CASE STUDY No. 9649

KEY WORDS BILGE OIL, REUSE OF

Madison Chemical Co., Inc.
P.O. Box 1599
3141 Clifty Drive
Madison, IN 47250-0599

Contact: William Torline, Chemical Engineer. Tel: 812-273-6000. Fax: 812-273-6002.

Summary

A bilge water treatment and recovery system has enabled a barge line to reclaim nearly 2 million gallons of fuel oil over a 4-year period, avoiding bilge water disposal costs of $1.2 million and new oil purchase costs of $1.5 million.

Action

Tow boat diesel engines generate an oily waste, much of which ends up on the floor of the engine room and eventually in the boat's bilge. Formerly, this waste water was pumped from the boat and trucked to a land-based treatment plant for disposal as an unusable hazardous waste, at a cost of about 80¢ per gallon. American Commercial Barge Line (ACBL) thought there must be a better way and asked Madison Chemical to design a system to collect, process, and reclaim the oil as fuel for ACBL's fleet of tugs.

Madison obtained bilge water samples from the ACBL fleet and analyzed them to determine the matrix--various chemical constituents. The two companies then formed a joint venture to establish a series of 7,000-gallon bilge water holding tanks along the Mississippi River for tow boats to use as bilge pit stops. Now, every six to eight weeks, a dedicated hopper barge from ACBL drains the contents of each holding tank for transport to a treatment site in Memphis at a former refinery tank farm with 400,000 gallons of capacity. Treatment consists of these steps:

  1. Packed media coalescer, to enhance oil/water separation
  2. Precipitation, for solids removal
  3. Ultrafiltration, for emulsified oil removal
  4. Carbon filtration, for organic removal
  5. Ion exchange, for heavy metal polishing
  6. Final pH adjustment, to assure proper pH before final discharge of purified water into the river.

The recovered oil is mixed with virgin diesel fuel for the tow boat fleet. The system has the capacity to process about 1.5 million gallons of waste bilge water per year.

The system has reduced waste bilge processing for disposal from an estimated previous 1.5 million gallons per year to about 5,000 gallons. Corresponding disposal costs have dropped from $1.2 million to $4,000 per year. Oil recovery on the order of 500,000 gallons per year has reduced diesel fuel purchase costs by more than $350,000 per year.

Payback

The system cost of $200,000 was paid back in less than a year.

Additional benefits

  1. The system achieved its design goals for wastewater discharge to meet NPDES requirements including pH levels.
  2. ACBL is considering entering into agreements for treating bilge water from other river operators.
 

 

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