the effect of active calcium treatments on the ph levels and amount of sludge in acid mine drainage...
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The Effect of Active Calcium Treatments on the pH Levels
and Amount of Sludge in Acid Mine Drainage
Amanda Grant
Deep Run High School
Henrico County Public Schools
Purpose
Determine which active calcium treatment would raise the pH of acid mine drainage closest to neutral while
creating the least amount of sludge.
What is acid mine drainage (AMD)?
Origin: abandoned coal or metal minesPyrites + water+ oxygen= AMD Potentially flows into waterways where it
disrupts the environment T. and L. ferrooxidans speed up the rate of
generation of AMD
Acid Mine Drainage….Can be visually detected by the yellow-
orange color which comes from iron-containing flocculates and precipitates.
Problems with AMD
Pyritesentering
waterways
Increased acidity levels:
Creation of flocculates:
Sterile waterways
Damage habitats
Decline in human outdoor activity
Destroysfood webs
Threatens
biodiversity
Corrosion of man-made objects
How to treat AMD…
raise pH above 7 Types of Alkaline Chemicals:
*limestone *hydrated lime*pebble quicklimecaustic sodasoda ashammonia
Drawbacks: sludge created
Types of Treatments: *Active Passive
Allow naturally occurring processes to decrease acidity in a controlled area
Methods and Materials
Collected water from Contrary Creek in Louisa County, Virginia
Methods and Materials…
Four beakers were filled with 50 ml of creek water Group A: control: no treatment Group B: 0.5 g of limestone Group C: 0.28 g of pebble quicklime Group D: 0.37 g of hydrated lime
pH meter was used to measure each pH every half hour until neutralized.
Results:
Descriptive Statistics
AMD Chemical Treatments
A: Creek Water (control)
B: Limestone C: Pebble Quicklime
D: Hydrated Lime
Mean 5.1 9.4 12.4 12.4
Range 1 1.1 0.2 0.2
Minimum 4.7 8.7 12.2 12.2
Maximum 5.7 9.8 12.4 12.4
Variance 0.11 0.11 0.006 0.006
Standard Deviation 0.33 0.33 0.077 0.077
Number of Trials 10 10 10 10
Inferential StatisticsA vs B t= 29 B vs C t= 27.9 C vs D t= 0 A vs C t= 67.8 B vs D t= 27.9 a = 0.05 A vs D t= 67.8 Df= 18 table t= 2.101
The Effect of Different Types of AMD Treatments on pH Levels
The Effect of Different Types of AMD Treatment on the Amount of Sludge Descriptive Statistics
AMD Chemical Treatments
A:Creek Water
(control)
B: Limestone C: Pebble Quicklime
D: Hydrated Lime
Mean 0 2.2 2.7 2.7
Range 0 3 3 3
Minimum 0 1 1 1
Maximum 0 4 4 4
Variance 0 0.67 1.1 0.57
Standard Deviation 0 0.82 1.05 0.75
Number of Trials 10 10 10 10
Inferential StatisticsA vs B t= 8.5 B vs C t= 1.2 C vs D t= 0 A vs C t= 8.2 B vs D t= 1.2 a = 0.05 A vs D t= 11.3 Df= 18 table t= 2.101
The Effect of Different Acid Mine Drainage Treatments on the pH levels and amount
of sludge(ml)
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Conclusions: Reasons for Findings
Limestone increased the pH closest to 7, while creating least amount of sludge Carbonate solutions such as limestone do not
increase the pH of water above 8.5. Hydroxides such as hydrated lime can raise
pHs above 10.
Some metals require pH levels around 10.5 to precipitate so limestone may not have been the most efficient.
Future Studies:
Test all six active treatmentsActive Treatments versus Passive Calcium versus sodium compounds
Improvements:
Larger quantities of water tested Flowing water rather than stagnantMore specific measurements: centiliters Test rate of neutralization, pH levels,
amount of sludge, and the amount of metals remaining in water after treatment.
The Effect of Active Calcium Treatments on the pH Levels and Amount of Sludge in Acid Mine
Drainage
Amanda Grant
Deep Run High School
Henrico County Public Schools