Arsenic Removal by Softening and Coagulation

EPA Grant Number: R822493
Title: Arsenic Removal by Softening and Coagulation
Investigators: Edwards, Marc , Amy, Gary
Institution: University of Colorado at Boulder
EPA Project Officer: Lasat, Mitch
Project Period: October 1, 1995 through September 30, 1998
Project Amount: $244,443
RFA: Exploratory Research - Engineering (1995) Recipients Lists
Research Category: Engineering and Environmental Chemistry , Land and Waste Management


Drinking water regulations for arsenic (As) and disinfection by-product precursor materials (measured as TOC) are becoming increasingly stringent. Among the modifications to conventional treatment that can improve removal of As and TOC, precipitative softening and coagulation are the most attractive. This work is aimed at improving As and combined As/TOC removals at existing water treatment plants through two phases of study. The first phase examines As(III) and As(V) behavior during softening in synthetic solutions, both with and without individual ionic constituents present (e.g., calcium, magnesium, manganese, carbonates, NOM and orthophosphates). This allows the precise role of each ion and corresponding solids in mediating As removal during softening to be elucidated. The second phase of the study will examine optimization of As and TOC removal during coagulation. An exhaustive experimental matrix will be completed that provides insight into the role of different NOM sources, acid addition, alkalinity and coagulants in the determining contaminant removals. The final phase of testing will provide confirmation of the most important optimization strategies in real waters.

Supplemental Keywords:

drinking water, water treatment, arsenic removal, combined As/TOC removal, precipitative softening, coagulation, role of alkalinity and coagulants in contaminant removals, optimization strategies, environmental engineering, environmental chemistry, RFA, Scientific Discipline, Water, POLLUTANTS/TOXICS, Environmental Chemistry, Arsenic, Chemistry, Water Pollutants, Drinking Water, Engineering, coagulation, public water systems, drinking water regulations, disinfection byproducts (DPBs), risk management, natural organic matter, treatment, environmental engineering, ionic constituents, arsenic exposure, drinking water contaminants, drinking water treatment, contaminant removal, water treatment, precipitative softening, alkalinity, drinking water system, removal of natural organic matter

Progress and Final Reports:

  • 1996
  • 1997
  • Final