Superfund Research Program
Development of a High Performance Bioprocess for Eliminating 1,4-Dioxane in Water
Project Leader: Joseph Salanitro
Grant Number: R43ES022123
Funding Period: Phase I: September 2012 – February 2013
Across the United States, water suppliers and managers are finding dangerous levels of 1,4-dioxane in water. This compound has been used for decades in a wide range of applications, including as (1) a solvent in paints, varnishes, and prints; (2) treatment agent in artificial leather, (3) ingredient in pesticides and fumigants, (4), purifying agent in pharmaceuticals, and (5) solvent in resins, oils, plastics, adhesives, waxes, and cement.
1,4-dioxane is a probable human carcinogen at extremely low levels in water (parts per billion). It is highly soluble and thus, travels extensively in underground water systems. Most importantly, no conventional water treatment technologies can remove 1,4-dioxane from water. There are only two routes of eliminating 1,4-dioxane in water: UV or hydrogen peroxide coupled with ozone oxidation (i.e., advanced oxidation) and biological degradation. The energy and chemical costs of UV and chemical oxidation processes are often prohibitively high. There is also a significant risk of producing harmful byproducts (such as carcinogenic bromate), and these technologies have limited applicability in certain circumstances.
Biological degradation also suffers from a number of drawbacks, including process stability, the need to induce degradation, limited performance, clogging, performance sensitivity, and the production of sludge or secondary waste streams. If these problems can be overcome, however, biological treatment offers a promising method of completely degrading 1,4-dioxane into harmless products and ensuring the integrity of the environment.
The researchers' work is founded on two novel discoveries. First, a high-rate biological treatment pathway has been found that apparently does not require pre-induction. This discovery may significantly simplify the treatment process. Second, this pathway can be utilized in a new high performance bioprocess that may overcome most or all of the engineering obstacles faced by conventional biological treatments. Specifically, this research builds on and certifies these initial successes by conducting a series of laboratory (kinetic) experiences using 1,4-dioxane alone and in the presence of a co-contaminant, trichloroethylene (TCE). A continuous-flow bioreactor prototype is then designed and constructed. This model is tested extensively over several months using actual groundwater from a contaminated site to determine its specific performance under a range of operating conditions. These performance parameters are used to design a larger pilot-scale reactor that will undergo further refining in a field site in the next phase of research.
The primary intended outcome of this research is a high performance bioprocess for eliminating 1,4-dioxane in water resources. Based on successful preliminary studies, it is expected that this new technology will be simpler, more effective, and less costly than any 1,4-dioxane treatment technology available on the market today. Most importantly, the research is intended to provide a valuable tool for protecting and remediating drinking water supplies, thus safeguarding public safety and environmental sustainability.