This study is part of a larger project, where the feasibility to build a wastewater treatment plant at the University of British Columbia (UBC) Campus is investigated. The focus of this thesis is to study potential solutions for the sludge handling process, with the goal to minimize the foot print as well as to maximize the overall energy efficiency of the sludge handling process.

Anaerobic digestion has been expressed to be the desired sludge reduction method. Anaerobic digestion of sewage sludge has shown to be a valuable stabilization method, resulting in destruction of pathogenic organisms, reduction of sludge volume and production of energy-rich biogas. However, digestion of sewage sludge is often limited by long retention times and a low overall degradation efficiency of the solids. These limiting factors are often associated with the hydrolysis step, which is the step where cell walls are ruptured and degraded, resulting in readily available organic material for the acidogenic micro-organisms, and further along biogas.

In this study, different system solutions have been designed, with the purpose to enhance the hydrolysis step during digestion, to optimize the net energy production and the land use. The systems that have been designed and investigated include anaerobic co-digestion of sewage sludge and food waste, as well as two pretreatment methods: microwave-enhanced advanced oxidation process and thermal hydrolysis. The systems have been evaluated from perspectives important to UBC; energy, land use, greenhouse gas emissions and phosphorus recovery.

The finding in this study does not show one clear solution that is the most favorable from all above-mentioned perspectives. However, the main goal of this study was to find the solution that results in the highest net energy production and smallest footprint. Based on the results in this study, anaerobic co-digestion without pretreatment is the recommended system.