Automatic Continuous Acid
Neutralization
ROBERT E. HUGGETT, Plant Engineer
and
WILLIAM H. TOLLER, Chief Chemical Engineer
Huntington Division
Houdaille Industries, Inc.
Huntington, West Virginia
The Huntington Division of Houdaille Industries, Inc., manufactures
automobile bumpers. As a result acid waste from pickling and plating operations are generated which must be neutralized before discharge into the city
sewer system. The plant is located in the city of Huntington and uses city
sewers for the disposal of liquid wastes. Houdaille Industries was required by
the city to install an acid neutralization plant to protect the city sewer collection system and treatment plant.
The treatment system to be used by the city of Huntington consists of primary settling with chlorination of the effluent. The settleable solids are
filtered and then incinerated. This incineration of solids enables the local
industries to utilize the city's disposal system to better advantage since it is
not necessary to remove the metallic ions before disposal of liquid wastes.
In order to design this neutralization system, a survey of the plant water
consumption and acid discharge was made. Past performance showed the average flow was 38. 3 MG/month. The peak flow during the summer months
amounted to about 51 MG/month. The treatment plant design capacity was
therefore based on the peak summer load divided by 21 operating days or approximately 2.4 mgd. The design flow was then set at 100, 000 gals/hr. This
peak hourly design flow was boosted by 25 per cent so that there would be an
ultimate capacity peak of 125, 000 gals/hr, or 2,100 gpm.
The total sulfuric acid discharge to the sewer amounted to about
230, 000 lbs per month based on purchases. The acid going into the sewers
was divided into two categories: acid discharge into the sewer via rinses, approximately 75, 000 lbs/month, and acid discharge to the sewers via batch
dumpings such as spent pickle baths. This was estimated at 155,000
lbs/month. The lbs of acid discharged to the sewers via rinses amounted to
3, 600 lbs/day. The excess acid from the rinses which required neutralization
amounted to 3, 600 minus 900 or 2, 700 lbs/day or 110 lbs/hi.
The 900 figure is based on the amount of alkaline rinse water that is
normally present in the total rinse water to be neutralized. A spent pickle
bath was analyzed and found to have the equivalent of two lbs of acid/gal and
therefore, 3,400 gals of pickle solution contained 6, 800 of acid. The lbs of
acid to be neutralized due to dumping pickle solution in a four-hr period is
1, 700 plus 110, which equals 1, 810 lbs/hr. The total acid to be neutralized
when pickle liquor is dumped during an eight-hr period is 850 plus 110, which
equals 960 lbs/hr. The total acid to be neutralized when the pickle liquor is
dumped during a 24-hr period is 280 plus 110, which equals 390 lbs/hr. This
analysis of batch dumping of pickle liquor was made in order to properly size
the neutralizing equipment.
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