| The management and the disposal of sludge produced in wastewater treatment represent between 25 and 65% of wastewater treatment plants operating costs. The amount of sludge produced also contributes to pollute the environment. In this context, a two-stage low sludge production system (LSP) was developed for the treatment of highly loaded effluents, such as pulp and paper industry effluents. The first stages consists in an aerated, chemostat reactor, operated at a short hydraulic retention time to remove rapidly biodegradable organic matter and produce dispersed bacterial biomass. The second stage is a biological process, such as an activated sludge or a biofilm reactor, where the bacterial biomass is consumed by a second type of biomasse composed of low yield microorganisms. This low yield biomass is responsible for the reduction of excess sludge production.; The main objective of this project is to achieve a reduction greater than 15% in growth yield with the development of the LSP system for the treatment of municipal wastewater. This document presents experimental results obtained at a bench scale at Ecole Polytechnique. The experiments consisted first in the study of the effect of HRT (1, 2, 4 and 6 hours) and temperature (8 and 18°C) on the efficiency of the first reactor. Municipal effluents from St-Hyacinthe were used. Four experiments were also realised with the LSP system (first and second stages) in order to evaluate its potential for treating municipal wastewater. Pilot scale experiments and a techno-economic study are also parts of this project, but will not be discussed in this document. (Abstract shortened by UMI.)... |
