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Controlling Microbiological Growth

and Foul Odors in Papermaking

Ezwar Roezzaman

Papermaking Process is Bioreactor

AspergillusMucorPenicillium

Protozoa

Algae

Aerobes

Facultative aerobesBacteria

AcinetobacterBacillus (spore-former)Pseudomonas

Single-cell:

BeggiatoaHaliscomenobacterSphaerotilus

Filamentous:

EnterobacterEscherichia coliKlebsiella

Clostridia Desulfovibrio Spirilla

Anaerobes

Filamentous or single-cell:

Paramecium

Coliforms:

(spore-former)

(sulfate-reducer)

Oscillatoria, Chlorella

Yeast

Mold

Fungi

Nutrients

PH

Retention

time

Oxygen

Levels

Temperature

Water

Slime Outbreaks

Higher Water Closure in Papermaking

Faster

accumulation of

solids & additives

Increased water

temperature

Higher System

Conductivity

Higher solid &

Microorganisms

contamination

load in effluent

• Lower oxygen

solubility in water

• Accelerate anaerobic

growth

Speedup corrosion

process

• Reintroduction of

microorganisms & odorous

agents to wetend

• Massive deposit problem

• Filamentous bacteria

bulking

• Difficulties in controlling

system retention

• Faster deposition

• Feeds Microorganisms

Anaerobic Bacteria Outbreaks

Anaerobic Bacteria

Reduced Fiber

strength

Bad smell

Toxic Gases

Explosion

Microbial Induced

Corrosion

Spoilage of Coating & Additives

Reduced brightness

Case Study : FW Consumption vs VFA in

recycled packaging mill

Negative correlation between FW consumption and VFA buildup in wetend.

Higher FW consumption reduces VFA

Common Microbiological Odors : H2S

and VFA

H2S• At 0.1 ppm - can be detected by the

human nose

• At 3 ppm - the odor becomes

objectionable

• At 10 ppm- Noticeable health affects

and headaches will occur

• At 100 ppm - people lose ability to

smell

• By 300 ppm - life threatening

• At 1000 ppm- irreversible

respiratory failure

• VFA• Fatty acids with a carbon chain of six

or fewer

• Intermediate chemistry of anaerobic

degradation into methanes

• Mainly acetic, butyric, propionic,

valeric acids

• VFA has different smell threshold

and characteristics

• Very common in recycled packaging

grades

• VFA may be generated in process or

come with reused water from WWTP

Degradation of organics

Sulfate reduction -230 mV

SO4

H2S HS- S2-

-250 to – 400 mv

VFA :

-100 to

-200 mV

Controlling microbiological related Odor

Mechanical / Design

Improvements

• Reduce generation of anaerobic conditions: improved agitation, Cascading ww, Chest aeration, reduce stagnant zone

• Use of Odor control equipments:

• Scrubbers

• Adsorbers

• UV, Plasma,

• etc.

Operational Improvements

• Proper chest level management

• Proper Housekeepings

Chemical Improvements

• Biocides

• Cleaners

• Air phase treatment

• Enzymes

• Living bacteria culture

• Oxidizers

• Alkaline soln.

• Metal precipitants

• etc.

Improving Biocide Program

• Change from “deposit control” focus to overall aspect

of Microbiological control

• Proper system survey and product selection

Some biocide actives are not effective in anaerobic

conditions

• Proper program design, application, and monitoring

Include monitoring of anaerobic bacteria

• Periodic program review and optimization

Minimizing Odor in WWTP

• Strict monitoring & control on WWTP operational

parameters on each process stage – continuous review

& optimize if necessary

• Preventing anaerobic conditions in aerobic stages

• Minimizing retention under anaerobic conditions

• Reduction on input of sulfates and control nutrients

• Periodic cleaning / maintenance of the WWTP system

• Addition of odor control chemicals

Advantages of Chemical Treatments

• Generally high removal efficiency

• Lower cost than mechanical systems – reduce big

capital investment

• Flexibility of treatment options based on type of chemistry,

system requirements, and regulatory compliances

• Little equipment maintenance and operation cost

• Ability to match chemical specific odor problems

• High ROI : savings on raw materials / chemical additives,

operational & cleaning costs

Paper Machine Dryer Exhaust

odor

Exhaust in dryer

Direct addition of Odor Neutralizer

Cooling Tower & vacuum Sealing

water treatment

Cool air in

few odor out

Warm water

Contain H2S

OC 3803/

OC 3801 spray nozzles

• Cooling Tower

OC 3808

/ OC 3818

OC 3808

H2S Control in Effluent Plant

H2S odor

H2S odor

Different Spray Application Method

Mist fan

Spray in exhaust / chimney

Sludge processing plant

Waste water tank

Brightness Improvement

• The pulp comes out from storage

tower turns black in color after

long shut down

• H2S generated by SRB reacts with

metals and create blackish metal

sulfide. Brightness of Pulp and the

finish paper was reduced. Foul

H2S odor also found

• Addition of AmiSense OC 3820

helps to recover the pulp & finish

paper brightness at shirt period of

time

Monitoring Equipment

• The monitoring Program is

tailored designed according to

program needs

• Biocide monitoring should include

anaerobic counts, ORP

• Measurement of total sulfides,

VFA

• Measurement of odorous gases Sulfide Test

Acetic Acid gas tester

H2S gas tester

Ammonia gas tester

Mercaptan gas tester

VOC tester

Summary

• Papermaking process is favorable environment for growth of

microorganisms, and may results is several microbiological related

• Microbiological related-odor problems in papermaking is an

increasing trend, especially with higher use of recycled fibers and

higher water closure

• Better control of microbiological related odors can be approached

through mechanical, operational, and chemical improvements

• Having and effective biocide program and odor control application

are important to produce paper process and products low in odor.