Commercialization of a Kenaf-Based Biosorptive Process for Use in the Treatment of Contaminated Aqueous Streams

The state of affairs facing engineers and scientists attempting to treat low-level contaminated water using current technologies has resulted in the selection of a process that has significant shortcomings. A technically superior, yet operationally simpler treatment process that is less expensive is needed to assist industries in meeting ever-changing environmental regulations. KenGro Corporation is working to provide kenaf-based products as an effective biobased alternative for treating contaminated aqueous streams. The envisioned process involves loading a vertical contact tank packed with chopped kenaf. Contaminated water will be passed through the column and contaminants will adsorb onto kenaf fibers. This adsorption step will be operated much like an activated carbon column. The results of Phase I provided a strong basis to continue efforts for commercialization of a kenaf-based biosorptive process for use in water treatment. Once the kenaf becomes spent, the fibers will be removed and placed into a compost bed. The compost bed will be used to reduce the volume of the kenaf mass (the adsorbent) while concentrating the heavy metals and degrading the adsorbed biodegradable contaminants (adsorbates) via biotreatment. The envisioned compost units are easy to operate and fit nicely into a rural industry’s capability because of a realistic footprint and low-tech training requirements. The main goal of Phase I was to develop key performance information on the use of kenaf for its ability to remove diesel fuel, zinc, and lead from aqueous solutions. This was performed via preparation of adsorption isotherms for the three water contaminants using three processed forms of kenaf (stalk, core, and bast). The effect of prewashing and/or preoxidizing the kenaf on the adsorption isotherms was evaluated for zinc and lead. The loadings show that kenaf fibers do have an adsorption affinity for both inorganic and organic adsorbates. Ozonation and washing appeared to provide some benefit, but differences in the value of this processing step were quite dramatic, indicating a need for more development of this novel approach. An additional goal of Phase I was to evaluate the rate of compost degradation and track the fate of a pollutant during this degradation process. Composting kenaf fibers was found to be a relatively straightforward process with relatively high mass degradation rates observed. The goals of Phase II are to: Study the effect of numerous washing techniques on adsorption capacity. More closely evaluate the surface benefits of surface oxidation on kenaf adsorption capacity. Evaluate the impact of product storage on the kenaf product toward lead, methylisoborneol, toluene, ethylbenzene, and o-xylene. Evaluate kenaf for adsorption of additional pollutant classes. Examine competitive adsorption of key contaminant classes. Optimize the rate of degradation observed within the composters and evaluate the impact of high levels of heavy metals on the observed compost rate. Set up a pilot system that fully mimics the envisioned full-scale system to be commercialized. Record the results of Phase II in a detailed project report. A common method to be used to conduct all necessary experimental tasks is the generation of adsorption isotherm data. Chemical analyses and reactor configurations will be performed using duplicate experimentation. Analytical techniques to be employed will be those approved by the U.S. Environmental Protection Agency and/or published peer-reviewed standard techniques. It is expected that the successful implementation of Phase II will yield the necessary information to determine the efficiency and commercialization potential of kenaf as a bioadsorbent for treating organic and inorganic contaminated waters.