The clear water met all federal secondary drinking water standards with the exception of surfactants.

Case Study #1

Valley Detroit Diesel Allison

In 1988 a diesel engine assembly and semi tractor repair facility in central California, Valley Detroit Diesel, installed an Electrocoagulation (EC) system to reclaim steam cleaner wash water and parking lot run off water.  The hazardous wastewater was being hauled off by truck for disposal at a cost of $0.60 per gallon in the dry season and $2.30 per gallon in the rainy season prior to installing the EC waste water treatment system.  Average savings per year is $70,000.

The hazardous wastewater contains a mixture of heavy metals, dirt, oil, and grease.

Valley Detroit built a containment facility, and placed the two-gallon per minute EC unit and clarifier in the corner.

Valley Detroit built a containment facility, and placed the two-gallon per minute EC unit and clarifier in the corner.  A 26,000-gallon holding tank store the surges of parking lot rain run off water and used steam-cleaning water.  The reclaimed water is stored in a 1,000-gallon clean water storage tank for reuse in the steam cleaner.  The containment facility includes tanks of diesel fuel, motor oil, antifreeze, and used motor oil for recycling.

The clear water met all federal secondary drinking water standards with the exception of surfactants.  The recycled surfactants reduced the need to add soap to the steam cleaner system.  Charcoal could be used in conjunction with the EC process to meet secondary drinking water standards.  The sludge from the EC process contained 90 mg/kg oil and grease. The heavy metals were converted into non-hazardous oxides.

The sludge passes the California states TTLC and STLC as required by CAC title 22.  As a result the State Health Board approved the EC processed sludge as a non hazardous waste.

The analysis of the recycled steam cleaner wash water follows : (004-263).


Constituent

Wastewater ppm

EC water ppm

% Removal

       

Antimony

<0.01

0.014

Arsenic

0.30

<0.01

96.7% +

Barium

8.0

<0.10

98.7% +

Beryllium

<0.01

<0.01

Cadmium

0.141

0.031

78.0%

Chromium

7.98

0.05

99.4%

Cobalt

0.13

<0.05

61.5% +

Copper

6.96

<0.05

99.3% +

Lead

7.4

1.74

76.5%

Mercury

0.003

<0.001

66.7% +

Molybdenum

0.18

0.035

80.7%

Nickel

0.4

<0.05

87.5%

Selenium

<0.005

<0.005

Silver

<0.01

<0.01

Thalliums

<0.10

<0.10

Vanadium

0.23

<0.01

95.7% +

Zinc

19.4

1.20

93.8%

The dry sludge separated from the Steam cleaner wastewater listed above (005-462) was tested for leach ability as follows:

Element

TTLC
Raw mg / kg

Max State

STLC
Raw mg / l

Max State

         

Antimony

2.4

500

Arsenic

3.85

500

Barium

307

10,000

Beryllium

nd

75

Cadmium

nd

100

Chromium

59.2

2,500

Cobalt

10.4

8,000

Copper

498

2,500

3.8

25

Lead

790

1,000

Mercury

0.15

0.20

Molybdenum

21.3

3,500

Nickel

25.5

2,000

Selenium

nd

100

Silver

2.7

500

Thalliums

14.2

700

Vanadium

42.1

2,400

Zinc

1,798

5,000

60

250

Oil & Grease

89,780

Note: Carol Carollo of the California Waste Extraction Unit required that a TTLC element that was 10 times the STLC limit be tested for the STLC. That is why Copper and Zinc was tested. As a result of these tests this sludge is acceptable for landfill disposal.

Because the water is recycled there is no water discharge concern. The unit requires about one (1) hour of maintenance per forty (40) hours of operation. The operating cost for electricity and blade replacement is less than one cent ($0.01) per gallon.

The facility is located in Bakersfield, CA

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