Biofiltration of WWTP sludge composting emission at contact times of 2 to 8 seconds

Abstract

The performance of a biotrickling filter for the abatement of composting emissions was evaluated at short contact times of 2 to 8 seconds. The effect of EBRT, pH control and water renovation rate were evaluated. The average elimination capacity was 13 and 3.3 g N/C m-3 h -1 for ammonia and VOCs, respectively, and the maximum EC obtained during a doping process were 40 and 20 g N/C m -3 h -1 . Biotrickling filters appear as a better alternative than biofilters due to their controllability. However, water renovation becomes a critical parameter to avoid substrate inhibition by nitrite and ammonia accumulation. Not only ammonia absorption is negatively affected at low renovation rate but it is also affected the biological process. A decrease of 40 % was detected in the nitrification step when the hydraulic residence time increased from 2 to 5 hours. Results presented herein demonstrate that high removal efficiencies can be achieved for composting emissions in a biotrickling filter operated at short contact times which entails a substantial reduction of operational and investment costs in comparison to traditional techniques.