Co-digestion of Municipal Sewage Sludges and Pre-hydrolysed Woody Agricultural Wastes

Sludges from municipal wastewater treatment were mixed with hemicellulose and starch hydrolysates, in proportions simulating the organic strength of hydrolysed agricultural wastes rich in woody materials, and subsequently digested in both batch and fed batch operations. The same range of residence time usually employed for traditional digesters fed with sewage sludges was investigated for this material, in order to establish by how much hydrolytic pretreatment could allow for increases in the organic loading rate. Hydrolysis allowed for an improved availability of organic substances, but their conversion to CH\+v\4\-v\ was affected by the formation of toxic inhibitors during the hydrolysis.