Gerenciamento do lodo em um sistema UASB + BF

Resumen

This paper presents and discusses the results of one year monitoring of a system consisting of an UASB reactor followed by an aerated submerged filter, as well as the management of the sludge produced in such units. The main operational rules were related to sludge disposal in the UASB, and to the biofilter frequency of backwashing. The UASB reactor achieved an average efficiency of BOD and COD removal of 85% and 81%, followed by an additional removal in the biofilter close to 30% (BOD) and 20% (COD). The coefficient of biomass production (Y) in the UASB was found to be 0.69 kgTSS/ kg COD and 0.20 kg VSS/kg COD. A routine of sludge disposal could be established as 2.4 m3 (volume of the drying bed) every 4 to 7 days, besides a frequency of filter backwashing every two days. The sludge management included the hygienization (with lime), under different mixing conditions (30, 40 and 50%). A “Class A” sludge was produced after a lime dosage of 50%, 40 days of storage after lime addition, satisfying the Brazilian legislation.