurations andsettings. This approach allows for a simple and flexible use of the ALVIM
probes, considering different applications, such as:
1. analysis and characterization of biofouling growth in terms of frequencyand 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. for
redundant equipment control);
4. automatic and/or remote control and optimization of industrial watertreatment.
The possibility of connecting multiple probes at the same time, even on a
spatially distributed approach, is granted by the underlying ALVIM technologyarchitecture, which includes an entire family of devices, from probes to
acquisition cards, to gsm/gprs modems. These features make feasible several
advanced applications, such as:
• • • • distributed water treatment systems, realized installing several
interconnected ALVIM probes 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 7/13
ALVIM system structure
Illustration 2.5 shows
the overall ALVIM
monitoring systemarchitecture: data
collected by probes are
sent (via cable orwireless
communication) to a
remote PC or server forstorage and further
processing. With the
basic software is justpossible to store & view
the data (basic
features) on a singlePC, while in the server
version collected data
can be accessed andvisualized by different
remote clients via a safe
protocol. It is thereforepossible to remotely
monitor a plant and, if
necessary, to set alarmthresholds and to
control complex industrial water-based systems.
The probe
ALVIM probe allows a real-time
measurement of biofilm growthrate and of its possible
decrease due to biocide
injection in the plant. The sensor is rapidly insertable
in any industrial plant thanks to
a simple threaded lock, and isconnected just to one cable,
which is in charge of
transporting data and poweringthe sensor.
The sensor has no moving part,
and its response is not affected by temperature variations.The sensor (composed by a sensitive element and an electronic device) is
based on an innovative electrochemical technology and detects the biofilm
covering since its very-early phase (surface covering ≥ 1%).
© ALVIM Clean Tech www.alvimcleantech.com 8/13
Illustration 2.6: ALVIM probe
A
B
Illustration 2.5: Scheme of ALVIM monitoring system
Basic software version (A) and Server version (B)
ALVIM, besides revealing and monitoring biofilm growth, is sensitive to
oxidizing substances (as many biocides are). This allows a real-time monitoringof biocides application, providing additional information on disinfection plant
functioning.
The server
Data acquired by sensors are collected by a PC (basic software / serverlessversion) 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 version it is possible to access thedata from different clients, and to automatically carry out different operations
on field acquired data, particularly:
•••• acquisition of the electrochemical signal generated by one or more ALVIMprobes on a programmable time basis;
•••• advanced data view / filtering;
•••• control of biocides application;•••• remote transmission of acquired data;
•••• field apparatus diagnostic;
•••• automated alarm signaling to operators in charge of plant maintenance,in response to programmed events (programmed biofilm level reached,
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 the people in charge of water
treatment.
© ALVIM Clean Tech www.alvimcleantech.com 9/13
3- Applications
Automated biocide dosing
The most common approach to biofilm prevention in industrial plants consistsin treating process waters with chemicals (biocides) in order to contrast biofilm
formation.
These chemicals, usually chlorine compounds (e.g. Clorine dioxide), presentseveral environmental risks, and their extreme toxicity makes 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 aninsufficient tratment or to a chlorine
"overdose", causing in turn an
insufficient biofilm protection or awaste of chemicals, with consequent
environmental and economical
damage.
It must be observed that biocides
effect on biofilm is strongly
influenced by its growth stage.During its early development stage,
biofilm is highly vulnerable to
biocides (mainly due to the absenceof EPS matrix, which acts as a "shelter" for bacteria), while in more advanced
stages biofilm develops a
stronger resistance totoxics, requiring higher
concentration of biocides
to achieve the requiredeffect.
Illustration 3.2 shows an
example of the ALVIMsystem employment for
pipelines chemical
cleaning triggering. Assoon as the ALVIM sensor
detects biofilm growth
inside the water line(more than 1% of the
surface covered by
© ALVIM Clean Tech www.alvimcleantech.com 10/13
Illustration 3.1: Early phase of biofilm growth
Illustration 3.2: ALVIM-triggered chlorinations inside the seawater
pipeline of a reverse-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 itsearly 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 thedifferent biocides employed within the plant;
✔✔✔✔ timely alert in case of malfunctioning of disinfection system;
✔✔✔✔ automated biocides dosing in function of the real needs.
Legionella risk prevention
Biofilm is known to represent the ideal environment for the survival of bacterial
colonies 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 ofdangerous bacterial contamination.
2 This percentage can be set/changed to reduce ALVIM sensitivity
© ALVIM Clean Tech www.alvimcleantech.com 11/13
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, increase 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 to the uncontrolled growth of 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 12/13
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
http://www.alvimcleantech.com
© ALVIM Clean Tech www.alvimcleantech.com 13/13