Influência da espessura do meio suporte em reator anaeróbio híbrido (UAHB) tratando esgoto sintético

Abstract

Considering the importance of the formation of biofilm, the influence of the support material for the retention of biomass, and the microbiology of internal processes in the hybrid anaerobic reactor (UAHB), it is necessary to develop studies that allow establishing the best characteristics of the filter medium in the different reactor’s operating conditions. This research contributed to the wastewater treatment knowledge by evaluating the variation of the heights of the filter medium composed of Conduit Polyvinyl chloride (PVC) corrugated rings in a UAHB pilot treating synthetic wastewater. Likewise, this research contributed to defining the relationship between the filter medium’s size and the UAHB response in terms of pH, alkalinity, volatile acids, COD, turbidity, conductivity, total solids, total fixed and volatile solids with the hydraulic retention time (HRT) variations. The research is justified based on the need to know the filter medium’s physical characteristics and the UAHB reactor’s performance to project systems with greater efficiency. The UAHB pilot was built based on the bibliographical review, establishing the operational parameters and the sizing of the treatment system (nominal diameter equal to 100 mm and length equal to 75 cm) to evaluate the efficiency of the UAHB reactor with the variation of the heights of the half support. Therefore, filter medium heights equivalent to 6 cm (8% of total volume), 15 cm (20% of total volume), and 24 cm (32% of total volume) are selected. The study developed three stages of operation: Stage 1 (HRT =10 h), Stage 2 (HRT =7 h), and Stage 3 (HRT =4 h), using the average concentration value equal to 500 mgCOD L-1, which is equivalent to the organic load rate (OLR) comparable to 1.20, 1.71 and 3.0 kgCOD m-3 d-1 for HRT equal to 10, 7 and 4 h respectively. In the first stage, the best results were obtained with average COD removals equal to 69.4%, 70%, and 72.6%, turbidity of 85.2%, 86.9%, and 90.2%, total solids equivalent at 61.6%, 63.2% and 63.9% for filter medium’s heights equal to 6, 15 and 24 cm respectively. The study indicated better operational results for a filter medium’s height equal to 24 cm using 10 hours of TDH. In the microstructural analysis of Scanning Electron Microscopy (SEM), the anaerobic sludge extracted from the reactor with a filtering medium’s height equal to 24 cm presented a more compact structure and with a smaller void, in addition to a higher concentration of carbon according to the analysis of chemical composition by energy dispersive X-ray spectroscopy (EDX). It is concluded that the greater the filter medium height, the higher values are achieved in removing organic matter (COD), turbidity, solids, gas production, and conductivity.