Denitrification Process Enhancement and Diversity of the Denitrifying Community in the Full Scale Activated Sludge System after Adaptation to Fusel Oil

Abstract

Implementation of anaerobic digestion of primary sludge in modern wastewater treatment plants (WWTPs) limits the availability of organic carbon for denitrification in conventional nitrification-denitrification (N/DN) systems. In order to ensure efficient denitrification, dosage of the external carbon source is commonly undertaken. However, application of commercial products, such us ethanol or acetate, greatly increases operational costs. As such, inexpensive and efficient alternative carbon sources are strongly desirable. In this study, the use of the fusel oil, a by-product from the distillery industry, was validated in terms of the denitrification process enhancement and impact on the activated sludge bacterial community structure. The experiment was conducted at a full scale biological nutrient removal facility (210,000 PE), in the set of the two technological lines: the experimental line (where fusel oil was introduced at 45 cm3/m3 dose) and the reference line (without an external carbon source addition). During the experimental period of 98 days, conventional nitrate utilization rate (NUR) measurements were carried out on a regular basis in order to assess the biomass adaptation to the fusel oil addition and denitrification process enhancement. While the NURs remained at a stable level in the reference line (1.4 ± 0.1 mg NO3-N/g VSS·h) throughout the entire duration of the experiment, the addition of fusel oil gradually enhanced the denitrification process rate up to 2.7 mg NO3-N/g VSS·h. Moreover, fusel oil contributed to the mitigation of the variability of NO3-N concentrations in the effluent from the anoxic zone. The bacterial community structure, characterized by 16S rRNA PCR—DGGE and the clone libraries of the genes involved in the denitrification process (nirS and nirK), was comparable between the reference and the experimental line during the entire experimental period. In both analyzed lines, the most frequent occurrence of denitrifiers belonging to the genera Acidovorax, Alcaligenes, Azoarcus, Paracoccus and Thauera was noticed. Our results proved that fusel oil would a valuable substrate for denitrification. The addition of fusel oil enhances the process rate and does not reflect a severe selection pressure on the bacterial community at applicable doses. Practical application of fusel oil generates opportunities for the WWTPs to meet effluent standards and reduce operational costs, as well as optimizing waste management for the distillery industry.

Disintegrated Waste-Activated Sludge (NO2/FNA Method) as a Source of Carbon for Denitrification in the Mainstream of a WWTP

“…The probable reason for the differences in NUR, which, in this study, were observed between the R1 and R2 reactors, was the adaptation of the activated sludge microorganisms to mechanically treated wastewater (as a carbon source). The phenomenon of biomass adaptation and its positive influence on NUR have been reported elsewhere [30].…”

Advanced Wastewater Treatment and Biomass Energy

“…The paper by Kowal et al [1] deals with possibility of enhancement of nitrogen removal efficiency by the addition of external organics to a biological part of a wastewater treatment system. The experiment was conducted at a full-scale wastewater treatment plant and, as a source of organics, fusel oil, a byproduct from the distillery industry, was applied.…”

Liquens artificiais e a integração de produtos de alto valor agregado a uma biorrefinaria

“…Esta tem sido uma das principais rotas para a produção de biolubrificantes (BOLINA; GOMES; MENDES, 2021). É composto principalmente de álcoois com dois a cinco átomos de carbono por molécula (por exemplo, etanol, álcool n-propílico, álcool isoamílico, álcool isobutílico e álcool n-butílico (SIMSEK; OZDALYAN, 2018;KOWAL et al, 2021).…”

“…O uso e descarte adequados do óleo fúsel, como resíduo químico, é de imensa importância econômica e ambiental, o que tem sido reforçado pela crescente demanda por álcool puro, provocada pela pandemia de COVID-19, que aumentou a produção de óleo fúsel (KOWAL et al, 2021). Possíveis usos para este subproduto incluem a produção de álcoois superiores purificados por destilação simples ou fracionada e síntese química ou biotecnológica de ésteres (CHU et al, 2021).…”