The Effect of pH and Mineral Additives on Filtration Rate and Heavy Metal Leaching in Marcellus Shale Drill Cuttings
Open Access
- Author:
- Hellgren, Luke Andrew
- Area of Honors:
- Environmental Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Mark Stephen Klima, Thesis Supervisor
Mark Stephen Klima, Thesis Honors Advisor
Mku Thaddeus Ityokumbul, Faculty Reader - Keywords:
- drill cuttings
additives
pH
filtration rate
heavy metal concentration - Abstract:
- Marcellus Shale drilling operations produce large quantities of drilling mud and drill cuttings. While drilling mud is recovered and reused, drill cuttings are often dried and disposed as waste in landfills. Beneficial reuse of drill cuttings has recently been explored for application as a road base, filler for construction and abandoned mines, and even fuel. This increased interest has sparked this study to research a specific method of removing metals from the leachate of oil-based drill cuttings (OBC). Laboratory analyses were conducted to determine the filtration rates and various metal concentrations of OBC leachate. The pH of OBC samples were altered from its natural state to measure the effect of pH on filtration rate and leached metal concentration. Natural and high pH values were found to correspond with high filtration rates and low degrees of metal leaching; samples tested at a low pH correlated with much slower filtration rates and elevated metal leaching. Three types and five amounts of Clean Age (CA) minerals were then added to the OBC filtrate and re-filtered to determine the iron, copper, and aluminum removal efficacy of CA. The cheapest CA (CA-1, or CA old) proved to be the least effective additive and failed to reduce the iron concentration in the filtrate; it was also unable to consistently remove copper. CA-2, the second type of CA tested, was found to reduce the iron concentration by a factor of 2-3 when larger amounts of CA were added (5-20%). CA-2 was unable to reduce the copper concentration of the leachate and actually slightly increased this concentration in each test. Furthermore, CA-6, the most expensive treatment, drastically removed iron from the leachate; between 93.7% and 99.8% of the iron was removed in each test. CA-6, however, also increased the copper concentration by between 207% and 1001%. CA-2 was found to slightly increase the pH of the filtrate, while CA-6 raised the pH from around 5-6 to a value over 12. The effect of CA on pH may explain its influence on metal leaching. Testing for additional metals and different methods of adding the CA may prove beneficial in defining the effectiveness of CA.