Bio-weathering Using Shewanella oneidensis MR-1 Enhances Selective Recovery of Rare Earth Elements from Alaskan Coal Mines

Coal mines in Alaska with high rare earth elements (REEs) levels (286-524 mg/kg) serve as an alternative domestic source for REEs. Existing leaching/separation technologies fail to selectively recover REEs from the feedstock and require downstream multiple purification stages that increase the overall operational cost. This study aims at bio-weathering coal from two Alaskan coal mines (Wishbone Hill and Healy) at three density fractions (1.3 float, and 1.3 and 1.5 sink) using Shewanella oneidensis MR-1 for achieving higher selective REEs recovery in one-step process. Optimizing the bio-weathering process by varying solids percentages (5.7 to14.3% w/v), particle size (-14 to -200 M), incubation temperatures (30 to 34 °C), and inoculum dosing (0.2 to 1% v/v) resulted in highest recovery of Neodymium (75.3%) and total REEs (98.4%) from 1.3 float Wishbone Hill and 1.3 sink Healy coal, respectively. When compared to the chemical leaching process, bio-weathering enhanced selective recovery of REEs including Scandium, Yttrium, Ytterbium, Terbium, Erbium, and Lutetium from Healy coal at low density, and Yttrium from Wishbone Hill coal at high density. The results indicate the future scope for developing cost-effective selective REEs recovery processes that may address the global critical minerals supply chain risk

Rural Alaska Water Treatment and Distribution Systems Incur High Energy Costs: Identifying Energy Drivers Using Panel Data Analysis for 78 Communities

The energy consumption for water treatment and distribution in rural Alaska communities that represent one of the coldest and most isolated regions in the US has been unexplored. Using energy audits data from Alaska Native Tribal Health Consortium (ANTHC), we investigate the annual energy consumption patterns for water treatment and distribution in 78 rural Alaska communities (average population < 500 people) along with seasonal, regional, and population impacts, and water treatment/distribution system types. Regional trends of per capita annual energy consumption are as follows: Interior > Northern > Southwest > Gulf coast > Southeast regions of Alaska. Our results indicate that the per capita energy consumption is highest during the winter and lowest during the summer. Generally, the per capita energy consumption decreases with an increasing population. The variation of per capita energy consumption based on water distribution types shows that piped circulating systems consume the most energy, followed by washeteria, piped pressure, and closed haul. At the water treatment plant, space heating and electrical motors have the highest per capita energy consumption, followed by domestic hot water, tank heating, and lighting. The findings in this work suggest that per capita energy consumption (kWh/p) for water treatment and distribution in rural Alaska is about 12–26 times higher than the national average and about two orders of magnitude higher economic costs for the same. Overall, this work sheds light on energy use for water treatment and distribution in rural Alaska and establishes a baseline that would be useful for the rural Alaska communities’ adaptation to climate change efforts, specifically in planning for and designing new water systems or updating existing systems