COST EFFICACY OF REUSING ABANDONED MINE DRAINAGE TREATMENT BYPRODUCTS AS A WASTEWATER TREATMENT COAGULANT

Abandoned Mine Drainage (AMD) is a source of pollution that is impacting thousands of miles of streams throughout Pennsylvania’s coal regions. AMD discharges large concentrations of dissolved metals and acidity, killing plant and animal life, and diminishing the buffering capacity of streams. Precipitation of these dissolved solids can occur when AMD discharges are channeled through treatment systems; however, constructing passive treatment systems is a financial burden to many towns and conservation groups. Another environmental and economic challenge in Pennsylvania is phosphorus loading in waterways. Wastewater effluent that contains phosphorus enters rivers and streams, inducing eutrophication, which depletes the water’s dissolved oxygen. Many wastewater treatment plants now have limits set for the amount of phosphorus allowed in wastewater effluent. Chemical coagulants like alum, lime, and iron salts can be added to wastewater to facilitate the flocculation of phosphorus, which allows for easier and faster removal. Commercial grade coagulants can cost treatment facilities $800 to $1000 per ton, which is another financial burden.

AMD and phosphorus loading are two separate environmental threats that can be managed together in a way that would make treatments cost-effective. AMD possesses high concentrations of dissolved iron and aluminum, two metals that effectively adsorb phosphorus and are found in most commercial grade coagulants. Several studies have confirmed that AMD treatment byproducts are just as effective, if not more effective than commercial coagulants when used to remove phosphorus from wastewater. Instead of disposing the iron-rich sludge that is removed from AMD treatment systems, it can be recovered and sold to wastewater treatment facilities to offset the capital costs of AMD treatment, and reduce phosphorus loading in a cost- effective manner.