BARS 2021

Liquid Gold: Recovered Energy Solutions from Urban Wastewater

Author: Itay Rubin

Mentor: Dr. Masato Nakamura

Institution: New York City College of Technology (City Tech)

Abstract: Cities, by virtue of being the densest areas of human concentration, are the largest consumers of water and producers of wastewater. Water treatment plants inside urban areas address this by treating polluted water, gray water and sewage. However, ordinary biological systems for sewage treatment require enormous energy resources. This research will attempt to identify new ways to harvest energy resources derived from recovered waste outputs, known as waste to energy (WtE). More specifically, it will explain how cities can use mechanical engineering technologies to uncover potential energy sources which are hidden within the city infrastructure, but currently wasted. By doing so, we can offset the environmental impact and costs of energy at sewage treatment plants to meet urban energy needs. Two types of energies are widely available in the city: (1) potential energy (from mass) and (2) heat energy. By using the WtE potential mass and heat energy sources, we reduce overall new energy production needs.

Potential Energy (from mass): High-rise buildings use energy to distribute clean water for household use. Once used, that water goes down the drains, along with potential mass energy. This energy can be harvested and either stored or sent to the grid before it is sent to wastewater treatment plants.

Heat Energy: Buildings emit heat that can be recovered. Wastewater from kitchens and bathrooms retain heat when going down drain. By using heat exchangers, they can transfer some of this heat to the inlet line of the boilers before the wastewater proceeds to the treatment plant.

Solar and wind energy have been recognized as a viable alternative energy source. However, recovered waste energy sources have been overlooked. This presentation will highlight wastewater as an inexpensive, available, and sustainable alternative energy source.