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

Threatensbiodiversity

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

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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