Emulsified Vegetable Oil for In Situ Bioremediation
Neutral Zone
An Insoluble Colloidal Buffer
Neutral Zone® is a colloidal calcium carbonate buffer used to maintain neutral pH during bioremediation. It is an easy to use liquid that contains 50% buffer solids. The solids are mobile during injection, but are retained in the treatment area after injection. In contrast, soluble buffers are commonly flushed out of the treatment area by ground water flow limiting their effectiveness.
Why Neutral Zone?
Neutral Zone is designed to provide buffering capacity where acids are present without creating an excessively high pH. The insoluble calcium carbonate dissolves only as needed to form bicarbonate, which normally limits pH in the injection area to 8.5 or less. Because the solids are retained in the treatment zone after injection, buffering can last longer than with soluble materials that may move out with groundwater flow.
Controlled pH Support
Maintains neutral pH during bioremediation while helping avoid the excessively high pH that can occur with some soluble buffers.
Retained in the Treatment Area
Mobile during injection but retained after placement, so buffering capacity remains where it is needed in the subsurface.
Stable Suspension
Formulated to keep calcium carbonate solids suspended for extended periods, supporting consistent handling, dilution, and injection.
Good Mobility with Minimal Permeability Loss
Distributes effectively during injection, with testing showing good movement through soil and minimal impact on permeability at typical use concentrations.
Technical Details
How It Works
When acids are present in groundwater, the food-grade insoluble calcium carbonate dissolves to form soluble bicarbonate. This provides buffering as needed while normally keeping pH at 8.5 or below in the injection area.
Application
Neutral Zone is normally diluted from 50% solids by weight to 0.5% to 2.0% solids and injected below the water table. After injection, the retained solids slowly release bicarbonate when acids are present. Best practice is to stir diluted material if it stands for several days, or prepare smaller batches every few hours.
Product Characteristics
Neutral Zone is an opaque white slurry with a density of 1.45 g/cm³ and a flash point greater than 200°F. The product contains 50% calcium carbonate, 44% water, and small amounts of preservative and surfactant blend.
Packaging & Storage
Neutral Zone is available in 5-gallon pails at 60 pounds net and 55-gallon drums at 600 pounds net. For large projects, ethanol-free Neutral Zone can also be shipped in totes at 3,000 pounds net.
It is stable for several years in chilled storage, with recommended on-site storage limited to two to four months without refrigeration before injection. Freezing should be avoided because it may cause permanent separation of the suspended solids.
Safety
The primary ingredient in Neutral Zone® is calcium carbonate. Stabilizing additives are food grade or
non-toxic. Neutral Zone® is not toxic, corrosive, or otherwise hazardous to the environment or to those
who ship, handle, or dispose of the material.
Need help selecting the right buffer for your site?
Talk with our team about site chemistry, injection approach, and treatment conditions.