What is the effect of mandatory pasteurisation on the biogas transformation of solid slaughterhouse wastes?. (February 2016)

• Record Type: Journal Article
• Authors: Ware, Aidan; Power, Niamh
• Is Part Of: Waste management. Volume 48(2016)
• Page Start: 503
• Page End: 512
• Publication Date: 2016-02
• Subjects: Anaerobic digestion -- Slaughterhouse waste -- Biochemical methane potential -- Pasteurisation -- Biogas; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2015.10.013
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: Effect of pasteurisation on biogas transformation of solid slaughterhouse wastes. SMY of offal not significantly increased/decreased due to the pasteurisation process. Pasteurisation promoted the bioavailability of organics in the offal. Reduced hydrolytic lag phase and more rapid accumulation of intermediate fermenters. LCFA inhibition proven to be temporary and full process recovery achieved. Abstract: The effect of mandatory pasteurisation on Category 3 offals, according to the Animal By-Products Regulation (ABPR 1069/2009/EC), was determined using Biochemical Methane Potential (BMP) assays as well as kinetic and statistical analysis. Pasteurised and unpasteurised offals sampled from cattle, pig and chicken slaughterhouses were characterised and their specific methane yields (SMYs) and their bioavailability was assessed. The resultant SMYs were high (465–650 mLCH4 gVS −1 ) with no statistically significant increase in methane production identified due to pasteurisation. However, the kinetics of the biogas transformation processes highlighted increased bioavailability of the organics due to pasteurisation. This was brought to light by the change in maximum daily SMY from day 22 to day 1 for the cattle offal ( p = 0.001), day 17 to day 1 for chicken offal ( p = 0.025) and an increase of 18.8% in the maximum daily SMY of the pig offal on day 1 ( p = 0.003). The increased bioavailability of the offals manifested itself in two ways with the determining factor being identified as the physical characteristics of the fats i.e. particle size. Firstly reducing the hydrolytic lag phase for the cattle offal, λ = 7.46–1.52 days ( p = 0.013). Secondly, causing increased accumulation of Long Chain Fatty Acids to acute inhibitory levels in the chicken and pig offal indicated by increased lag phases λ = 5.05–21.91 days ( p = 0.012), λ = 15.54–23.04 days ( p = 0.007) respectively.