Evaluation of the low technology tubular digesters in the production of biogas from slaughterhouse wastewater treatment

• Published in: Journal of cleaner production Vol. 199; pp. 633 - 642
• Main Authors: Martí-Herrero, J., Alvarez, R., Flores, T.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20-10-2018
• Subjects: Anaerobic digestion; Biofilm; Biogas production; Full scale; Low cost tubular digester; Slaughterhouse wastewater; Full scale; Biofilm; Low cost tubular digester; Biogas production; Slaughterhouse wastewater; Anaerobic digestion
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2018.07.148

The aim of this research is to identify the operational conditions and performance of low cost tubular digesters producing biogas from the slaughterhouse wastewater treatment. Three full scale sequenced tubular digesters (of more than 8 m3 each), operating in a slaughterhouse in Cochabamba (Bolivia), have been monitored during one year. The Organic Load Rate (OLR) varied from 0.04 to 1.13 kgSV/m3d (0.04–1.07 kgCOD/m3d), and the Hydraulic Retention Time (HRT) from 3.2 to 87.4 days. The passive solar heating design considered drove the slurry temperature to 27 °C, 8 °C more than mean ambient temperature. The first digester has been filled with soda bottle plastic rings in order to increase the internal effective surface and evaluate, obtaining that an increment in 67% of the internal effective surface, more than doubles the biogas production and enables higher OLRs. A Biogas Production Rate (BPR) peak of 0.2 m3/m3d was observed for OLR = 0.37 kgSV/m3d, HRT = 9.7d and Specific Biogas Production (SBP) = 0.55 m3/kgSV. COD removal achieves values above 70% from HRT>19 d. A comparison with other anaerobic digestion technologies demonstrates that low cost tubular digesters with biofilm carriers, are competitive for OLR<0.5 kg COD/m3d of biogas production, and for 0.25 kgCOD/m3d, when the focus is on COD removal.
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•Full scale tubular digesters treating slaughterhouse wastewater were monitored for one year.•Appropriate design methodology, passive solar heating and biofilm carrier were considered.•A Biogas production rate peak of 0.2 m3/m3d is found for 0.37 kgSV/m3d and HRT = 9.7d.•Chemical Oxygen Demand removal achieves values above 70% for HRT>19 d.•Biogas production is competitive for loads <0.5 kgCOD/m3d, and COD removal is for <0.25 kgCOD/m3d.