Analysis of a Multigeneration Energy System for Wastewater Treatment

The United Nations World Water Development Report claims that more than 6 billion people will suffer from clean water shortage by 2050. This is a result of climate change, demand increase for water, increase of water pollution, increasing population, and reduction of water resources [1]. In order to delay / prevent water scarcity, humans must take action using less water or perhaps recovering wastewater. Aerobic digestion is one of the best common methods to treat wastewater; however, this technology requires heavily on the use of electric motors and is estimated to consume 2–3% of US electricity. In this paper, a multigeneration energy system is developed to treat wastewater using a net-zero energy building model. This system consists of four major sub-systems: an aerobic digester, an anaerobic digester, a Brayton cycle, and a Rankine cycle. Using anaerobic digestion to produce bio-fuels, which can then be used on-site to power aeration systems, may offer significant advantages to reduce electricity usage. This study shows that the required energy for a sample aeration case study process can be supplied by a multigeneration system. Parametric analyses are performed to show how system efficiency may be increased as well as to investigate the required oxygen and power for an activated sludge process in a wastewater treatment plant. It is found here that the proposed CHP system can produce 6 times more energy than the required energy for the aeration in the activated sludge process.