Water Resources Research Act Program

Details for Project ID 2013NV194B

Optimization of ozone-biological activated carbon treatment for potable reuse applications

Institute: Nevada
Year Established: 2013 Start Date: 2013-03-01 End Date: 2016-02-28
Total Federal Funds: $39,991 Total Non-Federal Funds: $83,396

Principal Investigators: Daniel Gerrity

Abstract: There is an increasing global trend toward more efficient use of water resources in both urban and rural communities. In addition to innovative water management and acquisition strategies (e.g., water transfers, banking, and trading), numerous municipalities are turning to water reuse in a variety of contexts to bolster their water portfolios. The benefits of water reuse are generally more pronounced in arid and semi-arid regions, such as the American Southwest, but these benefits can also be experienced by coastal communities faced with saltwater intrusion or any region where the quantity or quality of the water supply may be compromised. In recent years, the most notable application has been potable reuse, which is essentially recapturing treated wastewater for potable applications. Significant research funding is being allocated to study the intricacies of potable reuse, including identification of critical contaminants, evaluations of existing and emerging treatment technologies, assessments of potential public and environmental health impacts, and surveys of public perception. Much of this research focuses on trace organic contaminants (e.g., pharmaceuticals), pathogens, and water quality parameters that can be used as surrogates or indicators of larger contaminant classes, notably total organic carbon. Since there are few established guidelines or regulatory frameworks for potable reuse, the treatment trains vary considerably from one system to another. The current standard in potable reuse is microfiltration, reverse osmosis, and an advanced oxidation process, but this treatment train is plagued by a number of concerns related to practicality and sustainability. The most popular alternative in the water reuse industry is some variation of ozone and biological activated carbon (BAC). This process is ~70% cheaper, consumes ~80% less energy, and does not suffer from the residuals problems associated with reverse osmosis. Variations of this treatment train have already been demonstrated in several pilot- and full-scale installations, but there is a critical need to optimize the process to satisfy pending regulatory guidelines, specifically an effluent total organic carbon concentration of 0.5 mg/L. The proposed 18-month study will allow for more widespread public and regulatory acceptance of the more sustainable ozone-BAC treatment train by optimizing the ozone dose, empty bed contact time for the BAC process, and geometry of the BAC contactor. In addition, the study will determine whether additional pre- or post-treatment is necessary to satisfy relevant regulatory and public health criteria. The optimization process will focus on achieving the 0.5-mg/L TOC benchmark, but the final operational conditions will also be evaluated against other potable reuse metrics, including trace organic contaminant mitigation, pathogen removal or inactivation, and sustainability. The proposed study will ultimately address several USGS research objectives and has the potential to impact a large number of graduate students in the laboratory and classroom.