Enhancing mesophilic anaerobic co-digestion of slaughterhouse waste with household waste under a pilot-scale reactor

In this investigation, mesophilic co-digestion of both slaughterhouse waste (SHW) with household waste (HSW) was carried out using a 50 L new pilot-scale digester operated in batch mode. Biomethane production of around 280 L CH4 kg−1 VS was achieved for the mixture of HSW with SHW giving a substrate to inoculum (S/I) ratio of 3:1 (volatile solids weight basis). However, mono-digestion of SHW mixed in a ratio (S/I of 1.3:1 produced about 225 L CH4 kg−1 VS under similar experimental conditions. Therefore, co-digestion of biowastes (HSW and SHW) improved biogas and methane production of process by increasing methane potential around 24.4%. Moreover, results showed that co-digestion of SHW with household wastes is feasible under favourable conditions, without affecting digester stability. The co-digestion of biowastes gave high performances of process, reaching a good reduction of organic content around 67.7%, while the volatile and total solid removing achieved 42.0 and 19.6%, respectively. Biogas produced was of a good quality with CH4 yields above 70%, low CO2 yields and negligible H2S concentrations. Therefore, mesophilic co-digestion of these wastes is suitable for industrial slaughterhouse applications regarding the high efficiencies and process stability.