alvim - alfa - inven · alvim - alfa biofilm ... market) based on the same phenomenon, ... of...

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


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).


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


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;


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


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.


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.


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.


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,


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.


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


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


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.


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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