Treatment OptionsPart 1

Tom Sorg Darren Lytle

Water Supply and Water Resources DivisionOffice of Research and Development

U.S. Environmental Protection AgencyCincinnati, OH

Topics – Part 1

• Arsenic Chemistry

• BAT Technology

• Adsorptive Media

Arsenic Chemistry

Arsenic Species

As (III) - H3AsO30 , H2AsO3

-1 , HAsO3-2

As (V) - H3AsO40 , HAsO4

-1 , AsO4-2

Arsenic ChemistryWhat is the significance of arsenic speciation?

As V more effectively removed than As IIIby most treatment technologies

Arsenic Occurrence

Surface waters - predominantly As (V)

Ground waters – usually found as As (III), however, it can As (V) or a combination ofAs (III) and As (V).

Arsenic Chemistry

For maximum As removal

oxidize As (III) to As (V)

before applying treatment

As III OxidationEffective!

Free Chlorine

Potassium Permanganate

Ozone

Solid Oxidizing Media (MnO2 solids)

Ineffective

Chloramine

Chlorine Dioxide

UV Radiation

Oxidation of As III by aeration

not effective

Topics – Part 1• Arsenic Chemistry

• BAT Technology

• Adsorptive Media

Arsenic RuleBest Available Technology (BAT)

Technology Maximum PercentRemoval (As V)

Ion Exchange 95Activated Alumina 90Reverse Osmosis >95Modified Coag/Filtration 95Modified Lime Softening 80Electrodialysis Reversal 85Oxidation/Filtration (20:1 Fe/As) 80

Arsenic RuleOther Ground Water Processes

Technology Reason for not beinglisted as BAT

Coagulation Assisted No full scale historyMicrofiltration

Granular Ferric Lack of published dataHydroxide (GFH)

Arsenic RuleSmall Systems Compliance Technologies

Centralized Treatment – IE, AA, MC/F, MLS, Fe Removal

POU - RO, Activated Alumina

POE – Activated Alumina

Arsenic Treatment - Process Selection Guide

Iron - mg/L0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Ars

enic

- ug

/L

0

5

10

15

20

25

30

35

40

45

50

As MCL

Fe -

SMC

L

AIron Removal Process

(Optimized for Maximium As Removal)

BModified Iron Removal Process

C

Media AdsorptionIron Coag/FiltIon ExchangeIron Removal(M)RO / NF

20 - 1 Fe/As ra

tio

or above

Topics – Part 1• Arsenic Chemistry

• BAT Technology

• Adsorptive Media

Arsenic Demonstration Program – Round 1

Technologies selected for demonstration (12 sites)

Adsorptive media – 9Iron media – 7 (E 33, Sorb 33, GFH)Iron based media – 1 (G2)Modified activated alumina –1 (AAFS 50)

Ion exchange – 1 (As & NO3)Iron removal – 1Treatment modification (iron removal process) - 1

Adsorptive Media Processes

Advantages• Simple process• High removal capacity• Non hazardous waste products• Low cost

Adsorptive Media Treatment

Disadvantages• Removal capacity impacted by water chemistry, such as pH• pH adjustment may be required• Media replacement

Adsorptive Media Treatment

Key design factors• Media• Bed configuration

Adsorptive Media Listed in NSF/ANSI STD 61

AAARM 100AluminiumEngelhardMod AAAqua-BindAluminiumApyronAACPNAluminiumAlcoa (2)

Zirconium Hydroxide

IsoluxZirconiumMagnesium Elektron

Mod ZeoliteZ – 33ZeoliteWRTIron OxideE 33IronBayer AGIron HydroxideGFHIronUS FilterIron/sulfurSMI IIIIronSMI

Iron OxideIron based

ARM 200G2

IronIron

EngelhardADI Internat.

Mod AAAAFS - 50AluminiumAlcan (4)MaterialNameBase MaterialCompany

Figure 1. Results of Arsenic Removal by Adsorptive Media Pilot Plant Studies.

Bed Volumes X 1000

0 5 10 15 20 25 30 35 40 45 50 55 60 65

Ars

enic

Con

cent

ratio

n - u

g/L

0

5

10

15

20

25

30

35

40

45

50

55

60

MCL

C2 Alcan Modified AAC3 ADI G2

C1 Alcoa CPN AA

C4 E33 C5 Englehard Modified AAC6 GFH

Adsorptive Media System Designs

Simple 1, 2, or 3 beds in parallel

Adsorptive Media System Design

A A Roughing filter

Polishing filterBB

Series Design

Activated Alumina System - New Hampshire

Arsenic Removal, Activated Alumina System(CS), NH. 1998-99

Week0 5 10 15 20 25 30 35 40 45 50

Ars

enic

con

cent

ratio

n - u

g/L

0

10

20

30

40

50

60

70

80

Influent water After 1st AA tank After 2nd AA tank System effluent

Influent water: pH 8.2, alk 58 mg/L (CaCO3), Fe <0.03 mg/L

Adsorptive Media Treatment

54$122,646$228,309Series37 AAFS50

73$112,600$153,000Parallel320 E33

68$157,646$232,309Parallel350 GFH

71$218,000$305,000Parallel640 E33

62$129,500$211,000Parallel300 E33

80$112,211$139,251Parallel145 E33

77$82,081$106,568Parallel100 E33

73$66,235$90,757Series45 E33

66$102,600$154,700Series70 G2

Eq Cost% of TCI

Equipment Cost

Total Capital Investment (TCI)

DesignFlow Mediagpm