Title

Predicting Arsenate Removal During Metal HydroxidePrecipitation

Document Type

Article

Journal/Book Title/Conference

Journal - American Water Works Association

Volume

89

Issue

1

Publisher

American Water Works Association

Publication Date

1997

First Page

75

Last Page

86

Abstract

Data from two utility surveys led to the development of a simple model for predicting arsenate removal at full‐scale alum coagulation, ferric coagulation, and iron–manganese removal plants.

A simplified isotherm is described that can predict the extent of arsenate removal at drinking water utilities practicing coagulation or iron–manganese (Fe–Mn) removal. If all possible sources of particulate iron and aluminum hydroxide present in the system are accounted for, the model predicts arsenic (As) removal to within ±13 percent (90 percent confidence) for Fe coagulation at pH 6.5–8 and alum coagulation at pH < 7.6. Analysis of full‐scale treatment data suggests that colloidal aluminum (Al) flocs with sorbed arsenate [As(V)] may pass through filters, thereby decreasing overall As removal efficiency. Thus, Al solubility and particle stability must be minimized to improve As removal. If stability and solubility of aluminum hydroxide flocs are not a problem, alum and Fe coagulants have nearly equal capacity for sorbing As(V). Survey results also demonstrate the importance of particulate As.

This document is currently not available here.

Share

COinS