Biological nutrient Removal, Post denitrification, Clarifier design, Pilot study
Methods to comply with the most updated low effluent total nitrogen (TN) regulations include, in addition to a high internal circulation ratio to a pre-denitrification stage, either a large intermediate anoxic zone, or a post denitrification stage with addition of an external, purchased, carbon source [ ]. Wastewater treatment cost considerations have yielded processes for on-site production of readily biodegradable organic carbon, in the form of VFA, by fermentation of primary sludge [ ], whereas secondary sludge has been found to be a less attractive source for carbon [ ]. These general principles apply to both suspended and attached growth wastewater treatment processes.
The work described in this document started off in an attempt to enhance endogenous denitrification following an attached growth bio-reactor, by holding a high concentration of suspended solids in the designated zone of the reactor, using a layer of structured floating media and a generally upwards flow pattern. However, the tested reactor also improved suspended solids settling properties and produced an effluent with low TSS.