Occurrence of quantifiable and semi-quantifiable poly- and perfluoroalkyl substances in united states wastewater treatment plants.

Both quantifiable and semi-quantifiable poly- and perfluoroalkyl substances (PFAS) were evaluated in the influent, effluent, and biosolids of 38 wastewater treatment plants. PFAS were detected in all streams at all facilities. For the means of the sums of detected, quantifiable PFAS concentrations were 98 ± 28 ng/L, 80 ± 24 ng/L, and 160,000 ± 46,000 ng/kg (dry weight basis) in the influent, effluent, and biosolids (respectively).

Release of poly- and perfluoroalkyl substances from finished biosolids in soil mesocosms.

Finished biosolids were collected and characterized from seven municipal water resource recovery facilities. Poly- and perfluoroalkyl substances (PFAS) for the 54 quantified in the biosolids ranged from 323 ± 14.1 to 1100 ± 43.

Diffusion of perfluoroalkyl acids through clay-rich soil.

Diffusion through a water saturated silty clay soil column was measured for six perfluoroalkyl acids (PFAAs), including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). An aqueous pore diffusion model, which incorporated linear adsorption parameters measured independently in batch tests and a tortuosity factor determined independently using a bromide tracer test, was used to describe the experimental diffusion data. The diffusion model substantially underpredicted PFAA diffusion through the soil column for the more strongly sorbing PFAAs (most notably PFOS).

Spatial impacts of inorganic ligand availability and localized microbial community structure on mitigation of zinc laden mine water in sulfate-reducing bioreactors.

Sulfate-reducing bioreactors (SRBRs) represent a passive, sustainable, and long-term option for mitigating mining influenced water (MIW) during release. Here we investigate spatial zinc precipitation profiles as influenced by substrate differentiation, inorganic ligand availability (inorganic carbon and sulfide), and microbial community structure in pilot-scale SRBR columns fed with sulfate and zinc-rich MIW. Through a combination of aqueous sampling, geochemical digests, electron microscopy and energy-dispersive x-ray spectroscopy, we were able to delineate zones of enhanced zinc removal, identify precipitates of varying stability, and discern the temporal and spatial evolution of zinc, sulfur, and calcium associations.

Pilot-scale Columns Equipped with Aqueous and Solid-phase Sampling Ports Enable Geochemical and Molecular Microbial Investigations of Anoxic Biological Processes.

Column studies can be employed to query systems that mimic environmentally relevant flow-through processes in natural and built environments. Sampling these systems spatially throughout operation, while maintaining the integrity of aqueous and solid-phase samples for geochemical and microbial analyses, can be challenging particularly when redox conditions within the column differ from ambient conditions. Here we present a pilot-scale column design and sampling protocol that is optimized for long-term spatial and temporal sampling.

Organoheterotrophic Bacterial Abundance Associates with Zinc Removal in Lignocellulose-Based Sulfate-Reducing Systems.

Syntrophic relationships between fermentative and sulfate-reducing bacteria are essential to lignocellulose-based systems applied to the passive remediation of mining-influenced waters. In this study, seven pilot-scale sulfate-reducing bioreactor columns containing varying ratios of alfalfa hay, pine woodchips, and sawdust were analyzed over ∼500 days to investigate the influence of substrate composition on zinc removal and microbial community structure. Columns amended with >10% alfalfa removed significantly more sulfate and zinc than did wood-based columns.

Polygold-FISH for signal amplification of metallo-labeled microbial cells.

An improved in situ hybridization approach (Polygold-FISH) using biotinylated probes targeting multiple locations of the 16 S ribosomal subunit, followed by fluoronanogold-streptavidin labeling and autometallographic enhancement of nanogold particles was developed as a means of signal amplification of metallo-labeled cells, without the need for Catalyzed Reporter Deposition (CARD). Bacterial cells were readily detected based on their gold-particle signal using scanning-electron microscopy and energy-dispersive X-ray spectroscopy when contrasted with controls or cells hybridized with a single probe. Polygold-FISH presents an alternative to CARD-FISH, circumventing the need for aggressive oxidants, which is useful when products of microbial respiration such as those relevant at the microbe-mineral interface could be altered during processing for visualization.