Influence of food wastewater loading rate on the reactor performance and stability in the thermophilic aerobic process

In this study, the feasibility of a single-stage thermophilic aerobic process for the treatment of high-strength food wastewater produced from the recycling process of food wastes was examined to substitute anaerobic digestion process. Also, the removal and stability of thermophilic aerobic process were assessed according to the changes of hydraulic retention times (HRTs) and organic loading rates (OLRs). When the OLR increased from 9.2 to 37.2 kg COD/ m³d, a pH value in R1 (HRT: 5d) significantly decreased to 5.0, due to the organic acid accumulation. On the other hand, the pH value in R2 (HRT: 10 d) was stable and R2 showed the high removal of COD, organic acid and lipid, even though the OLR increased from 4.6 to 18.6 kg COD/ m³ d. In R1, the COD loading rates for COD removal was suddenly dropped, as the COD loading rate in-creased from 18.6 to 28.4 kg COD/ m³ d. In contrast, R2 showed that the COD loading rates for COD removal increased with regard to increment in the loading rates of 3.61, 7.05, 9.43 and 12.2 kg COD/ m³d, indicative of the high COD removal efficiency. Therefore, the results demonstrated that over 10-d HRT, the high concentration of raw food wastewater was effi-ciently treated in the single-stage thermophilic aerobic process.