The exploitation of coal and metallic mineral resources worldwide invariably results in the production of large quantities of overburden, gangue, and tailings materials containing significant amounts of sulfide minerals. These sulfide minerals, which include sphalerite, chalcopyrite, galena, and other complex sulfides, are often disseminated in pyrite, which is the most abundant sulfide mineral in the earth's crust. Once exposed to water and oxygen through mining and mineral processing operations, these sulfides become immediately susceptible to chemical and biochemical oxidation with the consequent production of highly acidic, metal‐laden leachates, which are generally referred to as acid rock drainage (ARD) or acid mine drainage (AMD). This ARD production, which can be sustained for hundreds of years, has become the single biggest environmental problem facing the mining and mineral industry. Untreated acid rock drainage leads to serious contamination of large areas of land, as well as surface and ground water resources. The seriousness of the problem has led to major research efforts to find solutions. However, effective ARD treatment and prevention solutions have eluded the scientific community over the past decades. This paper presents a detailed review of the current state of scientific knowledge with regard to the magnitude of the problem, the chemistry and mechanism of sulfide mineral oxidation and ARD formation, the role of microorganisms in ARD formation process, and the proposed approaches for the treatment, control, and prevention of ARD formation. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.

Ammonium contamination in water is a major concern worldwide. This study focuses on the removal of ammonium from aqueous solution by batch adsorption experiments using biochar derived from a combination of various wood chips (spruce, pine, and fir). Adsorption characteristics of ammonium onto biochar were evaluated as a function of biochar dosages, initial concentrations of ammonium, contact time and pH. Results demonstrated that ammonium removal increased with the increase of biochar dosage. The percentage of ammonium removal reached a value of 80% at a biochar dosage of 100 g/L. Ammonium removal decreased by 15% with the increase of initial ammonium concentration by 50 mg/L. The optimum pH for ammonium removal was considered in the range from 6 to 8. Ammonium removal reached its stable value within 3 days. The maximum adsorption capacity of ammonium was 0.96 mg/g for 80 mg/L of initial ammonium concentration. The adsorption isotherm followed both the Langmuir and Freundich models for ammonium adsorption onto biochar. Fourier Transform Infrared (FTIR) spectroscopy results indicated the presence of amine, amide and nitrile functional groups on the surface of biochar which could contribute to the adsorption of ammonium onto biochar. Thus, biochar derived from various wood chips showed the potential to remove ammonium from aqueous solution.

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is a professor in the Department of Electrical, Computer, and Systems Engineering (ECSE) at Rensselaer Polytechnic Institute (RPI) where he teaches courses on electromagnetics, electronics and instrumentation, plasma physics, electric power, and general engineering. His research involves plasma physics, electromagnetics, photonics, biomedical sensors, engineering education, diversity in the engineering workforce, and technology enhanced learning. He learned problem solving from his father (who ran a gray iron foundry), his mother (a nurse) and grandparents (dairy farmers). He has had the great good fortune to always work with amazing people, most recently professors teaching circuits and electronics from 13 HBCU ECE programs and the faculty, staff and students of the Lighting Enabled Systems and Applications (LESA) ERC, where he is Education Director. He was RPI ECSE Department Head from 2001 to 2008 and served on the board of the ECE Department Heads Association (ECEDHA) from 2003 to 2008. He is a Life Fellow of the IEEE.

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