Oil Refinery Sludge Research Articles

Co-pyrolysis of refinery oil sludge with biomass and spent fluid catalytic cracking catalyst for resource recovery.

Catalytic co-pyrolysis of two different refinery oily sludge (ROS) samples was conducted to facilitate resource recovery. Non-catalytic pyrolysis in temperatures ranging from 500 to 600°C was performed to determine high oil yields. Higher temperatures enhanced the oil yields up to ~ 24 wt%, while char formation remained unchanged (~ 45%) for S1. Conversely, S2 exhibited a notably lower oil yield (~ 4 wt%) than S1. Pyrolysis oil of S1 consisted of phenolics (~ 50% at 600°C) whereas hydrocarbons were predominant in S2 oil (~ 80% at 600°C). Catalytic pyrolysis of S1 did not exhibit a substantial impact on oil yields but the oil composition varied significantly. High hydrocarbons, phenolics, and aromatics were obtained with molecular sieve (MS), metal slag, and ZSM-5, respectively. Catalytic co-pyrolysis of S2 with sawdust (SD) in the presence of MS enhanced the oil yield, and the resulting oil consisted of high hydrocarbons (~ 54%) and aromatics (~ 44%).

Aqueous extracts of composted oil refinery sludge and their possible environmental impacts

ABSTRACT Oil refinery sludge (ORS) management is a global concern, yet information on its low-cost biotransformation possibility is fairly limited. We present a novel approach for ORS mitigation by Eisenia fetida and Eudrilus eugeniae and aerobic composting (AC) in producing clean aqueous extracts (compost teas). Detailed physicochemical characterization, phytotoxicity assays, economic feasibility comparisons, and mathematical equation-based environmental and human health hazard prediction studies were done for all the earthworm and non-earthworm processed compost teas. The E. eugeniae-compost tea reduced Cr, Pb, Cu, Cd, and Zn contents by 52.7, 61.2, 41.8, 80, and 93.8%, respectively. The earthworm-sourced teas showed lower ecological risk (<300) than their aerobic counterparts. Seed germination in Pisum sativum and Cicer arietinum was 2–2.5 folds higher with vermi-derived tea application. Economic assessments illustrated the superiority of E. eugeniae-based biotransformation with higher cash flow and a lower payback time of 1.53 years. The mathematical predictions on human health showed no alarming status for any of the vermi/aerobic compost teas. Overall results implied that vermicomposting is safer and more beneficial than AC in the ORS bioconversion. However, this study warrants further research in exploring the efficiency of other earthworm species, feedstock selection, or seasonal variability in ORS management.

Unleashing synergistic potential of microbially enhanced anaerobic co-digestion of petroleum refinery biosludge and yard waste: Impact of nutrient balance and microbial diversity

Petroleum refinery sludge, an egregious solid residue generated from the wastewater treatment plants poses an environmental hazard owing to its intricate hydrocarbon composition, necessitating competent treatment for secure disposal. The study proposes a green solution through anaerobic co-digestion of nitrogen-rich petroleum refinery sludge (PS) with carbon-rich yard waste (YW), balancing the nutrients and moisture content for efficient microbial proliferation. Using Central Composite Design-Response Surface Methodology, 1 L batch experiments were conducted with varying carbon/nitrogen (C/N) ratios and pH to achieve maximum biogas yield within 50 days of co-digestion. However, the sluggish biogas recovery (40%) indicated a slow rate-limiting hydrolysis, necessitating pretreatment. Feedstock incubation with Bacillus subtilis IH1 strain, isolated from the microbially-enriched PS, at 108 colony forming units (CFU) per mL for 5 days maximized the soluble chemical oxygen demand and volatile fatty acids by 2.2 and 1.4 folds respectively compared to untreated feedstock. Scale-up Bacillus subtilis aided co-digestion studies further augmented biogas by 76% against untreated monodigestion of PS with significant total petroleum hydrocarbons, emulsions, and lignocellulosic degradation. Further identification of major organic pollutants in the batch digestate revealed significant degradation of the toxic organic hydrocarbon pollutants apotheosizing the efficacy of the synergistic sustainable technique for the management of PS. Environmental implicationThe effluent treatment plants (ETPs) of petroleum refining industries generate sludge which is a complex mixture of petroleum hydrocarbons, oil–water (O/W) emulsions and heavy metals. These petroleum hydrocarbon constituents can be linear/cyclic alkanes, polyaromatics, resins and asphaltenes, whose intricate composition is reportedly carcinogenic, cytogenic and mutagenic, classifying it as hazardous waste. Biological treatment of these sludge through anaerobic digestion leads to utilization of petroleum hydrocarbons with subsequent energy recovery. Co-digestion of these sludge with competent co-substrates leads to nutrient balance, diverse microbial proliferation and toxicant dilution. Microbially aided co-digestion further augments methane rendering a digestate with utmost pollutant degradation.

High-throughput bioamphiphile production by ethyl methane sulphonate induced mutant of hydrocarbonoclastic Enterobacter xiangfangensis STP-3: In depth structural elucidation and application to petroleum refinery oil sludge bioremediation

The environmental release of noxious petroleum hydrocarbons (PHCs) from the petroleum refining industries is an intractable global challenge. Indigenous PHCs degrading microbes produce insufficient yield of amphiphilic biomolecules with trivial efficiency makes the bioremediation process ineffective. In this concern, the present study is focused on the production of high yield multi-functional amphiphilic biomolecule through the genetic modification of Enterobacter xiangfangensis STP-3 strain using Ethyl methane sulphonate (EMS) induced mutagenesis. Mutant M9E.xiangfangensis showed 2.32-fold increased yield of bioamphiphile than wild-type strain. Novel bioamphiphile produced by M9E.xiangfangensis exhibited improved surface and emulsification activities which ensure the maximum degradation of petroleum oil sludge (POS) by 86% than wild-type (72%). SARA, FT-IR, and GC-MS analyses confirmed the expedited degradation of POS and ICP-MS analysis indicated the enhanced removal of heavy metals in connection with the ample production of functionally improved bioamphiphile. FT-IR NMR, MALDI-TOF, GC-MS and LC-MS/MS analyses portrayed the lipoprotein nature of bioamphiphile comprising pentameric fatty acid moiety conjugated with the catalytic esterase moiety. Further, homology modelling and molecular docking revealed the stronger interaction of hydrophobic amino acids, leucine and isoleucine with the PHCs in the case of wild-type esterase moiety, whereas in the mutant, aromatic amino acids were majorly interacted with the long chain and branched chain alkanes, thereby exhibited better efficiency. This is the first report on the adoption of EMS induced mutagenesis strategy to ameliorate the amphiphilic biomolecules for their sustainable applications in diverse biotechnological, environmental and industrial arenas.

Effect of noble bacteria Ochrobactrum intermedium (Alhpa-22) on decolorization of methyl orange dye in a bioreactor

Abstract In this study Ochrobactrum intermedium (Alhpa-22) was isolated from petroleum refinery sludge and characterized by using 16rRNA. In experimentation, for decolrization of methyl orange dye an indigenous noble bacterial ochrobactrum intermedium (Alhpa-22) at 35 °C has been used in a bioreactor. The ochrobactrum bacterial decolorized methyl orange dye having the concentration of 50 mgL−1 by 87 % within 9 days, which is a very encouraging result. decolorization of methyl orange dye by the isolated bacteria was elucidated using a UV–Vis spectrophotometer. The experimental data were fitted first and zero order kinetics models which show degradation of dye follows first order kinetics in presence of Lysinibacillus fusiformis KLm1, bacterial ochrobactrum intermedium (Alhpa-22) and mix consortia of Lysinibacillus fusiformis KLm1 and ochrobactrum intermedium (Alhpa-22). The rate constant were estimated to be 0.017 h−1, 0.020 h−1 and 0.014 h−1 respectively. Due to its higher decolorizing capability these may be used for the bioremediation of methyl orange dye (azo dye).

Microbial pretreatment using Kosakonia oryziphila IH3 to enhance biogas production and hydrocarbon depletion from petroleum refinery sludge

Petroleum refinery sludge (PRS) from the biological treatment unit was assessed for the extent of anaerobic biodegradability and pollutant removal through microbial pretreatment utilizing a novel lignin peroxidase (LiP) enzyme-producing bacterial strain, Kosakonia oryziphila to optimize the accelerated solubilization of PRS. K. oryziphila was incubated at different dosages (107, 108 and 109 CFU/mL) for 6 d resulting in maximum soluble chemical oxygen demand (3-fold increment) and volatile fatty acids concentration (2.53-fold increment) against untreated for dosage 108 CFU/mL on 4th d. The maximum LiP activity (20.52 IU/mL) was obtained at optimum conditions. The interactive effect of pretreated substrate and inoculum (S/I) ratios and pH on accumulated biogas yield was optimized using central composite design-response surface methodology in 1 L batch assay. This resulted in significant interaction of independent variables to obtain an optimal condition (S/I = 2.69 and pH = 7.38) for maximum biogas (5.15 L/g VSadded) with 1.56-fold increment against untreated PRS. During process scale-up (20 L study), total petroleum hydrocarbon, oil and grease, and total phenol removals were 56.2%, 62.5% and 88.4% respectively within 50 d of digestion. The digestate phytotoxicity assay revealed a significant reduction in seed-germination inhibition with an increase in seedling and biomass growth suggesting improved decontamination during the digestion process.

BIOTREATABILITY OF PETROLEUM REFINERY SLUDGE USING LAND - FARMING AND ANAEROBIC DEGRADATION TECHNIQUES

One of the major problems faced by oil industries and the environment, is the safe disposal of oily sludge generated during the processing of crude oil. Biotreatability of petroleum refinery sludge using bioremediation and anaerobic degradation techniques was studied. Analysis of the Nigerian Petroleum Refinery sludge used for this research indicated that the sludge is slightly acid with high total petroleum hydrocarbon (TPH) content of 340,000mg/kg and polyaromatic hydrocarbon (PAH) content of 0.075mg/kg. The heterotrophic bacterial and fungal counts were 5.86 x 105 and 4.72 x 105cfu/g respectively while the hydrocarbon degrading bacterial and fungal count were 2.85 x 102 and 2.75 x 102 cfu/g respectively. Results from biotreatability studies revealed that the sludge contamination at lower concentration 10,000 (1%) mg/kg, recorded high percentage degradation than the treatment with higher sludge concentration, 50,000 (5%) mg/kg. Biostimulation treatments enhanced the sludge degradation better than the natural attenuated treatment. Volume of biogas produced in the anaerobic microcosm was highest in the treatment with compost in both 1% (10.73 l/kg) and 5% (9.27 l/kg) sludge treatments. Though the NPK treated soil enhanced the biodegradation of sludge most, degradation started declining by the 9th week while that of compost continued to rise steadily till the 12th week. Anaerobic process was quite slow and did not degrade the sludge as much as the aerobic land – farming method.

Strategic implementation of integrated bioaugmentation and biostimulation for efficient mitigation of petroleum hydrocarbon pollutants from terrestrial and aquatic environment

Release of petroleum hydrocarbon pollutants poses a serious problem to the terrestrial as well as marine ecosystem. This study investigated and compared the potency of different biodegradation strategies for mitigating total petroleum hydrocarbon (TPH) of petroleum refinery sludge by an integrated action of bioaugmentation and biostimulation vis-à-vis separate bioaugmentation and biostimulation approaches. The implementation of a concomitant bioaugmentation-biostimulation strategy (BABSS) involving the indigenously developed bacterial consortium and poultry litter extract showed the best performance by mitigating the TPH up to 90.3 ± 3.7% in 21 days. The GC-FID analysis confirmed the efficacy of different TPH degradation strategies. The kinetic study of TPH degradation of BABSS resulted first-order with rate 0.11 day−1. Thus, the BABSS proved to be more efficient in degrading TPH in an eco-friendly manner and hence, may pave the way for better management of petroleum hydrocarbon pollutants, while providing a sustainable solution to the disposal of poultry wastes.

Biocatalytic lipoprotein bioamphiphile induced treatment of recalcitrant hydrocarbons in petroleum refinery oil sludge through transposon technology

The present investigation employed transposon technology to enhance the degradation of recalcitrant petroleum hydrocarbons present in petroleum oil sludge by using biosurfactant hyper-producing strain Enterobacter xiangfangensis STP-3. Out of 2500 transposon induced mutants, mutants M257E.xiangfangensis and M916E.xiangfangensis hyper-produce biocatalytic lipoprotein biosurfactant by1.98 and 2.34 fold higher than wild-type strain. Transposon induced mutation also modified the amino acid composition which improved the hydrophobicity and thermal stability of the biosurfactants produced by mutants, compared to the wild-type biosurfactant. GC-MS and LC-MS-MS revealed that biosurfactants have pentameric lipid moiety and esterase as protein moiety. Increased biosurfactant hydrophobicity and yield by the mutants resulted in the enhanced bioavailability of petroleum hydrocarbons, thereby mutants M257E.xiangfangensis and M916E.xiangfangensis demonstrated better petroleum oil sludge degradation by 82% and 88% respectively, than wild-type (72%). Disrupted genes vgr G and pgm M in M257E.xiangfangensis and M916E.xiangfangensis respectively hyper-produce biosurfactant by competitive pathway inhibition and increased precursor availability mechanism. Hyper-production of biosurfactant was also validated by comparing the expression of biosynthetic genes ent E, ent F and est using qPCR. This is the first report on the application of transposon technology to hyper-produce biosurfactant for the effective bioremediation of hydrocarbon contaminated environments.

Bioremediation of Hydrocarbon-Polluted Soil: Evaluation of Different Operative Parameters

The bioremediation of soils polluted with hydrocarbons demonstrated to be a simple and cheap technique, even if it needs a long time. The current paper shows the application of statistical analysis, based on two factors involved in the biological process at several levels. We focus on the Design of Experiments (DOE) to determine the number and kind of experimental runs, whereas the use of the categorical factors has not been widely exploited up to now. This method is especially useful to analyze factors with levels constituted by categories and define the interaction effects. Particularly, we focused on the statistical analysis of (1) experimental runs carried out at laboratory scale (test M, in microcosm), on soil polluted with diesel oil, and (2) bench scale runs (test B, in biopile), on refinery oil sludge mixed with industrial or agricultural biodegradable wastes. Finally, the main purpose was to identify the factor’s significance in both the tests and their potential interactions, by applying the analysis of variance (ANOVA). The results demonstrate the robustness of the statistical method and its quality, especially when at least one of the factors cannot be defined with a numerical value.

Solidification/stabilization remediation of heavy metal from petroleum Al-Dura sludge with Portland cement

The aim of this research is to evaluate the method of stabilization/solidification in the treatment of cadmium and iron from Al-Dura Oil Refinery sludge. In addition, the effect of organic matter was studied by using treated and untreated sludge. The procedure was applied in three treatments, where the cement was added to a mixture of sludge/sand prepared at three ratios (i.e., 1:2, 1:3, and 1:4) and also without any sludge (as the control), with the treated and untreated sludge used in proportions of 7, 15, and 25% by weight of sand. Tests of unconfined compression strength and a toxicity characteristic leaching procedure were used to evaluate the stabilization/solidification matrix. The highest unconfined compression strength was 3 Mpa for the samples with untreated sludge, while it was 2.1Mpa for samples with treated sludge. However, the results of the leaching test showed that the samples with the untreated sludge had more retention efficiency compared to the samples with treated sludge. The cadmium retention efficiency was 99.1%, while for iron, it was 97.5%. The organic matter (especially aromatic) had no effect on the leaching of either Iron or cadmium. Therefore, this method seems to be highly successful in the treatment of both Iron and cadmium with untreated Al-Dura Oil Refinery sludge.

Enhanced methane production and hydrocarbon removal from petroleum refinery sludge after Pseudomonas putida pretreatment and process scale-up

The influence of Pseudomonas putida 7525 strain on the pretreatment of petroleum refinery sludge was optimized at different dosages to maximize solubilization for improved biodegradability. Laccase-producing P. putida strain at a dosage of 108 CFU/mL resulted in 249% and 121.57% increments in soluble chemical oxygen demand and volatile fatty acids production respectively as compared to untreated within 6 days of incubation. 1L biochemical methane potential test conducted for optimization of different inoculum and pretreated substrate ratios (0.3, 0.4, 0.5, 0.7 and 1.0) revealed maximum methane augmentation (62%) and volatile solids degradation (66.7%) at ratio 0.5. Scaled-up study (20L) for ratio 0.5 resulted in 57.07% total petroleum hydrocarbon, 62.98% oil and grease and 91.9% phenol removal within 50 days of digestion of pretreated PS. Kinetic modelling of cumulative methane yield indicated that modified Gompertz model showed the best fit thereby, evincing the potency of bacterial species for bioremediation of PS.

Genomic characterization of Enterobacter xiangfangensis STP-3: Application to real time petroleum oil sludge bioremediation

Sustainable treatment of petroleum oil sludge still remains as a major challenge to petroleum refineries. Bioremediation is the promising technology involving bacteria for simultaneous production of biosurfactant and followed by degradation of petroleum compounds. Complete genomic knowledge on such potential microbes could accentuate its successful exploitation. The present study discusses the genomic characteristics of novel biosurfactant producing petrophilic/ petroleum hydrocarbon degrading strain, Enterobacter xiangfangensis STP-3, isolated from petroleum refinery oil sludge contaminated soil. The genome has 4,584,462 bp and 4372 protein coding sequences. Functional analysis using the RAST and KEGG databases revealed the presence of biosynthetic gene clusters linked to glycolipid and lipopeptide production and multiple key candidate genes linked with the degradation pathway of petroleum hydrocarbons. Orthology study revealed diversity in gene clusters associated to membrane transport, carbohydrate, amino acid metabolism, virulence and defence mechanisms, and nucleoside and nucleotide synthesis. The comparative analysis with 27 other genomes predicted that the core genome contributes to its inherent bioremediation potential, whereas the accessory genome influences its environmental adaptability in unconventional environmental conditions. Further, experimental results showed that E. xiangfangensis STP-3 was able to degrade PHCs by 82 % in 14 days during the bioremediation of real time petroleum oil sludge with the concomitant production of biosurfactant and metabolic enzymes, To the best of our knowledge, no comprehensive genomic study has been previously reported on the biotechnological prospective of this species.

Optimization of electrokinetic pretreatment for enhanced methane production and toxicity reduction from petroleum refinery sludge

This study examined the effect of electrokinetic pretreatment on petroleum sludge (PS) released from the wastewater treatment plants of petrochemical industries for enhanced biodegradation and contaminant removal. The application of electric field on PS through direct current is optimized with the combined variation of applied voltage (40–80 V), exposure duration (20–120 min) and distance between graphite electrodes (8–16 cm) using central composite design-response surface methodology (CCD-RSM). The optimization study revealed significant interaction among the response variables to obtain an optimum condition (60 V, 83.5 min, 11.6 spacing) for maximization of solubilization in terms of soluble chemical oxygen demand (230% increment against untreated) and volatile fatty acids (172% increment against untreated) concentrations for accelerated hydrolysis of complex PS. BMP batch assays were performed at different inoculum and sludge ratios (0.3, 0.4, 0.5 and 0.7) based on volatile solids content after pretreatment at the optimized condition which resulted in accumulated methane ranging from 5.16 to 6.61 L/gVSadded (untreated - 3.9 L/gVSadded). The mixing ratio of 0.4 showed the maximum methane enhancement of 69.2% compared to untreated. The maximum removal of organic content (62.8%), oil and grease (71.74%), and total petroleum hydrocarbon (52.9%) were also observed for the mixing ratio of 0.4. The FTIR study showed the efficacy in hydrocarbon dissociation and decomposition after pretreatment of PS. The net energy gain (3508 kJ) and phytotoxicity reduction of batch digestate after the anaerobic digestion suggest the economic feasibility and decontamination efficiency of the electrokinetic pretreatment technique respectively. Further research could be performed to evaluate the viability of this pretreatment for enhanced methane recovery at field-scale levels to relate to these lab-scale postulations.

Enhanced biodegradation of total petroleum hydrocarbons by implementing a novel two-step bioaugmentation strategy using indigenous bacterial consortium

In the present study, a two-step bioaugmentation strategy (TSBS) was implemented by using indigenous bacterial consortium to enhance the degradation of total petroleum hydrocarbons (TPH) from petroleum refinery sludge (PRS). A bacterial consortium was developed using four indigenous isolated strains, Dietzia sp. IRB191, Dietzia sp. IRB192, Staphylococcus sp. BSM19 and Stenotrophomonas sp. IRB19 from PRS. The optimum conditions of pH, temperature, and sludge concentration were 7, 34 °C, and 2% (w/v), respectively, for maximum TPH degradation, obtained using one variable at a time approach. Under the optimal culture conditions, the developed consortium was inoculated twice to the culturing medium, at the beginning (0th day) and again on the 10th day for implementing a novel TSBS. The maximum TPH degradation of 91.5 ± 2.28% was found with TSBS, which was 1.18 times higher than that of SSBS (77.3 ± 2.6%) in 15 days of incubation. GC-FID study also confirmed that the TPH present in the PRS was effectively degraded by the bacterial consortium with TSBS. The TPH degradation by using TSBS proceeded according to the first-order kinetics with a rate constant of 0.155 d−1. Hence, biodegradation using a TSBS can be considered an effective and eco-friendly process for safe disposal of petroleum refinery sludge.

A review on microbial diversity and genetic markers involved in methanogenic degradation of hydrocarbons: futuristic prospects of biofuel recovery from contaminated regions.

Microbial activities within oil reservoirs have adversely impacted the world's majority of oil by lowering its quality, thereby increasing its recovery and refining cost. Moreover, conventional method of extraction leaves behind nearly two-thirds of the fossil fuels in the oil fields. This huge potential can be extracted if engineered methanogenic consortium is adapted to convert the hydrocarbons into natural gas. This process involves conversion of crude oil hydrocarbons into methanogenic substrates by syntrophic and fermentative bacteria, which are subsequently utilized by methanogens to produce methane. Microbial diversity of such environments supports the viability of this process. This review illuminates the potentials of abundant microbial groups such as Syntrophaceae, Anaerolineaceae, Clostridiales and Euryarchaeota in petroleum hydrocarbon-related environment, their genetic markers, biochemical process and omics-based bioengineering methods involved in methane generation. Increase in the copy numbers of catabolic genes during methanogenesis highlights the prospect of developing engineered biofuel recovery technology. Several lab-based methanogenic consortia from depleted petroleum reservoirs and microcosm studies so far would not be enough for field application without the advent of multi-omics-based technologies to trawl out the bottleneck parameters of the enhanced fuel recovery process. The adaptability of efficient consortium of versatile hydrocarbonoclastic and methanogenic microorganisms under environmental stress conditions is further needed to be investigated. The improved process might hold the potential of methane extraction from petroleum waste like oil tank and refinery sludge, oil field deposits, etc. What sounds as biodegradation could be a beginning of converting waste into wealth by recovery of stranded energy assets.

Decomposition of oil refinery sludge using E+-Ozonation process for carbon source releasing and TPH removal.

To utilize carbon source and decompose the petroleum hydrocarbon substances simultaneously, adding the electrolysis to ozonation (E+-Ozonation) was employed to deal with hazardous activated petroleum waste sludge (P-sludge). It was found that E+-Ozonation could accelerate the ozone utilization and hydroxyl radical (·OH) generation rate. Soluble chemical oxygen demand (SCOD) increased around 16.3 times than the control one (from 471 to 7700 mg/L). The potential carbon source, such as the short-chain carbon of acetate and propionate, increased from 50 to 1088 mg/L and from 27 to 614 mg/L respectively, and approximately accounted for a quarter of total SCOD. Total petroleum hydrocarbon (TPH) decomposition was observed with a much higher removal rate of 84.3% simultaneously, and the substances with the function group of C=C and C-C bonds decomposed greatly. The long- and medium-chain substances in TPH were converted into the short-chain substances (90% of C28-C40 of hydrocarbons was removed, while C10-C18 increased by 13.8%). E+-Ozonation process could be one of the promising methods for P-sludge decomposition through carbon source releasing and TPH removal.

Method of smoldering combustion for refinery oil sludge treatment

Refinery oil sludge is a type of hazardous waste generated during petroleum refining. Smoldering combustion has been studied in waste treatment but has not been applied to refinery oil sludge treatment. This work verified the feasibility of smoldering combustion for refinery oil sludge treatment through bench-scale experiments. Experimental result showed that the solid residue that remained from smoldering combustion of oil sludge was odorless, granular, and brick-red. The mass and volume of the residue were much smaller than those of the original oil sludge. The typical substances in the oil sludge (i.e., petroleum hydrocarbons [C10–C40]) were not found in the residue, thereby indicating the good performance of smoldering combustion in treating oil sludge. Water and oil were recovered by condensing the off-gas. The composition of the recovered oil was similar to coking diesel. The calorific value of the recovered oil was higher than that of kerosene, thereby demonstrating the possibility of reutilization. The components of noncondensable off-gas contained a small amount of SO2 and NOx and a large amount of H2, CO, and H2S, which need to be further purified. Three factors influencing the smoldering performance of oil sludge, including moisture content, filler to oil sludge ratio, and airflow rate, were explored.

Treatment of petroleum refinery sludge by petroleum degrading bacterium Stenotrophomonas pavanii IRB19 as an efficient novel technology

Petroleum hydrocarbons (PHCs) in petroleum refinery sludge (PRS) are the most adverse components because of their toxic nature, which are harmful to human health and the aquatic ecosystem. This study aimed to identify and characterize an indigenous bacterium isolated from PRS of Indian oil corporation ltd. (IOCL), Haldia, India, and evaluate its performance for biodegradation of total petroleum hydrocarbon (TPH) of PRS. The bacterium molecularly characterized as Stenotrophomonas sp. IRB19 by 16S rRNA sequencing and phylogenetic analysis. The strain IRB19 showed a significant ability to utilize four different oils (kerosene, diesel, petrol and hexadecane) in-vitro. IRB19 could able to degrade up to 65 ± 2.4% of TPH in 28 d of incubation. Solvent extraction study showed that PRS contain 180.57 ± 3.44 g kg−1 of TPH and maltene fraction composed of aliphatic, aromatics and polar components of 52 ± 4, 39 ± 2 and 9 ± 1%, respectively. The TPH degradation best fitted for the Gompertz model and followed the first-order kinetics having the rate constant (k) and half-life period (t 1/2) of 0.036 d−1 and 19 d, respectively. Results of this study verified the suitability of the novel strain IRB19 for the biodegradation of PHCs.

Influence of inoculum variation and nutrient availability on polyhydroxybutyrate production from activated sludge

Carbon recovery through polyhydroxybutyrate (PHB) production can create a value-added waste management system. Activated sludge as inoculum enables PHB production using cheap and renewable carbons source, bringing PHB at par to conventional plastics. The PHB accumulating potential of activated sludge needs to be improved to realize the objective. The interaction between the origin of activated sludge, petroleum refinery sludge and brewery sludge, and nitrogen availability was explored to effect culture enrichment, improve PHB accumulation, and polymer characteristics through aerobic dynamic feeding. Consequently, nitrogen excess and limitation enrichment of both sludges produced mix microbial culture with adequate PHB storage of 7.8 ± 0.05%, 14.4 ± 0.04%, 14.4 ± 0.04%, 13.4 ± 0.02% respectively. Batch accumulation revealed higher PHB accumulation of 76.1 ± 0.03% and 71.7 ± 0.05% under nitrogen limitation for PRS and BS enriched under nitrogen excess condition compared to any other combination. The higher decomposition temperature of 285 °C, 293 °C, and a lower melting point of 168 °C, 165 °C with a higher molecular weight of 4.3x105g/mol and semi-crystalline arrangement indicates the potential applications for extracted PHB. PHB production enhanced under nitrogen limited conditions with culture enriched under nitrogen excess condition. However, similar PHB storage, physiochemical property, and overlapping microbial community show an insignificant effect of sludge origin on PHB production.