Wastes generated from oil fields include produced water, drilling muds and cuttings, and tank bottom sludges. These wastes are associated with the drilling, recovery, and storage of crude oil.
Wastes from petroleum refineries generally include process wastewater, wastewater from utility operations, contaminated storm water, sanitary waste, and miscellaneous contaminated streams.
These waste streams are usually discharged to a central wastewater treatment system; some of these streams, such as sour water, are pretreated first.
4.3.1 Oil Field Wastes
The most important wastes from oil fields are produced water and drilling muds. The characteristics of these waste streams are discussed below.
Produced water is the water brought to the surface with the oil from a production well. It is estimated that for every barrel of oil produced, on average 2 – 3 barrels of water are produced, ranging from a negligible amount up to values over 100 barrels of water per barrel of oil [7].
Once on the surface, the water and oil are separated. The oil is prepared for distribution, leaving the water to be disposed of by some means.
Produced water is typically saline. A great deal of data exist regarding the quality of the inorganic components of the produced water [8]. Table 2 is a summary of this information. To date very little information has been published regarding the concentration of the traditional pollutant parameters in the produced water.Table 3presents the ranges of various water quality Table 2 Inorganic Components in Oilfield Produced Water
Constituent Concentration (mg/L)
Sodium 12,000 – 150,000
Potassium 30 – 4,000
Calcium 1,000 – 120,000
Magnesium 500 – 25,000
Chloride 20,000 – 250,000
Bromide 50 – 5,000
Iodide 1 – 300
Bicarbonate 0 – 3,600
Source:From Ref. 9.
parameters measured in produced water from over 30 individual wells in several California oilfields [9]. Work done by Chevron showed that typical produced waters from the U.S. west coast and the Gulf of Mexico, after oil removal, had compositions ranging from 20,000 to 135,000 mg/L total dissolved solids, 45 to 130 mg/L ammonia (as N), and 0.1 to 3.0 mg/L phenols [10].
Drilling muds are fluids that are pumped into the bore holes to aid in the drilling process.
Most are water based and contain barite, lignite, chrome lignosulfate, and sodium hydroxide [11], but oil-based drilling muds are still used for economic and safety reasons [12]. Used muds can be removed by vacuum trucks, pumped down the well annulus, or allowed to dewater in pits, which are then covered with soil or disposed of by land farming.
The main components of pollution concern in drilling muds include (1) oil itself, especially in oil fluids, (2) salts, and (3) soluble trace elements consisting of zinc, lead, copper, cadmium, nickel, mercury, arsenic, barium, and chromium associated with low grades of barite [13]. Owing to its variability, very little information has been published regarding the concentration of pollutants in spent drilling mud. Copa and Dietrich [14]
conducted a wet air oxidation experiment on a sample of spent drilling mud taken from a storage lagoon. The material was a concentrated mud, having a suspended solids concen- tration of approximately 500 g/L. The original drilling mud contained emulsifying agents and oils, which inhibited dewaterability. The characteristics of the diluted (4 : 1) spent drilling mud are shown in Table 4.
Table 3 Produced Water Quality
Parameter Range (mg/L)
Biochemical oxygen demand 50 – 1,400 Chemical oxygen demand 450 – 5,900
Phenols 0.7 – 7.6
Oil and grease 15 – 290
Ammonia nitrogen 4 – 206
Total suspended solids 35 – 300
Sulfides 0.2 – 800
pH 6.7 – 9.0
Source:From Ref. 14.
Table 4 Characteristics of Spent Drilling Mud Analyses
Concentration (diluted 4 : 1)
COD, soluble (mg/L) 5,720
BOD, soluble (mg/L) 2,625
TOC, soluble (mg/L) 2,010
Total solids (g/L) 113.4
Ash (g/L) 107.5
Suspended solids (g/L) 103.7
Suspended ash (g/L) 100.9
Specific filtration resistance (cm2/g1027) 155 Source:From Ref. 14.
4.3.2 Refinery Wastewater
The sources of wastewater generation in petroleum refineries have been discussed previously in this chapter. Table 5 presents a qualitative evaluation of wastewater flow and characteristics by fundamental refinery processes [5]. The trend of the industry has been to reduce wastewater production by improving the management of the wastewater systems. Table 6shows waste- water loadings and volumes per unit fundamental process throughput in older, typical, and newer technologies [15]. Table 7 shows typical wastewater characteristics associated with several refinery processes [16].
In addition to those from the fundamental processes, wastewaters are also generated from other auxiliary operations in refineries.Figure 7 shows the various sources of wastewater and their primary pollutants in a refinery [17].
In the USEPA study to develop effluent limitation guidelines [7], refinery operations were grouped together to produce five subcategories based on raw waste load, product mix, refinery processes, and wastewater generation characteristics. These subcategories are described below.
1. Topping Includes topping, catalytic reforming, asphalt production, or lube oil manufacturing processes, but excludes any facility with cracking or thermal operations.
2. Cracking Includes topping and cracking.
3. Petrochemical Includes topping, cracking, and petrochemical operations.
4. Lube Includes topping, cracking, and lube oil manufacturing processes.
5. Integrated Includes topping, cracking, lube oil manufacturing processes, and petrochemical operations.
The term petrochemical operations means the production of second-generation petro- chemicals (alcohols, ketones, cumene, styrene, and so on) or first-generation petrochemicals and isomerization products (BTX, olefins, cyclohexane, and so on) when 15% or more of refinery production is as first-generation petrochemicals and isomerization products.
All five subcategories of refineries generate wastewaters containing similar constituents.
However, the concentrations and loading of the constituents (raw waste load) vary among the categories. The raw waste loads, and their variabilities, for the five petroleum refining subcategories are presented inTables 8to12[7].
In addition to the conventional pollutant constituents, USEPA made a survey of the pre- sence of the 126 toxic pollutants listed as “priority pollutants” in refinery operations in 1977 [5].
The survey responses indicated that 71 toxic pollutants were purchased as raw or intermediate materials; 19 of these were purchased by single refineries. At least 10% of all refineries purchase the following toxic pollutants: benzene, carbon tetrachloride, l,l,l-trichloroethane, phenol, toluene, zinc and its compounds, chromium and its compounds, copper and its compounds, and lead and its compounds. Zinc and chromium are purchased by 28% of all refineries, and lead is purchased by nearly 48% of all plants.
Forty-five priority pollutants are manufactured as final or intermediate materials; 15 of these are manufactured at single refineries. Benzene, ethylbenzene, phenol, and toluene are manufactured by at least 10% of all refineries. Of all refineries, 8% manufacture cyanides, while more than 20% manufacture benzene and toluene. Hence, priority pollutants are expected to be present in refinery wastewaters. The EPA’s short-term and long-term sampling programs conducted later detected and quantified 22 to 28 priority pollutants in refinery effluent samples [5].
Table 5 Qualitative Evaluation of Wastewater Flow and Characteristics by Fundamental Refinery Processes Production
processes Flow BOD COD Phenol Sulfide Oil
Emulsified
oil pH Temperature Ammonia Chloride Acidity Alkalinity
Suspended solids Crude oil and
product storage
XX X XXX X XXX XX O O O O XX
Crude desalting
XX XX XX X XXX X XXX X XXX XX XXX O X XXX
Crude distillation
XXX X X XX XXX XX XXX X XX XXX X O X X
Thermal cracking
X X X X X X XX XX X X O XX X
Catalytic cracking
XXX XX XX XXX XXX X X XXX XX XXX X O XXX X
Hydrocracking X XX XX XX XX
Polymerization X X X O X X O X X X X X O X
Alkylation XX X X O XX X O XX X X XX XX O XX
Isomerization X
Reforming X O O X X X O O X X O O O O
Solvent refining
X X X O X X O O X
Asphalt blowing
XXX XXX XXX X XXX
Dewaxing X XXX XXX X O X O
Hydrotreating X X X XX O O XX XX O O X O
Drying and sweetening
XXX XXX X XX O O X XX O X O X X XX
XXXẳmajor contribution; XXẳmoderate contribution; Xẳminor contribution; Oẳinsignificant; Blankẳno data.
BOD, biochemical oxygen demand; COD, chemical oxygen demand.
Source:From Ref. 5.
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Table 6 Waste Loadings and Volumes Per Unit of Fundamental Process Throughput in Older, Typical, and Newer Technologies
Older technology Typical technology Newer technology
Fundamental process
Flow (gal/bbl)
BOD (lb/bbl)
Phenol (lb/bbl)
Sulfides (lb/bbl)
Flow (gal/bbl)
BOD (lb/bbl)
Phenol (lb/bbl)
Sulfides (lb/bbl)
Flow (gal/bbl)
BOD (lb/bbl)
Phenol (lb/bbl)
Sulfides (lb/bbl) Crude oil and
product storage
4 0.001 — — 4 0.001 — — 4 0.001 — —
Crude desalting
2 0.002 0.20 0.002 2 0.002 0.10 0.002 2 0.002 0.05 0.002
Crude fractionation
100 0.020 3.0 0.001 50 0.0002 1.0 0.001 10 0.0002 1.0 0.001
Thermal cracking
66 0.001 7.0 0.002 2 0.001 0.2 0.001 1.5 0.001 0.2 0.001
Catalytic cracking
85 0.062 50.0 0.03 30 0.010 20 0.003 5 0.010 5 0.003
Hydrocracking Not in this technology Not in this technology 5 — — —
Reforming 9 T 0.7 T 6 T 0.7 0.001 6 T 0.7 0.001
Polymerization 300 0.003 1.4 0.22 140 0.003 0.4 0.010 Not in this technology
Alkylation 173 0.001 0.1 0.005 60 0.001 0.1 0.010 20 0.001 0.1 0.020
Isomerization Not in this technology Not in this technology — — — —
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refining
Dewaxing 24 0.52 2 T 23 0.50 1.5 T 20 0.25 1.5 T
Hydrotreating 1 0.002 0.6 0.007 1 0.002 0.01 0.002 8 0.002 0.01 0.002
Deasphalting — — — — — — — — — — — —
Drying and sweetening
100 0.10 10 — 40 0.05 10 — 40 0.05 10 —
Wax finishing
— — — — — — — — — — — —
Grease
manufacturing
— — — — — — — — — — — —
Lube oil finishing
— — — — — — — — — — — —
Hydrogen manufacture
Not in this technology Not in this technology — — — —
Blending and packaging
— — — — — — — — — — — —
Tẳtrace; —ẳdata not available for reasonable estimate; BOD, biochemical oxygen demand.
gal/bblẳgallons of wastewater per barrel of oil processed.
lb/bblẳpounds of contaminant per barrel of oil processed.
Source:From Ref. 15.
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Table 7 Typical Waste Characteristics
Spent caustic stream
Characteristic
Benzene sulfonation
scrubbing
Orthophenylphenol washing
Alkylate
washing Polymerization
Alkalinity (mg/L) 33,800 18,400 46,250 209,330
BOD (mg/L) 53,600 18,400 256 8,440
COD (mg/L) 112,000 67,600 3,230 50,350
pH 13.2 9 – 12 12.8 12.7
Phenols (mg/L) 8.3 5,500 50 22.2
NaOH (wt %) 1 0.2 – 0.5
Na2SO4(wt %) 1.5 – 2.5
Sulfates (mg/L) 3,760 2,440
Sulfides (mg/L) 2 3,060
Sulfites (mg/L) 7,100 4,720
Total solids (mg/L) 90,300 40,800
Process waste
Characteristic
Crude Desalting
Catalytic cracking
Naphtha cracking
Sour condensates from distillation
cracking, etc.
Ammonia (mg/L) 80 135 – 6,550
BOD (mg/L) 60 – 610 230 – 440 500 – 1,000
COD (mg/L) 124 – 470 500 – 2,800 53 – 180 500 – 2,000
Oil (mg/L) 20 – 516 200 – 2,600 160 100 – 1,000
pH (mg/L) 7.2 – 9.1 4.5 – 9.5
Phenols (mg/L) 10 – 25 20 – 26 6 – 10 100 – 1,000
Salt (as NaCl) (wt %) 0.4 – 25
Sulfides (mg/L) 0 – 13 390 – 8,250
(H2S) Acid waste
Characteristic
Acid wash:
alkylation
Acid wash:
phenol still bottoms
Acid wash:
orthophenylphenol
Sulfite wash:
liquid OP-phenol distillation
Acidity (mg/L) 1,105 – 12,325 24,120 675
BOD (mg/L) 31 20,800 13,600 105,000
COD (mg/L) 1,251 248,000 23,400 689,000
Dissolved solids (mg/L)
340,500 81,300 176,800
Oil (mg/L) 131.5
pH 0.6 – 1.9 1.0 1.1 3.8
Phenols (mg/L) 3,800 1,500 16,400
Sulfate (mg/L) 54,700
Sulfite (mg/L) 34,800 2,920 74,000
Total solids (mg/L) 403,200 81,600 176,900
BOD, biochemical oxygen demand; COD, chemical oxygen demand.
4.3.3 Refinery Solid and Hazardous Wastes
According to a USEPA survey, many of the more than 150 separate processes used in petroleum refineries generate large quantities of hazardous wastes. Typical wastes generated from refinery processes include bottom sediments and water from crude storage tanks, spent amines, spent acids and caustics, spent clays, spent glycol, catalyst fines, spent Streford solution and sulfur, Figure 7 Components of pollutants by source. These principal pollutants are present in waste streams from each refinery operations/sources. (From Ref. 17.)
coking fines, slop oil, and storage tank bottoms. Most are hazardous wastes.Figure 8 shows a refinery schematic diagram indicating representative sources of solid wastes in refinery systems [18].
Also, the plant’s utility systems often contribute to the volume of waste. Utility water systems generate raw water treatment sludge, lime softening sludge, demineralizer regenerants, and cooling tower sludge. These wastes may or may not be hazardous, depending on characteristics such as pH and metal concentrations. Figure 9 shows a refinery schematic Table 8 Topping Subcategory Raw Waste Load Effluent from Refinery API Separatora
Probability of occurrence, percent less than or equal to
Parameters 10 50 (median) 90
BOD5 1.29 (0.45) 3.43 (1.2) 217.36 (76)
COD 3.43 (1.2) 37.18 (13) 486.2 (170)
TOC 1.09 (0.38) 8.01 (2.8) 65.78 (23)
TSS 0.74 (0.26) 11.73 (4.1) 286 (100)
O&G 1.03 (0.36) 8.29 (2.9) 88.66 (31)
Phenols 0.001 (0.0004) 0.034 (0.012) 1.06 (0.37)
Ammonia 0.077 (0.027) 1.20 (0.42) 19.45 (6.8)
Sulfides 0.002 (0.00065) 0.054 (0.019) 1.52 (0.53)
Chromium 0.0002 (0.00007) 0.007 (0.0025) 0.29 (0.1)
Flowb 8.00 (2.8) 66.64 (23.3) 557.7 (195)
aValues represent kg/1000 m3(lb/1000 bbl) of feedstock throughput.
b1000 m3/10003feedstock throughput (gallons/bbl).
BOD, biochemical oxygen demand; COD, chemical oxygen demand; TOC, total organic carbon;
TSS, total suspended solids; O&G, oil and grease.
Source:From Ref. 7.
Table 9 Cracking Subcategory Raw Waste Load Effluent from Refinery API Separatora Probability of occurrence, percent less than or equal to
Parameters 10 50 (median) 90
BOD5 14.3 (5.0) 72.93 (25.5) 466.18 (163)
COD 27.74 (9.7) 217.36 (76.0) 2516.8 (880)
TOC 5.43 (1.9) 41.47 (14.5) 320.32 (112)
O&G 2.86 (1.0) 31.17 (10.9) 364.65 (127.5)
Phenols 0.19 (0.068) 4.00 (1.4) 80.08 (28.0)
TSS 0.94 (0.33) 18.16 (6.35) 360.36 (126.0)
Sulfur 0.01 (0.0035) 0.94 (0.33) 39.47 (13.8)
Chromium 0.0008 (0.00028) 0.25 (0.088) 4.15 (1.45)
Ammonia 2.35 (0.82) 28.31 (9.9) 174.46 (61.0)
Flowb 3.29 (1.15) 92.95 (32.5) 2745.6 (960.0)
aValues represent kg/1000 m3(lb/1000 bbl) of feedstock throughput.
b1000 m3/1000 m3feedstock throughput (gallons/bbl).
BOD, biochemical oxygen demand; COD, chemical oxygen demand; TOC, total organic carbon;
TSS, total suspended solids; O&G, oil and grease.
Source:From Ref. 7.
diagram indicating representative sources of solid waste in utility water systems [18]. Wastes generated from wastewater treatment systems include API/CPI separator sludge, dissolved-air flotation or induced-air flotation system floats, pond and tank sediments, and biosolids. Of these, only the biosolids from the biological wastewater treatment system may be nonhazardous.
Figure 10shows a refinery schematic diagram indicating representative sources of solids waste in wastewater treatment systems [18].
Table 10 Petrochemical Subcategory Raw Waste Load Effluent from Refinery API Separatora
Probability of occurrence, percent less than or equal to
Parameters 10 50 (median) 90
BOD5 40.90 (14.3) 171.6 (60) 715 (250)
COD 200.2 (70) 463.32 (162) 1086.8 (380)
TOC 48.62 (17) 148.72 (52) 457.6 (160)
TSS 6.29 (2.2) 48.62 (17) 371.8 (130)
O&G 12.01 (4.2) 52.91 (18.5) 234.52 (82)
Phenols 2.55 (0.89) 7.72 (2.7) 23.74 (8.3)
Ammonia 5.43 (1.9) 34.32 (12) 205.92 (72)
Sulfides 0.009 (0.003) 0.86 (0.3) 91.52 (32)
Chromium 0.014 (0.005) 0.234 (0.085) 3.86 (1.35)
Flowb 26.60 (9.3) 108.68 (38) 443.3 (155)
aValues represent kg/1000 m3(lb/1000 bbl) of feedstock throughput.
b1000 m3/1000 m3feedstock throughput (gallons/bbl).
BOD, biochemical oxygen demand; COD, chemical oxygen demand; TOC, total organic carbon;
TSS, total suspended solids; O&G, oil and grease.
Source:From Ref. 7.
Table 11 Lube Subcategory Raw Waste Load Effluent from Refinery API Separatora Probability of occurrence, percent less than or equal to
Parameters 10 50 (median) 90
BOD5 62.92 (22) 217.36 (76) 757.9 (265)
COD 165.88 (58) 543.4 (190) 2288 (800)
TOC 31.46 (11) 108.68 (38) 386.1 (135)
TSS 17.16 (6) 71.5 (25) 311.74 (109)
O&G 23.74 (8.3) 120.12 (42) 600.6 (210)
Phenols 4.58 (1.6) 8.29 (2.9) 51.91 (18.5)
Ammonia 6.5 (2.3) 24.1 (8.5) 96.2 (34)
Sulfides 0.00001 (0.000005) 0.014 (0.005) 20.02 (7.0)
Chromium 0.002 (0.0006) 0.046 (0.016) 1.23 (0.43)
Flowb 68.64 (24) 117.26 (41) 772.2 (270)
aValues represent kg/1000 m3(lb/1000 bbl) of feedstock throughput.
b1000 m3/1000 m3feedstock throughput (gallons/bbl).
BOD, biochemical oxygen demand; COD, chemical oxygen demand; TOC, total organic carbon;
TSS, total suspended solids; O&G, oil and grease.
Source:From Ref. 7.
The amount and type of wastes generated in a refinery depend on a variety of factors such as crude capacity, number of refining processes, crude source, and operating procedures. A 130,000 bpd integrated refinery on the West Coast generates about 50,000 tons per year of hazardous waste (including recycled streams and unfiltered sludges). The major wastes are wastewater treatment plant sludge, spent caustics, Stretford solution and sulfur, and spent catalysts [19]. A much simpler 50,000 bpd refinery generates only 400 tons per year of hazardous waste. Major wastes in this refinery are wastewater treatment plant sludge (dewatered by pressure filtration), spent catalysts, and spent clay filter media [19].