Progress 07/01/02 to 06/30/05
Outputs
Currently used snow/ice melting agents (e.g., sodium chloride) are causing serious corrosion and major environmental problems. This project explores the use of cheese whey permeate in the production of an environment-friendly substitute deicer (potassium acetate, PA) by fermentation. A free-cell coculture consisting of a homolactic bacterium (Lactococcus lactis) and a homoacetogen (Clostridium formicoaceticum) was used to convert whey lactose to lactic acid and then to acetic acid (AA) in a bioreactor. The AA concentration obtained using batch fermentation ranged from 1.6 to 2.1% after 60-72 h, which was increased to 1.8 to 2.5% by supplementing the nutrients. Application of fed-batch fermentation increased the concentration of AA to up to 3.2% (after 96 h), which was equivalent to 5.3% of PA. Application of fed-batch fermentation in conjunction with continuous flow cell-recycle fermentation in coculture system using lactate/acetate tolerant strains further increased
the AA concentration, which maintained at 3.5-4.2% (equivalent to 5.7-6.9% of PA) during the extended fermentation period from 84 h to 200 h. In comparison, experiments with the use of immobilized cells in a fibrous-bed bioreactor have been carried out and shown to produce 4-5% of PA after 80-90 h of fermentation. These results suggest that a cocultured fermentation process may be used to produce high yield acetate deicer from whey permeate. In order to recover and produce the PA deicer from the fermentation broth, three processing techniques have been explored: (1) PA was obtained directly from the broth by evaporation; (2) PA was obtained after the AA was extracted using organic solvent (e.g., alamine 336 and 2-octanol at 1:1 ratio), distilled at 117 C and neutralized with 2 M potassium hydroxide; (3) PA was obtained by back extraction of the organic layer (alamine 336 and 2-octanol) after neutralizing with 5 M potassium hydroxide, followed by drying under the oven at 105 C for 1 h.
Scale-up production of the PA deicer products and their effects on ice/snow in the laboratory and road applications should be considered in future studies.
Impacts
We have demonstrated that it is feasible to produce an environment-friendly substitute deicer (potassium acetate) from agricultural byproduct - cheese whey. Successful development and application of the alternative deicer to replace sodium chloride for road maintenance will be beneficial to the dairy industry, transportation systems, and the environment.
Publications
- Zhang, L., Gokavi, S., Li, J. and Guo, M.R. 2004. Optimization of fermentation conditions for development of environmentally friendly deicer. J. Dairy Sci. 87 (Suppl. 1):385.
- Zhang, L., Gokavi, S., Li, J. and Guo, M.R. 2004. Extraction of acetic acid from fermented whey permeate broth. J. Dairy Sci. 87 (Suppl. 1):385.
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Progress 10/01/03 to 09/30/04
Outputs
Biomass wastes such as liquid whey effluents from dairy industry are a burden on the environment due to their high biological oxygen demand (BOD). This project examines the use of whey permeate in the production of a road deicer substitute for sodium chloride, since currently used deicers are causing serious corrosion and major environmental problems. A combined anaerobic fermentation process was developed to produce potassium acetate from cheese whey permeate. A coculture consisting of Lactococcus lactis and Clostridium formicoaceticum was used to convert the whey lactose to lactic acid and then to acetic acid (AA) in a bioreactor. In this study, recovery of AA from the whey permeate fermentation broth was carried out by using a liquid-liquid reactive extraction method using Alamine 336 (extractant) dissolved in 2-octanol (diluent) as the extraction solvent. The effects of various conditions (pH, ions, ratio of extractant to diluent, and ratio of solvent to broth) on
the extraction efficiency (EE) were investigated. The fermentation broth was filtered through an ultra filter first, and then the filtrate was adjusted to different pH and treated with the extraction solvent. The amount of AA extracted by the best solvent identified (Alamine 336 dissolved in equal volume of 2-octonal) at pH 3.5, 4.7, 5.9, 7.1 and 8.3 were 63.5%, 59.7%, 60.9%, 53.0% and 12.0%, respectively. The EE was higher when the broth contained K+ (EE=66.0%) and Na+ (EE=61.0%) compared to the broth containing NH4+ (EE=7.8%). There was no significant difference between EE in the presence of anions SO42- or Cl-. Therefore, it is recommended to use NaOH or KOH to neutralize the pH during the fermentation and use HCl to decrease the pH during extraction. EE was 62.8% when the ratio of extraction solvent to broth was 1:1, 46.44% when 2:1 and 42.18% when 1:2. On the other hand, EE was 62.8% when the ratio of extractant to diluent was 50:50, 50.2% when 70:30 and 47.6% when 30:70. The
results suggested that high rate of AA recovery could be obtained when the pH of the broth was lower than 5.0, the ratio of Alamine 336 to 2-octanol was 1:1 and the ratio of solvent to broth was 1:1. Further experiments on the recovery and drying of the deicers are underway.
Impacts
The ultimate goal of this research is to develop a low-cost acetate deicer from agricultural byproduct - cheese whey. Successful development and application of such a product will be beneficial to the dairy industry, transportation system, and the environment.
Publications
- Zhang, L., Gokavi, S., Li, J. and Guo, M.R. 2004. Extraction of acetic acid from fermented whey permeate broth. J. Dairy Sci. 87 (Suppl. 1):385.
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Progress 01/01/03 to 12/31/03
Outputs
Conventional snow/ice melting agents are harmful to the environment, e.g., highways, bridges, and cars. It is imperative to minimize the use of these chemicals or to find other environmentally friendly substitutes for them. The objective of this project was to use lactose in cheese whey as the major raw material to produce an environmentally friendly snow/ice melting product. An anaerobic mesophilic fermentation process was developed to produce potassium acetate from whey permeate. A free-cell coculture consisting of a homolactic bacterium (Lactococcus lactis) and a homoacetogen (Clostridium formicoaceticum) was used to convert whey lactose to lactate and then to acetate via batch and fed-batch fermentations in a 5-L stirred-tank fermentor. The effect of substrate concentration, pH and other parameters on growth and organic acid production were investigated. Analytical methods employed included HPLC and optical density measurements, etc. The optimal conditions for the
free-cell cocultured fermentation were found to be 37-39?C and pH 7.3-7.6. Nutrient supplementation was necessary for the bacteria to grow well in whey permeate. The acetic acid concentration obtained in the batch fermentation ranged from 1.6 to 2.1% after 60-72 h, which was increased to 1.8 to 2.5% by supplementing the nutrients. Application of fed-batch fermentation further increased the concentration of acetic acid to up to 3.2% (after 96 h), which was equivalent to 5.32% of acetate. In order to further increase acetate yield, studies on adaptation and natural selection of lactate/acetate tolerant strains have been done. In our next studies, fed-batch fermentation in conjunction with continuous flow cell-recycle fermentation or immobilized cells in a fibrous-bed bioreactor in coculture systems will be examined and a two-stage bacterial fermentation process will also be explored.
Impacts
This project is expected to develop a low-cost organic and environmentally friendly snow/ice melting product from agricultural byproduct (cheese whey) to replace sodium chloride. If successful, it will be beneficial not only to dairy industry and transportation system, but also environment and consumers.
Publications
- There was no publication in this period (01/01/2003 to 12/31/2003)
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Progress 01/01/02 to 12/31/02
Outputs
We started this research in July of 2002. A fermentation specialist has been hired. The key instruments and starter cultures have been purchased. Preliminary experiments are being conducted in the laboratory. Our initial results showed that both sweet whey and acid whey can be used for this purpose.
Impacts
Conventional snow/ice melting agents are harmful not only to the environment, but to highways, bridges, and cars. This study is aimed to use agricultural byproduct-cheese whey to convert lactose to organic salt to replace NaCl. If successful, use of the alternatvie deicer for road maitainenance will be benefical to the environment, highway systems, and the dairy industry.
Publications
- No publications reported this period
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