ARA TOBL CHANGES THE SLUDGE CIRCULATION OF DIGESTION CHAMBER 1

01.07.2021

Digester circulation

In 2008, an agitator for the circulation of the digested sludge was installed in digestion tower 1 of the Tobl wastewater treatment plant, which has a digestion tower size of 2000m³. The agitator weighed 2,200 kg, was 18.2 m long and equipped with two propellers. One of them had a diameter of 4.3m, the other 2.5m. The agitator achieved a consistently good mixing of the digested sludge, but clogging was still a problem and the static load on the gas dome showed its effects over the years and cost-intensive repairs had to be carried out.

New gas injection

After intensive discussions about the pros and cons, we finally decided to switch back to the original gas injection system. The work went very well due to the precise preparation and now the new gas injection system has been in operation since June 2021.