THE STRONG REDUCTION OF BIOLOGICAL SLUDGE BY MEANS OF A THERMOPHILIC MEMBRANE REACTOR OPERATING WITH ALTERNATE AERATION CYCLES

The sewage sludge management in wastewater treatment plants (WWTPs) is a significant issue due to the uncertain recovery/disposal future options. In this work, the Thermophilic Aerobic Membrane Reactor (TAMR) was applied for the treatment of biological sludge derived from a municipal WWTP, to obtain its drastic reduction. The proposed treatment is based on a biological thermophilic process (T= 50 - 55 °C) coupled with an ultrafiltration system operating in alternate aeration cycles. Thickened sludge derived from a municipal WWTP was treated by TAMR plant at semi-industrial scale adopting a HRT of 10 days. The alternate aeration cycles were optimized in order to obtain the higher VS removal yields and to reduce the foaming issue mainly produced in the non-aerated phase. The proposed treatment seems to be very interesting for the reduction VS content in biological sludge. Moreover, the TAMR permeate can be treated in an ammonia stripping reactor followed by an absorption tower with the dosage of sulphuric acid for the ammonia sulphate production. The TAMR permeate (after the ammonia stripping) can be used as external carbon source in a post-denitrification scheme instead of methanol. The partial or total replacement of this reagent with the TAMR permeate could involve significant cost savings.