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 6 shows wastewater 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 petrochemicals (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 in Tables 8 to 12 [7].

In addition to the conventional pollutant constituents, USEPA made a survey of the presence 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, 1,1,1-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

Produ ction processes

Flow BOD COD

Phe nol

Sul fide

Oil

Emuls ified oil

Tempe Amm Chlo Acid Alkal ended rature onia ride ity inity solids

Crude

XX

X

XXX

X

XXX

XX

O

O

O

O

XX

oil and

product

storage

Crude

XX

XX

XX

X

XXX

X

XXX

X

XXX

XX

XXX

O

X XXX

desalting

Crude

XXX

X

X

XX

XXX

XX

XXX

X

XX

XXX

X

O

X X

distillation

Thermal

X

X

X

X

X

X

XX

XX

X

X

O

XXX X

cracking

Catalytic

XXX

XX

XX

XXX XXX

X

X

XXX

XX

XXX

X

O

XXX X

cracking

Hydro

X

XX

XX

XX

XX

cracking

Polymer

X

X

X

O

X

X

O

X

X

X

X

X

O X

ization

Alkylation XX

X

X

O

XX

X

O

XX

X

X

XX

XX

O XX

Isomeri

X

zation

Reforming

X

O

O

X

X

X

O

O

X

X

O

O

O O

Solvent

X

X

X

O

X

X

O

O

X

refining

Asphalt

XXX XXX XXX

X

XXX

blowing

Dewaxing

X

XXX XXX

X

O

X

O

Hydro

X

X

X

XX

O

O

XX

XX

O

O

X O

treating

Drying

XXX XXX

X

XX

O

O

X

XX

O

X

O

X

X XX

And

sweete

ning

XXX=major contribution; XX=moderate contribution; X=minor contribution; O=insignificant; Blank=no data.

BOD, biochemical oxygen demand; COD, chemical oxygen demand. Source: From Ref. 5.

Table 6 Waste Loadings and Volumes Per Unit of Fundamental Process Throughput in Older, Typical, and Newer Technologies

Older technology__Typical technology__Newer technology

Table 6 Waste Loadings and Volumes Per Unit of Fundamental Process Throughput in Older, Typical, and Newer Technologies

Funda Flow BOD Phenol Sul :

Flow BOD Phenol Sulfides Flow BOD Phenol Sulfides

mental (gal (lb

(lb fides (gal

(lb (lb

(lb

(gal

(lb (lb

(lb

process /bbl) /bbl)

/bbl) (lb

/bbl) /bbl) /bbl)

/bbl)

/bbl) /bbl) /bbl)

/bbl)

/bbl)

Crude 4 0.001

——

4

0.001 —

4

0.001 —

oil and

product

storage

Crude 2 0.002

0.20 0.002

2

0.002 0.10

0.002

2

0.002 0.05

0.002

desalting

Crude 100 0.020

3.0 0.001

so

0.0002 1.0

0.001

10 0.0002 1.0

0.00l

fracti

onation

Thermal 66 0.001

7.0 0.002

2

0.001 0.2

0.001

1.5

0.001 0.2

0.00l

cracking

Catalytic 85 0.062

SO.O 0.03

30

0.010 20

0.003

5

0.010 5

0.003

cracking

Hydro Not in this

Not in this

5

— —

cracking technology

technology

Reforming 9 T

0.7 T

6

T 0.7

0.001

6

T 0.7

0.00l

Polyme 300 0.003

1.4 0.22

140

0.003 0.4

0.010

Not in this

rization

technology

Alkylation 173 0.001

0.1 0.00S

60

0.001 0.1

0.010

20

0.001 0.1

0.020

Isomeri Not in this

Not in this

— —

zation technology

technology

Solvent refining

B—

3 T 8

3

T 8—

3 T

Dewaxing 24 0.S2

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 B 0.002 0.01 0.002

Deasphalting

Drying and 100 0.10

10 —40

0.05

10

— 40 0.05

l0 —

sweetening

Wax finishing

Grease

manufacturing

Lube oil finishing

Hydrogen

Not in this

Not in this

— —

— —

manufacture

technology

technology

T=trace;—=data not available for reasonable estimate; BOD, biochemical oxygen demand. gal/bbl=gallons of wastewater per barrel of oil processed. lb/bbl=pounds of contaminant per barrel of oil processed. Source: From Ref. 15.

Table 7 Typical Waste Characteristics

Spent caustic stream

Table 7 Typical Waste Characteristics

Spent caustic stream

Benzene

Characteristic

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

90,300

40,800

(mg/L)

Process waste

Sour condensates

Crude

from distillation

Characteristic

Desalting

Catalytic cracking

Naphtha cracking

cracking, etc.

Ammonia

80

135-6,550

(mg/L) 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

Sulfite wash:

Characteristic

Acid wash: alkylation

Acid wash: phenol still bottoms

Acid wash: orthophenylphenol

liquid OP-phenol distillation

Acidity (mg/L)

1,105-12,325

24,120

675

BOD (mg/L)

31

20,800

13,600

105,000

Phenols (mg/L) Sulfate (mg/L) Sulfite (mg/L) Total solids (mg/L)

1,251

248,000 340,500

3,800

34,800 403,200

23,400 81,300

1,500 54,700 2,920 81,600

689,000 176,800

3.8 16,400

74,000 176,900

BOD, biochemical oxygen demand; COD, chemical oxygen demand. Source: From Ref. 16,

16400 54700
Figure 7 Components of pollutants by source. These principal pollutants are present in waste streams from each refinery operations/sources. (From Ref. 17.)

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