Kornél L. Kovács
University of Szeged, Hungary
Title: Biomethane production from poultry manure: a circular economy model
Biography
Biography: Kornél L. Kovács
Abstract
Poultry manure (PM) is generated in massive and increasing amounts worldwide. This material is loaded with organic and inorganic nitrogen (N) and phosphorous (P) compounds offering great potential for biogas production in anaerobic degradation (AD). Its high nitrogen content inhibits the biogas forming a microbial community; therefore PM has limited use as biogas monosubstrate. A small fraction of PM can be utilized for AD in co-fermentation with other agricultural by-products, but even in this case, the majority of the valuable N and P content end up in the digestate.
The complex recovery of both the N and P and energy contents of PM is achieved by employing a simple water extraction of the raw PM. This removes water-soluble organics together with about half of N and P. The solid fraction is then separated from the supernatant by sedimentation and can be fed directly into the AD reactor for biogas production yielding about 500 L biogas/kg OTS, which contains 250 L methane/kg OTS. Biogas is composed mainly of methane and carbon dioxide. The biomethane component is a biofuel, which can replace fossil natural gas in every application. The valuable components in the supernatant are recovered by using it as a growth medium for heterotrophic/mixotrophic cultivation of microalgae. Chlorella Vulgaris removed the majority of N, P and dissolved organics within a few days at 50 μmol (m−2 s−1) light intensity and 25°C. Due to the non-sterile cultivation conditions, algae-bacteria biomass developed in about 50-50% wet weight ratio, which could be reused as biogas substrate.