Remediation of mechanical thermal expression product waters using raw Latrobe Valley brown coals as adsorbents

Abstract

Mechanical Thermal Expression (MTE) dewatering of Latrobe Valley brown coals produces water that contains both organic and inorganic impurities at levels that require some remediation before it can be used or released to the environment. Purification of this water may be a problem for future operations due to the economic and engineering difficulties associated with the treatment of large volumes of acidic, salty and organic-rich waters. This study investigates the ability of Latrobe Valley brown coal itself to adsorb organic and inorganic components from MTE product water. The adsorbent/water contact mechanism used in this paper is the physical mixing of MTE water with brown coal. The ability of the coals to remove Dissolved Organic Carbon (DOC) and cations increased with the concentration of these components in the MTE water. Approximately 5–6% of the feed coal to the MTE drying process would be required to remediate the water produced to the levels established in this paper. Potential for the use of a lower proportion of feed coal is possible by increasing the water to coal ratio, however it may be that increasing the amount of feed coal used to remediate MTE water results in a higher quality water postremediation.