Refinery Sludge Research Articles

Treatment and disposal of refinery sludges: Indian scenario.

Crude oil is a major source of energy and feedstock for petrochemicals. Oily sludge, bio-sludge and chemical sludge are the major sludges generated from the processes and effluent treatment plants of the refineries engaged in crude oil refining operations. Refineries in India generate about 28,220 tons of sludge per annum. Various types of pollutants like phenols, heavy metals, etc. are present in the sludges and they are treated as hazardous waste. Oily sludge, which is generated in much higher amount compared to other sludges, contains phenol (90-100 mg/kg), nickel (17-25 mg/kg), chromium (27-80 mg/kg), zinc (7-80 mg/kg), manganese (19-24 mg/kg), cadmium (0.8-2 mg/kg), copper (32-120 mg/kg) and lead (0.001-0.12 mg/ kg). Uncontrolled disposal practices of sludges in India cause degradation of environmental and depreciation of aesthetic quality. Environmental impact due to improper sludge management has also been identified. Salient features of various treatment and disposal practices have been discussed. Findings of a case study undertaken by the authors for Numaligarh Refinery in India have been presented. Various system alternatives have been identified for waste management in Numaligarh Refinery. A ranking exercise has been carried out to evaluate the alternatives and select the appropriate one. A detailed design of the selected waste management system has been presented.

Preparation of Calcium Sulfate Hemihydrate Using Stainless Steel Refinery Sludge and Waste Sulfuric Acid

ABSTRACT In this study, calcium sulfate(gypsum) powder was obtained using waste sulfuric acid and stainless steel refinery sludge by-produced from chemical reagent and the iron industry, by the neutralization of waste sulfuric acid. As variables for the experiment, the molar ratio of the H2SO4: Ca(OH)2, the pH, the reaction temperature and time, the amount of catalyst were used. The crystal shape and microstructure of obtained powder were observed by XRD and SEM, and the thermal property was investigated by DTA. As the NaCl is added 0–20 wt.% as a catalyst to the H2SO4-Ca(OH)2 system, it can be found that the crystal shape goes through the processes as follows; gypsum dehydrate gypsum → gypsum hemihydrate + gypsum dihydrate → gypsum hemihydrate. And gypsum hemihydrate is δ-type as the result of DTA. As waste sulfuric acid and stainless steel refinery sludge were used, the pH of reacted solution (which was 0.8) was rapidly raised up to 8–9 by the addition of stainless steel sludge and gypsum dihydrate was produced as a by-product. Therefore, it was found that stainless steel refinery sludge is sufficiently applicable for the neutralization of waste sulfuric acid.

Bitumenous paints from refinery sludge

This paper reports the data obtained on an attempt at the utilisation of the oily sludge, which is a dumped waste of petroleum refineries. Growing public concern over the health and environmental implications of these wastes has forced the regulatory agencies to make it mandatory for these industries to undertake the disposal of these wastes in an effective and environmentally safe manner. In the present work, the above sludge after purification was subjected to vacuum distillation to recover approximately 17% of lighter oils. The residue was subjected to heat treatment at 225°C for 2.5 h with ‘2.5% w/w AlCl 3’ to obtain industrial bitumen 90/15 grade (Industrial bitumen are of different types depending on the softening point–penetration relationship. The first figure 90 represents the softening point while the second figure 15, represents the penetration. Both penetration and softening points are a measure of consistency for bitumen). The usefulness of the above industrial bitumen was tried in the preparation of bituminous paints. All three formulations investigated were found to be homogeneous showing no separation of solvent. There was no coagulation of the asphalt base nor settling or packing in the container. These samples were found to meet the requirements of drying time, consistency, finish, stripping, flexibility and adhesion, keeping properties, etc. It was also seen that the heat resistance of these bituminous paints can be increased considerably by including cashew nut shell liquid–formaldehyde resin in the formulation. Cashew nut shell liquid (CNSL) is a cheap by-product of the cashew industry, and its utilisation can also help to reduce production costs of bituminous paints. This study also showed that incorporation of chlorinated rubber in the formulation would enhance the acid resistance considerably without affecting heat resistance and other desirable properties. This method of using sludge as bituminous paints can be a simple, eco-friendly and useful means of disposal in petroleum refining industries.

Oxidation of Gas Mixtures Containing Dimethyl Sulfide, Hydrogen Sulfide, and Methanethiol Using a Two-Stage Biotrickling Filter

ABSTRACT A biofiltration technique was developed for removing a mixture of hydrogen sulfide (H2S), methanethiol (MeSH), and dimethyl sulfide (Me2S) from waste gases. Since H2S, especially at high concentrations, disturbs the removal of Me2S, two biotrickling filters with different microbes and operating pH levels were connected in series to create a two-stage system. Different loads of these gases were studied in order to determine their impact on the removal capacity of the system. The microbial consortia for these filters were enriched from the sludge of a Finnish refinery with bubbling H2S or Me2S. Acclimation for Me2S took 2 weeks, though no acclimation time was needed for the other gases. The first filter, at a pH of 2, removed most of the H2S and some of the MeSH and Me2S. The second filter, at a pH of ~6.5, removed the rest of the MeSH and most of the Me2S. The total maximum loads of the whole two-stage biotrickling filter were 1150 g/m3/day for H2S-S (suffix S indicates the results are counted as sulfur amounts), 879 g/m3/day for Me2S-S, and 66 g/m3/day for MeSH-S treated in a gas mixture. The average removal efficiencies for all gases tested were 99% or higher.

Community dynamics of a mixed-bacterial culture growing on petroleum hydrocarbons in batch culture

The effects of various hydrocarbon substrates, and a chemical surfactant capable of enhancing crude-oil biodegradation, on the community structure of a mixed-bacterial inoculum were examined in batch culture. Of 1000 TSA-culturable isolates, 68.6% were identified at the genus level or better by phospholipid fatty acid analysis over 7-day time course experiments. Cultures were exposed to 20 g/L Bow River crude oil with and without 0.625 g/L Igepal CO-630 (a nonylphenol ethoxylate surfactant), 5 g/L saturates, 5 g/L aromatics, or 125 g/L refinery sludge. A group of six genera dominated the cultures: Acinetobacter, Alcaligenes, Ochrobactrum, Pseudomonas/Flavimonas, Stenotrophomonas, and Yersinia. Species from four of the genera were shown to be capable of hydrocarbon degradation, and counts of hydrocarbon degrading and total heterotrophic bacteria over time were nearly identical. Pseudomonas/Flavimonas and Stenotrophomonas normally dominated during the early portions of cultures, although the lag phase of Stenotrophomonas appears to have been increased by surfactant addition. Acinetobacter calcoaceticus was the most frequently isolated microorganism during exposure to the saturate fraction of crude oil. Regardless of substrate, the culture medium supported a greater variety of organisms during the latter portions of cultures. Understanding the community structure and dynamics of mixed bacterial cultures involved in treatment of heterogeneous waste substrates may assist in process development and optimization studies.Key words: mixed culture, phospholipid fatty acid analysis, petroleum hydrocarbons, community structure.

Community dynamics of a mixed-bacterial culture growing on petroleum hydrocarbons in batch culture

The effects of various hydrocarbon substrates, and a chemical surfactant capable of enhancing crude-oil biodegradation, on the community structure of a mixed-bacterial inoculum were examined in batch culture. Of 1000 TSA-culturable isolates, 68.6% were identified at the genus level or better by phospholipid fatty acid analysis over 7-day time course experiments. Cultures were exposed to 20 g/L Bow River crude oil with and without 0.625 g/L Igepal CO-630 (a nonylphenol ethoxylate surfactant), 5 g/L saturates, 5 g/L aromatics, or 125 g/L refinery sludge. A group of six genera dominated the cultures: Acinetobacter, Alcaligenes, Ochrobactrum, Pseudomonas/Flavimonas, Stenotrophomonas, and Yersinia. Species from four of the genera were shown to be capable of hydrocarbon degradation, and counts of hydrocarbon degrading and total heterotrophic bacteria over time were nearly identical. Pseudomonas/Flavimonas and Stenotrophomonas normally dominated during the early portions of cultures, although the lag phase of Stenotrophomonas appears to have been increased by surfactant addition. Acinetobacter calcoaceticus was the most frequently isolated microorganism during exposure to the saturate fraction of crude oil. Regardless of substrate, the culture medium supported a greater variety of organisms during the latter portions of cultures. Understanding the community structure and dynamics of mixed bacterial cultures involved in treatment of heterogeneous waste substrates may assist in process development and optimization studies.

Gasification in Petroleum Refinery of 21st Century

The worldwide trends in the crude oil supply indicate a continuous increase of the heavy crudes. The increase in the yield of distillation residues is complemented by an increase in their sulfur content. Additional distillates are produced by upgrading the residues. The upgrading step generates final residues, such as visbreaking tar, coke and asphalt which are produced by visbreaking, coking and deasphalting, respectively. The final residues can be converted to usable products such as hydrogen, steam, electricity, ammonia and chemicals. For this purpose, gasification has emerged as the technology of choice because of its superior environmental performance when compared with the competing means for residue utilization. Also, refinery sludges can be cogasified with the final residues and as such, be converted to usable products. If integrated with the petroleum refinery, gasification can diminish any environmental problems associated with residue and sludge disposal. The economic indicators of the refinery can improve as well. The trends in deregulation of the power market enable petroleum refineries to enter this lucrative market either alone or in a partnership with the utilities. The potential of coproduction of chemicals and steam with electricity offers the flexibility to respond to market demands. Gasification technology is commercially proven. Among several types, entrained bed gasifiers are the gasifiers of choice. A number of commercial projects in Europe, Asia and United States use a gasifier employing either a slurry feeding system or a dry feeding system.

Low cost processing aid from oil refinery waste for compounding of styrene/butadiene rubber

Data have been obtained in an attempt to use the oily sludge that is a dumped waste of petroleum refineries. The sludge, after purification, was used as a processing aid in the sulphur vulcanisation of styrene/butadiene rubber, in which carbon black is used as filler. Compounds containing aromatic oil were used as the control. Different mixes, containing varying concentrations of aromatic oil/refinery sludge were prepared. The mixes were evaluated for different cure characteristics and the vulcanisates were tested for various physical properties and chemical crosslink density. Aging resistance of the vulcanisates was also evaluated. Processability studies were carried out for the carbon black systems under review. It was found that the optimum cure time is reduced significantly when aromatic oil is replaced completely with refinery sludge. In the evaluation of tensile properties, vulcanisates containing 60% sludge gave the maximum value, while other vulcanisates containing refinery sludge gave values comparable with those containing conventional process aids. It is worthy of note that aromatic oil is becoming prohibitively costly while sludge is a dumped waste of the refinery.

Composting of a heavy oil refinery sludge

AbstractPreliminary experiments using a range of bulking agents, moisture contents, nutrients, cosubstrates and inocula were undertaken to determine suitable ingredients for the successful composting of a heavy oil refinery sludge. The best ingredients were then chosen for a detailed study of the CO2 evolution rate and Total Petroleum Hydrocarbon (TPH) reduction versus time during the composting process. The initial TPH content of the refinery sludge was found to be 30% (mainly C15‐C30), two thirds of which were saturates and aromatics that were thought to be biodegradable. The results show a significantly higher TPH reduction using Solv‐II (55% reduction) as a bulking agent/nutrient source compared to heat‐treated peat moss and barley straw (both at 30% reduction). The CO2 evolution was high with Solv‐II and barley straw indicating the presence of high microbial activities in those composters.

Refinery Sludge Treatment/Hazardous Waste Minimization Via Dehydration and Solvent Extraction

Abstract The patented Carver-Greenfield (C-G) Process®, a combination of dehydration and solvent extraction treatment technologies, has a wide range of uses in separating hydrocarbon solvent-soluble hazardous organic contaminants (indigenous oil) from sludges, soils, and industrial wastes. As a result of this treatment, the products from a C-G Process facility are: •Clean, dry solids which are typically suitable for disposal in nonhazardous landfills;•Water which is treatable in an industrial or Publicly Owned Treatment Works (POTW) wastewater treatment facility;•Extracted indigenous oil containing hydrocarbon soluble contaminants which may be recycled or reused or disposed of at less cost because its volume is smaller than the original waste feed. The C-G Process was demonstrated on spent oily drilling fluids as part of the U.S. Environmental Protection Agency Superfund Innovative Technology Evaluation (SITE) Program. This paper summarizes the use of the C-G Process for economical treatment and minimization of hazardous refinery wastes, reviews the SITE program results, and describes extending the C-G Process technology to treatment of other wastes. Estimated treatment costs are presented.

Background levels of polycyclic aromatic hydrocarbons (PAH) and selected metals in new England urban soils

Abstract Polycyclic aromatic hydrocarbons (PAH) are byproducts of combustion and are ubiquitous in the urban environment They are also present in industrial chemical wastes, such as coal tar, petroleum refinery sludges, waste oils and fuels, and wood‐treating residues. Thus, PAHs are chemicals of concern at many waste sites. Risk assessment methods will yield risk‐based cleanup levels for PAHs that range from 0.1 to 0.7 mg/kg. Given their universal presence in the urban environment, it is important to compare risk‐based cleanup levels with typical urban background levels before utilizing unrealistically low cleanup targets. However, little data exist on PAH levels in urban, nonindustrial soils. In this study, 60 samples of surficial soils from urban locations in three New England cities were analyzed for PAH compounds. In addition, all samples were analyzed for total petroleum hydrocarbons (TPH) and seven metals. The upper 95% confidence interval on the mean was 3 mg/kg for benzo(a)pyrene toxic equivalents, 12 mg/kg for total potentially carcinogenic PAH, and 25 mg/kg for total PAH. The upper 95% confidence interval was 373 mg/kg for TPH, which exceeds the target level of 100 mg/kg used by many state regulatory agencies. Metal concentrations were similar to published background levels for all metals except lead. The upper 95% confidence interval for lead was 737 mg/kg in Boston, 463 mg/kg in Providence, and 378 mg/kg in Springfield.

Utilization of Refinery Sludge for Lighter Oils and Industrial Bitumen

This paper reports the data obtained in an attempt to utilize the waste sludge of the Cochin Refineries Ltd., Kochi, India. About 17 % of a lighter oil fraction can be recovered from this sludge and the characteristics of the lighter oil are such that it can be used as diesel fuel by blending with other appropriate refinery streams. An attempt was also made to convert the residue left after the removal of the lighter oils into different grades of industrial bitumen. This residue, obtained after vacuum distillation, was heat treated without and with different catalysts. The change in softening point:penetration ratio when heat treated without any catalyst was not enough to meet the specifications of any industrial bitumen.

Low temperature thermal treatment for petroleum refinery waste sludges

AbstractTreatment requirements for waste sludges generated by petroleum refinery operations and designated as waste codes K048, K049, K050, K051 and K052 under the Resource Conservation and Recovery Act (RCRA) became effective in November, 1990 under the ‘Landban’ regulations. An experimental program evaluated low temperature thermal treatment of filter cakes produced from these sludges using laboratory and pilot‐scale equipment. One set of experiments on waste samples from two different refineries demonstrated the effective removal of organics of concern from the sludges to meet the RCRA Best Demonstrated Available Technology (BDAT) treatment standards. Cyanides were also within the acceptable limit. Combined with stabilization of heavy metals in the treatment residues, low temperature thermal treatment therefore provides an effective and efficient means of treating refinery sludges, with most hydrocarbons recovered and recycled to the refinery. A milder thermal treatment was used to remove the bulk of the water from a previously filtered waste sludge, providing effective waste minimization through a 40% decrease in the mass of sludge to be disposed. The heating value of the sludge was increased simultaneously by one‐third, thereby producing a residue of greater value in an alternative fuels program. A process based on this approach was successfully designed and commercialized.

Fate of mutagenic chemicals in soil amended with petroleum and wood preserving sludges

A field study using monoliths (lysimeters) of a sandy clay loam soil was conducted to assess the fate of mutagenic chemicals after refinery and wood preserving bottom sediment sludges were land treated. The Ames Salmonella/microsome assay ∗ was used to determine the direct (without metabolic activation, −S9) and indirect (with metabolic activation, + S9) mutagenicity of the wastes, unamended soil, waste amended soils, and leachate. Extracts having a mutagenic ratio (MR) (MR= No. colonies from sample extract/No. colonies from DMSO solvent control) of ⩾ 2 were considered positively mutagenic. Extracts of the wood preserving waste sludge without activation were non-mutagenic (MR < 2) but extracts with activation ( + S9) produced very strong indirect mutagenicity (MR = 7.9). After soil incorporation, the waste amended soil produced very strong direct (MR = 8.9) and indirect (MR = 11.9) mutagenicity by day 180 and remained mutagenic (MR = 5.7, −S9; MR = 3.95, + S9) through day 350. The amount of residue in leachate from the wood preserving waste amended lysimeters was significantly greater ( P <0.05) than the unamended soil during the first 90 days after waste application, but was not different after 90 days. The leachate residue from wood preserving waste amended lysimeters in the 90–180-day period produced mutagenic responses both with (MR = 2.24 and 2.51) and without (MR = 2.29) activation. Polynuclear aromatic hydrocarbons were the main constituents identified in the leachate residues that produced a mutagenic response. Soil treatment of the refinery sludge reduced its weak indirect mutagenicity before soil incorporation (MR = 2) to non-mutagenic (MR = 1.4) immediately following soil treatment. The MR of the waste amended soil increased to 1.7 by day 180 but by day 350 decreased to a level equal to that observed at day 0 (MR = 1.4). Leachate from the refinery amended lysimeters had significantly greater ( P < 0.05) amounts of organic residue than unamended lysimeters 180 to 350 days after waste application. The leachate from one refinery waste amended lysimeter (90–180 days after waste application) produced a mutagenic response (MR = 3.16). The refinery sludge was detoxified shortly after soil treatment, but the wood preserving sludge required > 350 days to detoxify in the soil environment. The possibility exists that mobile mutagenic chemicals may leach into underlying groundwater from the treatment zone of soils amended with refinery and wood preserving sludges.

Fate of Mutagenic Chemicals in Soil Amended Petroleum and Wood Preserving Sludges

A field study using monoliths (lysimeters) of a sandy clay loam soil was conducted to assess the fate of mutagenic chemicals after refinery and wood preserving bottom sediment sludges were land treated. The Ames Salmonelialmicrosome assay* was used to determine the direct (without metabolic activation, - S9) and indirect (with metabolic activation, + S9) mutagenicity of the wastes, unamended soil, waste amended soils, and leachate. Extracts having a mutagenic ratio (MR) (MR=No. colonies from sample extract/No, colonies from DMSO solvent control) of ≥ 2 were considered positively mutagenic. Extracts of the wood preserving waste sludge without activation were non-mutagenic (MR &lt; 2) but extracts with activation (+ S9) produced very strong indirect mutagenicity (MR = 7.9). After soil incorporation, the waste amended soil produced very strong direct (MR =8.9) and indirect (MR = 11.9) mutagenicity by day 180 and remained mutagenic (MR = 5.7, - S9; MR = 3.95, + S9) through day 350. The amount of residue in leachate from the wood preserving waste amended lysimeters was significantly greater ( P&lt;0.05) than the unamended soil during the first 90 days after waste application, but was not different after 90 days. The leachate residue from wood preserving waste amended lysimeters in the 90-180-day period produced mutagenic responses both with (MR = 2.24 and 2.51) and without (MR = 2.29) activation. Polynuclear aromatic hydrocarbons were the main constituents identified in the leachate residues that produced a mutagenic response. Soil treatment of the refinery sludge reduced its weak indirect mutagenicity before soil incorporation (MR = 2) to non-mutagenic (MR =1.4) immediately following soil treatment. The MR of the waste amended soil increased to L7 by day 180 but by day 350 decreased to a level equal to that observed at day 0 (MR = 1.4). Leachate from the refinery amended lysimeters had significantly greater (P&lt;0.05) amounts of organic residue than unamended lysimeters 180 to 350 days after waste application. The leachate from one refinery waste amended Ivsimeter (90-180 days after waste application) produced a mutagenic response (MR =3.16). The refinery sludge was detoxified shortly after soil treatment, but the wood preserving sludge required &gt; 350 days to detoxify in the soil environment. The possibility exists that mobile mutagenic chemicals may leach into underlying groundwater from the treatment zone of soils amended with refinery and wood preserving sludges.

Design considerations and metals disposition in fluidized‐bed incineration of refinery wastes

AbstractDisposal of refinery biotreatment sludges through land application is being strictly controlled and, in many cases, eliminated by regulatory constraint. An alternative to land application of sludges is incineration. This paper discusses fluidized‐bed incineration pilot studies conducted on refinery sludges obtained from two different refineries. Destruction of hazardous organic constituents, as well as the fate of inorganic metals, is discussed. Metal emissions are examined and the impact of the new EPA metals emissions limits is investigated. Installation of a waste heat recuperator to preheat combustion air is explored as an alternative to a high‐pressure sludge dewatering process.

Stabilization of acidic refinery sludges

Petroleum refineries historically have generated large quantities of acidic oil sludge, a waste product from the production of fine lubricating oils. The refining process included adding sulfuric acid to crude oil to remove impurities. The waste product that remained behind after filtration was customarily disposed of in open lagoons. The physical and chemical characteristics of this sludge vary from lagoon to lagoon and with depth. The material ranges from a solid, charcoal-like material at the bottom of the lagoons to a liquid mixture of sulfuric acid and rainwater at the surface. The sludge utilized for this study varied in pH from less than two to six and has an average loss on ignition of 78.2%. Results are presented from almost 200 separate stabilization tests.

Photolysis primes biodegradation of benzo[a]pyrene.

14C-labeled benzo[a]pyrene (BaP) was used as a model-compound for polycyclic aromatic hydrocarbons (PAH) in order to assess the effect of photolytic pretreatment on the subsequent fate of BaP in sewage sludge and soil test systems. Photolysis was performed in methanolic solution with or without 0.1 M H2O2, under either UV light (300 nm) or natural sunlight. The presence of H2O2 greatly enhanced the rate of photolysis both with UV and with natural sunlight. Intact BaP resisted biodegradation in both test systems. Photolysis transformed BaP to polar materials that were subject to increased mineralization and binding in both biological test systems. As shown by the Ames assay, photolysis decreased the mutagenicity of BaP to test strains TA98 and TA104 only moderately. The photolysate had an increased acute toxicity and lost its need for activation by S-9 enzymes. However, during subsequent incubation in soil or sewage sludge, mutagenicity decreased rapidly by one to two orders of magnitude and acute toxicity disappeared due to the mineralization and binding of photoproducts to humic materials. Photolysis of BaP and similar PAH compounds represents a useful treatment option that could be applied to certain PAH-containing petroleum refinery sludge and to coal tar residues in order to facilitate their detoxification and environmentally safe disposal.

Heavy metals analysis in Bahrain refinery sludge

The analysis of lead, zinc and cadmium in Bahrain refinery sludge collected from various deposition sites at Bahrain petroleum company (BAPCO) are reported. Atomic Absorption spectrophotometric method, both flame and flameless (graphite furnace) techniques, were used for the analysis. The concentrations of lead, zinc and cadmium were found in the range, 66.1 to 14630.9 mg/kg (0.007% to 1.46%), 47.4 to 1791.1 mg/kg (0.005% to 0.17%), 0.24 to 5.40 mg/kg (0.00002% to 0.0005%), respectively. These concentrations are less than 1% as is accepted internationally. Nevertheless, these are hazardous and should be managed properly.

Effects of mineral nutrients, sludge application rate, and application frequency on biodegradation of two oily sludges

A continuous flow soil respirometer was used to evaluate the effect of nutrient addition, application rate, and application frequency on biodegradation of 2 complex oily sludges in soil. The most rapid biodegradation of the refinery sludge occurred when nitrogen was added to reduce the carbon to nitrogen (C∶N) ratio to 9∶1. The petrochemical sludge was degraded most rapidly when nitrogen, phosphorus, and potassium were added at a rate of 124∶1, C∶NPK; CO2evolution from both wastes increased with increasing application rates, but the fraction of applied sludge which degraded decreased with increasing application rates. Small frequent applications resulted in a slight increase in respiration rate per unit applied over a single equivalent application, indicating that repeated applications of smaller amounts of sludge result in a more rapid rate of decomposition. The population of total soil bacteria was greatest when 1% of either sludge was added to the soil, whereas 5 and 10% sludge additions resulted in slightly lower microbial populations.