Effect of microaerophilic treatment on swine wastewater (SWW) treatment: Engineering and microbiological aspects.

The microaerobic process on swine wastewater (SWW) treatment was investigated, evaluating its effect on organic matter hydrolysis and removal, biogas production, operational stability, and microbial community structure. UASB reactors operating under higher organic loading rates (OLRs) and lower hydraulic retention times (HRTs) than those found in the SWW treatment literature were also assessed. The microaerophilic reactor R2 presented a higher total and particulate organic matter removals and operational stability than the anaerobic reactor R1, reaching COD removals of 79.4 ± 4.6%. In the specific methanogenic activity (SMA) tests, the microaerobic sludge (R2) showed hydrolytic and acetogenic/methanogenic activity superior to inoculum and anaerobic sludge (R1). The microbiological evaluation of R2 revealed the high presence of hydrolytic microorganisms, therefore justifying the higher hydrolytic activity found in the SMA tests and higher particulate organic matter removal found in the microaerobic reactor.