Biodegradation of toilet wastewaters generated in aircrafts

Wastewater generated in buses and aircrafts are known as blue water due to the addition of blue chemical products to deodorize, sanitize and break down solid waste in tank holdings. The blue water at high concentration presents inhibitory effects on microorganisms making difficult their treatment. This research evaluates the acclimation and degradation of aircraft blue water using discontinuous and continuous bioreactors. Acclimation was conducted in batch mode. In a discontinuous biological process with an initial COD concentration of 1150 mg COD/L, the removal efficiency was higher than 80% as COD, TOC and BOD₅. Total Suspended Solids in the effluent were lower than 60 mg/L. In the continuous activated sludge system an initial concentration of 850 mg COD/L of blue wastewater was applied. Here, removal efficiencies up to 72 and 88% as COD and BOD5 were obtained, respectively. For both processes, the application of punctual high concentration of blue water resulted in decrease of removal efficiency (< 40%). The blue water showed an inhibitory effect on the microorganisms. Due to acclimation, the efficiencies were higher than 80% as COD, DOC and BOD₅ and total suspended solids in the effluent lower than 60 mg/L, respectively. It was demonstrated that the toilet aircraft can be effectively treated in a continuous and discontinuous reactors using acclimated microorganisms.