Labscale Evaluation of Biomass-Derived Elements Used in Anaerobic Digestion

Disclaimer: This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference here in to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. SUMMARY The performance of a three-phase up-flow integrated high-rate anaerobic digestion reactor system utilizing corn cob biochar as biofilm support was characterized at 10-liter total scale on waste-trap grease wastewater at defined hydraulic retention times (HRT) and packing densities. Performance was evaluated in terms of chemical oxygen demand (COD) reduction, total volatile organic acid variability, and total suspended solids reduction, as well as headspace gas composition and production rate. High resolution images of biofilms revealed extensive biofilm coverage and microbial analysis of their underlying composition revealed evidence of broad populations of anaerobic bacteria that ferment organic substrates to produce acetate, ethanol, and hydrogen as major end products as well as archaeal populations that produce methane gas. Under conditions of a two day HRT and organic loading rate of 9.75 kg COD m-3 d-1 total and soluble COD reductions of 92 and 95% were achieved with TSS reductions of 75%. The total volatile organic acids in the feed were almost completely digested and a total gas production rate of 6.1 m 3 m-3 d-1 was achieved with a methane composition of 73%.