Aeration Treatment Units (ATU) work on the principle of septic tank aeration to treat waste water and human effluent. Whilst a septic tank decomposes waste matter sent to it by the action of anaerobic bacteria; a septic tank aeration unit treats the waste it receives under aerobic conditions. Subsequently, the discharge they produce is substantially less contaminated than that from a traditional septic tank without an aeration unit
Advantages of having a Septic Tank Aeration System
Whilst an ATU requires an electrical supply and can even have mechanical parts to it, they also have advantages over traditionally designed septic tanks. The key to their advantage is that the discharge they produce is of a good enough quality to be sent directly to a local water-course, which then means that there is no need for a soak-away or drainage field.
So, if the site at which a septic tank is required is not suitable for the construction of a soak-away/drainage field due to: lack of space, impervious soil or a high water-table; a septic tank aeration unit will be ideal. Also, of course, by producing a much purer discharge they are more environmentally friendly all round.
How Septic Tank Aeration Units Work
Septic tank aeration units are constructed as a series of separate compartments. As with any septic tank system, in an Aeration Treatment Unit the waste water and effluent first enters into a sludge tank where any solid material is allowed to settle. The waste water is then forced into a second chamber where it is aerated by a stream of small bubbles, pumped in by a compressor. This stimulates the growth of aerobic bacteria which decompose the organic matter by feeding on it.
The treated effluent can then pass into a holding tank before being discharged. This holding tank can also be referred to as a clarification chamber and may contain a chlorination unit to kill any remaining bacteria. (Any debris/solids still present in the aeration chamber or holding tank are allowed to return to the ‘first’ settling chamber via a sloping floor.)
Dependant on the local terrain the treated effluent might be able to seep/drain into a local water course or it may require a pump to move it to a suitable discharge point. If a pump is used the treated effluent will be stored in an ‘on-demand’ pump tank, which will use floats to determine when pumping needs to take place.
To maintain the aeration process, the compressor must be constantly running. Therefore, if you live in an area where power outages occur, you must have a back-up electrical supply in order to keep the septic tank aeration system working. The same is also true if the system requires a pump. Ideally the back-up electrical supply could be a solar or wind powered option.
Both the aeration compressor unit and, if required, the pumps need to be included in your regular program of septic tank care. The manufacturer of your ATU will, of course, provide full details for its regular inspection and maintenance. NB. Aeration Treatment Units can also be known as Continuous Aeration Plants.
If the treated effluent is being discharged into a field, especially if by spray nozzles, routinely check the site and don’t locate it near a children’s play area or food source. The treated effluent will still contain some impurities that could be harmful and which have yet to be dealt with by absorption through plants and soil. If your system has a chlorinator be very careful when replenishing it. Chlorine is a very harmful gas causing severe eye irritation, respiratory problems and can even be lethal.