ALVIM - Alfa - INVEN

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).


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.


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.


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


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.


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 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%).


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.


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


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


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.


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

[email protected]

http://www.alvimcleantech.com


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ALVIM - Alfa - INVEN