An assessment of anaerobic thermophilic co- digestion of dairy cattle manure and separated tomato greenhouse waste in lab-scale reactors

Anaerobic co-digestion of dairy cow manure (DCM) and separated tomato greenhouse waste (tomato stalks and leaves (TSL) and rotten and damaged tomato fruits (TF)) was conducted in batch thermophilic regime (T = 55 °C) during 45 days. The substrates (tomato waste) concentrations were 5 and 10 % (w/v). Each substrate as well as experimental mixtures was analyzed for pH, total solids (TS), volatile solids (VS), total nitrogen (TN) and total carbon (TC). Biogas yield and composition as well as cumulative biogas curves were reported. In comparison to monodigestion of DCM (329.5 cm3g-1 VS), biogas yield was significantly improved in experiment C (365.1 cm3g-1 VS) (with 5 % (w/v) TF added), while methane yield was not statistically different. Experiment D (with 10 % (w/v) TSL added) resulted in significantly lower biogas and methane yields if compared to all other experiments. Average methane content in all analyzed experimental samples ranged from 65 to 69 %. It is evident from the results that with addition of separated tomato greenhouse waste to DCM process of biogas production can be improved and at the same time the problem of organic waste disposal could be effectively solved.