Aeration Testing Difuser Cleaning

Aeration in Wastewater Treatment Plants (WWTP) is typically undertaken via diffused aeration systems (membrane or ceramic diffusers and aeration blowers). Operational costs for aeration are typically 30-40% of total plant OPEX and 50-70% of the electricity consumption in an activated sludge process.

Over time diffusers accumulate biological growths and inorganic material. This fouling can increase the pressure required to deliver air to the process. It can also reduce oxygen transfer into the mixed liquor.

Measuring the diffuser backpressure allows an assessment of their condition relative to new diffusers and can be used to quantify additional power costs caused by fouling. Carrying out diffuser cleaning using formic acid in parallel helps to maintain their performance and minimise energy wastage. Offgas tests can also be performed to determine oxygen transfer efficiency.

These tests have been undertaken at the Rotorua WWTP. Results show the very positive impact of diffuser cleaning on the backpressure, and an oxygen transfer improvement. An analysis of the aeration system performance in a MBR (membrane diffusers) and in conventional activated sludge (ceramic diffusers) is presented.

All of the above is undertaken with portable equipment, without interrupting the treatment process and represents very limited costs compared to the savings it can generate.