| In this study, a series 21d mesophilic followed by a 7d or 14d thermophilic process was developed and compared to a one-stage 28d mesophilic process for a 33% solid-state anaerobic co-digestion of a synthetic high-paper-content solid waste with waste secondary sludge.; Seven mesophilic (M1 through M7) and two thermophilic (T1, T2) digesters were monitored for pH, volatile acids, ammonia, Total Kjeldahl nitrogen, biogas productivity, methane content, and their composts examined for coliforms and cumulative oxygen consumption. M2 and M4 were operated as the one-stage 28d process while M6 and T2 made up the 21d mesophilic and 14d thermophilic reactors in the series process.; Biogas productivity for the series process was 13.2 L BG/kgTSrc.d compared to 9.1 L BG/kgTSrc.d for the one-stage process and methane content were 60.1%(M6{dollar}sb{lcub}rm 21d{rcub}),{dollar} 55.3%(T2{dollar}sb{lcub}rm 14d{rcub}){dollar} and 38.7%(M4{dollar}sb{lcub}rm 28d{rcub}).{dollar} Volatile solids removal of 52.3% and 20.5% were respectively reported for the series and one-stage process. Cumulative oxygen consumption of 142.3 and 141.5 mg O{dollar}sb2/{dollar}gTS.10d, respectively for the one-stage and series composts were lower than the 150-160 mg O{dollar}sb2/{dollar}gOM obtained in an independent aerobic windrow composting process (De Wilde, 1990). (Abstract shortened by UMI.)... |
