Removal of organics from wastewater using a novel biological hybrid system

This paper summarizes the results obtained using the hybrid aerated submerg ed fixed-film (HASFF) process. HASFF is an innovative system comprising a f our-compartment reactor having an array of fixed ceramic plates maintained under diffused aeration to support attached biomass, with activated sludge recycle to promote suspended growth in the reactor. Wastewater from a munic ipal treatment plant was fed to the reactor and its activated sludge was us ed for recycling in the hybrid system. Four pilot units were operated in th e plant at various hydraulic retention times, HRTs (2, 4, 6 and 8 h), using primary-settled wastewater under organic loading rates up to 0.7 g BOD/gML TVS. d. Data obtained showed that the overall BOD percentage removal effici encies were consistently above 94.0% at all HRTs including the 2 hours whil e the GOD percentage removal efficiencies ranged between 65.7-76%. The effl uent's mean filtered BOD concentration ranged between 4.5-7.5 mg/l whereas the mean filtered COD concentration ranged between 70.0-89.6 mg/l. Increasi ng the hydraulic loading rate by four-folds from 0.08 to 0.32 m(3)/m(2).d h ad a minor effect on the unit's BOD and GOD percentage removal efficiencies indicating a robust biological process that is resilient to hydraulic shoc k loads, thereby offering a viable upgrading option.