Continuous Co‐biodegradation of linear and cyclic naphthenic acids in circulating packed‐bed bioreactors

Abstract

Continuous co‐biodegradation of a linear and three cyclic surrogate naphthenic acids namely octanoic acid, trans‐4‐methyl‐1‐cyclohexane carboxylic acid (trans‐4MCHCA), and cis‐ and trans‐4‐methyl‐1‐cyclohexane‐acetic acids (cis‐4MCHAA and trans‐4MCHAA) at concentrations of 100, 50, and 50 mg/L, respectively, was investigated in two circulating packed‐bed bioreactors. Using different combinations of naphthenic acids in the bioreactor influent effects of loading rate on biodegradation of each compound was evaluated. In all tested mixtures biodegradation of octanoic acid proceeded with the fastest rate, followed by trans‐4MCHCA, trans‐4MCHAA, and cis‐4MCHAA. Biodegradation of the linear compound (octanoic acid) was not influenced by the presence of any cyclic compound, even the most recalcitrant naphthenic acid with the highest removal rate of 372.8 mg/L‐h observed at a loading rate of 666.7 mg/L‐h. Presence of octanoic acid negatively impacted the biodegradation of trans‐4MCHCA, with the removal rates of trans‐4MCHCA in the presence and absence of octanoic acid being 74.6 and 208.8 mg/L‐h, respectively. With cis‐ and tran‐4MCHAA, presence of octanoic acid improved the biodegradation of these compounds. In a mixture containing all three cyclic compounds, the maximum removal rates for cis‐ and trans‐4MCHAA were 0.5 and 1.3 mg/L‐h, respectively, which improved to 1.7 and 2.4 mg/L‐h when octanoic acid was included in the mixture. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 835–843, 2014

Effect of Alkyl Side Chain Location and Cyclicity on the Aerobic Biotransformation of Naphthenic Acids

“…Both the carbon number and spatial arrangement of the carboxylic group influenced the biodegradation rates of the three model NAs. D’Souza et al . found that the acyclic octanoic acid biodegraded the fastest in circulating packed-bed bioreactors followed by trans -4-methyl-1-cyclohexanecarboxylic acid, trans -4-methyl-1-cylcohexaneacetic acid, and cis- 4-methyl-1-cyclohexaneacetic acid; the biodegradation of octanoic acid was not affected by the presence of any of the cyclic NAs.…”

Water treatment technologies for the remediation of naphthenic acids in oil sands process-affected water

“…A 2014 report by the same group [72] discussed the co-biodegradation of octanoic acid (n = 8, z = 0, MW = 144.21 g mol À1 ), trans-4-methyl-1-cyclohexane carboxylic acid (n = 8, z = À2, MW = 142.2 g mol À1 ), cis-4-methyl-1-cyclohexane acetic acid (n = 9, z = À2, MW = 156.22 g mol À1 ), and trans-4-methyl-1-cyclohexane acetic acid (n = 9, z = À2, MW = 156.22 g mol À1 ), one linear and three monocyclic model NAs, using the circulating packed-bed bioreactor (Fig. 10).…”

“…Several of the reviewed papers report on cost reduction [73,85,106,108,109], improved energy efficiency [49,53], and higher throughput [70,72,92], characteristics of a process that ultimately determine its industrial applicability. That being said, major strides must be made for many of the proposed technologies to realize its full-scale implementation.…”