1. The use of calcite contactors for Iron and Manganese removal
Tim Bradley
Dr. Martine Poffet
Jochen Kallenberg 1

2. Overview
Background on Fe and Mn Removal - Chemistry
Methods for removal
Calcite Contactors for Fe and Mn removal
Water Quality specifics
Omya’s Calcium Carbonate Products
Questions

3. Drinking water treatment
For protecting the customer’s health: to guarantee the water quality and stability
to avoid the dissolution of heavy metals from the water works
to avoid red colored water from the tap
For maintaining the water works: against corrosion
against scaling

4. Neutralization / Remineralization
Neutralization: to increase the water pH
(→ neutralization of free CO2)
Remineralization: to increase the water hardness
(→ increase calcium content)
Stabilization: to obtain a stabilized water quality
(→ to reach the calco-carbonic equilibrium)

5. Iron Iron is the fourth most abundant element in earth’s crust.
The ferrous oxides and sulfides are the usual source of dissolved Iron in waters.
The weathering of iron silicates also produce dissolved iron in surface water.
Common deposits
ferric oxides, hematite, FeO3
ferric hydroxide Fe(OH)3 source of red and yellow color
Sedimentary forms of iron may include sulfides:
pyrite and marcasite FeS2
Carbonates FeCO3
mixed oxides, magnetite Fe3O4

6. Iron
Iron is very soluble in a reducing environment or in natural waters such:
low oxygen containing ground water,
low oxygen surface waters,
deep waters of eutrophic lakes, larger rivers and reservoirs.
Depending on water quality, iron can exist in three physical forms,
As soluble reduced form
Small oxidized colloidal particles
Large Oxidized particles

7. Iron

8. Iron Limits EPA Secondary Drinking Water Regulations 1991
Limit iron to 0.3 mg/L for taste and aesthetic reasons.
Disadvantages
Metallic taste - threshold reported at 0.1 to 0.2 mg/L
Ferrous iron can stain laundry, household fixtures, glasses, dishes.
Iron discolors industrial products such as Textiles and Paper.
Iron precipitates can clog pipes and support growth of iron bacteria which can cause taste and odor problems.

9. Manganese
Manganese is and the eleventh most abundant element in earth’s crust.
Manganese is similar to Iron in that it is usually found in the Mn+2 oxidation state in anoxic ground waters.
Oxidation of Mn2+ can lead to three different oxides of manganese depending on pH MnO2, Mn2O3,and Mn3O4, with the predominant form being MnO2.

10. Manganese

11. Manganese Disadvantages
Impairs the taste of drinking water and heated beverages such as coffee and tea.
This was found at levels above 0.05 mg/L.
Staining of laundry, especially black spots
Staining of household fixtures, glasses, dishes.
Build up in pipes which slough off occasionally causing spotting.

12. Manganese
Limits In 1977 the USEPA issued a proposed rule for manganese control under the Safe Drinking Water Act (SDWA) for a non-enforceable Secondary Maximum Contaminant Level (SMCL) of 0.05 mg/L. This was done for aesthetic reasons not health reasons. In 2001 the limits were reviewed with a focus on potential health concerns. The EPA concluded in 2004 that setting National Primary Drinking Water Regulations was unwarranted due to lack or meaningful opportunity of health risk. However, some states have enacted their own regulations. New York has set a limit of 0.3 mg/L for Mn alone and a combined limit of 0.5mg/L if both Fe and Mn are present. The WHO established a health guideline of 0.4mg/L and aesthetic limit 0.05mg/L.

13. Methods of Removal
1. Oxidation using oxygen (aeration), Chlorine, Chlorine dioxide, Potassium permanganate or Ozone, all followed by sedimentation and filtration.
Manganese Greensand, again followed by sedimentation and filtration
Ion Exchange
Lime Softening
Sequestering Chemicals
Calcite Contactors.

14. Omya products for water remineralization
Filtracarb ® / Puri-cal ®
Calcite contactor (filtration bed)
Closed / Open system
Upstream / Downstream
Long term international expertise
40 years technical feedback
Germany, France, Spain, USA, Qatar
New products evaluation from Morocco, Serbia, Greece, Australia, Jordan, UAE
Juraperle JW – Wasserstudie Omya 14 14 14

15. Fe and Mn Removal - Nethen Germany
Nethen Water Treatment Plant installed in 1994.
Omya has supplied material to treat aggressive waters in this region for 40 yrs.
One side effect of the treatment is the removal of Fe and Mn.
In Nethen the focus is on the removal of Fe
and Mn because of the high levels in the
incoming water.

16. Process Overview

17. Process Overview - Degassification / Oxidation
Air is bubbled through the raw water to remove CO2 and odor causing gasses The incoming air is sent through a dust filter and the exiting air treated with a carbon filter to remove odors Oxidation occurs at this step. Precipitating both Fe(OH)3(s) and MnO2(s) Air Volume ~1,300 cubic feet per minute

18. Process Overview – First Stage, Fe Removal
Four Coarse Calcite contactors in series Calcite Granules measuring 1.8 – 2.5 mm, 12 inch gravel base in bottom of filter pH rise from 5.7 to 7.1 Fe precipitates, is captured in filter and later back flushed Flow ~ 970 gallons per minute

19. Process Overview – Second Stage, Mn Removal
Four Fine Calcite contactors operated in series
Calcite Granules measuring mm
pH rise from 7.1 to 7.7
Mn precipitates, is captured in filter and later back flushed

20. Process Overview – Third Stage, Degassification
In this stage the final water is further degassed to reach final pH
It has been found that this stage is unnecessary. But has been left in place for security.
Turbidity 0.07

21. Process Overview – Water Quality

22. Contactor Specifics Flow 1.4 MGPD, (970 gals/min)
Eight Calcite Contactors
(4) Fe, (4) Mn
Operate 2–4 filters based on flow and contaminant demand
1st Stage (Fe) – Recharge 28 to 48 hours with 3 metric tons
2nd Stage (Mn) – Recharge 340 to 470 hours with 6 metric tons
Bed Height 72 – 90 inches
Back flush volume 38,000 gals

23. Remineralization process
Example:
Downstream closed system
Contact time: 20 – 40 min
Airing
Refill
Height over the filter
Calcite bed (Filtracarb ®)
Filtering media
Filter support
Air inlet
Intlet = Raw water Outlet = Backwash wastewater
Inlet = Backwash Outlet = Remineralized water
Drain / Manhole
Eau de rinçage
Eau reminéralisée 23
Juraperle JW – Wasserstudie Omya

24. Materials Gravel Coarse Calcite Fine Calcite Base for coarse
1.8 – 2.5 mm
Fine Calcite
1.2 – 1.8 mm

25. Calcite Material with impurities

26. Puri-cal material for remineralization
Filtracarb / Puri-cal applications:
CO2-removal and remineralization of soft water,
remineralization of distillate and/or R.O.-water,
removal of iron and manganese as well as aluminum.
Omya’s quality
Very pure products
Insoluble part: 0.1 – 2% (Acid insol. content)
Ca and Mg carbonate > 98%
CaCO3: marble, calcite, chalk
MgCO3 : 0.5 – 3.5%
NSF 60 Certified EN 1018 norm
Calcium Carbonate used for treatment of drinking water
Omya Calcium Carbonate Products
Filtracarb / Puri-cal for Remineralization

27. Calcium carbonate (CaCO3) – carbon dioxide (CO2) system
L. Birnhack, et al., Desalination (2011)
System H2O – CO2 – CaCO3
CO2 in water: CO2 + H2O ↔ H2CO3
CaCO3 and CO2: CaCO3 + H2CO3 ↔ Ca(HCO3)2
Product consumption: g CaCO3 per g CO2
Hardness increase: g CaCO3 par g CO2
CaCO3
Geology
Chemistry
Granulometry
Water
Physico-chemical properties (temperature, conductivity, hardness, free CO2, alkalinity)
Infrastructure
Setting
Flow rate
Equipment

28. Calco-carbonic equilibrium
Managing Aggressiveness / Scaling:
Saturation pH is dependent on Water Hardness
Ideal LSI value is slightly positive +0.3 in order to be slightly scaling and non leaching to piping.
Hardness > 50 Soft Water
< 150 Hard Water
Must adjust both pH and hardness
Calcium Carbonate Provides a cost effective means to accomplish this.

29. Thank you for your attention!

30. T H E O M Y A A D V A N T A G E . .
Experience
Commitment
Results