Why use biocides

Report
Mirrico Seminar, Kazan, September 2011
Paul Wood and Anna Vatsurina
Outline
 Learnings from an incident
 Review Risk, Hazard and Exposure
 Exposure issues
 Examples of how Dow Microbial Control, controls exposure to
biocides
 Packaging
 Labelling
 Safe Removal
 Transport
 Lab Safety
 Storage
 Dosing
 Suggestions
 Conclusions
Everyone Learns from an Incident
Biocides are not dangerous when handled correctly
Chemical Handling: Level of Risk
Two factors to determine the risk when handling a chemical
•
Hazard Type or Consequence of Exposure
 Corrosive = will cause burns (contact may not be detected immediately)
 Toxic = a poison
 Respiratory irritant = like household bleach or ammonia
 Skin sensitizers = cause “skin allergy”
•
Exposure Potential or Likelihood of Event
 How much product ?
 Probability of an exposure ?
Level of Risk
Priority in hazard management reduces the exposure potential
Hazard
x
Hazard = HIGH
LOW
HIGH
Risk
Safe
LOW
=
x
Hazard = HIGH
=
=
x
Ethanol
Ethanol
Exposure Potential
Unsafe
HIGH
Exposure Potential
How do we come into contact with a chemical ?
 There are many routes to exposure
Inhalation
Skin
Ingestion
Types of Workplace Exposure
Exposure to biocide residues
 Gloves left lying on the floor
 Water collecting on top of a drum
 Contaminated cleaning cloth left in a bin
 Opening, moving, connecting / disconnecting, emptying
apparently “Empty” drums
 Containers used for hazardous materials without labels
 Cleaning / repair of contaminated installations
 Door handles / Doors opened by someone wearing gloves
Types of Workplace Exposure
Exposure to liquid biocides
 Spills from damaged packaging, or pipe work
 Dosing from drums, or pails manually
 Decanting from drums, or pails into smaller vessels
 Using samples
 Collecting samples from the production process
 Taking samples for Quality Control of raw materials
 Samples shipped to customers
 Handling samples in the lab.
Exposure Control
If there is the potential for exposure
 Perform a hazard- and safety analysis of the intended task
according to your internal rules ( EHS review )
 Follow the recommendations on MSDS* and Labels
 Installations and tools you intend
to use for the planned task
 Industrial Hygiene / Cleanliness
and Housekeeping
 PPE (Personal Protective
Equipment): type and control
intervals

Working Instruction

Spill-/Leakage Handling

Emergency Procedures

Training !!!
 Appropriate ventilation of the
working place / area
 Safety installations: Safety
Showers / Eye rinsing stations
Biocide Packaging
Packaging has to be designed to be safe
 Containers
 Have to be UN approved

3H1/Y1.4/150/** GB/3380

Stringent testing

Drop tested
 Are fitted with tamper evident
seals for security reasons
 Are palletised to prevent damage
 The number of drums are limited
on a pallet to prevent overhang
and restrict weight
 Packaging ergonomics
On Site Signs & Labelling
Product labelling is one source of information but there are others…
 Signs placed around the workplace inform
operators on which and when personal
protective equipment should be worn in
specific areas
 In addition use educational posters as part
of an on-going safety education program
Personal Protective Equipment ( PPE )
• Helmet
• Goggles
• Suit
• Gloves
• Rubber
Overshoes
Burns caused by not wearing
gloves
Burns caused by improper removal of
gloves
Lab Safety
To avoid mishandling and accidents
Always ensure samples are clearly labelled
Warning symbols are visible
Store products in clearly labelled cabinets
To prevent exposure during use
Handle biocides in a fume cupboard
Make sure lab technicians wear the correct
protective clothing:
Gloves
Goggles
Ensure the area where biocides are
handled is kept clean
Warehouse Storage
Store biocides safely
•
To maximise the safety of people
 Training
 Keep pedestrians separate from
•
product
 Safety barriers around offices
 Special bins for hazardous waste
 Ventilate warehouse
To prevent blind corners, or falling
containers
 Restrict pallet height
 To avoid mishandling
 Use painted areas
 Good lighting
Suggestions
 Be proactive
 Review the MSDS and label warnings
 Do a safety review of the job
 Have a written procedure and follow it
 Evaluate and inspect the equipment to be used
 Inspect your Personal Protective Equipment
 Have the spill deactivation kit equipment and chemicals
in place before an incident occurs!
Why use biocides ?
Essential To:





Maintain Efficient Heat Exchange
Prevent Corrosion
Prevent Plugging of Orifices
Prevent Potential Health Concerns
Maintain Aesthetic Appearance
18
Why use biocides ?
 Microbes can be:
 algae if light reaches the collection basin
 aerobic bacteria
 anaerobic bacteria (SRB’s)
 Moulds and yeast
19
Bio-films
 Microbes can attach to surfaces and produce slime
 impairs the heat transfer
 induces microbial corrosion (MIC)
 clogs filters, screens, casings and nozzles
 potentially harbours Legionella pneumophila
20
Biofouling Control – Biofilm Issue


A biofilm is a layer of slime that is produced by microbes after they
attach to a surface
 Biofilms serve to protect the microbial community that is
underneath it
 Corrosion and H2S production result from the growth of microbes
within a biofilm
Removing biofilm is more difficult than preventing the formation of a
biofilm
Stage 1
Conditioning
Layer
Stage 2
Bacterial
Attachment
Stage 3
Slime Formation
(EPS Production)
Stage 4
Slime
Thickening
Stage 5
Slime
Detachment
Examples of “Patchiness” in Bio-films on 316
Stainless Steel
 Review of the active ingredients used
in indistrial water cycles
23
Oxidisers
 Cl2, HOCl, Br2, HoBr,
 Chloramaines ; ClO2, H2O2 / Peracetic acid




Corrosive
Very fast acting
Effect is short-lived – no permanance
Generate high levels of AoX ( adsorbable organic
halides )
24
Glutaraldehyde
1, 5-pentanedial
O
O
H
H
Glutaraldehyde Features
 Quick kill (1-3 hours) under alkaline conditions (pH
7-9)
 Broad spectrum efficacy
 Highly effective against SRB, biofilm, and Legionella
 Readily biodegradable at concentrations < 5-ppm
 Compatible with dispersants, surfactants and most
WT chemicals, including CMIT/MIT
 Compatible with halogens and other WT additives
 Does not contain or release formaldehyde
 Kills via cross-linking proteins in cell wall
Glutaraldehyde Limitations




Weak efficacy versus fungi and algae
Stability with ammonia (NH3) and alkaline pH
De-activated by bisulphites
Polymerises under alkaline and high temperature
conditions (haziness / yellowing)
 Evaporation (volatilization) potential increases with
temperature and /or aeration
DBNPA
2,2-dibromo-3-nitrilopropionamide
Br
H
Br
C
C
N
N
C
H
O
Registered Applications
Cooling Water (Re-circulating / Once-through / Open / Closed)
Retort Systems, Pasteurizers
Reverse Osmosis Membranes
Air Scrubbers and Washers
Paper Mills
Additives/Mineral Slurries
Enhanced Oil Recovery
Publicly Owned Treatment Works
DBNPA Features









Extremely fast acting (15 - 60 min)
Broad spectrum efficacy
Highly effective against biofilm and Legionella
Effective at low dose levels
Easy to dose liquid
Non-corrosive at in-use concentration
Low environmental impact
Short half-life at more alkaline pH’s
Kills via reactions with sulphydryls and
disruption of respiration and metabolism
DBNPA Limitations




Liquid product shelf life is limited (6 months)
Weak versus fungi and algae
Low solubility in water
Incompatible with strong nucleophiles and
reducing agents
 Not UV stable
 Occasionally referred to as an oxidizer
THPS
C H 2O H
H O H 2C
+
SO4
2-
P
C H 2O H
H O H 2C
2
tetrakis(hydroxymethyl) phosphonium sulphate
THPS
Feature
Benefit
Fast acting, broad spectrum
Control of wide range of
microorganisms
Active against SRB; Algae and Useful for a wide range of industrial
Legionella
applications
Dissolves FeS
Reduces FeS related problems such
as fouling of equipment
Low dosages
Cost effective
Favourable aquatic toxicity
Very low impact on ecology
and minimal effect on environment
Degradation to inert
components
Non-foaming
Easy to use in high-flow systems
No organic solvents
Safety in use; completely water
miscible
THPS Limitations
 Known to release formaldehyde rapidly (25% of total
dose)
 Cationic properties react with anionic inhibitors
 Not compatible with oxidizing biocides
 Unstable at high pH
 Issues with use of THPS in high calcium waters
CMIT / MIT
Registered Applications








Recirculating Cooling Water (Open and Closed)
Air Washers & Industrial Scrubbing
Industrial Process Water
Brewery Pasteurizers and Can Warmers
Industrial Wastewater
RO / UF Membranes (non-medical; non-potable)
Pulp and Paper Slimicide
Additive and Slurry Preservation
CMIT / MIT Features
Product Feature
Broad-spectrum activity
Customer Benefit
Fast Acting
Provides control over bacteria, algae, and fungi with
no performance gaps. Effective vs Legionella, SRB,
and biofilm
Provides immediate control circa 10 minutes
Stable over a wide range of pH
(<9) and temperature (<40° C)
Effective under conditions typically encountered in
most processes
Clear, water soluble, liquid
Fully water soluble at use levels and easy to dose
Broad chemical compatibility
Compatible with most cooling water and papermill
additives and biocides
Low use rates
Cost effective
Biodegradable and does not
generate AOX or formaldehyde
Environmentally friendly
CMIT / MIT Limitations
 Poor stability above pH 9 and >40º C
 Poor stability with nucleophiles and reducing agents
(sulphides, sulphites, amines,)
 Perceived weakness versus SRB
 Slow killing
 Safe handling concerns / sensitization / burns
 New solid version will address safety issues
Comparison of Biocides for WT
Oxidizing
Products
Cl2/HOCl
BCDMH
ClO2
DBNPA
Glutaraldehyde
AM 7287
Sump Buddy
UCARCIDE 24, 50
THPS
AQUCAR
THPS 75
CMIT/MIT
KATHON WT
Rate of kill
Very very
fast
Very fast
Fast
Fast
Slow
Persistence
No
No
Yes
Yes
Yes
Excellent
Medium
Excellent
Good
Medium
pH range
4 - 7.5
Up to 8.5
Up to 9.5
Up to 9.5
2 to 9
Organisms
A,B,F
A, B, F biofilm
++
A, B, (F)
biofilm +++
A, B
B, F, Y, M
Biodegradability
n.a.
Fast (readily
biodeg.)
Very fast
(readily
biodeg.)
Inherently
biodegr.
Inherently
biodegr.
FA release
No
No
No
Yes
No
Thermal resistance
Actives Used for Industrial Water
Treatment and Paper
Biocide
Cooling
Water
Air Wash.
RO / UF
Paper
Slimicide
Glutaraldehyde
x
x
x
x
DBNPA
x
x
x
x
CTAC
x
CMIT/MIT
x
DCOIT
x
x
x
x
x
Spasibo 

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