Appraising different models for predicting biomethane potential: the case of avocado oil processing by-products

Abstract

Biomethane potentials (BMPs) for avocado oil processing by-products were determined using six different theoretical BMP prediction models and results were compared with empirical values found in literature. The by-products were classified as kernels, skins, decanter pomace and decanter wastewater prior to physicochemical characterisation and BMP calculation of individual by-products. The estimated BMP values for the different by-products ranged between 152 and 889 mLCH4/gVS using the different prediction models across substrates. These values compare favourably with biomethane potentials for popular biogas plant substrates such as cow manure and food waste-based floatable oil whose biomethane potentials are 150 and 847 mLCH4/gVS, respectively. Results from the nutritional based and statistically derived canonical mixtures theoretical BMP prediction models for kernels (289 mLCH4/gVS) closely matched empirical values (284 mLCH4/gVS) from literature. We conclude that anaerobic digestion for biogas production can be preliminarily considered as a viable waste-to-energy technology option for managing avocado oil processing by-products. The statistically derived (nutritional based) theoretical BMP prediction models offer the best approach for evaluating these substrates’ candidature for biomethane production.