Year Established: 2014 Start Date: 2014-03-01 End Date: 2015-02-28
Total Federal Funds: $19,623 Total Non-Federal Funds: $32,560
Principal Investigators: Srijan Aggarwal
Abstract: State of Alaska and the Alaska department of environmental conservation (AK-DEC) are concerned about the availability of clean drinking water resources in the rural and remote Alaskan communities. While attempts have been made to set up centralized facilities in such communities, their upkeep and maintenance over the long term is expensive. Often such centralized systems also lead to spread of pathogenic organisms owing to the proximity of water and wastewater facilities as well as unsanitary hauling of drinking water and wastewaters by the individual homeowners (Chambers et al., 2009). Thus, there is an increasing need of innovative yet simple, decentralized individual home-based point-of-use drinking water treatment/reuse systems in the Alaskan rural communities. In recent times, there has been a significant research and application of nanotechnology in environmental engineering and specifically water treatment arena (Theron et al., 2008). Nanoparticles, owing to high surface area, antimicrobial capacities and unique physical/chemical properties, hold immense promise in varied fields, including environmental engineering (Li et al, 2008). While nanoparticles such as titanium dioxide (TiO2), zero valent iron (nZVI), and silver (Ag) have been explored for water treatment applications, novel nanoparticles are being discovered due to tremendous advances in the field. One such novel nano-material, ‘graphene’, recently discovered in 2004, is a sheet of carbon atoms just one atom thick and is said to be the strongest material ever measured. With its excellent thermal, electrical and material properties, it is being dubbed the find of the twenty first century and is predicted to revolutionize the fields of engineering and technology. The discoverers of graphene were awarded the Nobel prize in the year 2010, signifying the importance of this discovery. Inspired by its excellent properties, research on this material is attracting researchers from diverse fields. Owing to nano-porous structure of graphene sheets, early research has shown great potential for their use in membrane filters for particle removal, distillation, disinfection and water reuse. However, the potential of nanomaterials in environmental applications is marred by the threat of accidental discharge and leaching in environmental systems (Li et al., 2008). And release of nanomaterials in the open environment is risky because their effect on human, aquatic and ecosystem health are not properly understood in most cases. One way to minimize accidental discharge is to immobilize the nanoparticles in alginate gel. Even though few early experiments have shown comparable contaminant removal efficacies for bare and immobilized nanoparticles, more work is needed for complete understanding of performance of immobilized nanoparticles in treatment systems. Especially, no information is available on the efficacy of graphene oxide nanoparticles immobilized in alginate gel for water treatment purposes. We plan to evaluate the potential of gel-immobilized graphene oxide nanoparticles as a water treatment option in batch and column experiments to be conducted in the WERC laboratories. We will study the removal of following contaminants from the source waters: natural organic matter (disinfection by-product precursors), heavy metals (Cd and Pb), microbial contamination, and arsenic. Batch studies with bare and immobilized nanoparticles will be performed to study (a) extent of removal (b) kinetics of removal. Experiments will be conducted to obtain adsorption isotherms for bare and immobilized nanoparticles. Moreover, experiments will be conducted to systematically vary bead size, and concentration of nanoparticles in the beads to determine the optimum values in terms of contaminant removal. Time permitting; column studies will be performed to study the breakthrough properties of these systems. This is the first phase of the study wherein entrapped nanoparticles will be evaluated for their efficacy in water treatment. A follow up study will look at entrapment of microbes with biodegradation potential and then using a mixture of two beads (i.e. those entrapping nanoparticles and those entrapping useful microbes) in the packed bed columns to be able to custom ‘design’ the columns depending upon source water characteristics and desired contaminant removal.