AboutDavid L. Russell, PE Expertise I`m a Chemical,Civil and Environmental Engineer and have a number of projects in all phases of the environment.
I have worked in the chemical industry and am active in professional societies, and am currently on an industrial wastes committee for the Water Environment Federation, and have taught courses in remediation in the US and abroad.
I have written one book on Remediation of petroleum Contaminated Sites, and have a second book on PRACTICAL WASTEWATER TREATMENT to be published by John Wiley in September, 2006. I've also written over 30 articles on various elements of environmental problems and cleanup. Most Recently, I have addressed a NATO Scientific and Techical Conference on Ecoterrorism, and have worked with the same group on remediation of sites contaminated with Chemical Warfare Agent materials and othe materials as well. . I can answer q`s about Chemical and Environmental Engineering, land development, air pollution, water pollution, soil and water cleanup, combustion, international environmental problems, industrial processes chemical processes. Civil and Environmental and Chemical Engineering. Overall, I have over 35 years of experience in this area. Note: I do not answer homework questions
Experience I love work in the third world and developing areas
because it is challenging and one can get a sense of accomplishment.
Question QUESTION: Are there brands of detergents, or generic types of them, that are safer than others on the aquifer? I am referring to laundry detergent, dishwasher detergent, or even car wash detergent, which end up in the septic tank or on the ground. I'm wondering if these will find their way into the aquifer before degrading, thus harming the water supply, and if so, what products would be least harmful to use.
ANSWER: Frank:
You pose a very interesting question. The answer unfortunately, depends upon the amount of organic material and the permeability of the soil. This works in two ways.
1. The organic material will adsorb the nutrients and chemicals in the detergents and adsorb them and treat them biologically and incorporate them into new soil mass or new bacteria. As soil is a heterogeneous population, it depends upon the amount of air in the soil (aerobic reactions are about 3x faster than anaerobic reactions), the chemistry of the soil, and a host of other factors including the exchange capacity of the soil.
2) The permeability and water table of the soil controls how fast things will reach the water table. Clay soils, as you know are very impermeable. Sandy soils are very permeable. Without knowing the specifics of the soils in your area, there are a few general rules which may be applicable. There are some sources of help as well..
First the help: http://www.nesc.wvu.edu/wastewater.cfm is the National Small Flows organization set up for septic systems etc. Their data base will be able to provide you with some guidance.
Second: Phosphate detergent builders were once the darlings of the detergent industry. No longer because they have a tendency to be persistent and create algae blooms in surface waters (the groundwater and the surface water are connected). Silicates in the detergents might be a better bet. Also look for biodegradable detergents, as the older detergents use to contain alkyl benzene sulfonate which was very slowly degradable, and now most detergents contain LAS or Linear Alkyl Sulfonates which are biodegradable.
All detergents will have a high pH, especially dish detergents and laundry detergents. Those which are pH balanced might be a bit better, but that's just a guess without knowing what the specific formulation of the detergent is. What works in one area does not necessarily work in another area.
I realize that I have not give you much of an answer, but At least I tried. Good luck.
Dave
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QUESTION: Dave, my follow-up question: The area I am interested in is coastal and is virtually all sand. Surprisingly, there are no recommendations that came with the septic system. I am also concerned about washwater that does not pass through the system, like car-washing, house window washing, deck cleaning, etc. Is there a difference between the two, that is, septic system vs direct discharge to the ground? I want
to minimize the effects of such detergents, so I will use whatever detergents are least damaging, if any exist.
Thanks for the opportunity to follow-up. Frank
Also, recognize that trace amounts of carcinogens may not necessarily be harmful in humans, but that there is a law called the Delaney Amendment which prohibits any carcinogen from being introduced into food materials for human consumption. There are a few exceptions, because of concentration, and lobbying, but generally harmful levels of carcinogens cannot be introduced into foodstuffs.
Dave
Even in coastal areas in sandy soils, there is some bacteria, and your septic system will contribute to a natural bacterial population by the nutrients in your sewage.
To answer your specific question: Yes, there is a difference between the chemicals used in each. For cars you want a non-phosphate builder, such as Non Phosphate TSP to supplement your grease cutting of the automobile grease and road oils. This is a silicate based detergent booster.
The house and deck are usually cleaned by a chemical application of a chlorine solution to clean up the house. Window washing is usually a biodegradable alcohol- no worries there. The spray compounds are generally non-biodegradable but reactive enough that they will disappear into the soil, so don't worry about the house and deck washing chemicals unless they are applying something with a preservative.
The difference between the material which does go into the septic system versus that which is spilled on the ground is that the septic system has a fixed tile field and contains bacterial populations which will degrade the waste put into the system. The other chemicals are often applied indiscriminately and generally are not a problem when used because they are diluted with a rinse, or with rainfall before they can do much damage.
Enjoy your house and don't stary worrying about things unless you start apply pesticide compounds indistriminately, or washing off trucks regularly. Even if you were to do that the soils could be brought back and the groundwater restored with the application of some air and some other nutrients to eat the compunds. However it's better to avoid high repetetive use of the washing (think commercial applications) in almost any situation.
