40 C.F.R. § 471.21

Current through October 31, 2024

Section 471.21 - Effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT)

Except as provided in 40 CFR 125.30 through 125.32 , any existing point source subject to this subpart must achieve the following effluent limitations for the process operations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT):

(a)Rolling spent emulsions.

Subpart B-BPT

Pollutant or pollutant property	Maximum for any 1 day	Maximum for monthly average
	mg/off-kg (pounds per million off-pounds) of magnesium rolled with emulsions
Chromiun	0.033	0.014
Zinc	0.109	0.046
Ammonia	9.95	4.37
Fluoride	4.440	1.97
Oil and grease	1.49	0.895
TSS	3.06	1.46
pH		(1)

¹ Within the range of 7.5 to 10.0 at all times.

(b)Forging spent lubricants-subpart B-BPT. There shall be no discharge of process wastewater pollutants.

(c)Forging contact cooling water.

Subpart B-BPT

Pollutant or pollutant property	Maximum for any 1 day	Maximum for monthly average
	mg/off-kg (pounds per million off-pounds) of forged magnesium cooled with water
Chromium	1.27	0.520
Zinc	4.22	1.77
Ammonia	385	170
Fluoride	172	76.3
Oil and grease	57.8	34.7
TSS	119	56.4
pH		(1)

¹ Within the range of 7.5 to 10.0 at all times.

(d)Forging equipment cleaning wastewater.

Subpart B-BPT

Pollutant or pollutant property	Maximum for any 1 day	Maximum for monthly average
	mg/off-kg (pounds per million off-pounds) of magnesium forged
Chromium	0.018	0.007
Zinc	0.059	0.025
Ammonia	5.32	2.34
Fluoride	2.38	1.06
Oil and grease	0.798	0.479
TSS	1.64	0.778
pH		(1)

¹ Within the range of 7.5 to 10.0 at all times.

(e)Direct chill casting contact cooling water.

Subpart B-BPT

Pollutant or pollutant property	Maximum for any 1 day	Maximum for monthly average
	mg/off-kg (pounds per million off-pounds) of magnesium cast with direct chill methods
Chromium	1.74	0.711
Zinc	5.77	2.41
Ammonia	527	232
Fluoride	235	105
Oil and grease	79.0	47.4
TSS	162	77.1
pH		(1)

¹ Within the range of 7.5 to 10.0 at all times.

(f)Surface treatment spent baths.

Subpart B-BPT

Pollutant or pollutant property	Maximum for any 1 day	Maximum for monthly average
	mg/off-kg (pounds per million off-pounds) of magnesium surface treated
Chromium	0.205	0.084
Zinc	0.681	0.285
Ammonia	62.1	27.3
Fluoride	27.8	12.3
Oil and grease	9.32	5.59
TSS	19.1	9.09
pH		(1)

¹ Within the range of 7.5 to 10.0 at all times.

(g)Surface treatment rinse.

Subpart B-BPT

Pollutant or pollutant property	Maximum for any 1 day	Maximum for monthly average
	mg/off-kg (pounds per million off-pounds) of magnesium surface treated
Chromium	8.32	3.4
Zinc	27.6	11.5
Ammonia	2520	1110
Fluoride	1130	499
Oil and grease	378	227
TSS	775	369
pH		(1)

¹ Within the range of 7.5 to 10.0 at all times.

(h)Sawing or grinding spent emulsions.

Subpart B-BPT

Pollutant or pollutant property	Maximum for any 1 day	Maximum for monthly average
	mg/off-kg (pounds per million off-pounds) of magnesium sawed or ground
Chromium	0.009	0.004
Zinc	0.029	0.012
Ammonia	2.60	1.15
Fluoride	1.16	0.515
Oil and grease	0.390	0.234
TSS	0.800	0.381
pH		(1)

¹ Within the range of 7.5 to 10.0 at all times.

(i)Degreasing spent solvents-subpart B-BPT. There shall be no discharge of process wastewater pollutants.

(j)Wet air pollution control scrubber blowdown.

Subpart B-BPT

Pollutant or pollutant property	Maximum for any 1 day	Maximum for monthly average
	mg/off-kg (pounds per million off-pounds) of magnesium sanded and repaired or forged
Chromium	0.273	0.112
Zinc	0.904	0.378
Ammonia	82.5	36.3
Fluoride	36.9	16.4
Oil and grease	12.4	7.43
TSS	25.4	12.1
pH		(1)

¹ Within the range of 7.5 to 10.0 at all times.

40 C.F.R. §471.21