Optimizing Remedial Product Vendors’ Products with Common Sense Chemistry

PHILADELPHIA - Oct. 28, 2013 - PRLog -- When applying remedial products, we as remedial professionals need to look at the basic premises of the technologies to be applied.  The optimization of available products and processes is the topic of this press release.

Simple Optimization of Geochemistry:  In general remedial products fall into four categories:  Oxidation, Reduction, Bio-enhancement and Augmentation.  Each of these segments can be easy optimized for significant cost savings and efficiencies.

Oxidation:  Many oxidation processes are burdened with overcoming the half-life of the oxidation reaction.   Frequently, the sorbed mass of the targeted compound will result in a “rebound” equal to or greater than the starting groundwater concentration of the compound of interest.  In the worst case, IET has seen numerous sites in which an oxidative technology has simply oxidized the Natural Organic Demand (NOD) of a site resulting in significant increases in dissolved concentrations of targeted compounds.  Vendors of oxidants, rather than offer chemistry compatible with the geochemistry, simply anticipate subsequent oxidation events.  How often has an oxidation based solution required a half-dozen or more applications?

Reduction:  The number of suppliers of “organic hydrogen donors” is ever increasing, these providers supply a wide range of fermentable products, ranging from vegetable oils, plant based products, esters etc.  All of these products, if applied into an oxidizing environment, rely on aerobic bacterial to consume the oxygen while utilizing the fermentable product as a growth substrate.  There are even suppliers who sell bacterial cultures which are purported to facilitate the degradation of chlorinated solvents in-situ which are actually just turning the environment anoxic due to their respiration.  The use of an inexpensive oxygen scavenger such as sodium sulfite, rapidly converts the in-situ environment reducing without the associated costs of additional substrate while minimizing a “lag” phase seen with the application of these products in accordance with their manufacturer’s recommendations.  For products utilizing a zero-valent-iron component, the addition of the oxygen scavenger to the injectant inhibits the oxidation of the iron in the mixing and injection process.

Bio-Enhancement:  Many vendors provide metallic peroxides as oxygen sources for aerobic processes, yet many geochemical sumps can consume these products (reduced iron and manganese as examples).  The use of dilute peroxide with these product applications will inexpensively address these inorganic sumps allowing for more efficient remedial product utilization and a longer-lived oxygen source.

Augmentation: The frequency IET sees in RFPs requiring augmentation has exploded in the past several years.  The addition of biological cultures be they aerobic, facultative or anaerobic is almost always driven by vendor recommendations.  Ignoring for a moment the recommendation itself, the application process of these products are often technically inappropriate.  Such recommendations as adding KB-1 into “anaerobic water” ignores the oxygenation that occurs in the mixing process; application of KB-1 and other strict anaerobes should occur in nitrogen blanketed processes.  Recommendations of mixing aerobic organisms which come  dormant on a bran substrate in open tanks with sugar or other “growth substrates” only insures that when injected sugar degraders are present and that in-situ the excess sugar is consumed utilizing the dissolved oxygen.  In the majority of these applications a review of the targeted product distribution, geochemistry, etc. provides evidence that no augmentation is required.

This press release is the first in a series in which the discussion of remedial process optimization will be discussed.