# Presentation: 617357

## Arsenic Removal During Iron Removal

- Darren A. Lytle
- U.S. Environmental Protection Agency
- ORD, NRMRL, WSWRD, TTEB,
- Cincinnati, Ohio 45268
- Lytle.darren@epa.gov**	****	**		**Arsenic Rule Webcast **
**	****	****	****	****	****	****October 20,  2004**

## Iron-Based Arsenic Removal Processes

**Adsorptive properties of iron mineral toward arsenic are well known**
**That knowledge is the basis for many arsenic treatment processes**
***IRON REMOVAL***
**Coagulation with iron coagulant**
**Iron-based adsorption media**

## Slide 3

## Removal of 1 mg/L of iron 

**achieves**
**removal of ****50 ug/L**** arsenic**
**(0ptimized conditions and As[V])**

## Iron and Arsenic (and Mn) Removal

## Iron and Arsenic (and Mn) Removal

**Oxidation**

**Contact Basin**

**Aeration**
**Cl****2****,**
**KMnO****4****, other**

**Oxidation, particle development**

**Fe(II), As(III)**

**Fe(II)/Fe(III), As(III) and/or As(V)**

## Iron and Arsenic (and Mn) Removal

**Contact Basin**

**Aeration**
**Cl****2****,**
**KMnO****4****, other**

**Oxidation, particle development, arsenic adsorption/coprec.**

**Fe(II), As(III)**

**Fe(II)/Fe(III), As(III) and/or As(V)**

**Fe(III)-As particle**
**+**
**arsenic**

**Iron and Arsenic (and Mn) Removal**

## Iron and Arsenic (and Mn) Removal

**Contact**** ****Basin**

**Aeration**
**Cl****2****,**
**KMnO****4****, other**

**Oxidation, particle development**

**Fe(II), As(III)**

**Fe(II)/Fe(III), As(III) and/or As(V)**

**Fe(III)-As particle**
**+**
**arsenic**

**arsenic**

**Iron and Arsenic (and Mn) Removal**

## Case Studies

**Factors the impact arsenic removal during iron removal.**

## Form of ArsenicAs(III) vs As(V)

**As(III) is removed during iron removal and other iron-based processes- just not as well as As(V)**
**Aeration will oxidize Fe(II) to Fe(III) but not As(III) to As(V)**

## Case Study 1-OhioAs Oxidation State-Removal of As (III)

**Oxidation**

**Contact Basin**

**Aeration**

**Fe(II)=2.7 mg/L, As= 0.043 mg/L (80% As(III))**

**No contactor**
**Fe(III)-As particle**
**+**
**Arsenic (III)**

**As= 0.008 mg/L**
**Ammonia=nd**

- X

**As= 0.033 mg/L (80% As(III))**
**Ammonia>1 mg/L**

## As (III) Oxidation

**Effective!**
**Free Chlorine**
**Potassium Permanganate**
**Ozone**
**Solid Oxidizing Media  (MnO****2**** solids)**
**Ineffective**
**Chloramine**
**Chlorine Dioxide                                **
**UV Radiation**
**Oxygen****                                  **

## Oxidant Type

- Depends on As, Fe and Mn
- Aeration
- May need contact basin
- Will not address Mn and As oxidation
- Iron particles have less surface area
- May have longer filter run lengths
- Strong oxidants (chlorine, permanganate, etc)
- Address Mn and As oxidation
- Shorter filter run time possible
- More particle surface area
- Difficult to feed
- Probably no contactor needed

## Oxidation- Case Study 2- Ohio 

**Source Water Quality**

- _Parameter_		  _Concentration__ _
- Arsenic – ug/L		69 - 132
-    As III			85 %
-    As V			15 %
- Calcium – mg/L		115
- Magnesium – mg/L	58 - 60
- Iron – mg/L		0.5 - 1.4
- Manganese –mg/L	0.2 - 0.9
- Sulfate – mg/L		1.2 - 10.0
- Silica – mg/L		NA
- pH - units		         7.9

## Effect of Oxidant Type and Concentration Case Study 2- Ohio- pH 8.2, 1.7 mg O2/L

## Effect of Oxidant Type and Concentration Case Study 2- Ohio- pH 8.2, 1.7 mg O2/L

## OxidationpH=8, DIC=10 mg C/L, As(V)=100 ug/L, Fe=1 mg/L Point of Application and Contact Time

## Oxidation- Point of Application

**Case Study 3- Michigan**

_**Parameter**_**	****	****  **_**Concentration**__** **_
**Arsenic – ug/L****	****         19 - 24**
**   ****As III****	****	****         95 %**
**   ****As V****	****	****         5 %**
**Calcium – mg/L****	****         74 - 84**
**Magnesium – mg/L****	****   30 - 33**
**Iron – mg/L****	****	****   0.5 - 0.6**
**Manganese –mg/L****	****   0.02**
**Sulfate – mg/L****	****         50 - 60**
**Silica – mg/L****	****         12 - 13**
**pH - units****	****	****         7.1 - 7.3**

## Oxidation- Point of Application

**Case Study 3- Michigan**

**20 min CT**

**Wells**

**Aeration tower**

**Pressure filters**

**Cl****2**

**50 % removal**

## Oxidation- Point of Application

**20 min CT**

**Wells**

**Aeration tower**

**Pressure filters**

**Cl****2**

**50 % removal**

**Oxidation- Point of Application**
**Case Study 3- Michigan**

## Oxidation- Point of Application

**20 min CT**

**Wells**

**Aeration tower**

**Pressure filters**

**Cl****2**

**75 % removal**

**Oxidation- Point of Application**
**Case Study 3- Michigan**

## Pilot Plant Rapid Mix, Flocculation, Sedimentation

## Pilot Plant Filters

## Arsenic Pilot Plant Screening RunsArsenic Removal (pH 7.2 with 20 mg/L DIC and 1.5 mg/L Fe)

- _Date_	     _Floc_	            _Cl__2__ (mg/L)_       _As (mg/L)_  _A__s(mg/L)*__final_
- 8/12	       Yes		   1		100 (V)		7
- 8/13	       Yes		   -		100 (V)		13
- 8/14	       No		   -		100 (V)		30**
- 8/18	       No		   1		100 (V)		 7
- 8/19	       Yes		   -		100 (V) added after floc	 85
- 8/20	       Yes		   1		100 (V) added after floc	 48
- 8/22	       Yes		   -		100 (III) 	 44
- 8/25	       Yes		   1		100 (III)	  8
- *  Average filter effluent value over complete test run
- **  Soluble iron passed filter

## Arsenic Pilot Plant Runs Headloss Build-Up(pH 7.2 with 20 mg/L DIC and 1.5 mg/L Fe)NO Calcium

## Process Modifications

**Increasing As Removal**

- Utility with iron removal in place or will be in place but can not meet MCL:
- 	Increase iron concentration
- 	Adjust pH
- 	Replace media w/ As adsorption 	media
- 	Change point of oxidant addition

## Conclusions

**Iron removal = arsenic removal****	**
**Arsenic speciation is important**
**Oxidant type is important**
** ****Point of oxidant application is important**
**Arsenic removal impacted **
**Plant operation impacted**

## Thank-you.