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Passive Remediation of High Metal Loading, Net Acidic Mine Impacted Water Using Crab

Shell Chitin as a Substrate Amendment

Amanda K. Brown and Dr. Rachel A. BrennanDepartment of Civil and Environmental Engineering, The Pennsylvania State University

This research was funded by a Research Experience for Undergraduates grant from the National Science Foundation under CAREER award CBET-0644983Klondike Mine Discharge, 15 gpm KL-1, Cambria County, PA

(Image Courtesy of Dr. Rachel Brennan)KL-1 Vertical Flow Wetland, Cambria County, PA

Risk Analysis Matrix for Net Acidic Water

Summation of Fe and Al Concentration

(mg/L)

Design Flow Rate for each treatment cell (gpm)

<25 >25<50 >50<100 >100<200

> 5 but < 15 Low Medium Medium Medium

> 50 High High High High

More than 5000 miles of PA streams are impacted by acidic mine drainage. Mine impacted water (MIW) is problematic for aquatic plants and animals, as well as water delivery systems, and human consumption. MIW can be economically treated with passive vertical flow wetlands. Under certain conditions, these passive treatment systems can clog with metal precipitate. New PA DEP “Set Aside Guidelines” warn against treating “high risk” water passively.

Source: http://www.orangewaternetwork.org

Source: PA DEP BAMR AMD Set-Aside Program Implementation Guidelines (2009)

An existing passive treatment system at the Klondike mine discharge in Cambria county, PA (indicated by the star on the above map) has experienced problems with clogging. With an average flow rate of 15gpm, an average pH of 3.3 and an average 137 mg/L total iron; the Klondike discharge is considered “high risk.”

Crab shell chitin provides alkalinity as well as a slowly degrading

source of carbon and nitrogen. In field trials,

crab shell chitin substrate has not clogged with metal

oxides while other substrates have.

Protein 40%

Chitin 20%SC-20

chitin Calcium carbonate 40%

Goal: To evaluate the performance of crab-shell chitin (both on its own, and as a fractional amendment to SMC) in treating “high risk” water

Microcosm Contents:•100mL Klondike MIW•0.25g substrate

Substrates: Increasing amounts of SC-20 ChitoRem™ with the balance spent mushroom compost. (SMC)

Sampling:At each sampling point pH, alkalinity, acidity, and dissolved metal content were measured

0.0

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0 5 10 15 20 25 30 35 40 45 50 55Time (days)

Al (

mg/

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(mg/

L)}

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L) }

Initial Laboratory Conditions of KL-1

discharge water

pHAlkalinity

(mg/L as CaCO3)

Acidity

(mg/L as CaCO3)Dissolved Fe

(mg/L)

Dissolved Mn

(mg/L)

Dissolved Al

(mg/L)

2.38 0 481 62.79 38.14 2.77

Final Conditions After 50 Days Of Treatment

Substrate pHAlkalinity

(mg/L as CaCO3)

Acidity

(mg/L as CaCO3)Dissolved Fe

(mg/L)

Dissolved Mn

(mg/L)

Dissolved Al

(mg/L)

100% Sand (control) 2.68 +/- 0 0 +/- 0 375 +/- 0 52.57 +/- 0 39.34 +/-0 2.67 +/- 0

10% Chitin 4.52 +/- 1.26 21 +/- 30 52 +/- 40 0.20 +/- 0.15 38.78 +/- 1.17 0 +/- 1.34

Traditional VFW Substrate

6.46 +/- 0.18 81 +/- 21 -28 +/- 12 0.29 +/- 0.44 31.90 +/- 6.58 0 +/- 0

30% Chitin 6.21 +/- 0.01 198 +/- 25 -129 +/- 37 5.40 +/- 0.08 35.91 +/- 0.41 0 +/- 0.01

50% Chitin 6.43 +/- 0.03 266 +/- 32 -175 +/- 17 20.92 +/- 5.23 35.11 +/- 0.42 0 +/- 0

70% Chitin 6.39 +/- 0.06 360 +/- 29 -248 +/- 60 7.24 +/- 8.03 32.02 +/-1.46 0 +/- 0

100% Chitin 6.60 +/- 0.02 564 +/- 62 -329 +/- 40 0.20+/-0.18 30.58 +/- 0.96 0 +/- 0.01

•Substrates containing >30% chitin performed equal to or better than traditional VFW substrate

pH

• approached neutrality more rapidly in substrates containing >30% chitin

A continuous flow column study is in progress to further evaluate substrates containing greater than 30% crab shell chitin for treating “high risk” mine impacted water.

Alkalinity

Addition

• substrates containing >30% chitin rapidly surpass the traditional VFW substrate.

Acidity

Removal

• substrates containing >30% chitin rapidly surpass the traditional VFW substrate.

•Thanks to Zach Clement, Abby Caporuscio, Jen McElhoe, and Mary Ann Robinson-Lora

•Printing Funded by UPAC