FYI see scialert.net/fulltext/?doi=jas.2012.2586.2591
Published: January 10, 2013

ABSTRACT
Transformation of organic waste to energy is a complex process which involves hundreds of possible intermediate compounds and reactions. Simulation process can provide suitable assessment of a bioconversion system before its actual fabrication and commercialization. In addition, process simulation is a suitable tool for optimization of technical factors (e.g., bioreactor configuration and conversion units design) and economical factors (e.g., throughput, production cost, revenue and gross margin). In this study, biodegradation process of a small-scale anaerobic bioreactor was simulated using SuperPro Designer®. Process simulation flow sheet, materials registration and process reactions were conducted during model setup. Next, model validation was carried out by comparison between the outputs and actual data achieved during experimental phase. Results show the appreciable agreement between predicted and actual data due to appropriate process definition during simulation. Two different bioreactor configurations were investigated and efficiency and performance of each pattern was tested based on biogas production rate, methane content in biogas and biochemical and chemical oxygen demands (BOD and COD) removal efficiencies. Finally, economical analysis was performed in the model which indicates, biogas production from organic waste in a single small-scale bioreactor is a promising method for renewable energy generation.

CONCLUSION
Design and process simulation of a small-scale anaerobic bioreactor was done using SuperPro Designer®. The system was able to successfully simulate complex intermediate reactions of anaerobic digestion system for production of biogas as appreciable agreement between predicted and actual results was achieved. Results reveal the bioreactor with configuration of doubled-size first compartment is able to produce more biogas and methane which was 0.318 m3 kg-1 VS and 58%, respectively compare to configuration with four same size compartments which produced 0.295 m3 kg-1 VS of biogas contains 56% methane. Cost analysis results show revenue of RM 930 year-1 and gross margin of 75.5%. Therefore, the results obtained from this study are useful in proposing waste-to-energy systems to enterprises which are dealing with organic feed stocks as waste.

In relation to the 4 phases during anaerobic digestion: hydrolysis; fermentation; acetogene; methanogene, more or less "working" one after another in each of 4 ABR- compartments: biogas-infoboard.de/pdf/Biologie_der_Biogaserzeugung.pdf
(in German language only)

Regards,
Detlef SCHWAGER