Sioux City wastewater treatment plant (WWTP) has experienced filamentous bacterial growth in their secondary clarifiers. The filamentous bacteria create bulking sludge, which causes solids to remain in suspension, thereby creating high solids discharge in the WWTP effluent. Iowa State University (ISU) was contracted to conduct a three-phase study to investigate the WWTP operational problems. Phase I was a paper study that examined the causes of high volatile fatty acid (VFA) loading into the WWTP. Phase II characterized four selected industrial wastewaters in order to determine appropriate wastewater pretreatment techniques. Phase III involved the aerobic biological pretreatment of the four industrial wastewaters in laboratory-scale bioreactors to remove VFAs. Phase II and III are evaluated in this report. The four industrial wastewaters selected were Feed Energy, which produces acid oil that is used as a livestock ingredient; Darling, which is a rendering facility; Menu Food manufactures pet food; and John Morrell, a hog slaughtering facility that manufactures pork products, in Phase II, industrial wastewater samples were characterized based on VFA, soluble chemical oxygen demand (SCOD), biochemical oxygen demand (BOD), and volatile suspended solids (VSS) concentrations. Wastewater pretreatment recommendations were given to Sioux City WWTP and the WWTP decided that aerobic biological pretreatment should be tested for all four selected industries in Phase III. The Phase III results showed that the Feed Energy wastewater was not successfully pretreated aerobically to remove VFAs with HRTs ranging from 3 hours to 6 days. The Darling condensate wastewater achieved VFA removals of 43 to 74% with HRTs ranging from 12 to 48 hours and a 95% VFA removal was possible at an 18-hour HRT with phosphorus supplementation. VFA removals of 55% and 63% were achieved for the Menu Food wastewater with HRTs of 4.5 and 9-hours. The John Morrell blood stick wastewater achieved VFA removals ranging from 25 to 71% with HRTs ranging from 12 to 24 hours.