(366a) Analysis of a Circular Economy: From Food Waste to Foods

The US-EPA estimated that 38 million tons of food waste went to landfill in 2014 and in 2010 66.5 million tons of food didn’t make it to consumers. The food waste streams total to around a billion pounds of food waste, where the majority go to landfill. Publicly owned waste water treatment plants in U.S. process approximately 14 billion kilograms of dry solids per year.¹ Turning waste streams into valuable products is the goal of the circular economy.²

Hydrothermal carbonization (HTC) process is proposed to be a solution to the large streams of food waste and biosolids from waste water treatment plants that creates a highly valuable, multiuse product. HTC is a thermochemical process that converts wet biomass materials to a coal-like product. Under sub-critical conditions, water in the HTC reactor stays in liquid form and acts as a reaction medium to promote the breakdown and cleavage of chemical bonds in the solid biomass. The absence of liquid-to-vapor phase change of the water makes the process significantly less energy intensive compared to a process that involves water vaporization or drying. The temperature range for HTC is from 180-240^oC producing solid hydrochar as the main product.

The solid product of hydrothermal carbonization, hydrochar, has multiple applications ranging from a combustion fuel source, a catalyst for anaerobic digestion that increases the purity of methane production, a soil amendment, and the base for other carbon product such as activated carbon.

In this study we will explore the circular economy of utilizing organic wastes into foods. The steps involved in the circular economy system include: 1) collecting organic wastes (specifically food wastes and bio-solids), 2) converting the organic waste streams to hydrochar via HTC process, 3) growing food produces by indoor gardening, and 4) using hydrochar from step 2) as fuels to power the indoor gardens.

Utilizing organic waste streams in cities such as Chicago or Philadelphia, where there are a multitude of abandoned warehouses, provides an opportunity to produce locally grown produces that would typically come from across the country from California or Mexico. Not only will this circular economy reduce environmental impacts, but it will increase positive societal impacts by benefitting the local economy, providing educational opportunities of farming that would not typically be available in cities, and serving fresher produces to the local community.

A comparative life cycle assessment of our proposed process will be applied to compare conventional farming to our circular economy proposal. We hope to prove a reduction of environmental impacts, such as global warming potential, fossil fuel depletion, natural resource depletion. The life cycle assessment results will aid in a full system analysis which evaluate the proposed circular economy idea from societal, technical, environmental, economic, and political perspectives.

• https://www.epa.gov/sustainable-management-food/sustainable-management-food-basics
• https://www.sciencedirect.com/science/article/pii/S0301479717303808

*Contact: Dr. Justinus Satrio (justinus.satrio@villanova.edu)