SOME PASSIVE AND SEMI-PASSIVE TREATMENT METHODS

FOR ACID MINE DRAINAGE

 

Anoxic limestone drains (ALD's) and ponds (see diagram below)

1) very low dissolved oxygen (DO)

2) no Fe 3+ or Al present to clog drain by forming precipitates (at least according to conventional wisdom)

1) Yellow boy precipitates

2) Organic matter (such as compost) allow sulfate reduction, which adds alkalinity

3) Alkalinity may also be added by including limestone in the wetland below the compost (a SAPS system)

SAPS (successive alkalinity-producing system) (see diagram below)

Aluminator

Limestone sand dosing

Limestone channels

Limestone diversion wells

 

SOME IMPLICATIONS FOR LANDOWNERS

Sampling and treatment cannot proceed without landowner cooperation. In all cases, some maintenance is required, so permission to access discharges and treatment facilities must be granted by landowners. Some sites may require improved access so trucks can reach the site. Access will also be needed for chemistry and flow monitoring and possibly visits by tours or classes.

 

Anoxic limestone drains (ALD's)

 

Settling Ponds (oxidation ponds, SAPS, Aluminator)

 

Limestone dosing (and channels)

 

Limestone diversion wells

 

Public Relations

 

WHERE DOES THE MONEY COME FROM? WHERE DOES IT GO?

 

 

IRON OXIDE RECOVERY - A BUSINESS OPPORTUNITY?

 

The iron hydroxides (yellow boy) that precipitate in pond treatment systems may be resources. The idea to recover the iron has been around at least since the turn of the century, but it may be becoming a reality now. The iron hydroxides deposited in passive pond treatment systems are consistently very high in iron content, and are being seriously proposed for use in sewage treatment, as pigment, as colorants in construction material, and other uses. The economics are being worked on now by a consultant in western PA (Bob Hedin, Hedin Environmental). Dr. Hedin has shipped tons of iron oxide to a pigment company for processing..

 

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