Physiologic impact of 2-chlorophenol on denitrification process in mixture with different electron sources

Abstract

The aim of this study was to evaluate the physiologic behavior of sludge in the absence and presence of 2-chlorophenol (2-CP) with different electron donors (phenol, glucose, and acetate) during denitrification process. In batch assays with phenol in the presence of 2-CP, a significant decrease of phenol consumption efficiencies (E phenol) up to 99% was observed regarding the cultures without 2-CP. However, in most of the cases, nitrate consumption efficiencies (E NO − 3), and yields of nitrogen gas (Y N 2) and bicarbonate (Y HCO − 3) were high, showing that the denitrifying respiratory process successfully occurred with phenol and 2-CP. The specific consumption rates of nitrate (q NO − 3) and phenol (q phenol) decreased up to 6.0 and 32.3 times, respectively. In assays with glucose in the presence of 2-CP, the denitrifying performance was not significantly altered in terms of efficiencies and product yields; however, q NO − 3 was up to 1.6 times smaller than that obtained without 2-CP whereas q glucose was increased up to 1.17 times. In assays with acetate plus 2-CP, the E NO − 3 , E acetate , and Y N 2 values remained high but 2-CP caused a decrease in Y HCO − 3. Moreover, q NO − 3 and q acetate increased up to 1.4 and 2.0 times, respectively. These results show that the negative or positive effects of 2-CP on denitrification process depend on the type and concentration of electron source. The obtained physiologic and kinetic information might be useful to define strategies to maintain successful denitrification processes in wastewater treatment bioreactors fed with 2-CP.

Physiological and kinetic evaluation of ampicillin oxidation as unique electron source by a denitrifying sludge

“…Nitrate and nitrite concentrations were quantified by capillary electrophoresis (DL = 0.5 and 0.75 mg L −1 , respectively) (CIA 4000, Beckman‐Coulter, USA) according to Martínez‐Jardines et al 37 . The composition of gas samples in molecular nitrogen (DL = 0.7 mg L −1 ), carbon dioxide (DL = 0.3 mg L −1 ) and nitrous oxide (DL = 0.3 mg L −1 ) was measured by gas chromatography (Varian 3350, USA) with a thermal conductivity detector and a steel column (packed with Porapak Q mesh 80–100, USA), according to Martínez‐Gutiérrez et al 31 . VSS content was measured according to standard methods 38 .…”

“…A packed stainless steel column (Porapak Q mesh 80-100, USA) was used, as reported by Martínez-Gutiérrez et al 30 Organic and inorganic carbon were determined using a total organic carbon analyzer (Shimadzu TOC-5000, Australia) with a detection limit (DL) of 1 mg L −1 . Nitrate and nitrite concentrations were quantified by capillary electrophoresis (DL = 0.5 and 0.75 mg L −1 , respectively) (CIA 4000, Beckman-Coulter, USA) according to Martínez-Jardines et al 37 The composition of gas samples in molecular nitrogen (DL = 0.7 mg L −1 ), carbon dioxide (DL = 0.3 mg L −1 ) and nitrous oxide (DL = 0.3 mg L −1 ) was measured by gas chromatography (Varian 3350, USA) with a thermal conductivity detector and a steel column (packed with Porapak Q mesh 80-100, USA), according to Martínez-Gutiérrez et al 31 VSS content was measured according to standard methods. 38 For each analytical method, standard curves were constructed in triplicate, wherein the variation coefficient was <8% and r 2 > 0.98.…”

“…Acetate has been extensively reported as an easily and fast biodegradable organic compound under several experimental conditions, including denitrification. 31,55,56 When using the antibiotic as the sole electron source, several kinetic effects were observed on denitrification; with regard to the reference assays with acetate, differences in specific consumption and formation rates were respectively determined (⊍ = 0.0001). Regarding this, two main kinetic effects were observed.…”

“…27 Studies on AMP removal from wastewaters by denitrification would be of practical importance. In this sense, denitrification has been successfully used for eliminating aromatic compounds, 29 chlorinated contaminants 30 and mixtures of 2-chlorophenol (2-CP) with phenol, glucose and acetate as external electron donors, 31 as well as mixtures of emerging contaminants such as personal care products, hormones, different classes of pharmaceuticals and pesticides, among others. 32,33 There are some reports in the literature concerning the elimination of antibiotics under denitrifying conditions.…”