Investigating Links in the Sanitation Chain: Collection of Human Waste and Anaerobic Treatment of Food Waste.

This project explored the anaerobic co-digestion of food waste with two differentco-substrates, thickened waste activated sludge (in the wet system) and decomposing municipalsolid waste (in the dry system). Three types of food waste, high protein, high carbohydrate andhigh lipids were prepared based on USDA consumption data. The objective of this study was tobetter understand the microbial community - substrate interaction, as loading rate and substratetype are changed over time. The wet system was studied using fed-batch (semi-continuous)reactors, while the dry system was studied using batch reactors. In the wet system, high proteinreactors were able to withstand ammonia levels of 6000 mg/L and were the only food wastecategory that did not experience failure throughout the experiment. High carbohydrate and highlipids reactors were inhibited at lower organic loading rates than the protein reactors, but wereable to recover and successfully converted the substrates at the previous organic loading rate. Inthe dry system, lipid substrates yielded the highest methane production while carbohydratesresulted in the fastest production of methane. Overall, the lipids reactors achieved the highestmethane yield in both wet and dry system, 475 and 615 mL CH4/g-VS, respectively. The nextimportant step is performing microbial community analysis to elucidate the relationship betweenmicrobial communities and performance at higher loads. Ultimately, these results will informhow to actively develop resistant and resilient anaerobic digestion systems.