Evaluation of bioavailable dissolved organic nitrogen in municipal wastewater using green algae Chlamydomonas reinhardtii and Chlorella vulgaris

Bioavailable dissolved organic nitrogen (ABDON) along the treatment train in a trickling filter (TF) wastewater treatment plant was evaluated using two different microalgal species, which were Chlamydomonas reinhardtii and Chlorella vulgaris with/without presence of mixed cultured bacteria. ABDON was determined after 14 and 21 days of incubation period for the samples collected from after primary clarifier, after BOD TF, and after nitrification TF locations in the plant. The results showed that about 37 to 81% of DON was bioavailable to either algae-only or algae + bacteria inoculum in all three locations. For algae + bacteria seeded samples, statistically there was no significant difference in ABDON values for 14 and 21 days of incubation while in algae-only seeded samples up to 22% higher ABDON was obtain in 21 days of incubation in all the locations. ABDON for algae + bacteria inoculated samples were always higher than algae-only inoculated samples.