refineries is estimated to be: When the data is arrayed according to the six refining waste stream categories used in the survey Figure 1 , the Aqueous Waste category represents approxi
SURVEY DESIGN
A census approach was adopted for this study Respondents were asked to supply information for the years 1987 and 1988
To develop a comprehensive list of all active domestic refineries, the listings developed by ,the National Petroleum Refiners Association (NPRA), the U.S Oil and Gas Journal,
A comparison was made between Perinwell's Worldwide Refining and Gas Processing Directory for 1987 and 1988 and the Department of Energy's Petroleum Supply Annual, Volume 1 for the same years After excluding facilities that solely produce asphalt or process natural gas without refining crude oil, 176 refineries were identified These refineries were owned by 86 companies, including 29 members of the API and 43 members of the NPRA, with 14 companies not affiliated with either trade association.
DATA COLLECTION
The survey questionnaire consisted of 13 short answer questions and 56 "data sheets." (See Appendix A.) Two series of 28 data sheets -one for 1987 and another for
1988 - were included in each survey package
The short answer questions gathered details regarding the refinery's age, size, and complexity, along with descriptive insights into practices or events that may affect the reliability of the collected data.
To facilitate the collection of comparable data across refineries, a list of 28 typical refinery waste streams was developed Two criteria that guided the development of that listing were:
1) the need to parallel the actual grouping/co-mingling of wastes and secondary materials that occurs in refineries; and,
2) the desire to keep the number of discrete streams manageable from a survey com pl et ion perspective
As listed in Table I and described in more detail in the Appendix, five of the waste streams are the RCRA listed hazardous wastes for the refining industry; the remaining
23 categories are generally broader groupings of wastes and secondary materials, such as Pond Sediments, Waste Oils/Spent Solvents, or Other Contaminated Soils
Oily SludgeslOther Organic Wastes Spent Catalvsts
API Separator Sludge' DAF Float*
Slop Oil Emulsion Solids' Leaded Tank Bottoms' Other Separator Sludges Pond Sediments Nonleaded Tank Bottoms Waste OildSpent Solvents Other Oily SludgedOrganic Wastes NOS"
Fluid Cracking Catalyst or Equivalent Hydroprocessing Catalyst
Other Spent Catalyst NOS Aqueous Waste
High pHlLow pH Waters Spent Sulfite Solution Spent Stretford Solution
Heat Exchanger Bundle Cleaning Sludge' Contaminated SoiüSolids
Waste Amines Other Inorganic Wastes NOS
RCRA listed hazardous wastes for the petroleum refining industry
NOS, or Not Otherwise Specified, refers to the data sheets that recorded quantitative information on the generation and management of various waste and secondary materials Respondents provided details on the quantities of materials handled through different onsite and offsite recycling, treatment, and disposal methods.
Waste Generation, Treatment Additives, and Wastes removed from or placed into storage are classified as "Inputs" in the waste management system, while Recycling, Treatment, and Disposal serve as the "Outputs" that balance these Inputs Additionally, data was gathered on source reduction practices and the waste volumes that must be reported to federal and state agencies.
The survey was also supplied in a computerized format on a floppy disk so respondents could report in a manner suitable for direct uploading to a mainframe computer
SURVEY ADMINISTRATION
Data Verification
Using the Statistical Analysis System (SAS), programs were developed to ensure the internal consistency of responses, identifying errors such as unbalanced waste input and management quantities, invalid responses, and missing required data A thorough data cleaning effort involved contacting nearly every respondent to verify their answers, resulting in approximately 3000 corrections This process, detailed in Appendix B, highlighted the need to revise certain questionnaire and data sheet items, particularly those related to source reduction and hazardous waste reporting, to enhance the quality of the collected data.
The frequency of corrections is believed to indicate the complexity of data collection forms rather than the accuracy of the data itself This notion is reinforced by the fact that more than half of the corrections were related to the incorrect placement of management codes, such as recycling codes being entered in the source reduction section and treatment codes being used in the disposal column.
The accuracy of waste response data can vary due to several factors, including the lack of automated record-keeping for certain types of waste, challenges in measuring waste amounts, and instances where tonnages are estimated based on volume and approximate densities.
During the development of estimation models, a second phase of data verification was conducted to extrapolate quantities generated by the entire U.S refining industry Upon plotting the data, six outlier cases were identified, prompting verification calls to the respective refineries In each instance, the respondents confirmed the accuracy of their reported values.
Because these extreme values skewed the extrapolation, they were considered to be
"outliers" and treated differentially during the model development
In 1987 and 1988, two refineries reported zero waste generation, while four other refineries produced significant amounts of Other Aqueous Waste, opting for deep well injection for disposal Unlike their counterparts that discharge waste under NPDES permits or to POTWs, these facilities only remove solids that could obstruct well pores before injection, without further treatment to reduce water content.
A brief table of the affected streams and quantities follows:
Table II Summary of Outlier Values
# of 87 Generation 88 Generation WASTE STREAM Facilities (Wet Tons)' (Wet Tons)*
(it should be noted that the facilities with large quantities of "Other Aqueous Wastes NOS" reported quantities of the other waste streams that were in the normal range.)
Non-respondent Estimation Procedures
To estimate the total amount of waste generated for all (176) of the U.S refineries, the data obtained from the 11 5 survey participants had to be combined with estimates for the
A regression model was employed to estimate the generation quantities for 61 refineries that did not participate in the study, based on the assumption that non-respondents are similar to those who did respond.
After assessing the hazardous waste produced by each participating refinery, correlation coefficients were determined for various refinery characteristics, such as capacity, age, and sewer system, in relation to total waste generation Additionally, scatterplots were created to investigate potential relationships that could facilitate the development of models for estimating total waste generation.
The strongest correlation was between operable crude capacity (Question 3) and waste generation, with quantity of waste increasing as refinery capacity increased
The analysis evaluated simple linear, multiple regression, and nonlinear models based on significance levels, mean squared error, R-squared values, and model complexity Ultimately, the simple regression model utilizing capacity as the independent variable was selected as the most effective option.
Analysis of the data revealed that refining capacities significantly impact regression outcomes By modeling refineries with capacities below and above 200,000 barrels per stream day (BED) separately, we observed distinct relationships While smaller facilities exhibited a linear correlation between total waste generation and capacity, larger facilities did not As a result, we developed separate regression models for these two categories to enhance accuracy.
For the less than 200,000 B E D facilities, waste generated was modeled as being directly related to capacity:
At refineries having capacity greater than 200,000 BED, however, the increase in waste was modeled as a function of the square of the capacity:
Both a, and a, were estimated based on the data from 109 refineries2
To assess the models' effectiveness in explaining data variability, R² values were calculated, revealing 0.55 for smaller facilities and 0.79 for larger facilities in 1987, and 0.58 and 0.79, respectively, in 1988 The corresponding correlation coefficients were 0.75 and 0.89, indicating a reasonably good fit for this type of data Notably, the six outliers mentioned in Section 2.4.1 were excluded from the calculations for non-respondents.
DATA ANALYSIS
Using the Statistical Analysis System (SAS), programs were developed to ensure the internal consistency of responses, identifying errors such as unbalanced waste input and management quantities, invalid responses, and missing required data A thorough data cleaning effort involved contacting nearly every respondent to verify their answers, resulting in approximately 3000 corrections This process, detailed in Appendix B, highlighted the need to revise certain questionnaire and data sheet items, particularly those related to source reduction and hazardous waste reporting, to enhance the quality of the collected data.
The frequency of corrections is believed to indicate the complexity of data collection forms rather than the accuracy of the data itself This notion is reinforced by the fact that more than half of the corrections were related to the incorrect placement of management codes, such as recycling codes being entered in the source reduction section and treatment codes being used in the disposal column.
The accuracy of waste response data can vary due to several factors, including the lack of automated record-keeping for certain types of waste, challenges in measuring waste amounts, and instances where tonnages are estimated based on volume and approximate densities.
During the development of estimation models for the U.S refining industry, a second phase of data verification was conducted This phase aimed to extrapolate quantities based on the responses received Upon plotting the data, six outlier cases were identified, prompting verification calls to the respective refineries In each instance, the respondents confirmed the accuracy of their reported values.
Because these extreme values skewed the extrapolation, they were considered to be
"outliers" and treated differentially during the model development
In 1987 and 1988, two refineries reported zero waste generation, while four other refineries produced significant amounts of Other Aqueous Waste, opting for deep well injection for disposal Unlike their counterparts that discharge waste under NPDES permits or to POTWs, these facilities only remove solids that could obstruct well pores, without further treatment to reduce water content.
A brief table of the affected streams and quantities follows:
Table II Summary of Outlier Values
# of 87 Generation 88 Generation WASTE STREAM Facilities (Wet Tons)' (Wet Tons)*
(it should be noted that the facilities with large quantities of "Other Aqueous Wastes NOS" reported quantities of the other waste streams that were in the normal range.)
To estimate the total amount of waste generated for all (176) of the U.S refineries, the data obtained from the 11 5 survey participants had to be combined with estimates for the
A regression model was employed to estimate the generation quantities for 61 refineries that did not participate in the study, based on the assumption that non-respondents are similar to those who did respond.
After assessing the hazardous waste produced by each participating refinery, correlation coefficients were determined for various refinery characteristics, such as capacity, age, and sewer system, in relation to total waste generation Additionally, scatterplots were created to investigate potential relationships that could facilitate the development of models for estimating total waste generation.
The strongest correlation was between operable crude capacity (Question 3) and waste generation, with quantity of waste increasing as refinery capacity increased
The analysis evaluated simple linear, multiple regression, and nonlinear models based on significance levels, mean squared error, R-squared values, and model complexity Ultimately, the simple regression model utilizing capacity as the independent variable was selected as the most effective option.
Analysis of the data revealed that refining capacities significantly impact regression outcomes By modeling refineries with capacities below and above 200,000 barrels per stream day (BED) separately, we found that larger facilities exhibited a non-linear relationship between total waste generation and capacity, unlike their smaller counterparts This led to the development of distinct regression models for each group, enhancing the accuracy of our findings.
For the less than 200,000 B E D facilities, waste generated was modeled as being directly related to capacity:
At refineries having capacity greater than 200,000 BED, however, the increase in waste was modeled as a function of the square of the capacity:
Both a, and a, were estimated based on the data from 109 refineries2
To assess the models' effectiveness in explaining data variability, R² values were calculated In 1987, the R² values for smaller and larger facilities were 0.55 and 0.79, respectively, while in 1988, they were 0.58 and 0.79 The corresponding correlation coefficients were 0.75 and 0.89, indicating a reasonably good fit for this type of data Notably, the six outliers mentioned in Section 2.4.1 were excluded from the calculations for non-respondents.
2.4.3 Estimation of Waste Generation Quantities
The models were used to estimate the total quantity of waste generated for each of the
61 non-responding refineries (based on their crude capacities) for both 1987 and 1988
The total waste generated by all refineries was calculated by incorporating estimates for non-respondents alongside the data from 115 survey participants This report presents waste estimates for a total of 176 refineries.
Following the determination of total waste generation, calculations were conducted to estimate the quantities for each of the 28 waste streams Similar to the total waste calculation, the initial step involved estimating values for non-respondents.
A step by step summary of the procedure used follows:
1) The total waste generation quantity for each of the 1 O9 non-outlier respondents was calculated
The contribution percentage of each waste stream to the overall waste quantity was determined by dividing the generation quantity of each individual waste stream by the total sum of all 28 waste generation quantities.
3) These percentages were applied to the total waste generation quantity estimated for the 61 non-respondents (calculated in Section 2.4.2)
To calculate the total generation quantity for the 28 waste streams, the estimates for non-respondents were combined with the actual quantities reported by the 115 participants.
The margin of error for total waste generation and individual stream estimates was calculated, revealing an approximate 2 percent margin for total waste and a 10 percent margin for individual streams These error estimates indicate a high level of precision in the estimates, reflecting an excellent response rate.
RESPONSE RATE
A total of 1 15 refineries responded to the survey When compared to the universe of 176 refineries active during 1987 and 1988, this represents a 65 percent response rate
When response rate is viewed as a function of refinery capacity, the 115 respondents represent over 80 percent of the crude refining capacity in the country
Figure 1 illustrates the response distribution based on refining capacity, revealing that the lowest response rate occurred in the 0 to 10 thousand barrel-per-day category In contrast, just over half of the respondents were from the 11 to 50 thousand barrel-per-day group, while response rates exceeded 76 percent among the larger refinery classes.
Figure 1 Number of Refineries Responding by Capacity Groups
The expected response pattern indicates that larger refineries, primarily owned by active members of API and NPRA, dominate the survey Smaller facilities, with fewer employees, are less likely to have automated record-keeping, leading to a greater manpower commitment for survey completion However, since these refineries, processing less than 10,000 barrels per day, account for only 1 percent of the nation's total refining capacity, their lower response rate does not significantly impact the overall representation of industry practices in the survey.
RESPONDENT CHARACTERISTICS
Information was obtained on the location and complexity of each refinery, its age, and its type of wastewater sewer system
As anticipated the highest number of respondents (40) clustered in the historical oil producing region, the Department of Energy’s Petroleum Administration for Defense
(PAD) District III The PAD II region followed with 29 respondents and the PAD V region with 21 As graphically depicted in Figure 2, PAD District I contributed 13 refineries and
PAD Region IV contributed 12 responding refineries
Figure 2 Distribution of Respondents by PAD Districts
The number of responding refineries by the complexity of their operations and capacity is presented in Figure 3 The complexity categories are those used by the EPA in the
The Effluent Guideline Limitations for Petroleum Refining Point Source Categories, known as the National Pollutant Discharge Elimination System (NPDES), play a crucial role in wastewater permitting Detailed definitions for each category are provided in the relevant documentation.
2 presented in Appendix A Generally, a "Topping" refinery is the simplest type of facility and an "Integrated" refinery the most complex
Topping Cracking Petrochem Lube Integrated
Figure 3 Distribution of Respondents by NPDES Classification and Refinery Capacity
As illustrated, there are approximately equal numbers of responding refineries in the simplest category - Topping - as there are in each of the more complex categories of
Petrochemical, Lube, and Integrated Ail four of those categories are dwarfed by the preponderance of facilities in the "Cracking" category
The age of refineries, determined by their operational start year, reveals that more than half commenced operations before 1940, with 85 percent having been established prior to 1960, as illustrated in Figure 4.
Figure 4 Distribution by Refinery Age (Year Operations Started)
The study examined the type of wastewater systems utilized at various refineries, revealing that contrary to expectations, a greater number of intermediate-age refineries (30 to 50 years old) possess completely segregated stormwater and process sewers Figures 5 and 6 illustrate the relationship between sewer system type, refinery age, and size While partially segregated sewer systems are the most common across all age categories, non-segregated sewers are primarily found in the two oldest refinery groups.
Partially segregated sewer systems are prevalent across all facility sizes, with a notable disparity in the largest category, where there are seven non-segregated systems compared to just one totally segregated facility This trend suggests a broader industry movement towards upgrading to at least partially segregated storm and process water systems, reflecting both age and size considerations.
Figure 5 Refinery Age versus Sewer Type
Figure 6 Refinery Capacity versus Sewer Type
TOTAL WASTE MANAGEMENT QUANTITY
Waste Generation
To encourage the broadest reporting, the term "waste" was not specifically defined in the survey materials Respondents were guided by the instructional materials that stated:
The term "solid waste" in this survey is used in a broad, non-regulatory sense, differing from the specific definitions established by EPA regulations under RCRA API encourages participants to report on the management of all residual materials from petroleum refining, including those that are recycled, reclaimed, or discarded This comprehensive reporting will facilitate the collection of industry data aligned with the waste management hierarchy, which prioritizes source reduction, recycling, treatment, and disposal.
In the petroleum refining industry, "waste generation" encompasses a wide array of activities, as many wastes are collected only during scheduled maintenance of process units or tankage This collection can occur infrequently, with intervals ranging from annually to every three or even ten years.
Some waste types are generated continuously, such as oil, water, and solids separators that feature mechanisms for ongoing sludge removal Due to the diverse activities and frequencies associated with waste generation, specific guidelines were not established to direct or restrict how respondents interpret the term "generation."
Based on the procedure described previously, the total amount of waste generated by the population of 176 US petroleum refineries is estimated to have been:
16.1 million wet tons in 1987 and 16.0 million wet tons in 1988
The analysis of the refining waste stream categories, as shown in 'Table I', reveals that the relative proportions of different waste types remained relatively stable over the two survey years This consistency is further illustrated in Figure 7.
The Aqueous Waste category accounted for about 76 percent of all waste generated in both survey years, including all four outliers Among the remaining waste categories, Oily Sludges/Other Organic Wastes was the largest, followed by Chemicals/Inorganic Wastes.
When the contributions of the different waste classes are compared over the two years, it is apparent that slightly less Aqueous Wastes, Oily SludgeslOrganic Wastes and
Table III highlights the individual waste streams ranked by their generation in 1987, demonstrating the significant impact of outliers The waste stream labeled Other Aqueous Wastes NOS was notably influenced, with these facilities alone contributing over eleven million wet tons to the total waste generated that year Consequently, the remaining 170 refineries, out of a total of 176, accounted for only 30 percent of the waste presented.
Table IV reveals the variability in survey data by detailing the number of facilities reporting waste generation The most frequently reported waste streams for both years were API Separator Sludge, FCC Catalyst or Equivalent, and Other Wastes NOS Additionally, Other Aqueous Wastes NOS, despite having only 13 responses in 1987 and 12 in 1988, emerged as the highest quantity waste stream reported, largely influenced by outlier data.
The median number of reported streams was just 13, which is less than half of the total 28 streams Additionally, there was significant variability in waste generation, with some refineries reporting zero wet tons for certain waste streams, while others reported millions of wet tons for the same streams.
Variations in waste generation rates and management practices among refineries highlight their differences Even if two refineries have similar capacities and produce comparable products, their refining methods can vary significantly due to factors such as location, age, and the types of crude feedstock utilized.
FIGURE 7 COMPARISON OF WASTE GENERATION: 1987 - 1988
Total Waste Quantity Non-Aqueous Wastes
Chemicals 11 39 Spent Catalysts 246 Oily Sludges 1944
Aqueous Wastes All Other Wastes
Total Waste Quantity Non-Aqueous Wastes
Aqueous Wastes All Other Wastes Spent Catalysts 266
Table 111 Estimates of Wastes Generated for the Total US Refining Industry
Other Aqueous Wastes NOS Biomass
The article discusses various types of industrial waste, including spent caustics, DAF float, API separator sludge, and pond sediments It also highlights other inorganic wastes not otherwise specified (NOS), nonleaded tank bottoms, slop oil emulsion solids, and additional wastes NOS Furthermore, it addresses FCC catalyst or equivalent materials, contaminated solids, and both high pH and low pH waters, as well as spent acids.
Other Contaminated Soils NOS Other Separator Sludges Waste Coke/Carbon/Charcoal Spent Sulfite Solution Hydroprocessing Catalysts Other Oily SludgesAnorg Wastes Spent Sbetford Solution Other Spent Catalysts NOS
33 Oil Contam Water NOT Wastewater 28
Heat Exch Bundle Cleaning Solids 3
Table IV Number of Refineries Responding to the Survey that
Reported Generating Each Waste Stream
Other Wastes NOS API Separator Sludge FCC Catalyst or Equivalent Spent Caustics
Contaminated Soilslsolids Other Inorganic Wastes NOS Nonleaded Tank Bottoms Other Contaminated Soils NOS Other Spent Catalysts NOS Hydroprocessing Catalysts DAF Float
Waste Oiis/Spent Sdvents Heat Exch Bundle Cleéuting Solids Other Oily Sludges 8 Inorg Wastes Waste Coke/CarboniCharcoal Biomass
Slop Oil Emulsion Solids Waste Sulfur
Leaded Tank Bottoms Waste Amines Pond Sediments Spent Acids Other Separator Sludges High pH/Low pH Waters Oil Contaminated Water NOT Wastewater Other Aqueous Wastes NOS
Spent Stretford Solution Spent Sulfite Solution
The number of refineries responding to the survey was 115.
Treatment Additives
After waste generation, chemicals or treatment additives are often introduced to enhance handling processes For instance, alum is commonly added to DAF Float to improve flocculation Additionally, other chemicals may be utilized to regulate pH levels or stabilize organic materials for further treatment.
The amount of treatment additives used in the refining industry is quite small, less than 0.5 percent of the total wet tons of waste generated
In both 1987 and 1988, additives were reported as being used with 19 of the 28 waste streams The amount of additives used with Biomass was the largest observed in 1987;
In 1988, API Separator Sludge saw the highest utilization of additives, which accounted for 4 percent of its total composition, up from less than 1 percent in 1987 Notably, the peak proportion of additives reached 5 percent during this period.
Oiher Catalysts NOS 38 4 11 in 1987 and over 6 percent in 1988 was with the Other Separator Sludges waste st ream
Storage
In a comparison of waste management data between 1987 and 1988, significant differences were observed In 1987, a total of 14 waste streams had net quantities added to storage, while 8 streams had net quantities removed Conversely, in 1988, only 5 streams saw net amounts placed into storage, whereas 17 streams experienced net amounts removed from storage.
In 1987, the API Separator Sludge represented the largest volume of waste removed from storage, accounting for over a quarter of the total hazardous waste managed This substantial quantity significantly impacted the overall trends in hazardous waste management during the period from 1987 to 1988.
Table V Estimated Net Waste Quantities Removed From Storage for the Total US Refining Industry (Thousands of Wet Tons)
The other high-quantity waste streams removed from storage were the same over the two survey years: Pond Sediments, Contaminated Soils/Solids, Other Contaminated Soils
During the two-year survey period, the percentage of waste removed from storage compared to the total input quantity varied but remained low, generally under 14 percent, except for API Separator Sludge.
In both years, the Biomass waste stream accounted for the highest net amount of waste stored, consistently representing 7% of the total This was mainly due to the accumulation of biomass in secondary wastewater treatment ponds and impoundments.
Total Quantity of Waste ManagedAnput
As displayed below, the total waste management quantity equals the summation of the estimated quantity of waste generated, the treatment additives used, and the net waste i nt o/f ro m storage
Total Quantity = Quantity + Treatment + Net From
Waste Managed Gen e rated Additives Sto rage
This information for each waste stream, for both 1987 and 1988, is presented in Table VII
The inclusion of treatment and storage factors has minimal impact on the ranking of waste streams, as the order remains largely consistent with that determined by generation amounts alone (refer to Table III).
Table VI1 and the following discussion outline the derivation of all waste management statistics in this report Adhering to the "input = output" principle used in each data sheet, the total waste management quantity provided here forms the foundation for estimating the waste quantities managed through recycling, treatment, or disposal.
WASTE MANAGEMENT
Recycling
The petroleum industry has a strong commitment to recycling, focusing on the recovery of hydrocarbons lost in waste oils, off-specification products, and used oils These recovered oils are then reintegrated into various processing units for further refining into valuable products.
Most hydrocarbons are recycled through the refinery's oil recovery system before being classified as waste A significant portion of this recovery occurs through the skimming of oil from the surface of water in the wastewater treatment system Therefore, the actual amount of hydrocarbon recycling is much greater than reported in this survey, as these materials are not considered wastes or secondary materials within the survey's context and were thus not included.
Recycling activities are classified as "source reduction" within the waste management hierarchy, as they help prevent the generation of additional waste However, both API and EPA have faced challenges in gathering reliable data on source reduction activities, primarily due to the recent emergence of this concept and the technical difficulties associated with measuring the avoidance of waste.
Materials classified as waste or secondary materials generally contain lower oil concentrations Participants indicate that these materials undergo various recycling processes aimed at reusing non-hydrocarbon components Additionally, recovery procedures are implemented to extract any remaining hydrocarbons.
Appendix C, specifically Tables C-1 and C-2, details the recycling quantities for 28 waste streams In 1987, recycling accounted for 1.1 million wet tons, representing 7 percent of the total waste The following year, 1988, saw a slight increase to 1.2 million wet tons, maintaining the 7 percent rate However, when excluding outlier data (1.3 million wet tons for 1987 and 11.0 million wet tons for 1988), the recycling rate rises to 21 percent.
Far both survey years, Spent Caustics, with close to 500 thousand wet tons recycled, w a s the highest recycle stream, while DAF Float was second highest in both years
Table VIII outlines the waste streams that experience significant recycling, along with the specific recycling practices employed Notably, large volumes of oily waste materials, such as API Separator Sludge, DAF Float, and Slop Oil Emulsion Solids, are redirected to the crude unit for the recovery of valuable hydrocarbons Additionally, substantial amounts of DAF Float, API Separator Sludge, Slop Oil Emulsion Solids, and Biomass are processed in the coker to recycle oily materials unsuitable for the crude unit.
Table VIII Estimated Waste Quantities Recycled
API Separator Sludge DAF Float
Spent Acids Waste Coke/Carbon/Charcoal Hydroprocessing Catalysts Other Spent Catalysts NOS
Slop Oil Emulsion Solids FCC Catalyst or Equivalent
The "Other" category includes materials sent to desalters, industrial furnaces, sour water strippers, and practices not specified by the respondent
The refining industry significantly contributes to waste recycling through the reclamation and regeneration of spent catalysts, chemicals, and inorganic wastes, with the volume of waste eliminated nearly double that recycled back to crude units and cokers Onsite regeneration opportunities include utilizing spent acids or caustics for neutralization in refining processes, while offsite activities involve selling spent caustics to the paper industry, reclaiming precious metals from catalysts, and regenerating carbon The distribution of onsite versus offsite recycling activities for streams exceeding 10,000 wet tons is detailed in Table IX.
Table IX Location of Recycle Activities (Quantity Recycled in Thousands of Wet Tons)
Spent Acids Biomass Other Spent Catalysts NOS FCC Catalyst or Equivalent Nonleaded Tank Bottoms Slop Oil Emulsion Solids DAF Float
API separator sludge, spent caustics, waste coke, hydroprocessing catalysts, and high pH/low pH waters are key waste materials in industrial processes Additionally, contaminated soils and solids, various inorganic wastes, oily sludges, and spent sulfite solutions contribute to environmental challenges Proper management and treatment of these substances are essential for sustainable operations and compliance with environmental regulations.
Treatment
Treatment activities are classified into categories that include separation techniques like decanting, centrifugation, and filtration These methods often serve as preliminary steps, with decanting leading to the recycling, further treatment, or disposal of the separated components.
In the refining industry, various waste treatment methods are employed, including chemical, physical, heat, and stabilization/fixation techniques Incineration is also utilized, with the resulting ash categorized as a residue for disposal.
During the data collection phase of the survey, Laiid treatment was classified under the treatment category, as it was included in the list of treatments However, for reporting purposes, land treatment data will be presented separately This separation highlights the unique status of land treatment as a combination of treatment and disposal technology.
Tables C-5 and C-6 in Appendix C provide detailed information on the treatment quantities for each of the 28 waste streams for 1987 and 1988, respectively In 1987,
1.58 million wet tons were eliminated from the management system by treatment This amount decreased in 1988 to 1.44 million wet tons
After removing the outlier facilities that generated Other Aqueous Wastes NOS, the amount of waste eliminated through treatment was 31 percent in 1987 and 28 percent in
Table X outlines the waste streams that predominantly required treatment for disposal, categorized by the management methods employed For a comprehensive overview of the treatment methods associated with each waste stream, please refer to Tables C-7 and C-8 in Appendix C.
The data differentiates between "Dewatering" and "Wastewater" treatment, although it was collected under the general category of "wastewater treatment." Notably, wastewater treatment, particularly through the NPDES system, significantly dominated the figures, with over 1 million wet tons treated in both 1987 and 1988.
Dewatering and wastewater treatments address two primary types of waste: oily sludges and aqueous chemical wastes/inorganics Oily sludges, characterized by their high water content, require specific treatment processes to effectively manage their disposal and environmental impact.
API Separator Sludge DAF Float
Slop oil emulsion solids, nonleaded tank bottoms, pond sediments, and other separator sludges undergo dewatering, and in some cases deoiling, to minimize the volume of sludge sent for disposal The water extracted during this process is treated in the NPDES system or discharged to a POTW, as indicated in Table X Although the volumes of water from dewatering are significant compared to the waste volumes reported in this survey, they remain relatively small when compared to other wastewaters treated in the NPDES or discharged to a POTW As previously noted by API in discussions with the EPA, wastewater from dewatering activities typically constitutes less than 8 percent of the total wastewater flow Additionally, the quality of wastewater from dewatering is comparable to that of other wastewaters managed within the NPDES or POTW treatment systems.
Aqueous wastes and inorganics are characterized by a low solid content, making them very dilute compared to sludges As a result, these waste streams are directed to the NPDES system and publicly owned treatment works (POTWs) without undergoing significant prior treatment.
This survey defines "wastewater treatment" as the various processes, including neutralization, chemical, and physical treatments, utilized in refinery wastewater treatment systems Additionally, it aimed to gather data on other non-waste "wastewater" streams directed to the NPDES system or to Publicly Owned Treatment Works (POTWs).
Table X Estimated Quantities of Wastes Treated, by Treatment
Practice* (Thousands of Wet Tons)
Oil Contam Water NOT Wastewater 26
Treatment does not indude Land Treatment
In 1987, chemical and physical treatment emerged as the second most utilized method, processing 117 thousand wet tons, which increased to 148 thousand wet tons in 1988 The waste streams primarily treated with chemical methods, especially neutralization, included spent acids, caustics, and waters with high and low pH levels.
Table X also shows that the industry does use incineration, however, primarily for
Biomass and to a lesser degree for DAF Float Overall, incineration accounts for only
In 1987, waste treatment methods managed 7 percent of total waste, which increased to 9 percent in 1988 Notably, incineration accounted for less than 1 percent of the total waste managed in both years.
Table XI illustrates the distribution of treatment methods, highlighting that the majority of treatments were performed onsite due to the nature of the NPDES wastewater treatment system In contrast, offsite treatments were minimally utilized, with Spent Caustics being the only notable exception.
Biomass and Spent Stretford Solution materials of no further use to the refiner sent to an offsite treater
Table XI Location of Treatment*
(Quantity Treated in Thousands of Wet Tons)
Other Inorganic Wastes NOS Spent Caustics
High pH/Low pH Waters
Oil Contam Water NOT Wastewater
API Separator Sludge Spent Acids
DAF Float Spent Stretford Solution Slop Oil Emulsion Solids Pond Sediments Biomass Spent Sulfite Solution Nonleaded Tank Bottoms Other Separator Sludges
Treatment does not include Land Treatment
Land Treatment
Land Treatment, or "Land Farming," is a method that utilizes the natural biodegradation of organic materials by soil organisms In this process, organic waste is spread on the soil, tilled to enhance oxygen availability, and may be fertilized and watered to ensure adequate nutrients and moisture These conditions promote the activity of biological organisms that break down the organic waste Proper management of the remaining residue is essential when closing the landfarm.
The process is a combination treatment and disposal system and is subject to the RCRA land ban restrictions for hazardous wastes
Tables C-9 and C-10 in Appendix C summarize the information on land treatment for the
In 1987 and 1988, a total of 28 waste streams were analyzed, revealing that land treatment usage remained relatively stable, with 850 thousand wet tons in 1987 and 832 thousand wet tons in 1988 After adjusting for facilities producing significant amounts of Other Aqueous Waste NOS, land farming accounted for 17 percent of total waste managed in 1987 and 16 percent in 1988.
Table XII highlights the primary wastes processed through the Land Treatment process, with significant emphasis on Biomass, API Separator Sludge, and DAF Float Additionally, considerable amounts of other organic waste types were also treated Detailed data in Tables C-9 and C-10 of Appendix C reveal that several other waste streams, albeit in smaller quantities, were also subjected to land treatment.
Table XII Estimated Quantities of Waste Undergoing Land Treatment
As can be seen from Table XIII, Land Treatment is conducted almost exclusively onsite
The exceptions are Biomass and Other Separator Sludges, with about 80 percent and
60 percent, respectively, that were treated offsite in 1987
Table XIII Location of Land Treatment (Quantity of Land Treated Wastes in Thousands of Wet Tons)
Other Inorganic Wastes NOS Biomass contaminated SoilsiSolids Other Oily Sludges & Inorganic Wastes Nonleaded Tank Bottoms
Pond Sediments Other Separator Sludges Slop Oil Emulsion Solids API Separator Sludge DAF Float
Disposal
After recycling activities and treatment steps diminish the quantity of managed waste, the remainder is disposed in impoundments, landfills, injection wells, or by landspreading
Appendix C, specifically Tables C-1 1 and C-12, provides data on the disposal quantities for 28 refining waste streams In 1987, a total of 12.8 million wet tons were disposed, closely matching the 12.7 million wet tons disposed in 1988 This disposal accounted for 79 percent of all waste in both years.
To establish a more standard disposal rate for facilities with minimal reliance on deep well injection, the four outliers with significant amounts of Other Aqueous Wastes NOS were excluded from the analysis Consequently, this adjustment led to a decrease in the disposal rate to 31 percent in 1987 and 33 percent in 1988.
Table XIV outlines the disposal methods for significant waste streams, with detailed information available in Tables C-13 and C-14 of Appendix C for each of the 28 waste streams Notably, deep well injection is the predominant disposal method for the largest volume of waste, particularly among the four refineries managing substantial amounts of Other Aqueous Wastes NOS.
(Le., the outliers) used this disposal method
Landfills represent the second largest method of waste disposal, primarily because valuable materials are typically managed through alternative methods, leaving only waste that is suitable for landfill disposal.
There was also a significant quantity of waste disposed in impoundments With the land ban restrictions, that method will probably decrease
Table XIV Estimated Quantities of Wastes Disposed by Disposal
Practices (Thousands of Wet Tons)
High pH/Low pH Waters 25
Other Inorganic Wastes NOS 155 Contaminated Soils/Solids 141 FCC Catalysts or Equivalent 1 23 Other Contaminated Soils NOS 82
Table XV gives the distribution of disposal onsite and offsite The major onsite disposal is for Other Aqueous Waste NOS, Inorganic Wastes NOS and API Separator Sludge;
Nonleaded Tank Bottoms and FCC Catalysts or Equivalent were the waste streams with the highest percentage of offsite disposal
Table XV Onsite and Offsite Disposal (Quantity Disposed in Thousands of Wet Tons)
Other inorganic Wastes NOS Spent Caustics
High pHiLow pH Waters Biomass
Nonleaded Tank Bottoms Pond Sediments Other Contaminated Soils NOS DAF Float
FCC Catalysts or Equivalent Contaminated SoiVSolids Other Aqueous Wastes NOS API Separator Sludge
WASTE GENERATION
As; reported in Section 3.3.1, it is estimated that the petroleum refining industry generated
In 1987, the refining industry generated 16.1 million wet tons of waste, slightly decreasing to 16.0 million wet tons in 1988 Although these figures represent significant waste volumes, they are minimal compared to the hundreds of millions of tons of crude processed This highlights the efficiency of the refining process, as waste constitutes less than 3 percent of the total throughput, demonstrating the industry's ability to maximize the production of usable products.
Table XVI Comparison of Waste Generation with Crude Throughput
Adjusting the generation rates to counteract the inflation caused by the four facilities that produce unusually high amounts of specific waste streams would result in waste generation being less than one percent of the total throughput.
In comparing the generated quantities for the two survey years, a slight reduction from
Between 1987 and 1988, the observed reduction in waste generation should not be interpreted as a trend in waste minimization Instead, it is more accurate to state that the waste generation rates remained relatively stable during these two survey years.
Although the survey response identifies some consistencies in waste generation across refineries, it tends to underscore the individual differences between refineries
Table IV shows that Other Wastes NOS, API Separator Sludge, and FCC Catalyst or Equivalent were the most commonly reported waste streams in both survey years, with over 70 percent of participants indicating their presence each year This suggests that the majority of refineries consistently generate and manage these waste types annually.
The reporting frequency for 25 waste streams shows that fewer than 50 percent of respondents report generating 16 of these streams Future data collection over the next few years will clarify whether this low reporting is due to many refineries not producing these waste types or if the two-year data collection period is insufficient to capture less frequently handled waste streams.
Source: DOE/IEA Petroleum Supply Annual, Volume 1
For example, 26 and 29 respondents, respectively, reported generation of Pond
In the two survey years, the low reporting rate of pond sediments may indicate the periodic cleaning of ponds However, the consistent reports of sediment generation from many respondents in 1987 and 1988 suggest that not all refineries produce pond sediments Therefore, further data is essential to understand the implications of these reporting frequencies accurately.
An analysis of waste generation across different refineries reveals significant variations, particularly among outliers In 1987, Other Aqueous Wastes NOS was the highest quantity stream, with only 13 refineries reporting, and this number decreased to 12 in 1988 However, when excluding the over 11 million wet tons produced by the four outlier refineries, Other Aqueous Wastes NOS ranks as the seventh lowest quantity stream.
This extreme example highlights the significant variability in waste generation rates across different refineries Additionally, given the low waste to throughput ratio, it is essential to evaluate waste reduction strategies on an individual refinery basis.
Collecting additional data over time will clarify areas suitable for generic waste reduction planning instead of a case-by-case approach Successive reporting will define the variation in waste generation within refineries over time, allowing for the identification of variability sources, such as periodic clean-ups If needed, these can be statistically controlled by amortizing increases over the maintenance cycle This process will establish a more reliable baseline for each waste stream, enabling the calculation of meaningful averages for refineries of varying complexity and capacity.
WASTE MANAGEMENT
The petroleum refining industry employs diverse waste management practices tailored to the unique processing configurations of each refinery, ensuring responsible handling of various waste types.
Waste management profiles vary widely, similar to petroleum refineries, but they follow a fundamental logic Initially, the value of specific waste constituents is assessed for potential recycling through direct removal or treatment The remaining material is then evaluated for further treatment options After all necessary treatment steps, any residual waste is considered for final disposal Some wastes may only require one of these steps, while others may undergo the entire process.
Figure 8 illustrates the waste management practices across six major waste categories identified in the survey, with individual pie charts available for the 28 specific waste streams.
Appendix D; this same information is presented in Tables C-15 and C-16 in Appendix C.)
The analysis of the six sets of pie charts reveals that each waste category is managed differently, with consistent handling practices evident in the chart patterns across two survey years The proportions for recycling, treatment, land treatment, and disposal remain relatively unchanged between the two years, highlighting the intentionality behind these distinct management strategies.
In substantively reviewing the charts, one notes that Chemical/lnorganic Wastes have the highest proportion of recycling (at least 50 percent in both survey years), followed by
Spent Catalysts and Contaminated Soils/Solids Oily Sludgedother Organic
Wastes had the highest proportion of waste eliminated by treatment (40 percent in 1987) as well as the greatest reliance on Land Treatment
The pie charts indicate that Disposal is the management practice most frequently employed for four waste streams: Contaminated Soils, Spent Catalysts, Aqueous
The survey reveals that among the various waste categories, three are the smallest, while Aqueous Wastes stands out as the largest due to the influence of outliers This highlights the need to further investigate the disposal practices prevalent in the refining industry.
In the context of waste management practices, as shown in Figure 9, disposal represents a small portion of the total waste managed, accounting for only one third, with 31 percent in 1987 and 33 percent in 1988, after excluding outliers.
In the field of waste management, Figure 9 illustrates that treatment is a significant method, accounting for 31 percent of waste elimination in 1987 and 28 percent in 1988, which is comparable to the one-third of waste that was disposed of during the same period.
Landfilling remains the predominant waste management practice, handling over 1 million wet tons annually Following this, dewatering and wastewater treatment are also significant methods in the treatment and disposal of waste.
It should be noted that the materials disposed in landfills include substantial quantities of
Other inorganic wastes and contaminated soils and solids share a common characteristic: they are generated periodically A notable example of this is the sludges produced from cooling towers and boiler feed systems.
Inorganic Wastes NOS category are generated when these units are periodically cleaned out Contaminated Soils/Solids largely result from spills or remedial actions such as replacing tanks and piping
OILY SLUDGES /OTHER ORGANIC WASTES
Figure 9 Summary of Waste Management Practices (Outliers Removed)
LANDFILL 1 199 IMPOUNDMENT 246 LANDSPREAD 160 INJECTION55 OTHER 2
Both waste categories share a significant characteristic: they consist of high solids content and typically contain minimal commercially valuable materials For instance, contaminated soils and solids often arise from spills involving hydrocarbons or chemicals like acids and bases The predominant component of this waste is soil, which is tainted with substances that current recovery technologies cannot effectively process Consequently, the waste that ends up in landfills generally lacks any material of present commercial worth.
The refining industry utilizes recycling techniques, specifically reclamation and regeneration, to manage nearly 25% of its waste It is important to note that this survey focused on waste and secondary materials, excluding the oily materials that are typically recycled during the refining process before reaching waste management practices.
Land treatment effectively eliminated 17 percent of waste in 1987 and 76 percent in 1988, demonstrating its judicious use for organic materials suitable for biodegradation The largest waste stream treated was biomass, a dilute aqueous stream with less than 5 percent solids Additionally, oily sludges, such as API Separator Sludge and DAF Float, were also suitable for this treatment method.
The one-year gap between the 1987 and 1988 surveys is insufficient for a dependable trend analysis; however, comparing these results with earlier observations can offer valuable insights into advancements in waste generation and management within the industry.
The 1981 study, sponsored by API, provides the most comparable data among the two previous studies Like the 1987-1988 effort, it utilized mail-out data collection materials and gathered responses from 11 O refineries Both the 1981 study and the current surveys collected data on the five waste streams classified as hazardous.
The 1981 RCRA survey utilized a list of 10 non-hazardous waste streams, while the 1987-1988 survey expanded this to 23 non-hazardous waste streams As a result, comparisons between the two surveys are restricted to the hazardous waste streams that were included in both efforts.
Firstly, it is interesting to note the similarities in the response frequencies for the two investigations In 1981, 1 1 O refineries participated in the survey while 1 15 did so in 1987
- 1988 Moreover, as noted in Table XVII, the number of respondents reporting disposal of each hazardous waste stream also remained fairly constant, with the exception of
Leaded Tank Bottoms, which, because of the lead phase down, dropped by close to 50 percent
Table XVII Disposal Frequencies for Listed Wastes:
WASTESTREAM API Separator Sludge DAF FI&
Slop Oil Emulsion Solids Leaded Tank Bottoms Heat Exchanger Bundle Cleaning Sludge