Aerated and advanced wastewater treatment systems

These systems treat sewage to a higher level than septic tanks, allowing it to be safely used for gardening or even recycled for toilet flushing.

Aerated water treatment systems (AWTS) and advanced sewage treatment systems (ASTS) are secondary treatment systems, that is, they involve both anaerobic and aerobic (with oxygen) treatment to a higher level than a primary treatment system, resulting in effluent that is suitable for garden (excluding fruit and vegetables) and landscape irrigation.

At the highest level of treatment (from ASTS), the treated effluent can be used in non-potable situations such as toilet flushing, vehicle washing and firefighting.

In many areas, a secondary treatment system is the only option permitted.

How an AWTS works

Water flows through a series of chambers or tanks that progressively treat and filter the wastewater
Stage	Type of treatment	Process
Chamber 1	Anaerobic	Settlement of solids and anaerobic decomposition
Chamber 2	Aeration	Effluent passes through filter to aeration chamber Pumped in air creates turbulence and aerates effluent The chamber may incorporate a bioreactor to give additional bacterial treatment
Chamber 3	Clarification	Effluent passes through second, finer filter to clarification chamber Fine sludge particles settle and are pumped back to the first chamber
Chamber 4	Pump	A submersible pump distributes treated effluent to the disposal field

After treating wastewater in a similar process, an advanced treatment system may pass the effluent through a sand filter, a packed bed filter or a textile bed reactor, where effluent trickles through the bed material containing micro-organisms that treat any remaining fine solids before being pumped to the disposal field.