ANALYSIS AND DESIGN OF FRACTIONAL CRAB-SHELL AMENDMENTS TO SPENT MUSHROOM COMPOST FOR THE TREATMENT OF HIGH-STRENGTH MINE IMPACTED WATER
Open Access
- Author:
- Sick, Bradley
- Area of Honors:
- Civil Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Eric Todd Donnell, Thesis Supervisor
Rachel Alice Brennan, Thesis Supervisor
Eric Todd Donnell, Thesis Honors Advisor - Keywords:
- acid mine drainage
mine impacted waters
crab-shell
crab shell
chitin
AMD
mine remediation
passive remediation - Abstract:
- Anaerobic passive treatment systems remediating high-strength mine impacted water (MIW) have not displayed consistent success. A promising new substrate, crab-shell, has shown to provide improved remediation of low-strength MIW over the traditional spent mushroom compost (SMC) and limestone mixture used in vertical flow wetlands (VFWs). This study utilizes high-strength MIW (140 mg/L iron and 380 mg/L as CaCO3 hot acidity) from an abandoned mine site in Cambria County, PA, (Klondike-1 site) to determine the effectiveness of treatment with crab-shell. Column studies were used to quantify acidity reduction rates and metal removal capacities, as well as confirm suitable hydraulic residence times (HRTs). Six columns were wet-packed with incremental fractions (50% - 100% by mass) of crab-shell in SMC, and two additional columns were used as controls: one with SMC and limestone (standard treatment), and one with 100% silica sand (negative control). Effluent samples collected throughout the 153 day test reveal greater alkalinity generation from crab-shell containing substrates (average 680 mg/L as CaCO3 before breakthrough) compared to the traditional SMC-LS substrate (average 136 mg/L as CaCO3 before breakthrough). Greater fractions of crab-shell correlated to greater longevity in water neutralization and metals removal, with overall substrate capacity (L of MIW treated per kg substrate) ranging from 441 L/kg (60%) to 830 L/kg (100%) in crab-shell containing substrates, compared to 347 L/kg for the traditional LS substrate A cost analysis of treatment using a VFW containing the various substrates was developed based on the longevity of the substrate to maintain a pH greater than 5.5. Considering included costs, a VFW using 70% crab-shell is determined to be the most economical ($101,341 total cost for 25 year treatment).