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Arsenic Research Project

Engelhard Corporation, Iselin, NJ

B.F. Environmental Consultants Inc., Dallas, PA

Wilkes University, Wilkes-Barre, PA

Introduction

The scope of the project was limited to a preliminary evaluation of the general quality, solubility, structural stability, and uptake capacity / kinetics for a line of ferric hydroxide zeolites designed and manufactured by Engelhard Corporation to reduce and control the level of arsenic in a treated water.

Project Status and Milestones as of March 8, 2002

1. Initial permeability testing of the materials has been completed.
2. Preliminary flow-through testing chamber has been redesigned and a pilot unit has been constructed.
3. Static testing of the materials for As V and As III removal at ambient pH and pH 7 has been completed.
4. Initial kinetics testing for As V removal at pH 7 using 7 materials at an initial total arsenic concentration of 100 ppb to 1 mg/L has been completed.
5. Preliminary testing has been conducted to determine the effect of the solution pH and the arsenic removal capacity of the materials.

Photos of Various Phases of Project

Initial Static Testing
Mixing Apparatus Used to Conduct Static Testing

Samples were then filtered, preserved with acid, digested, and analyzed for Arsenic using a Graphite Furnace.

Kinetics Experiments

Because mixing did NOT provide adequate contact the with the material

An EPA tumbling / extraction device was used to try and maximize contact between the material and the fluid

As part of the Kinetics Experiments, the seven materials were evaluated by exposing a controlled amount of the material to a known mass of arsenic. Subsamples were collected at the following time intervals: 1 minute, 15 minutes, 30 minutes, 2 hours, 4 hours, 8 hours, and 24 hours.

As part of the project, the pH / mv of the test solution was monitored prior to starting the testing and during each sampling. A series of samples were tested under a variety of solution pH.

After preservation and digestion the samples were analyzed by Graphite Furnace Atomic Absorption. During the analysis, known samples were analyzed to evaluate the accuracy of the data.

A preliminary summary report has been submitted by Mr. Brian Oram et. al. to Mrs. Valerie Bell, Engelhard Project Researcher.

The laboratory technician in the photos is Mr. John Pagoda. He is a research assistant and consultant working with the Center for Environmental Quality at Wilkes University and B.F. Environmental Consultants Inc.

Results

The results can not be disclosed, but the work did document that the zeolites did provide significant capacity to uptake arsenic and the kinetics of each zeolite varied.  In a few cases, we discovered that the zeolite was not stable and "partially" dissolved or broke down when hydrated.

Note - The research has expanded to evaluate a new treatment process known as POW. POW is a new treatment process that has applications related to Mine Water Treatment, Flow-Back Water Treatment, and Water Reuse. The process can be used to treat fluids and process waters. The by-products consist of activated materials that can be used for other applications in water treatment such as cation reduction, anion reduction, and as a potential biocide.  For groundwater systems, we have seen that repeated shock-disinfection of wells with very strong chlorine-based solutions appear to cause a short-term increase in arsenic and antimony content and we have seen elevated levels of arsenic associated with biofilm development and sulfur-reducing bacteria in groundwater systems.

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