Testing the function of the WWTP during a long-term shutdown and subsequent commissioning

Based on the requirement to verify the possibility of the WWTP function during a long-term shutdown, especially for recreationally inhabited objects with a long seasonal break, we tested the wastewater treatment plant for these modified operating conditions. We carried out the testing at the Modřice WWTP test site on a functioning, properly run-in wastewater treatment plant, where various hydraulic loading modes had been tested in previous months.

The testing took place in two phases. In the first phase, we shut down the wastewater treatment plant from regular inflow, set the expected limited aeration mode, and in the second phase, we then restored the inflow to the WWTP, in a mode corresponding to the wastewater treatment plant testing in accordance with the EN 12566-3+A2 standard.

In the first four-month phase, we regularly checked the volume of activated sludge and the amount of oxygen in the activation chamber of the WWTP using a sedimentation test in the set aeration mode. During this phase, the sediment volume decreased from the original 340 ml/l to a stable 100 ml/l.

In the subsequent second phase, we measured the volume of activated sludge on a daily basis, monitored its quality, measured the amount of oxygen in the activation tank and collected and analyzed samples of the treated wastewater. In this second phase, the testing of which lasted 14 days, the volume of activated sludge sediment increased very quickly from the original 100 ml/l to the resulting 600 ml/l. The biological purification processes started very quickly and stabilized after less than five days, and after three days the WWTP showed the values ​​of a normal, standard functioning wastewater treatment plant in all essential parameters.

Through this testing, we were able to prove that with proper controlled aeration of the activation tank of a wastewater treatment plant, it is possible to maintain the activated sludge in the wastewater treatment plant in good condition for a long time even without the introduction of influent wastewater or another source of nutrients, and it is also possible to easily and quickly put such a wastewater treatment plant back into full operation, even with the achievement of the appropriate parameters of the treated wastewater.

Ing. Antonín Vondruška