Converting biodegradable plastic waste into green energy

Recovering biodegradable plastic waste through anaerobic co-digestion treatment with sludge from sewage treatment plants (STP) to obtain a biogas stream that can be used as an energy vector and a digestate for agriculture.

This is the main objective of Valplast(Recovery of bioplastics through anaerobic co-digestion at sewage treatment plants), a strategic project in which a consortium of members participates, including Aimplas, the Calagua Group UPV-UV Mixed Unit, and the companies Global Omnium Medioambiente and Fych Technologies.

The project, financed by the Valencian Institute of Competitiveness and Innovation (IVACE+i) within the framework of the European Union’s 2023 strategic cooperation projects, seeks to implement an alternative to current management of biodegradable plastic packaging waste that is aligned with circular economy principles.

“The main innovation of the project involves understanding that bioplastics are a resource that can be recovered and transformed into green energy”, according to researchers participating in the project.

The aim will therefore be to study, at laboratory and pilot scale, the degradation of different plastics through biological treatment with sludge from municipal sewage treatment plants under anaerobic conditions. The possible effects of the additives used in the synthesis of plastics (conventional and bioplastics) in the anaerobic treatment process and the subsequent quality of the digested sludge will also be evaluated, given that its main application is agricultural use.

Work will also be done on the development and optimization of pilot plant instrumentation and control systems, as well as the analysis of costs and the life cycle. As consortium members highlighted, “They are essential to be able to evaluate the environmental and economic sustainability of the proposed treatment”.

After the recovery process, analysis will be carried out to measure the presence of microplastics in the sludge. For this analysis, the methodology developed by AIMPLAS in previous projects will be used. This method makes it possible to measure these emerging contaminants in both wastewater and the sludge generated at treatment plants.

This process will be used to develop a methodology for energy recovery from bioplastics at STP digesters for better management of these wastes resulting in greater energy recovery.
Also of note is the previous experience that part of this consortium acquired during implementation of and collaboration on other R&D projects related to the goal of this project.