TOPAS WWTP works on the principle of an activated sludge process. The air which is necessary for the life of microorganisms is supplied by small diaphragm blowers. The blowers are installed inside the plant. Air from the blowers is also used to drive air-lift pumps which circulate wastewater trough the chambers of the WWTP. The operation of the TOPAS WWTP is flexible with automatic adaption to variable load without any demand on maintenance. The principle of the patent is a simple hydraulic design of an accumulation tank at the inflow with a float switch that ensures automatic switching of the WWTP function every day – approximately 3 or 5 times – into a maintenance phase (regeneration phase)

FLOW – TREATMENT PHASE 

• Raw wastewater enters into the accumulation (equalization) tank where any irregularity of daily inflow is constantly balanced. From this tank, wastewater which is already cleaned of rough primary dirt is being pumped by the raw sewage air lift pump into the activation tank.
• There the biological treatment process, by use of activated sludge, takes place. The mixture of treated water and activated sludge is pumped by the settling tank air lift pump into the dirt trap pipe which is part of the settling tank. The sludge sinks to the bottom of the settling tank and falls back into the activation tank. Treated water without sludge rises up to the surface and falls over into the anoxic-sand filter where the cleaning of water is mechanically accomplished. Water than runs down through the sand filter.
• Filtered water is pumped from bottom of the sand filter by the treated water air lift pump to the outlet pipe.
• The sand filter is also equipped with a level float switch which keeps an optimal level of water above the sand filter layer. Low inflow of sewage to the sand filter results in a decreased level of water above the sand filter. This in turn causes the level float switch deactivates the treated water air lift pump. By this way decreasing of function of this pump is ensured and a sufficient level of water above the sand filter, necessary for automatic cleaning of the sand filter is ensured.

BACKWARD – REGENERATION PHASE 

•  The outlet pipe also serves as a safety by-pass. In the case of  low wastewater inflow, the level of water in the accumulation tank reaches the adjusted minimum level. In that case the control level float switch switches over the three – way electro valve so that air supply into the air distributor of flow regime is closed and air supply into the air distributor of excess sludge decanting regime is opened.  Within this regime, which is called “the excess sludge decanting mode”, the accumulation tank is being aerated as well as the sand filter.
• At the same time excess sludge re-pumping by the excess sludge air lift pump is being carried out. The excess sludge is automatically pumped from the activation tank to the sludge storage tank. Excess water from the sludge tank falls over into the accumulation tank.
• After the level of water in the accumulation tank reaches the level of “standard flow mode” then the control level float switch switches-over the electro valve back into the initial position.
• By this means the operation of the WWTP is returned to the standard flow mode. The rising  water level in the accumulation tank can also be caused by inflow of new wastewater.
• The operation of the WWTP is fully automatic. All excess sludge from the activation tank is regularly exhausted by the excess sludge air lift pump; the WWTP automatically regulates an optimal amount of activated sludge in the activation tank.
• Within the excess sludge decanting mode the sand filter is being automatically washed. The bottom of the sand filter is being aerated and released dirt along with water above the level of sand filter is pumped to the accumulation tank by the air lift pump for decantation of the sand filter dirt.