Abstract:The study has assessed the denitrification performance of fermented and dark-fermented biosolids as external carbon sources using lab-scaled Sequencing Batch Reactors (SBRs). This was done by adding fermented and dark-fermented biosolids into anoxic zones of two SBRs, and then assessing the change of effluent characteristics comparing to before adding and to a third controlled reactor. The results showed that by adding 150-170 mg rbCOD/L of either of the selected fermented biosolids, almost complete denitrification could be reached for tested SBRs (reduced from initial ~20 mg NO 3 /L to < 1 mg NO 3 /L). Finally, the experiment also found that the impact of NH 4 components of fermented and dark-fermented biosolids onto the final effluent were much lesser than expected, where only less than 2.5 mg NH 4 /L were detected in the effluent, much lower than the added 5.0-5.7 mg/L.

Abstract:The aim of this study was to assess the impact of industrial-grade sucrose as external carbon source on post-anoxic denitrification. This was done through the use of lab-scaled Sequencing Batch Reactors (SBRs) modelling after a standard post-anoxic Waste Water Treatment Plant (WWTP). Each reactor holds an effective volume of approximately 4 L, with the decant volume of 2 L per cycle, a Hydraulic Retention Time (HRT) of 8 hours, Sludge Retention Time (SRT) of about 11.5 ± 0.5 days. The experiments showed that adding industrial-grade sucrose into the post-anoxic zone has a very significant improvement where the nitrate removal rate increased from 10% to 68%. The experiment also verifies that most of the Specific Denitrification Rate (SDNR) calculated from the lab-scaled SBRs lie within the range of earlier study (2.29-2.85 mgNO 3 -/gMLVSS/h), and verified the results of both this experiment and the SDNR batch tests in previous study.