Methane Potential of Household Waste; Batch Assays Determination

Abstract

An assay for determination of the methane potential of household waste (HHW) was developed. The assay was performed in batch vials with thermophilic inoculum from a biogas plant co-digesting swine manure with industrial waste. Methane potential of 500 mL g^-1VS was achieved within 10 d. Blending of the HHW household waste was suitable method for homogenization of the material. Although blending altered the physical image of the sample, it did not alter the original composition of the material. Thermal pre-treatments of the waste (70 °C for 1 h) and combined thermal alkaline pre-treatment (70 °C for 1 h and addition of NaOH for achieving pH 10) did not influence to the methane potential of household waste. The absence of effect on the methane potential by the applied pre-treatment indicates that pre-treatment is not required for determination of the methane potential of easily biodegradable substrates. Different amounts of household waste were added to the vials, while the amount of inoculum was the same resulting in different I/S ratios. All the tested I/S ratios in the range of 5 to 15 were found to be appropriate for the methane potential assay from household waste, as no significant volatile fatty acids (VFA) accumulation was observed at any of the tested ratios.