Fenton Pre-oxidation Research Articles

Long lasting degradation of all alkanes in soil by Pseudomonas activated after Fenton pre-oxidation

This study investigated the function and mechanism of Fenton pre-oxidation on the long lasting degradation of all alkanes in soil contaminated by petroleum. The findings demonstrated that the biological removal amount of all alkanes in the respiratory regulation group reached 4083.46 mg/kg, which was twice that of the non-regulation group, and the removal amount gradually increased in the four stages of bioremediation. In addition, the removal amount of all alkanes in the non-regulated group did not change much and showed a downward trend, indicating that long lasting degradation of all alkanes could be achieved by the respiratory regulation group, and the biodegradation cycle was saved by 251 days compared with the non-regulated group. Furthermore, the total number of bacteria in the respiratory regulation group (6.73 log CFU/g) was significantly higher than that in the non-regulation group (2.25 log CFU/g). Pseudomonas became the dominant genus in the respiratory regulation group with an average relative abundance of 32.17 %. In the respiratory regulation group, a large amount of ammonia nitrogen (1703.62 mg/kg) was consumed during the degradation process, which stimulated the tricarboxylic acid cycle respiratory metabolism process of Pseudomonas and accelerated the hydrocarbon conversion. This may be the reason why the long lasting degradation of all alkanes in soil could be achieved by the respiratory regulation group.

Long-lasting degradation of long-chain alkanes through activating Bacillus-like microbes after Fenton pre-oxidation in soil

To explore the effects and mechanisms of long-lasting degradation of long-chain alkanes (C25-C30) in petroleum-contaminated soil, a solid iron catalyst prepared by adding different proportions of (5 % and 15 % (w/w)) chitosan (CS) was used for Fenton pre-oxidation experiment. Bioremediation experiments were performed for 100 days after pre-oxidation. The results indicated that the degradation for long-chain alkanes and Total Petroleum Hydrocarbons (TPH) were 76.95 % and 76.89 %, respectively. Furthermore, long-lasting degradation of long-chain alkanes was achieved by activating Bacillus-like microbes. In each biodegradation cycle, the long-chain alkanes degradation in the active control group increased by 77.39 mg/kg, 76.74 mg/kg, 36.88 mg/kg, and 76.51 mg/kg compared to the previous cycle. Besides, the half-life of long-chain alkanes was 131 days shorter in the active control group than in the inactive control group. Higher microbial enzyme activity for degrading long-chain alkanes was observed after Fenton pre-oxidation because the expression of alkane metabolism genes was activated by the high consumption of dissolved organic carbon. Finally, the dominant bacterial genera in the active control group shifted predominantly to Paenibacillus (13.26 %), Acinetobacter (8.02 %), and Microbacterium (17.64 %). Therefore, this study possesses significant engineering application value.

Enhanced dewatering of dredging slurry by Fenton preoxidation and composite coagulants: optimization experiments and dewatering mechanisms.

In this work, the Fenton preoxidation and composite coagulant method was used to carry out the rapid dewatering experiment of Chaohu Lake (China) dredging slurry. The changes in extracellular polymeric substances (EPS), particle size distribution, zeta potential, specific resistance to filtration (SRF), and capillary suction time (CST) of the dredging slurry were characterized. The results showed that the molar ratio of H2O2 and Fe2+ had the greatest effect on the dewatering of dredging slurry by Fenton preoxidation. The coagulant selected through the coagulation test was polyaluminum ferric chloride. The model simulated by the response surface method exhibited significant adaptability and high accuracy (p < 0.01, R2 = 0.9461, accuracy is 12.115). Fenton preoxidation resulted in the transformation of tightly bound EPS to soluble EPS. After preoxidation-coagulation treatment, the dewatering performance of the slurry improved significantly. The EPS quantity rose by 20.3%, while the SRF (3.65 × 109 s2/g), CST (71.25s), and zeta potential (- 28.0mV) shifted to 0.33 × 109 s2/g, 27.60s, and - 14.9mV, respectively. The disintegration of EPS by Fenton peroxidation and the subsequent adsorption bridging and charge neutralization through coagulation were the key mechanism for improving the dewatering performance of the dredging slurry.

Effect of Fenton pre-oxidation on the physicochemical properties of sludge-based biochar and its adsorption mechanisms for ammonia nitrogen removal

Fenton pre-oxidation, as a promising technology for sludge deep dehydration, has been used intensively; however, the outputs (i.e., low-water-content sludge cakes) need to be further disposed for a full line sludge resource utilization. Carbonization presents a promising approach for disposing of the sludge cake within the process. Here, the physicochemical properties of sludge-based char obtained after Fenton pre-oxidation were studied. Both Fenton pre-oxidized sludge-based char (FSC) and raw sludge-based char (RSC) were produced within the temperature range of 400–600 ℃, and the adsorption performance of the prepared chars, exemplified by their ability to adsorb ammonia nitrogen (NH4+), was tested under various conditions. FSC exhibited superior char yield and adsorption performance compared to RSC, with chemical adsorption being the primary controlling factor. The optimum conditions for FSC were observed at 400 ℃, resulting in a char yield of 72.2 %, and an adsorption capacity of 221.7 mg/g. Notably, FSC demonstrated an increase in C-C, C-N, OC-O, C-O and CC functional groups in comparison to RSC, which suggests that pre-oxidation increases organic matter decomposition and chemical reactivity of the sludge. The introduction of Si-O-Si, Si-O-C and Fe-O-H functional groups in the FSC facilitated ion exchange with NH4+ in an aqueous solution. The key findings indicate that Fenton pre-oxidation not only enhances the adsorption performance of FSC but also reduces the required carbonization temperature for excellent-char preparation. These results demonstrated the potential to integrate sludge deep dewatering, including pre-oxidation, with char preparation.

Rapid degradation of long-alkanes by mild Fe-SOM pre-oxidation in soils

In this study, a novel mild pre-oxidation mode was successfully explored by fabricating Fe-SOM prepared by adding 2.5% and 20% fulvic acid (FA). This study explored the mechanism of mild Fe-SOM pre-oxidation to stimulate rapid biological degradation of long-alkanes in oil-contaminated soils. Results showed that under mild Fe-SOM pre-oxidation, the total •OH intensity and bacterial killing degree（D） were low, and hydrocarbon conversion（C）was fast, resulting in rapid degradation of long-alkanes. Additionally, the fast group removed 1.7-fold more than slow group and biodegraded long-alkanes 182 days significantly faster. Furthermore, compared with slow group (8.26 log CFU/g), the fast group (51.48 log CFU/g) characterized much more bacteria. Besides, the fast group had higher C (5.72%–15.95%), thus increasing the degradation rate of long-alkanes (7.61%–18.86%). A shift in the microbial community was found after mild Fe-SOM pre-oxidation, with an average relative abundance of 18.6% for the dominant genus Bacillus. Therefore, the mild pre-oxidation reduced the D, and the high bacterial abundance promoted nutrients consumption and C, which shortened bioremediation period and increased the long-alkanes degradation rate. This study provided a promising novel mild Fenton pre-oxidation mode to rapid remediate heavily multicomponent oil-contaminated soils.

Pilot-scale advanced treatment of actual high-salt textile wastewater by a UV/O3 pressurization process: Evaluation of removal kinetics and reverse osmosis desalination process

Advanced oxidation processes (AOPs) such as ozonation and Fenton processes are widely used in the treatment of high-salt wastewater. The UV/O3 pressurization process was designed and applied at the pilot-scale for treatment of actual high-salt textile wastewater. The UV/O3 pressurization process achieved the highest decolorization (85 %) and chemical oxygen demand (CODCr, 43.2 %) removal efficiency at an O3 dosage of 200 g·t−1 and a pressure of 0.2 MPa. Compared to ordinary ozonation, the UV/O3 pressurization process improved the solubility and gas-liquid mass transfer efficiency of O3 in wastewater and generated a large number of O3 microbubbles. Hydroxyl radical (·OH), superoxide radicals (O2·−) and single oxygen (1O2) all played a significant role on the removal of pollutants in wastewater during the UV/O3 pressurization process. The reverse osmosis (RO) process was used to evaluate the effect of UV/O3 pressurization and Fenton pre-oxidation processes on the desalination process as the last process in treating high-salt organic wastewater. The pre-oxidation processes improved the initial RO water flux. Compared with the Fenton process, the UV/O3 pressurization process had less membrane fouling (thin fouling layer vs thick fouling layer), and final water flux (59.4 LMH) was higher than that of Fenton process (34.9 LHM). The total dissolved solids (TDS), Cl− and SO42− of the effluent from UV/O3 pressurization process (37.2, 7.6 and 3.0 mg·L−1) were better than that of Fenton process (65.7, 13.9 and 7.1 mg·L−1). Therefore, the UV/O3 pressurization process without secondary pollution is more suitable for the advanced treatment of high-salt organic wastewater than the Fenton process.

Fast biodegradation of long-chain alkanes in heavily polluted soil by improving C/H conversion after pre-oxidation

This study aimed to explore the effects of Fenton pre-oxidation under different conditions on the indigenous bacterial communities and the mechanism of soil C/H conversion and rapid degradation of long-chain alkanes. The soil total petroleum hydrocarbons (TPH) content for this study was 27998 ± 883 mg/kg of soil. The results showed that the half-life period of the rapid long-chain degradation group was 266 days faster than that of the slow long-chain degradation group. After pre-oxidation, the number of bacteria in the fast group (5.07 log CFU/g) was higher than slow group (2.57 log CFU/g). Further studies showed that the consumption of ammonia nitrogen in the long-chain rapid degradation group was 1.37 times higher than that in the long-chain slow degradation group. The mapping characterization by DEEM revealed a high level of humic acid-like and organic matter produced by microbial metabolism in the fast group, and the long-chain degradation group had higher C/H conversion (35%), thus improving the degradation rate of long-chain alkanes (47%). High biomass and ammonia nitrogen consumption promoted higher C/H conversion. After proper pre-oxidation, the bacterial community changed, with an average relative abundance of 34% for Actinobacteria. This study has good engineering application value.

Arsenic chemistry in municipal sewage sludge dewatering, thermal drying, and steam gasification: Effects of Fenton-CaO conditioning

In sludge disposal, Arsenic (As) poses serious secondary pollution due to its high toxicity and low stability. This work systematically studied the effects of Fenton-CaO composite conditioning on As chemistry throughout sludge dewatering, thermal drying, and steam gasification processes. The experimental results showed that, for raw sludge, 40.9% of As was released with filtrate discharging and 26.8–57.3% emitted with flue gas emission. When sludge was conditioned by Fenton-CaO, all of the As in the filtrate was fixed in the sludge cake and the releasing rate of gaseous As was reduced by up to 86.0%. Furthermore, the comprehensive results of the model compounds experiment, sequential extraction, and thermodynamic calculations revealed the effects of Fe/Ca conditioners on As species evolution. In the Fenton pre-oxidation, As(V) was reduced to As(III) due to the decreasing Eh caused by the excessive Fe(II). After adding CaO, As(III)/DMA (dimethyl arsenic) was adsorbed onto the surface of amorphous Fe(OH)3 that was introduced by Fenton's reagent, 50% and 43% of which were then oxidized or demethylated to form As(V)/MMA (monomethyl arsenic), respectively. In the following drying process at 120–180 °C, the FeOOH and CaO derived by residual Fe/Ca conditioners could promote the oxidation of 30% of the rest As(III) by the catalytic effect or directly reacting with it. In the final steam gasification process, the very little As(III) left in the dry sludge was released with the gas phase and the proportion of As(V) in gasification ash almost reached 100%. In short, Fenton-CaO composite conditioning could achieve the near-zero emission of As and reduce the toxicity of the products throughout the whole sludge treatment process.

Efficient removal of heavily oil-contaminated soil using a combination of fenton pre-oxidation with biostimulated iron and bioremediation

Crude oil contamination severely deteriorates soils quality. Bioremediation utilizing soil indigenous organisms could be employed to decompose petroleum hydrocarbons thanks to its low cost and minor environmental disturbance. However, slow kinetics limit the successful application of this biotechnique. Pretreating oil-contaminated soils with Fenton pre-oxidation could accelerate the subsequent bioremediation process. This study was to explore the mechanisms behind the rapid propagation of indigenous petroleum-degrading bacteria (IPDB) and the efficient degradation of total petroleum hydrocarbons (TPH) in soil after Fenton pre-oxidation with biostimulated iron. Biostimulated iron and non-biostimulated iron were used in the experiments, where Fenton pre-oxidation was combined with the bioremediation of oil-contaminated soil (TPH = 13221 mg/kg). Although the amount of Fenton pre-oxidized TPH (3331–3775 mg/kg) was similar with biostimulated and non-biostimulated irons, the biodegradation of TPH after Fenton pre-oxidation with biostimulated iron (5840 mg/kg) was much higher than that with non-biostimulated iron (3034–4034 mg/kg). Moreover, abundant nutrients and a high population of residual IPDB were found after Fenton pre-oxidation with biostimulated iron, which benefited stable consumption of NH3–N and dissolved organic carbon (DOC) by IPDB during the subsequent bioremediation. However, Fenton pre-oxidation with non-biostimulated iron either resulted in greater damage to IPDB or produced fewer nutrients, thereby failing to ensure the continuous propagation of IPDB during the subsequent bioremediation. Therefore, we propose that Fenton pre-oxidation with biostimulated iron should be applied to heavily oil-contaminated soils prior to bioremediation.

Fast biodegradation of long-alkanes by enhancing bacteria performance rate by per-oxidation

The long-alkanes biodegradation rate was generally found slow during widely used pre-oxidation combined with biodegradation for oil contamination treatment, resulting in long and unsustainable removal. In this study, different chitosan content was used to produce iron catalysts for pre-oxidation, and nutrients were added for the long-alkanes biodegradation experiment. Mechanism of Fenton pre-oxidation and improvement in the biodegradation rate of long-alkanes were studied by analyzing the change in organic matter and bacterial community structure, the amount and activity of bacteria in the biological stage, and the degradation amount long-alkanes hydrocarbon before and after pre-oxidation. Results showed that the destruction of bacteria greatly reduced when hydroxyl radical intensity decreased to 4.40 a.u.. Also, the proportion of humic acid-like was high (40.88%), and the community structure was slightly changed with the pre-oxidation for the fast biodegradation (FB) group. In the subsequent biodegradation, it was found that the degradation rate of each long-alkanes in the FB group increased significantly (C30: 4.18–8.32 mg/(kg·d)) with the increase of the degradation of long-alkanes (10–50%). Further studies showed that the high nutrient dynamics (6.05 mg/(kg·d)) of the FB group resulted in high bacteria performance rate (0.53 mol CO2 × log CFU/(104 g2 d)), which further accelerated the substrate transformation(41%). Therefore, the biodegradation rate of long-alkanes was increased (43.8 mg/(kg·d)) with the removal rate of long-alkanes of 76%. The half-life of long-alkanes for the FB group (64 d) was 33 d shorter than the slow biodegradation group (99 d). These results exhibited that pre-oxidation regulation can shorten the bioremediation cycle by improving the biodegradation rate of long-alkanes. This research has good engineering application value.

Fenton pre-oxidation of natural organic matter in drinking water treatment through the application of iron nails

ABSTRACT This study investigated for the first time the efficiency of an advanced oxidation process (AOP) zero valent iron/hydrogen peroxide (ZVI/H2O2) employing iron nails for the removal of Natural Organic Matter (NOM) from natural water of Regent’s Park lake, London, UK. The low cost of nails and their easy separation from the water after the treatment make this AOP attractive for water utilities in low- and middle-income countries. The process was investigated as a pre-oxidation step for drinking water treatment. Results showed that UV254 removal in the natural water was lower than that of simulated water containing commercial humic acid (HA), indicating a matrix effect. Statistical analysis confirmed the maximum removal of dissolved organic carbon (DOC) in natural water depends on the initial pH (best at 4.5) and H2O2 dosage (best at 100% excess of stoichiometric dosage). DOC and UV254 removals under this operational condition were 51% and 89%, respectively. Molecular weight (MW) and specific UV absorbance (SUVA254) were significantly reduced to 74% and 78%, respectively. Formation of Chloroform THM in natural water sample after the ZVI/H2O2 process (initial pH 4.5) was below the limit for drinking water, and 48% less than the THM formation in the same water not subjected to pre-oxidation. Characterization of oxidation products on the iron-nail-ZVI surface after the ZVI/H2O2 treatment by SEM, XRD, and XPS identified the formation of magnetite and lepidocrocite. Results suggest that the investigated ZVI/H2O2 process is a promising technology for removing NOM and reducing THM formation during drinking water treatment.

Fast-stimulating bioremediation of macro crude oil in soils using matching Fenton pre-oxidation

This study aims at exploring the mechanism of fast-stimulating bioremediation of macro crude oil using matching Fenton pre-oxidation. The 80-day biodegradation experiment for soil S1 and S2, containing macro crude oil: C19–C29 and C17–C29 respectively, was conducted after Fenton pre-oxidation with three concentrations of H2O2 (225 mM, 450 mM, and 900 mM). Experimental results indicated that the bioremediation efficiency of macro crude oil was up to 57.1% (8853 mg/kg, S1) and 64.4% (11,719 mg/kg, S2) for 80-day fast-stimulating bioremediation using matching Fenton pre-oxidation (450 mM H2O2), which was 1.8–2.6 times that (S1: 22.2–37.1%; S2: 36.1–39.6%) for slow-stimulating bioremediation using un-matching Fenton pre-oxidation. Furthermore, the high-throughput analysis revealed that genera Sedimentibacter, Caenispirillum, and Brevundimonas became the dominant bacteria after matching Fenton pre-oxidation. Meanwhile, the highest logarithmic growth rate of indigenous hydrocarbon degraders (IHD) was obtained (S1: 64% and S2: 60%) for fast-stimulating bioremediation. And the consumption of NH4+-N was up to 90% and 94% in S1 and S2 within 60 days for fast-stimulating bioremediation, approximately 1.4 and 2.2 times that (S1: 65% and 62%; S2: 47% and 41%) for slow-stimulating remediation. The results showed that the macro crude oil became the main carbon source for IHD for the fast-stimulating bioremediation, resulting in the rapid growth of IHD. Thus, this study provides a fast and efficient remediation technology for bioremediation of macro crude oil-contaminated soils.

Application of Fenton pre-oxidation, Ca-induced coagulation, and sludge reclamation for enhanced treatment of ultra-high concentration poly(vinyl alcohol) wastewater

Poly(vinyl alcohol) (PVA) wastewater contains up to 10,000 mg/L dissolved organic carbon. A concentration of this magnitude results in a high chemical oxygen demand (COD), which generates major problems for industrial wastewater treatment in general, and the textile and chemical industries, in particular. Thus, we propose a two-stage treatment process that uses Fenton pre-oxidation, coupled with Ca-induced coagulation, to reduce the PVA and COD wastewater concentration. The optimal concentrations of FeSO4 and CaCl2 per gram of PVA were 0.8 g/g-PVA and 4.0 g/g-PVA, respectively, which is significantly lower than that of other reported treatments. Due to successful oxidation, the long chains of PVA molecules were broken up and the OH groups were partially oxidized to COOH. During the coagulation stage, Ca2+ was able to efficiently bind with the PVA pre-oxidation products, thereby forming insoluble compounds. Given initial COD and PVA concentrations of 20,450 and 10,000 mg/L, respectively, a maximum of 81.3 % COD and 96.0 % PVA was removed following this two-stage procedure. Furthermore, the sludge residue was used to remove Sb(III) from the wastewater, achieving an Sb(III) adsorption capacity of 16.0 mg/g. Thus, this study provides new insight into affordable and effective treatment of high concentration PVA-containing wastewater.

Enhanced Biodegradation of Long-chain Alkanes in Soils Using Matching Fenton Pre-oxidation

ABSTRACTThe purpose of this study is to find matching Fenton pre-oxidation that can enhance the subsequent biodegradation of long-chain alkanes in soils. After matching Fenton pre-oxidation, the hydrocarbon degraders in soils grew quickly, which was stimulated to degrade the long-chain alkanes as its main carbon sources. Therefore, the long-chain alkanes removal was improved significantly. The results of this study suggested that the degradation of C25 – C30 after matching Fenton pre-oxidation was up to 5463 mg/kg (67%), which was 5.2 times higher than that of unmatching Fenton pre-oxidation (1044 mg/kg). In addition, after matching Fenton pre-oxidation, the hydrocarbon degraders were stimulated to degrade the long-chain alkanes and nitrogen sources hugely so that the hydrocarbon degraders can increase considerably (73%). This was the reason that the biodegradation of long-chain alkanes was enhanced by matching Fenton pre-oxidation.

Improving Bioremediation of Crude Oil-contaminated Soil by Mild Pre-oxidation

To obtain a mild Fenton pre-oxidation method, which could promote the efficient degradation of total petroleum hydrocarbons (TPH) in subsequent bioremediation, the differences in the characteristics of the hydroxyl radical (·OH), nutrient consumption, activity of indigenous bacteria (CO2), and TPH removal were investigated during subsequent bioremediation after different Fenton pre-oxidation treatments. The results showed that high biodegradation of TPH was observed after mild Fenton pre-oxidation (·OH existence time:73 h; H2O2 concentration:225 mmol·L-1), because of the high activity of residual bacteria. Moreover, the same TPH removal with the addition of bacteria could be achieved without adding bacteria (the TPH removal rate 38%) because the activity of the residual bacteria was strong after mild Fenton pre-oxidation. Under the condition of no additional bacteria source, mild Fenton pre-oxidation TPH removal (approximately 38%) was higher than that after ordinary Fenton pre-oxidation (15.32%-33.15%). Further analysis of the removal efficiency of each chain of hydrocarbons revealed that the mild pre-oxidation group could reduce the inhibition of the chain hydrocarbon components (C17-C21) in the subsequent bioremediation stage. Comparing the activity of the indigenous bacteria in each group, revealed that mild pre-oxidation could appropriately stimulate the growth and increase the activity of indigenous microorganisms, all of which are beneficial to the removal of TPH.

Study on the composition of resistant organics in winery wastewater and their degradation technique

Winery wastewater contains a large number of resistant organic compounds, and the residual effluent COD is high after common biological treatment processes, which is hard to meet the increasingly rigorous wastewater discharge standard in China. Two techniques, Fenton oxidation and Fenton oxidation + SBR processes, were applied to treat winery wastewater in this study, and Gas Chromatography (GC) was used to analyze the resistant organic compounds in the effluent. The results indicated that resistant organic compounds in winery wastewater are mainly composed of long chain alkanoic acids, polyphenols, macromolecular esters and alcohols, and the combination treatment of Fenton + SBR process could eliminate COD effectively, and only 0.43% COD left in the effluent compared to the raw winery wastewater. Fenton pre-oxidation not only can oxidize the resistant organics directly, but also can improve the biodegradability of winery wastewater, and the effluent COD meets 60 mg/L standard. The combination of Fenton pre-oxidation and SBR aerobic treatment is the optimal process treating winery wastewater.

Enhancement of waste-activated sludge dewaterability using combined Fenton pre-oxidation and flocculation process

Enhancement of waste-activated sludge dewaterability using combined Fenton pre-oxidation and flocculation process

Effect of Fenton pre-oxidation on mobilization of nutrients and efficient subsequent bioremediation of crude oil-contaminated soil

Fenton pre-oxidation and a subsequent bioremediation phase of 80 days were used to investigate the importance of matching concentration of residual indigenous bacteria and nutrient levels on subsequent bioremediation of crude oil. Experiments were performed using either high (>107.7 ± 0.2 CFU/g soil) or low (<105.9 ± 0.1 CFU/g soil) concentrations of bacteria and three different nutrient levels: enough (C/N > 9.8), moderate (C/N:5–9.8), and lacking nutrient level (C/N < 5) conditions. Weak Fenton pre-oxidation (225 mM H2O2 and 2.9 mM Fe2+) resulted in highly matching between nutrient level and the population of residual indigenous bacteria. Up to 53% of total petroleum hydrocarbon (TPH) and 58% of main hydrocarbon (C15C25, during the first 10 days) were removed from the soil. Under matching conditions, the activity of indigenous bacteria and nutrient mobilization were enhanced, promoting the bioremediation of crude oil. In addition, the biodegradation of long chain molecules (C26C30) required a high level of NH4+-N.

Impact of chemical oxidation on indigenous bacteria and mobilization of nutrients and subsequent bioremediation of crude oil-contaminated soil

Fenton pre-oxidation provides nutrients to promote bioremediation. However, the effects of the indigenous bacteria that remain following Fenton oxidation on nutrient mobilization and subsequent bioremediation remain unclear. Experiments were performed with inoculation with native bacteria and foreign bacteria or without inoculation after four regimens of stepwise pre-oxidations. The effects of the indigenous bacteria remaining after stepwise oxidation on nutrient mobilization and subsequent bioremediation over 80 days were investigated.After stepwise Fenton pre-oxidation at a low H2O2 concentration (225×4), the remaining indigenous bacterial populations reached their peak (4.8±0.17×106CFU/g), the nutrients were mobilized rapidly, and the subsequent bioremediation of crude oil was improved (biodegradation efficiency of 35%). However, after stepwise Fenton pre-oxidation at a high H2O2 concentration (450×4), only 3.6±0.16×103CFU/g of indigenous bacteria remained, and the indigenous bacteria that degrade C15–C30 alkanes were inhibited. The nutrient mobilization was then highly limited, and only 19% of total petroleum hydrocarbon was degraded. Furthermore, the recovery period after the low H2O2 concentration stepwise Fenton pre-oxidation (225×4) was less than 20 days, which was 20–30 days shorter than with the other pre-oxidation treatments. Therefore, stepwise Fenton pre-oxidation at a low H2O2 concentration protects indigenous bacterial populations and improves the nutrient mobilization and subsequent bioremediation.

Degradation of Chemical Industry Integrated Wastewater by Sequential Fenton's Pre-oxidation and Aerobic Biological Treatment

Degradation of Chemical Industry Integrated Wastewater by Sequential Fenton's Pre-oxidation and Aerobic Biological Treatment