# Presentation: 107981

## Technologies

** ****for**
** ****Arsenic Removal**

**Tom Sorg**
**U. S. Environmental Protection Agency**

## Arsenic Chemistry

-   As (III)
-   As (V)

**Arsenic Chemistry**

## H3AsO30

- H2AsO3-1
- HAsO3-2

_**Arsenic III**_

## H3AsO40

- _H__2__AsO__4__-1_
- _HAsO__4__-2_
-  AsO4-3

_**Arsenic V**_

## Why is arsenic form important? 

- Final Answer!
- As V more effectively removed
- by
-  ALL technologies

## Example!

-                                          _As III_          _As V_
- Iron Coag/Filt - pH 7         55               97
- Alum Coag/Filt - pH 7       18               95

**Example!**

## Example!

- As III - 0 percent removal
- As V  - 98+ percent removal

**Example!**

## Arsenic Occurrence

- Surface waters predominantly As(V)
- Ground waters generally As(III), but not always

## Arsenic Speciation Method

- On site anion exchange separation

- As
- V

- As III, As V

- As III

**As V retained on resin column**
**As III passes through column**

## Arsenic Speciation - Anion separation of AsIII/AsV

**Arsenic Speciation - Anion separation of AsIII/AsV**

## Good News!

- As III easily oxidized  to As V
- by
-  several oxidants

## As III Oxidation Study

**  ****Oxidants Studied                                   ****	****	****1.  **_**Free Chlorine**_**                              ****	****	****2.  Chloramine                                   ****	****	****3.  **_**Ozone**_**                                          ****	****	****4.  Chlorine Dioxide                                ****	****	****5.  UV Radiation                                     ****	****	****6.  **_**Potassium Permanganate**_**                 ****	****	****7.  **_**Oxidizing Media**_

**As III Oxidation Study**

## Arsenic Removal Processes

**Precipitative processes**
**Adsorption processes**
**Ion Exchange process**
**Iron Removal processes**
**Membrane processes**
**POU/POE devices**

## Arsenic Removal Processes

- Iron coagulation with microfiltration
- Iron based adsorption media

**Arsenic Removal Processes**

## Precipitative Processes

_**Process**_**                 **_**Removal**_
**Coagulation/****	****	****   95 %****	**
**Filtration**
**  **
**Lime softening ****	****   85+ %**

## Adsorption Processes

_**Processes**_**                     **_**Removal**_
**Activated Alumina       90+ %**
**Iron Media****	****	****	****   90+ %**

## Ion Exchange

**95 + % removal**

## Iron Removal Processes

_**Process**_**                         **_**Removal**_
**Oxidation/filtration****	**** 80+ %**
**  **
**Manganese greensand ****	**** 80+ %**
**(Dependent on amount of Fe)**

## Membrane Processes

_**Process**_**                           **_**Removal**_
**Reverse osmosis (RO)****	****    90+ %**
**Nanofiltration (NF)****	****   65-90 %**
**Ultrafiltration (UF)****	****   35-75 %**
**   **

## Arsenic Removal Processes

- Coagulation/filtration
- Direct filtration
- Lime softening

**Arsenic Removal Processes**

## Arsenic Removal Processes

- Lime softening
- Membrane Separation Processes
-   -reverse osmosis (RO)
-   -ultrafiltration (UF
-   -electrodialysis reversal (EDR)
- Iron Removal processes - oxidation/filtration

**Arsenic Removal Processes**

## Arsenic Removal Processes

- Coagulation/filtration package plants
- Iron Removal processes -      oxidation/filtration
- Lime softening package plants

**Arsenic Removal Processes**

## Arsenic Removal Processes

- Anion Exchange
- Activated Alumina adsorption
- Iron Removal processes - oxid/filt.
- Membrane Separation Processes
-   -reverse osmosis (RO)
-   -ultrafiltration (UF)
-   -electrodialysis reversal (EDR)

**Arsenic Removal Processes**

## Arsenic Removal Processes

- Point-of-use systems
-   -RO, AA
- Point-of-entry systems
-   -RO, Ion Exchange

**Arsenic Removal Processes**

## Evaluation of Treatment Plant Performance

**Investigator - Battelle, Columbus, OH    **
**  ****Processes - 5                 ****	****	**
** ****Conventional Coag. -- 2 Systems  **
** ****Lime Softening -------  1 System**
** ****Iron Removal ----------2 Systems**
** ****Anion Exchange -------2 Systems**
** ****Activated Alumina ----2 Systems                            **

## AA System - Source Water Quality (Avg)

- _Analysis - ug/L_        _CS (30)_
-  Total As	                   63
-    Particulate As           2
-    Soluble As	           66
-    As III	  	           <1
-    As V	                   66 (100%)
- pH - Units	             8.4
- Hardness – mg/L        37
- Sulfate – mg/L           14
- Alkalinity - mg/L       57

## A

**B**

**B**

**A**

**Activated Alumina System - New Hampshire**

- Roughing filter
- Polishing filter

**Non regeneration**
**system**

## Activated Alumina System, 20 gpm - NH

**Activated Alumina System, 20 gpm - NH**

## Activated Alumina System, NH

## IE System - Source Water Quality (Avg)

- _Analysis - ug/L_          _MMA (45)_
- Total As                          57
-  Particulate As	               <1
-  Soluble As	               57
-   As III	  	                <1
-   As V	                        57 (100%)
- pH - Units	               8.3
- Hardness – mg/L            38
- Sulfate – mg/L               45
- Alkalinity - mg/L           64

## Ion Exchange System, ME

**B**

**Ion Exchange System, ME**

- Oxidizing
- filter media
- KMnO4
- regeneration

- Mixed bed resin

## 2 gpm

**Ion Exchange System with Oxidizing Filter, ME**

**2 gpm**

## Ion Exchange System, ME

## Iron Media System, MI

**Source Water Quality**

- _Parameter_		  _Concentration - mg/L_
- Arsenic			0.025 - 0.041
-    As III			       85 %
-    As V			       15 %
- Calcium			     80 - 90
- Magnesium			     34 - 35
- Iron				  1.06 - 1.35
- Manganese			  0.02 - 0.03
- Sulfate			     21 - 30
- Silica 				     19 - 20
- pH				    7.1 - 7.2

## Iron Media System, MI

- Distribution system

**Tank 1B**

**Tank 2B**

**Tank 3B**

**Tank 1A**

**Tank 2A**

**Tank 3A**

**Softener**

**Well**

**Acid**

**Cl****2**

## Iron Media System, MI

## Iron Media System, MI

## Soluble arsenic occurs in natural water in the As III and As V oxidation states.

**Soluble arsenic occurs in natural water in the As III and As V oxidation states.**
**As V is dominant in oxygenated waters**
**As III is dominant in anoxic water**

## Treatment processes remove As V more effectively than As III

**Treatment processes remove As V more effectively than As III**
**As III can be converted to As V with strong oxidants**

## Most conventional treatment processes have capability to reduce arsenic to less than 10 ug/L, many to to 5 ug/L or less. 

**Most conventional treatment processes have capability to reduce arsenic to less than 10 ug/L, many to to 5 ug/L or less. **

## Tom Sorg

**USEPA**
**Cincinnati, OH 45268**
**513-569-7370**
**sorg.thomas@epa.gov**