ABSTRACT
The production rate and volume of municipal and industrial waste are increasing rapidly with the increase of population growth worldwide. The management of these wastes under current practices is through landfilling which requires a vast area of land. The increasing demand of energy, climate change, limited reserve of fossil fuel, and greenhouse gas emissions by fossil fuels are driving the world to explore the alternative source of energy such as renewable energy. Municipal and industrial waste-based renewable energy production, such as biogas and biodiesel, has high potential to provide sustainable and economic energy supply and reduce the greenhouse gas emissions. On the other hand, this process presents a sustainable waste management and resource recovery benefits. The microorganisms produce biogas and biosolids by breaking down organic materials in the anaerobic digestion process. This process reduces the volume of sewage sludge, producing methane, which can generate heat, electricity or can be converted top biofuel, and generate biosolids/compost/fertilizers. This chapter conducted the technical and economic assessment of biogas and liquid energy systems from sewage sludge and industrial waste with a particular focus on the lifecycle assessment and sustainability. Hydrolysis is an important rate-controlling step in the digestion of complex substrate. However, different pre-treatments such as mechanical, thermal, chemical, and biological interventions can enhance the hydrolysis and digestion of feedstock. There are several anaerobic reactor processes, such as up-flow anaerobic sludge blanket reactor, anaerobic moving-bed biofilm reactor, anaerobic fluidized bed reactor, anaerobic membrane bioreactor, expanded granular sludge bed reactor or internal circulation reactor, bench-scale EGSB reactor, and integrated internal and external circulation reactor. The co-digestion of food waste, restaurant grease trap waste/fatty residues, and industrial waste (e.g., biodiesel glycerin waste, sludge from pulp and paper industry) substantially increase methane production. The integrated algal biodiesel and advanced integrated wastewater pond systems can provide sustainable energy supply and wastewater treatment. Besides macronutrients, certain trace elements are necessary to increase the microbial growth and biogas production.
