Evaluation of bed materials on the performance of an anaerobic sequencing batch biofilm reactor treating sewage wastewater

Author(s)

Marcelo Loureiro Garcia

• Document type: Master's Dissertation
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 2006-01-06

Examining board members

Marcelo Zaiat; Eugenio Foresti; Samantha Cristina de Pinho

• Advisor: Marcelo Zaiat

Abstract

The main objective of this study was the evaluation of bed materials on the performance of an anaerobic sequencing batch biofilm reactor, with agitation, treating sewage wastewater of the Campus of University of São Paulo in São Carlos. The study of the global performance of this reactor configuration is extremely linked with the bed material which provides adhesive and growing conditions. In this work three different bed materials were investigated : polyurethane foam, vegetal carbon and recycled low-density polyethylene. The global evaluation was performed under analysis of three different and dependant local variables: the reactor performance, kinetic analyses and microbial exams. The polyurethane foam was considered the most suitable material. Using the polyurethane foam as a bed material were obtained the highest COD removal efficiencies, 61% and 71% corresponding to total and filtered samples, respectively. In Addition, the polyurethane foam showed the best modified first-order kinetic model (k1T) of 0,52 ± 0,04 h-1, and a biomass predominately characterized by microorganisms resembling to methanogenic archea and phototrophic bacteria . The vegetal carbon showed intermediate results, which were not satisfactory enough, in the COD removal. Also, the vegetal carbon showed an incompatible biomass in accordance with the expected anaerobic biomass. In others words, it can be inferred that, using this type of material, there was a selective biomass process in which an inappropriate biomass was selected. Finally, the recycled low-density polyethylene showed the less expressive results. However, because of its microbial characterization, it can be concluded that the polyethylene material has potential to be applied as a bed material in the sewage wastewater treatment. Nevertheless, a previous treatment physics-chemical must be applied in this kind of bed material to improve the physics-chemical properties such as porosity and surface area. (AU)