3 – Analysis and characterisation of biogas feedstocks

: The abundance and variety of possible feedstocks for biogas plants necessitate detailed characterisation and evaluation of specific feedstock types. Feedstock characterisation requires reliable feedstock analysis. This chapter describes in detail the different feedstock analysis methodologies. The following essential analyses are described in detail: pH, total solids/dry matter, volatile solids/organic dry matter, chemical oxygen demand, total Kjeldahl nitrogen, ammonia nitrogen and biochemical methane potential. Additional analyses on biogas feedstocks are described, including total organic carbon, trace element analysis, sulphur, phosphorous and continuous anaerobic fermentation tests. Important details for feedstock evaluation are described. Firstly, different approaches for estimating a realistic energy recovery potential are laid out. Secondly, the effect of the carbon oxidation state in a feedstock on methane concentration in the produced biogas is described. Thirdly, the availability of macro- and micronutrients is estimated and a short summary of possible inhibitory or toxic components in biogas feedstocks is given.