Full scale validation of a model to predict anaerobic digester performance: PRESENTATION ONLY
Oxtoby, S.1,2, Winter, P.1, Smith, S.R.2, 1Thames Water, UK, 2Imperial College, London, UK
(free)
Anaerobic digestion is the main technology implemented for the treatment of sewage sludge. A number of complex operational factors influence the efficiency of the digestion process in terms of biogas production, achievable throughput and digester stability. Consequently, optimisation of the process during normal operation is challenging and operators have few diagnostic and optimisation tools available to improve digester performance.
A previous project (Giacalone, 2017) developed a stochastic and mechanistic model of the anaerobic digestion process to predict steady state biogas production, volatile solids destruction, digester ammonium-N, alkalinity, pH and E. coli removal, based on a dynamic experimental programme using large, bench scale, autofed digesters to identify key process indicators and interactions. The model uses inputs such as feed dry and volatile solids, digester conditions and feed composition.
This paper will build upon the model validation presented at last year’s European Biosolids Conference, outlining the results of the model validation at three sites. Experience so far has shown that a thorough understanding of the site data, including knowledge of flow meter calibration and performance is crucial to creating a reliable data set for full scale validation. Over the three conventional digestion sites investigated so far, the model has proved reliable across a range of operating conditions, predicting monthly average biogas yield to within 10 m3/tDS. The predictions of volatile solids destruction may be less accurate, which will be discussed in the paper.
