Desenvolvimento de reator anaeróbico de leito fluidizado associado a membranas de microfiltração

Abstract

The requirements to achieve what is demanded by the environmental laws make important the use of areas for sanitary landfills. The adequate disposal of waste associated with the current legislation also demands larger efficiencies to the treatment processes of the leachate generated in the sanitary landfills. The high concentrations and the different kind of pollutant compounds in the leachate, require more adequate treatment processes to the wastewater. One of the most promising technologies is the use of anaerobic fluidized bed reactors due to the possibility of increasing the contact between the biomass and the wastewater, with improvement in the global efficiency of the treatment, besides the reduction of the size of the reactors. Associated to this, membrane systems have been object of researchers in wastewaters treatment processes, because besides the biomass retention, the final wastewater of a process using membranes shows a possibility of reuse due to the good physical-chemical characteristics. It was made an experimental unit consisted of an anaerobic fluidized bed reactor associated with a microfiltration membranes unit for evaluation of this process. The bed of the anaerobic reactor was constituted of river sand with granulometry of 28/35 Mesh. The feeding flow rate resulted in the upflow velocities 0.000479 m.s-1 and 0.00118m.s-1, according Leva and of 0.00364 m.s-1, according to Ergun. It was calculated a upflow velocity of 0.0099 m.s-1 when was considered only the cross-sectional area. The upflow velocity calculated by Ergun equation was 63% that calculated using the cross-sectional area, only. The hydraulic detention time laid in the range of 16.5 to 33.0 hours, during the experiment. The system of membranes presented satisfactory operational results, having been submitted to chemical cleanings and cleanings with water along the process. The chemical cleaning was better than water when executed in the recovery of the flow of having permeated. The permeate flux value was 62.55 L.m-2.h-1 immediately after the chemical cleaning, while the value after the cleaning with water reaching 14 L.m-2.h-1. Despite these flux values, the membrane resistances during the operation time were reduced in up to 91% with the cleaning with water only, proving the viability of this strategy cleaning for short periods in the operation of these systems.