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BIOLOGICAL IRON AND MANGANESE REMOVAL,PILOT AND FULL SCALE APPLICATIONS

Brian Gage, Aqua Technical Sales Inc.*

Dr. Dennis H. O’Dowd, BOD Consulting

Paul Williams, ONDEO Degremont Ltd.Presented at the Ontario Water Works Association conference, May 3rd , 2001

INTRODUCTION

Both manganese and iron are found in surface and ground waters at varying

concentration levels. When present even at low concentrations they can be linked to thefollowing problems: discolouration, turbidity and taste problems or form slime and ironoxide or manganese dioxide accumulations in pipes. Both metals promote the growth of

certain types of chlorine tolerant micro-organisms in water distribution systems. Thisbiota, as in Walkerton, can provide protected sites for noxious organisms and

consequently, vastly increase the costs of cleaning and sterilizing systems that containorganisms dangerous to human health. Although there is little evidence that theconsumption of water with natural concentrations of these metals have adverse effects on

public health, and they are in fact essential elements for human diet, they do remainproblematic from an aesthetic, technical and economic point of view. The Guidelines for

Canadian Drinking Water has a recommended limit for aesthetic reasons for iron of 0.3mg/l and an objective concentration target of 0.05 mg/l. The recommended limit foraesthetic reasons for manganese is 0.05 mg/l and the objective concentration is 0.01

mg/l.. Ontario drinking water objectives have aesthetic objectives of 0.05 mg/l ormanganese and 0.30 mg/l for iron.

Conventional iron and manganese removal plants typically rely on physical-chemicalreactions using manganese greensands, intense aeration or chemical oxidation (with O3,

KMnO4 or ClO2). These processes provide treatment but they can have operatingproblems and they do not always provide an effluent that meets the water quality

objectives.

C l 2 / O 3 o rK M n 0 4

C l 2

R a w

W a t e r

F i l t e rM e d i a o r

G r e e n s a n d

Figure 1 Conventional Treatment Plant



Due to the limited success of traditional treatment methods, Ondeo Degrémont has

investigated the use of biological iron and manganese removal for municipal drinkingwater in Canada. They are doing so because biological iron and manganese removalsystems can sometimes have the following advantages: smaller plants because of higher

applied filtration rates, (sometimes in excess of 50 m/hr versus 10 – 15 m/hr) or becauseaeration and filtration can take place simultaneously in the same vessel; longer filter runs

because the iron or manganese retention in the filter due to the formation of more denseprecipitates and the use of a more course media; denser backwash sludge that is easier tothicken and de-water; higher net productions due to less water being required for

backwashing and being able to use raw water for the backwash; require no chemical

addition; and no deterioration of water quality over time; lower capital and operatingcosts through the elimination of chemicals, less frequent backwashing, fewercomponents, etc.

Development of Biological Manganese and Iron Removal

Iron was the first element for which biological removal techniques were developedbecause water rich in iron is more common and also because iron is more readilyremoved biologically. It was noticed that in some physical-chemical iron removal

plants, in spite of raw water quality that was not well suited for conventional ironremoval, that satisfactory iron removal occurred anyway. Large amounts of bacteria,

either stalked species such as Gallionella ferruginea, or filimentous ones such asLeptothrix orhracea were found present in the backwash sludge and those bacteria werein fact found to be responsible for removing the iron. In addition it was noticed that when

iron or manganese was complexed with substances like humic acids, polyphosphates ,silica etc., which normally interfered with the ability of physical chemical treatment

plants to work, that the bacteria could still remove the metals. It was realized that thesebacteria could be used for iron removal in water treatment plants before the water entersthe municipal distribution system. These bacteria which can remove iron or manganese,

A i r

RawW a t e r

S ta t i c Mixer

C l2

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Bioli te SFilter

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Air f o r B ack wash

Figure 2 Biological Treatment Plant



are referred to as ‘Iron Bacteria’. In general, these bacteria are found wherever there is adetectable level of iron or manganese in water.

Biological Iron and Manganese Removal Process

In anaerobic ground water, iron and manganese may remain in their soluble forms of Fe2+ and Mn2+. Physical chemical removal processes require the oxidation of this water in

order to sufficiently raise the oxidation-reduction potential (ORP) of the water so that theiron and manganese present will be converted into their insoluble oxidized forms. TheORP or rH of the water is directly related to the pH and the Eh, (the potential energy

expressed in volts, of a substance compared to that of hydrogen, to proceed in a reductionreaction, calculated from an equation rH = Eh/0.029 +2pH =(A +or- Ehg) /0.029 +2 pH

).

The metabolic activities of iron bacteria are not fully understood but it is believed that the

same oxidation of iron is carried out by some variation to the physical chemical reaction:

4Fe2+ + O2 + 10H2O ? 4 Fe(OH)3 + 8H+ + Energy

Whatever the metabolic pathway for the iron oxidation reactions, the biological process iscatalytic in nature and causes a rapid oxidation. The red insoluble precipitates formed areall slightly hydrated iron oxides that, beneficially, are more compact forms than the

precipitates formed when using physical chemical processes. This feature partially

Figure 3 Common Forms of Iron Bacteria

1. Leptothrix ochracea2. Gallionella ferruginea



explains the greater iron retention capacity between backwashes of biological filterswhen compared to physical chemical treatment filters.

Manganese is also oxidized by ‘iron bacteria’ but at higher rH, or oxidation reduction

potential (ORP) values than that for iron, according to some variation of the following

three step reaction:

Mn2+ + 02 ? MnO2 + Energy

Mn2+ + MnO2 ? ?MnO2 oo Mn2+

MnO2 o Mn2+

+ O2 ? 2MnO2

Oxidation of manganese by oxygen alone is slow but the reaction is catalyzed by thepresence of previously oxidized manganese. The ion in its reduced form is adsorbed by

the manganese dioxide which allows the normally slow oxidation reaction to go tocompletion.

As with iron oxidation, the manganese dioxide, or some hydrated variant, remains as ablack precipitate trapped within the filter media until a backwash is carried out. The iron

bacteria species of particular interest for manganese removal are Leptothrix, Crenothrix,

Hyphomicrobium, Siderocapsacaes, Siderocystis, Metallagenium and Pseudomonas

manganoxidans.

It is important to recognize that iron bacteria catalyze the oxidation reactions under

conditions of pH and Eh that are intermediate between those of natural groundwater andthose required for conventional treatment. The field of activity of catalyzed oxidation for

iron bacteria thus straddles the theoretical boundaries between the fields of Fe2+ and Fe3+ stability expected strictly by chemical thermodynamics. This can be visualized in a

stability diagram, using pH and Eh as ordinates, as shown in Figure 4.



76 8 9

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Fe 2+

Fe(OH) 3

Mn2+

Mn 2 0 3

MnO 2

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IronRemovalField

ManganeseRemovalField

EH vs. pH

Figure 4 Stability Diagram for Biological Iron and Manganese Removal

By aerating the raw water and raising the dissolved oxygen concentration, the rawwater’s rH or ORP can be increased into the pH and Eh range where biological oxidationcan take place. By controlling the quantity of air supplied, the ORP or rH can be

adjusted to a level which is either ideal for iron or for manganese removal. When bothiron and manganese are present the iron must be removed first through one aeration-

filtration step, and then the manganese with another after raising the pH by strippingcarbon dioxide. In some cases, if the pH is below 7.0, chemical addition may also benecessary in order to raise the pH to make manganese removal possible.

Once a biological iron or manganese removal plant is constructed, the system must be

given time to ‘seed’ with bacteria naturally present in the water source. This seededbiomass is naturally and continuously regenerated during the life of the plant and isperiodically partially removed through backwashing. For iron removal plants, the

seeding period is quite short requiring anywhere from a day to about one week. Formanganese removal plants the seeding time can be considerably longer, anywhere from 3

weeks to 3 months. At the end of the seeding period, the metal concentration in theeffluent falls to near detection levels. The seeding period is affected by the temperature

of the water source, and is generally longer for cold water sources.

Iron bacteria are generally robust, and because of the variety of species involved, one

type or another is able to thrive under most environmental conditions. Given the correctpH, between 6 – 8, and Eh, the bacteria are normally able to oxidize iron at temperatures

ranging from 5 ?C to 50 ?C. Inhibition of the biological process can however be caused

by the presence of H2S, Chlorine, NH4+, and some heavy metals normally not present inwater sources. Under certain conditions of alkalinity and hardness, it can also be



impossible to raise the ORP sufficiently for biological manganese removal even with atheoretically sufficient quantity of dissolved oxygen. It is therefore critical to have a

complete and accurate analysis of the influent water because a biological removal systemwill only be effective if the proper water conditions are present.

PILOT STUDIES

Pilot Plant

ONDEO Degremonts’ pilot plant for biological iron or manganese removal consists of atransparent filtration column that operates in a down flow mode through what ONDEO

Degremont calls “Biolite S” growth media. One column is necessary for removal of asingle metal while two columns must be used in series if removal of both iron and

manganese is desired.

The pilot filter columns have the following dimensions:Diameter: 100 mmHeight: 2000mm

Normal Media Height: 1500mm

On the top and bottom of each unit are small stainless flanged columns that permit

connections for the influent and effluent water as well as to accommodate pressuregauges. The bottom of the column is equipped with a special nozzle designed to prevent

loss of the “Biolite S” during filtration.

A raw water peristaltic pump with a variable speed motor provides the process and

backwash water for the system. A positive displacement piston type compressor providesboth the process and backwash air for the system. Flow indicators and manual control

valves for both the air and water are all centrally located on a panel at the front of thepilot unit. Two pressure gauges measure the pressures on either side of the media toprovide the differential pressure or head across the filter. Normal head is 3-5 psi and at

15 psi the filter should be backwashed .

Woodstock Mangazur Pilot

The town of Woodstock New Brunswick is located about 100 km north of Fredericton on

the St. John River and the town draws its drinking water from wells located below the

adjacent river. Unfortunately this water contains a significant quantity of manganese andthe town noticed a dramatic increase in its’ concentration in recent years. The manganeseconcentration in the well water during the summer of 1997 was 0.67 mg/l or fourteentimes the provincial recommended maximum limit of 0.05mg/l for drinking water. The

town tested physical-chemical removal systems but they were dissatisfied by theinconsistent effluent quality, high chemical costs and the degree of operator attention

required. After an analysis of the raw water, ONDEO Degremont suggested that thetown consider a biological manganese removal plant. It was agreed that a pilot plant was



On-site testing was used for the day-to-day operation of the pilot plant because these testsare more accurate (especially for pH and D.O. tests that are sensitive to water

temperature) and to allow instantaneous adjustment of system parameters whennecessary. The operator carried out the following tests on a daily basis on-site: dissolved

oxygen concentration; pH; temperature; manganese concentration

During the first phase of the pilot study, a filtration rate of 15m/h (6.1 USgpm/ft2) was

maintained. After the column was properly seeded and the effluent manganeseconcentration was below the desired limit of 0.05mg/l, the speed was increased to 25 m/h

(10 USgpm/ ft2). The flow was then further increased to a velocity of 37 m/h (15 USgpm/ ft2) without any deterioration in effluent quality. The system was tested at this speed onlyto determine if the unit could handle this high filtration rate. At a 37 m/h filtration speed,

filter headloss was significant and more frequent backwashes were required. (The fullscale system was designed to operate between 20 and 30 m/h.)

The day-to-day operation of the pilot required little operator attention. During the start

up phase it was necessary to adjust the airflow to obtain the appropriate quantity of dissolved oxygen, but once adjusted, pilot operation required only water testing andbackwashing. The operation protocol required backwashing to be carried out after a head

loss increase (? P) of 1.5m or every 5 to 10 days. During the seeding phase, the firstbackwash was carried out four weeks after the start-up because it was feared that a

backwash would remove the biomass that had accumulated. Immediately after the firstbackwash, the manganese concentration dropped in the effluent by approximately 25%.It was clear that backwashing was necessary during the seeding phase even if the desired

increase in head loss had not been achieved. In theory, backwashing removes deadbiomass and allows for fresh or endogenous bacteria growth. During the seeding phase,

the period between backwashes should not be more than ten days to help ensure that the

biomass is in a healthy and hungry growth phase much like our teenage years.

Backwashing is carried out using an air scour, then a simultaneous air and water wash,and lastly a water rinse. This process fluidizes the bed and allows the removal of the

accumulated manganese dioxide.

Woodstock Results

The pilot plant was producing water that had a manganese concentration below 0.05mg/l

after six weeks as shown in Figure 5. The water quality remained between 0.02 and0.03mg/l consistently after this time even just after backwashing, increased filtration rates

and a pilot shut down. As long as backwashing is carried out regularly, the system canrun for an indefinite period without any replacement or regeneration of the growth

media.

After 15-20 minutes following backwash, the effluent water quality returned to levelsbelow the required level of 0.05 mg/l Mn. In the full-scale system the effluent produced

following backwashing is filtered to waste. Because the biological process produces largefloc, the turbidity of the effluent is also low immediately following backwash.



Figure 5 Manganese Concentration in Woodstock Pilot Effluent

During the pilot test the system was completely shut down for a period of six days to testthe effect on the system’s operation as this type of interruption will occur during theoperation of a full-scale system. During the period of time when the system was stopped,

the filter was drained. Iron bacteria can survive intermittent system interruptions as longas 6 months and this has been demonstrated during the normal operation of several plants

in France. The pilot was restarted after six days and the effluent manganeseconcentration was below the acceptable concentration of 0.05 mg/l within 15 minutes.

The town of Woodstock had the opportunity to test biological, greensand and intensiveoxidation manganese removal systems for its drinking water. The biological system was

shown to be superior to the others in terms of treatment efficiency, cost, flexibility andsystem life. The biological system could operate at higher filtration rates (>30 m/h),required less frequent backwashing, used no chemicals other than oxygen from the air,

and provided consistent water quality when compared to the other systems. Thebiological system also used less water for backwashing and produced a smaller quantity

of sludge than other treatment methods. Backwashing could also be carried out withuntreated water and this increased the net production capacity of the plant.

If the raw water quality were to change significantly the biological system would under

some circumstances need minor modifications (a possible pH adjustment, an additionaliron removal step, H2S removal etc.), but this is unlikely given the fact that the wells usedprovide water of highly consistent quality. Based on the results of the pilot it wasdetermined that a system designed to operate at a filtration rate of 20-25 m/h would serve

the towns’ current and future treatment requirements. Although the system could run athigher filtration rates (up to 35 m/h), a speed of 20-25 m/h provided an acceptable margin

of safety, a more stable system and a reserve if the town were to have some temporaryincrease in demand.

W o o d s t o c k P i l o t S t u d y R e s u l t s

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Woodstock Mangazur Full Scale Start Up

As a result of the successful pilot study an order was placed with ONDEO Degremont for

a full-scale plant. The full-scale plant utilized automatic valves, in-line ORP and Oxygen

meters, magnetic flowmeters and PLC controls to provide automatic operation of thefilter backwash and the filter-to-waste cycles. The two filters are each 3 M diameterwhich at the design flow rate of 272.5 m/h (1200 USgpm) provides a conservativefiltration rate of 20 m/h. The plant was built and installed in 1998 and began operation

November 18th , 1998.

Figure 6 Manganese Concentration in Full Scale Plant Effluent Seeding of the plant took 34 days to get the effluent concentration down to below the

acceptable level of 0.05 mg/l of manganese. This compares well with the 40 days takento seed the pilot filter. The initial flows through the filters were limited to rates below thedesign flow rate of 20 m/h (8.2 Usgpm/ft2). Operating at flow rates of 9.6 - 14.3 m/h the

full-scale plant has, as shown in Figure 6, demonstrated consistent manganese removal tolevels below the guideline objective of 0.05 mg/l. Since April of 1999 the plant flow rate

has been increased to the design rate of 20 m/h or 1200 USgpm.

The frequency of backwash has remained as low as once every 3 - 4 weeks based on

headloss. This extended time between backwashes was subsequently reduced to once

every 2 weeks based on the desire to keep the biomass fresh. Backwashing utilizesuntreated well water and, as no chemical is added to the water, the backwash water isdischarged directly to the St. John River.

When compared to the original estimates for the water treatment plant, the total installedcost for the plant was about 60% less than a physical chemical type plant, (about

$800,000 versus $1,460,0000). Chemical costs were eliminated which saved an

Woodstock Mangazur Full Scale Start Up

00.10.20.30.4

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Influent Effluent Guideline



additional $7,000 to $ 16,000 per year. Offsetting the elimination of the chlorine orpotassium permanganate costs was the need for

aeration blowers to supply air (oxygen) upstream of the filters. Sludge handling costswere almost non-existent due to the fact that the sludge had no chemical addition and the

filters used raw water for backwash.

Barrie, Ontario Ferazur Pilot

Located north of Toronto on the shores of Lake Simcoe, the City of Barrie draws its’

water from a number of wells that have unacceptable levels of iron. The wells arelocated on glacial till that due to changing ancient shorelines, has a number of aquifer“blisters” which can cause significant changes in raw water quality. Levels of iron,

manganese and oxygen can vary significantly depending on the weather and the rates of withdrawal. These conditions were considered appropriate for testing the strengths and

weaknesses of the ONDEO Degremont Ferazur Biological Iron Removal Filter. As aresult of the need of the City of Barrie PUC to test various alternate technologies and the

desire on the part of the Ontario Ministry of the Environment to test a biological ironremoval filter, side by side with conventional greensand and electromedia filters, fundingwas allocated by the Ministry and the City for a pilot test at Well # 3 at 55 Anne Street in

downtown Barrie. BOD Consulting of Toronto was retained to perform the pilot testing,led by Dr. Dennis H. O’Dowd, PhD. Dr. Anthony Edmonds, PhD of the Ministry of theEnvironment has overseen the pilot study on behalf of the City of Barrie and the OMOE

and will be issuing a comprehensive report in the near future that covers the results fromall of the technologies tested.

The well pump was operated 24 hours per day and a water head reduction deviceconsisting of a plastic line with a tee discharge into a pail provided the transition from the

pump pressure down to 20 kPa (3 psi) for the auto samplers. An on site lab in the pumphouse was equipped with a Hach Dr 2000 with reagents for testing for all forms of iron,

manganese, chlorine and other strong oxidizers, a lab scale, pH meter, oxygen meter withbuilt in temperature compensation , a lap top computer with Hach link and otherinstrument programs, a computer driven electron microscope (to 600 x) for particle

viewing and microphotography and a Hach Colourimeter. Testing was



Figure7 Barrie Ferazur Initial Start Up with Seeded Media

performed twice a day, (4.30-5.30 a.m. and 4.30-5.30 p.m.) seven days a week by Mr.Roy Symes, a federally certified water treatment plant operator for 25 years. The

standard tests performed twice daily were: raw and finished water oxygen, temperature,pH, total iron, free iron and manganese (irregularly): finished water chlorine and visualturbidity, odour and color observations. All microbiological sampling was performed by

Dr. O’Dowd and shipped on ice to Barbara J. Butler, PhD, University of WaterlooGroundwater Microbiology, Department of Biology.

The ONDEO Degremont Ferazur pilot unit was installed and started up on August 25,2000. The pilot was initially operated at a filtration rate of 22 m/hr. With raw water levels

averaging approximately 0.5 mg/l of ferrous iron, Fe2+, the level of ferrous in the effluent

was below 0.05 after two days. This rapid start up partially the result of seeding of thefilter with media from an earlier pilot unit. Although the immediate results were good,the practice of seeding the pilot to shorten the start up is not a good idea. Not only does itprevent a proper evaluation of the time needed to seed the filter, it also presents a remote

but very real possibility that should the feed pump discharge check valve fail, the biota inthe filter could contaminate the existing aquifer with new bacterial “pests” like a sulfur

fixer that could significantly alter the aquifers’ water quality.

Barrie Ferazur Pilot Seeded Start

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Due to the fact that the well being tested shared its’ draw down zone with two other oldwells, the influent had a large amount of fine particulate oxidized iron that had been

accumulated around the old wells. These particles which contributed approximately 70%of the iron going to the well would be filtered by the Ferazur and would have shown up in

the total iron removal. This highlights the importance of performing an analysis of both

ferrous and ferric iron and not just total iron.

Figure 8 Barrie Ferazur Second Start-Up with Unseeded Media

Raw water oxygen levels varied from 0.0 to 1.2 mg/l. Interestingly, as the weather

cooled, the average oxygen dropped. Manganese levels were low, about 0.01 to 0.03,with excursions to 0.05 but usually only slightly or occasionally above the target level of 0.01 mg/l.

Shortly after the initial start up, microbiological analysis showed an elevated level

bacteria in the effluent. Whereas the raw water had on average about 50 organisms per

ml, the effluent had 3500. To compare this result with the conventional plants, sampleswere taken from an existing manganese-greensand plant in Ontario. Although not as high

as the levels seen in the effluent of the Ferazur, the levels were above the Ontario MOEguideline level of less than 100. The significance of this finding is that both conventional

and biological filters are discharging chlorine tolerant bacteria into the distributionsystem and although they are not pathogenic they are pest bacteria which will proliferatein the distribution system so long as the proper nutrients, Fe2+ and Mn2+, are passed

along.

B a r r i e F e r a z u r P i l o t U n s e e d e d R e - S t a r t

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The backwash from the Ferazur appeared the same colour as that from the competing

technologies but the live protein count is too high for the MOE to allow its’ disposal back to a river and must go to the sewer. Another concern is the potential for a failure of the

biofilter due to an attack by a viral bacteriophage. As phages are usually specific for only

one type of bacterium or metabolic pathway, the chances of a complete failurecomparable to those found in the cheese industry is remote due to the diverse community

of species normally co-existing in the filter at any one time.

Some things that were expected by Dr. O’Dowd that apparently did not happen includednot finding a proliferation of pathogens in the biofilter. Although two molds and 2gelatinous saprophytes were found, molds, mildews and fungi were not present in large

quantities. It was also expected that there would be a cyclical shedding of bacteria ascolony forming units (CFUs) are sent downstream and a consequential decrease in

removal efficiency. Although CFUs’ may be migrating, again, due to the community of bacteria present in the filter at anyone time, there was no apparent difference in shedding

from one day to the next as reflected in the iron removal efficiencies.

Figure9 Barrie Ferazur Pilot after Sterilization Showing Oxygen Effects

As can be seen in Figures 9, 10 and 11 the effluent levels of Fe2+ and total iron shot upfollowing an extended period of over oxidation. The ferrous iron was being oxidized in a

physical chemical reaction and the faculative bacteria were starved of food. It took 4

Barrie Ferazur Pilot Post Sterilization

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days for the biofilter to revive. A full explanation hopefully will be provided in thereport as to what exactly was being tested over the last couple of weeks of the study.

Oxygen Applied

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N o v 8 - 1 7 0 0

N o v 1 0 - 1 3 3 0

N o v 1 2 - 1 3 0 0

N o v 1 4 - 1 7 0 0

N o v 1 6 - 1 7 0 0

N o v 1 8 - 1 4 4 5

N o v 2 0 - 1 7 1 5

N o v 2 2 - 1 7 0 0

Date

[ O x y g e n ] m g / l



Figure 10 Barrie Ferazur Raw and Final Oxygen Levels

As can be seen there is a close relationship between applied oxygen and filterperformance. The pilot plant has a primitive rotameter that made control of the air supply

very rough. In addition there was a period several weeks when the stainless float in therotameter was lost.DISCUSSION

Although it may not be apparent from the information provided in this paper, the authorbelieves the following recommendations are justified.1. Biofilters should not be seeded with media from another aquifer.2. Ensure that the aquifer can not be contaminated with backflow from any filter.

3. Ensure that the biofilter can be isolated and sterilized in case of a phage attack.4. Consider having a certified, FDA or Health Canada approved culture of bacteria

to seed the filter initially and also as backup in the unlikely event of system failuredue to a phage attack.

5. Ensure that the biofilter operator has a background in biological treatment and

understands that the effects from any process modifications are delayed .6. Look for applications for iron removal with high pH values, i.e. above 8 where the

chemical costs for conventional treatment begins increase significantly.7. Consider using a biofilter as a pretreatment for manganese- greensand filters in

retrofit applications where an increase in capacity is required.

8. Consider biofiltration for manganese removal due to its operating costsadvantages over conventional treatment.

ACKNOWLEDGEMENTS

Barrie Ferazur Post Ster i l izat ion

0.01

0. 1

1

10

Oct 6- 0450

Oct 8-

0545

O c t10 -

0 4 4 5

Oct11 -

1700

Oct13 -

1645

Oct15 -

1 4 5 0

Oct17 -

1700

Oc t19 -

1 7 0 0

Oct21 -

1440

Oct23 -

1620

Oct25 -

1 7 0 0

Oct27 -

1845

Oc t29 -

1500

Oct31 -

1 7 0 0

No v2 -

1700

No v4 -

1 4 0 0

No v6 -

1700

Nov8 -

1700

No v10 -

1 3 3 0

No v12 -

1300

Nov14 -

1700

No v16 -

1 7 0 0

Nov18 -

1445

Date

C o n c e n t r a t i o n m g / l

oxy finish Fe ra w Fe fini



The author would like to thank the City of Barrie and the Ontario Ministry of theEnvironment for funding the Barrie pilot study. I would also like to acknowledge the

support provided by Dr. Dennis O’Dowd of BOD Consulting in providing the basic data,much background information on the microbiology of groundwater, and many of the

insights gained from the pilot at Barrie.

BIBLIOGRAPHY

Bergel, J.Y. & Mouchet, P. Unpublished Paper. “Biological Filtration for Iron and

Manganese Removal: Some Case Studies”.Bergel, J.Y. & Trudel, J.P. Unpublished Paper. “Operating Results of Canada’s FirstBiological Manganese Removal System”.

Krimbein, W.E. (editor). 1983. “Microbial Geochemistry”, ISBN 0-632-00683-8..Ministry of Environment and Energy. 1994. “Ontario Drinking Water Objectives”.

Government of Ontario Report.Mouchet, Pierre. 1992. “From Conventional to Biological Removal of Iron and

Manganese in France”. Journal of American Water Works Association. Vol. 84, No. 4,April 1992.O’Dowd, D. Unpublished Paper. “Iron (Fe) and Manganese (Mn) Removal Trials at

Barrie Ontario”.O’Dowd, D. Unpublished Paper. “Project 2000. The Barrie Iron and ManganeseRemoval Trials”.

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