Anaerobic mono-digestion of wastewater from the main slaughterhouse in Yamoussoukro (Cote d'Ivoire): Evaluation of biogas potential and removal of organic pollution

In Cote d'Ivoire, the rejection of wastewater into nature from slaughterhouses is an environmental problem because these agro-industries do not have any treatment system. Anaerobic mono digestion is a possibility for the treatment of slaughterhouse wastewater. The main objective of this study is to evaluate the performance of the anaerobic mono-digestion of wastewater from the main slaughterhouse in Yamoussoukro. The study was carried out using a 5 L laboratory batch reactor under mesophilic conditions (32 +/- 3 degrees C). In the reactor wastewater was kept under constant stirring by a magnetic stirrer at a speed of 300 rpm until the biogas exhausted. The pH, ammonia nitrogen and VFA/TA ratio were monitored so as to verify the stability of the process. Biogas production and organic matter (TCOD, SCOD and BOD) removal permitted to evaluate the treatment purification performance. The results showed that the duration of the treatment was 60 days and the reactor stability was obtained at VFA/TA ratio lower than 0.4. The ammonia nitrogen concentration varying from 684 to 1239 mg L-1, had no inhibition effect on methanogenesis. The total volume of biogas (20,870 mL) proved that slaughterhouse wastewater itself provided the microorganisms necessary for AD. The TCOD, SCOD and BOD removal efficiency of 49.93, 65.85 and 82.22 % respectively showed the high purification performance of anaerobic mono-digestion of slaughterhouse wastewater.