Shen_2020_Sci.Total.Environ_732_139333

In this work, the influence mechanism of temperature on solid phase denitrification (SPD) was investigated using a pilot-scale reactor supported with polycaprolactone (PCL). The results showed that under nitrate loads of ~31.5 mg N/(L.h), as temperature decreased from 30 degrees C to 13 degrees C, the nitrate removal efficiency declined from 94% to 57%. Furthermore, denitrification rate constants were input into Arrhenius equation and the resulting temperature coefficient was 1.04. Significantly nitrite accumulation and less effluent COD residue occurred at low-temperatures. Via stoichiometry, the sludge yield coefficient and COD demand for nitrate removal both increased as a function of increasing temperature; and were calculated at 20 degrees C as 0.069 g MLVSS/(g COD.d) and 3.265 g COD/g N, respectively. Carbon balance analysis indicated that the COD release rate (upsilon) at 30 degrees C was twice that at 13 degrees C. LEfSe analysis demonstrated that Desulfomicrobium, Desulfovibrio, and Meganema were abundant at low-temperature, while Simplicispira, Aquabacterium, and Acidovorax were enriched at high-temperature. Besides, carboxylesterase (PCL depolymerase) was more abundant at high-temperature, implying an association with a fast upsilon. Moreover, nar was enriched at low-temperature, while nir was depleted, which led to nitrite accumulation. These results provide reference for SPD design parameter estimation and/or optimal operation strategy.