Aerobic (requiring air)
vs.
An-Aerobic (with out air)
History
Anaerobic: Conventional septic systems are the overwhelming majority of residental septic systems in this country and they have all been based on anaerobic bacteria decomposition. Because of the overall low cost and passive ease of use, residental anaerobic septic treatment has been a wholly accepted standard for a long time. But because anaerobic decopposition is slower, less clean and less efficient, there is very limited municipal treatment use.
Aerobic: Historically, because aerobic treatment for residental applications compaired to anaerobic is a little more costly and sightly more complex, it's residental application has been minimal until recently. On the other hand, aerobic bacteria decomposition has been utilized in virtually every major municipal wastewater sewage treatment system in the U.S. Because Aerobic treatment is faster, cleaner and more efficent, it is universally accepted on a massive scale for the municipal treatment of household waste.
Facts
Anaerobic: There are four main problems with anaerobic residental septic treatment. First, the treated effluent from an anaerobic septic tank is only about 40-65% clean, therefore its dependent on a secondary treatment phase, where naturally occuring aerobic bacteria in the soil of the leachfield finishes reducing the effluent pathogens. It is critical that a conventional anaerobic leachfield be designed large enough and deep enough to throughly allow for this second phase of treatment of the effluent to occur. Secondly, when the effluent is discharged into the field, it accumulates as a sludge and builds up in the leach field, there it forms a "bio-mat" and will lead to eventual system failure. Third, the anaerobic biological breakdown process is slow and inefficient compaired to aerobic treatment. And lastly, anaerobic bacteria breakdown produces noxious gases such as methane and leaves offensive odors.
Aerobic: What makes Aerobic systems increasingly attractive to the public is that aerobic treatment systems produce septic effluent that is 98% clean right out of the treatment tank. This allows for a much smaller and shallower leach field. Aerobic systems are essentially a one phase process and unlike anaerobic, they are not dependent on bacterial breakdown in the field. Secondly, because the effluent is 98% clean when its discharged into the leach field there are is no "bio-mat" problems and a leach field will last indefinitely. Third, the aerobic bacteria treatment process is significantly more efficient, accelerated and thorough. And lastly, aerobic treatment generally produces safe and odorless gas.
Anaerobic Systems (no oxygen) Example: Conventional systems |
Aerobic Systems (requiring oxygen ) Example: Southern Manufacturing or Advan-Tex. |
|
| Effluent quality | 40%-65% clean out the tank | 98% clean out the tank |
| Speed/Time | slow | fast |
| Bio-mat | #1 cause of failure | minor/non issue |
| Treatment Phases | two phases: the tank, and the field | one phase: the treatment tank |
| Odor | noxious gasses | generally odorless |
| Cost | generally, the least costly |
generally, more costly |
| Size | large field, and deep trenches 3'-8' deep | small field and shallow trenches 8"-10" deep |
| Life of system | 10-40 years (average 25) | indefinite when maintained |
| Historical use | residential septic | municipal sewage treatment |
