AWAM International Conference on Civil Engineering 2019 (AICCE'19) - Nibong Tebal - Malaysia (2019-08-21)

Oxidation of Deep Well Saline Groundwater Generates the Precipitation of Ferrous Sulfide (FeS)

H2S gas which is well known for its rotten egg smell can be traced once the ground-water is pumped out from the tube well. The initial color of the groundwater is green yellowish. After 40 seconds exposed to the oxygen, its colour suddenly turned to black and become sludgy. Afterwards, the black colour turns to partially cloudy af-ter 8 hours being exposed to the oxygen, subsequently, the H2S gas vanishes along with the disappearance of the black colour. Hence, from this reaction, this study aims to investigate the cause of the black precipitate formation which comes from the oxidation of the deep well saline groundwater. As a result, it is found that the black precipitate is a troilite mineral (FeS). The fast precipitation is caused by the chlorine content which is triggered by the presence of oxygen. The elements that contained in the groundwater mostly originated from the seawater. The increase of Fe2+ is caused by the weathering process during the travel of the groundwater through the aquifer. Meanwhile, the decomposition of sulfate by microorganism produces the S2- and this causes the reaction of Fe2+ and S2- to form FeS despite in saline condition.
Mr. Muhammad Fitri Mohd Akhir, Dr. Noor Aida Saad, Professor Nor Azazi Zakaria