Efficient sustainable bioremediation of long‐chain crude oil in soils using instant Fenton pre‐oxidation

Abstract

BACKGROUND: Many studies have reported that most Fenton pre-oxidation steps either do more damage to the indigenous hydrocarbon degraders (IHD) or produce lower concentrations of ammonium-nitrogen (NH 4 + -N) during Fenton oxidation combined with bioremediation for oil-contaminated soils, which causes the subsequent bioremediation to be unsustainable and poor. The aim of the present study was to find an instant Fenton pre-oxidation for the efficient sustainable biodegradation of long-chain alkanes, and to determine the ratio (K) of residual concentration of NH 4 + -N to residual population of IHD that can reach a balance after this instant Fenton pre-oxidation. RESULTS: FiveFenton oxidation experiments were carried out with iron bound to soil organic matter (SOM). On this basis, a 75-day field experiment of instant Fenton pre-oxidation with K = 46 combined with bioremediation was performed. Experimental results showed that a similar efficient biodegradation (≈261 mg kg −1 ) of long-chain alkanes C 30 -C 25 at each stage was obtained after instant Fenton pre-oxidation with K = 46. So up to 75% of the biodegradation of long-chain alkanes occurred after instant Fenton pre-oxidation with K = 46, which was 2.3-and 2.0-fold greater than the corresponding biodegradation of long-chain alkanes after noninstant Fenton pre-oxidation with K ≠ 46. CONCLUSION: The study indicated that efficient sustainable bioremediation of long-chain alkanes can be achieved after instantFenton pre-oxidation with K = 46. Analyses of microbial diversity revealed that a possible explanation for the efficient sustainable bioremediation of long-chain alkanes in soils was that sensitive, slow growth of the IHDs Nocardiode and Noviherbaspirillum was not damaged after instant Fenton pre-oxidation with K = 46.

Fenton oxidation for soil remediation: A critical review of observations in historically contaminated soils

“…(ii) Shortening the contact time of the oxidant with microbes: Minimizing the amount of direct contact that soil microbes have with the concentrated oxidant can minimize the negative impacts of oxidation and can aid microbes to exhibit better bioremediation. This has been obtained by the incremental addition of H 2 O 2 (Xu et al, 2011b) or by instant Fenton pre-J o u r n a l P r e -p r o o f 21 oxidation (Xu et al, 2020). The biodegradation of long-chain alkanes after instant Fenton pre-oxidation was two times higher than that after non-instant oxidation (Xu et al, 2020).…”

“…This has been obtained by the incremental addition of H 2 O 2 (Xu et al, 2011b) or by instant Fenton pre-J o u r n a l P r e -p r o o f 21 oxidation (Xu et al, 2020). The biodegradation of long-chain alkanes after instant Fenton pre-oxidation was two times higher than that after non-instant oxidation (Xu et al, 2020). In another effort to improve subsequent bioremediation, stepwise addition of H 2 O 2 instead of adding all amount in the beginning has been suggested (Sutton et al, 2014a;Xu et al, 2011b).…”