Increased regulatory scrutiny has created a big market for treatment of wastewater being discharged directly to receiving streams rather than to municipal treatment plants by more than 90,000 facilities in the U.S. These facilities in general have large enough flows to justify the investment in treatment equipment rather than pay municipalities for this service. The McIlvaine Company has compiled rankings of these facilities by number within each industry category and included this display in an online database: U.S. Industrial Facilities With Water Discharges.
The heavy construction industry heads the list with just under 4,000 facilities. This does not include 2,000 ready mixed concrete plants and another 1,800 crushed and broken limestone plants. It does not include 1,700 sand and gravel plants. 1,854 power plants are direct dischargers. But this is equaled by the number of gold mines. 1,200 bituminous and lignite coal operations are also included.
The food and related industries are significant discharges. Here are the totals for the largest categories:
Category # of plants
Dairy farms 688
Chicken processing 514
Cattle lots 506
Fish hatcheries 497
Poultry and eggs 233
Poultry processing 190
Wet corn milling 47
These facilities are subject to existing and proposed discharge rules. EPA finalized a rule June 30 to reduce discharges from farm-raised fish facilities that generate wastewater and discharge it directly into U.S. waters. The rule will reduce annual discharges of suspended solids by more than 500,000 pounds and also will reduce the amount of toxic pollutants at 245 facilities that produce at least 100,000 pounds of fish per year and discharge at least 30 days per year.
The chemical industry is another segment with large numbers of direct dischargers. Included are:
Category # of plants
Industrial organic chemicals 372
Plastics and synthetic resins 316
Medicinal chemicals 116
Pharmaceutical preparations 110
Paints and varnishes 109
Nitrogen fertilizers 70
Cyclic crudes/dyes 70
Phosphate fertilizers 42
The 90,000 plants include many commercial facilities such as hotels and retail operations. There are also 2,400 gasoline service stations and 1,600 crude oil and gas operations in the database.