Background
With the advent of ever increasing environmental concerns, regulations and the increased use of ANSULITE^® AFFF products we have been receiving more and more requests on the environmental impact characteristics of the ANSULITE product line. There are four areas of interest with regard to the environmental fate of AFFF products. They are fish toxicity, biodegradability, sewage treatment plant treatability and nutrient loading. All of these are of concern when the end-use foam solutions reach natural or domestic water systems. Since the end-use foam solutions (i.e., after they have been proportioned with water), are all essentially equivalent with regard to levels of active ingredients, we may discuss the product lines as a whole rather than as individual concentrates.

Fish toxicity tests are normally run on both estuarine and fresh water species. The two most common test species are the Killifish, (Fundulus heteroclitus), and the Rainbow Trout (Salmo gairdneri). The Killifish is a tolerant, (eurytopic), fish while the Rainbow Trout is a sensitive, (stenotopic), fish. This combination gives an indication of the broad range over which various fish populations may be affected. The values are given as the 96 hour LC50 which is a measurement of the concentration which is lethal to 50 percent of the test population after 96 hours of exposure to that concentration. The units of measure are milligrams/liter or parts per million (ppm) which, in the case of water based solutions, are considered to be equivalent. Obviously, the higher the value, the greater the tolerance of the fish to the AFFF. Testing indicates that Rainbow Trout have a 96 LC50 for end-use ANSULITE AFFF solutions of from 4,000 – 6,500 ppm while Killifish have a 96 LC50 of from 26,000 – 36,000 ppm. It is evident from this broad range that fish toxicity is extremely dependent upon fish species. Other factors will also include water quality, water temperature, dissolved oxygen levels and general health of the fish population.

The biodegradability of AFFF solutions is a measure of how readily the chemicals in the AFFF are broken down by bacteria in the environment. As the bacteria use up the chemicals as food, (oxidizable carbon source), they also use up dissolved oxygen in the water as part of their metabolic process. To determine the theoretical biodegradability of ANSULITE AFFF, we use two different tests and compare the results. The first test is called a chemical oxygen demand test, (COD), and measures how much oxygen would be required to completely break down the chemicals contained in a given amount of AFFF to their most oxidized state. The second test is called a biological oxygen demand test, (BOD), and measures how much oxygen will be used up by bacteria, over a given time period, as they use up the chemicals contained in a given amount of AFFF as a food source. Normally, BOD tests are  conducted over a five day period, however, for AFFF solutions, this period is extended to twenty days. The reason for this extension is that there is a lag phase in the bacterial population growth curve as the bacteria become acclimated to the chemicals in AFFF. After they become acclimated, they exhibit a logarithmic growth cycle as they use up the chemicals in AFFF. This long lag phase is actually an advantage in that it allows the AFFF time to reach "infinite" dilution before there is any substantial demand for dissolved oxygen. To determine the theoretical biodegradability, we look at the ratio of biological oxygen demand, BOD, to the total possible oxygen demand, COD, i.e., BOD20/COD. Masseli et. al. from the Industrial Waste Laboratory of Wesleyan University conclude that a BOD/COD ratio above 50% for a chemical mixture is readily biodegradable while ratios below 15% show that the mixture is nonbiodegradable. ANSULITE AFFF products are well above the 50% level.

As far as sewage treatment plant treatability is concerned, ANSULITE AFFF products are not  particularly toxic to the microbial populations normally found in treatment plants. However, a problem does exist with AFFF, (or any type of foam concentrate), entering a sewage treatment plant. That problem, especially if the plant uses the activated sludge process for secondary treatment, is in foaming, which tends to carry over suspended solids, and consequently, a rather large amount of BOD. Present data show that concentrations of AFFF up to 250 ppm can be handled without adverse effects. Often times, the normal volumetric dilution which takes place on the way to the sewage treatment plant will bring the concentration down below the 250 ppm level. If it doesn't, the use of a defoaming agent which is compatible with the treatment plant's flora may allow handling of concentrations above the 250 ppm level.

With regard to the nutrient levels of AFFF, the concern is that, if additional nutrients are added to a body of water which is already high in nutrients, an algal bloom may occur. Nutrients in water act to promote growth the same way that fertilizers do on land. Generally, only two nutrients are of concern in aquatic ecosystems, they are phosphates and nitrates. On very rare occasions, organic carbon may also act as a limiting nutrient. There is no need to worry about any nutrient loading when using ANSULITE AFFF products as they contain no sources of nitrates or phosphates and they are extremely low in total organic carbon when compared to other types of foam concentrates.

ANSULITE AFFF concentrates are formulated to provide maximum fire performance with minimal environmental impact.