Application of Oxygen Limited Autotrophic Nitritation/Denitrification (OLAND) for anaerobic latex processing wastewater treatment

Abstract

The study aimed to remove nitrogenous compounds from anaerobic latex processing wastewater by using Oxygen Limited Autotrophic Nitritation/Denitrification (OLAND) process in a single reactor with rotating bio-carrier and sequencing batch regime. The anaerobic latex processing effluent, of which suspended solids (SS) and biodegradable COD (bCOD) were removed by latex scum trap, coagulation-flocculation and followed by Upflow Anaerobic Sludge Blanket Reactor (UASB), contained 100–200 mg l−1 NH4+-N, 150–250 mg l−1 total nitrogen (TN) and 50–80 mg l−1 COD. Dissolved oxygen (DO) in the experiment was maintained at different concentration ranges of 0.4–0.8 mg l−1; 0.2–0.4 mg l−1 and 0.1–0.2 mg l−1. The highest performance (TN and COD removals, 94% and 61%, respectively) obtained at DO range of 0.10–0.20 mg l−1. Moreover, the low effluent nitrate (8.5 ± 3.1 mg l−1 NO3−-N), which was less than that of theoretical reaction of OLAND, shown that, in the single reactor, co-existence of denitrifiers using the remaining bCOD (less than 50 mg l−1) in the feed wastewater or carbon source from cell lysis at high sludge retention time (about 90 days). Analysis of bacteria community showed that Candidatus Kuenenia, anammox bacteria, was dominant species in the sludge mixture of biofilm and bioflocs (4.8%) with 99% of sequence identities. AOB species, nitrifying bacteria, had 6.6% with 98% of sequence identities. Besides, denitrifying Proteobacterium E4-1 was found in the reactor.