Submerged biofilm can make septic systems more effective

The Cronitech AMB uses the leading edge technology of submersed biofilm to improve the performance of a conventional septic tank. This technology allows the septic tank to be converted into a high performance aerobic bio-reactor. Residential systems of this type have been used in Europe since 1989. Testing has consistently demonstrated over 80% reduction in the organic load and bacterial contamination of the waste water effluent. In other words, when a system of this type is installed, the water leaving the septic tank is a clear odourless liquid which is 80% cleaner than it would otherwise be.

Submersed biofilm technology exploits the completely natural formation of a complex diversity of organisms, including fixed and mobile bacteria and protozoa. The biofilm spontaneously grows when water circulation and dissolved oxygen are optimized in conjunction with a suitable support substrate. The system closely replicates the way organic waste is removed from water in a natural setting; the slippery rocks that are found in a shaded forest stream are covered with a layer of submersed biofilm.

How does it work?

A small air pump is placed in the basement or garage of the dwelling. Low pressure air goes out to the septic tank through a buried flexible air hose. In the tank, the hose connects to a header pipe and manifold that distributes the air to the aerators which are placed at the bottom of the septic tank. Contemporary septic tanks are two chambered (see diagram). Wastewater enters through the inlet into the larger chamber first. This is where primary sedimentation and some anaerobic digestion take place; also sand and floating material such as oil and grease are trapped here.

The wastewater then passes through a sub-surface connection into the second chamber, where it is subjected to intense fine bubble aeration. The air bubbles and water appear to “boil” up from the bottom. The entire subsurface cavity of this second chamber is filled with a biofilm substrate which provides approximately 100 sq. m. of surface area on which biofilm naturally develops. In this way, the wastewater in the second chamber is subjected to the process of biological oxidation by the bacteria and protozoa of the biofilm. Finally, the water passes through the outlet into some form of receptor.

Conventional receptors are leaching fields and seepage pits. Alternative systems may use sand filters, peat moss beds or some form of irrigation or engineered wetland. In some cases, the discharge can be into open water such as a stream or river.

The components of the Cronitech AMB are designed for minimum maintenance:

• Biofilm substrate is an inert cube of tubular net-like structures placed in the wastewater to provide a surface for biofilm growth. The substrate is not in any way consumed or degraded and never needs to be replaced.
• Aerators are made from a highly elastic synthetic rubber (EPDM) enabling the unit to be self-cleaning and auto-sealing. The other aerator components are made from PVC and/or stainless steel to assure a long underwater service life.
• Header pipe and manifold are made from PVC and/or 316 stainless steel for long life and durability. They also maintain the relative placement of the components under water.
• Air pump is an industrial quality compressor using oil-less carbon fibre vanes. The integral 1/3 hp electric motor is maintenance-free and UL/CSA approved. The air pump operates intermittently about 66% of the time and is controlled by a solid state programmable timer. The timer program is maintained in the event of a power outage by a permanent capacitor, eliminating the need to maintain batteries.

Where can it be used?

This product is for use in residential wastewater systems where a conventional system is inadequate. Some examples of this would be where:

• The existing leaching field is old and unable to accept its original organic load.
• The high density of septic systems is contaminating adjacent lake or source of potable water.
• A high water table is leading to contamination of the ground water.
• A small lot size has insufficient ground surface for a suitable leaching field.
• Conditions are inappropriate for leaching field or seepage pit construction such as: insufficient soil depth, steep slope, and in clay or gravel soils.

The Cronitech technology can also be applied to larger systems for use in communities and industrial applications.

How is it installed?

The Cronitech AMB can be installed into any conventional two chambered septic tank. This can be done in one day without excavation and without interrupting the use of the residence. New residences can also benefit, where additional advantages can be gained through installing a communal system shared between neighbours.

Prior to installation, the septic tank is pumped out and rinsed. The AMB components are installed through the access cover of the septic tank. A small air compressor is placed in the garage or basement and an air hose leads out to the tank. The air hose does not need to be buried below the frost line.