Temperature-induced changes in treatment efficiency and microbial structure of aerobic granules treating landfill leachate

Abstract

This paper investigates the effect of temperature on nitrogen and carbon removal by aerobic granules from landfill leachate with a high ammonium concentration and low concentration of biodegradable organics. The study was conducted in three stages; firstly the operating temperature of the batch reactor with aerobic granules was maintained at 29 °C, then at 25 °C, and finally at 20 °C. It was found that a gradual decrease in operational temperature allowed the nitrogen-converting community in the granules to acclimate, ensuring efficient nitrification even at ambient temperature (20 °C). Ammonium was fully removed from leachate regardless of the temperature, but higher operational temperatures resulted in higher ammonium removal rates [up to 44.2 mg/(L h) at 29 °C]. Lowering the operational temperature from 29 to 20 °C decreased nitrite accumulation in the GSBR cycle. The highest efficiency of total nitrogen removal was achieved at 25 °C (36.8 ± 10.9 %). The COD removal efficiency did not exceed 50 %. Granules constituted 77, 80 and 83 % of the biomass at 29, 25 and 20 °C, respectively. Ammonium was oxidized by both aerobic and anaerobic ammonium-oxidizing bacteria. Accumulibacter sp., Thauera sp., cultured Tetrasphaera PAO and Azoarcus–Thauera cluster occurred in granules independent of the temperature. Lower temperatures favored the occurrence of denitrifiers of Zooglealineage (not Z. resiniphila), bacteria related to Comamonadaceae, Curvibacter sp., Azoarcus cluster, Rhodobacter sp., Roseobacter sp. and Acidovorax spp. At lower temperatures, the increased abundance of denitrifiers compensated for the lowered enzymatic activity of the biomass and ensured that nitrogen removal at 20 °C was similar to that at 25 °C and significantly higher than removal at 29 °C.

Nitrogen loading effects on nitrification and denitrification with functional gene quantity/transcription analysis in biochar packed reactors at 5 °C

“…Curvibacter had positive correlation with NO 2 − , SNOR, and SNNR in Fig. 5B , which could use both nitrate and nitrite as an electron acceptor under both aerobic and anoxic conditions 48 , 49 . DON had no significant correlation with any bacterial genus, which was consistent with our previous study 22 , and no single bacterial genus could degrade DON effectively.…”

Treatment of petroleum wastewater using an up‐flow anaerobic sludge blanket (UASB) reactor and turf soil as a support material

“…The flocculent seed sludge had an average size of smaller than 0.067 mm. Granules are defined as particles with diameters >0.125 mm . Visible granules were observed in both reactors on day 30.…”

“…Granules are defined as particles with diameters >0.125 mm. 17 and R1, respectively. Average granular particle sizes increased with operating time.…”

Microbial community dynamics during aerobic granulation in a sequencing batch reactor (SBR)

“…Comamonadaceae to which Delfia belongs, dominate often in bacterial communities of a SBR (Ge, Batstone & Keller, 2013) and Delftia acidovorans is a non-fermentative Gram-negative Betaproteobacteria that produces biofilm (Liu et al, 2016). Phylotypes belonging to Rhodobacter have been found in the outer layer of a mature granule (Mieczkowski et al, 2016). They produce extracellular polymeric substances so probably participated in the formation of the outer layers of a mature granule (Sheng, Yu & Wang, 2006).…”