Progress 07/01/03 to 06/30/06
The primary deicing chemical used in Vermont and other northern States of America is sodium chloride (NaCl) or rock salt. Salt is the most effective deicer presently available. According to the data published by the salt institute, an average of about 10 million tons of salt are spread on American roads for snow and ice removal each year. However, environmental impact is a major concern in using salts for winter road maintenance. Studies show that soils, vegetation, water, highway facilities, and vehicles are all adversely affected. In addition salts are highly soluble and follow with any water flow. In Vermont, groundwater, carrying deicing chemicals has contaminated wells and water bodies. Deicing salts also cause vehicles corrosion. Therefore, it is very important to minimize the use of these chemicals or to find other environmentally friendly substitute for them. We are trying to use cheese whey as the major raw material to produce an environmentally friendly
ice/snow melting product. Currently, the United States dairy industry produces 67 billion pounds of cheese whey annually. However, only half of the whey is being utilized into human food products/animal feed. With continuous increases in milk and cheese production in the United States and specially in Vermont disposing of surplus cheese whey is one of the most critical problems for the dairy industry due to its high biological oxygen demand (BOD). One of the highest priorities of the dairy industry therefore, today is to seek ways to expand the use of why-based products for value added products. Therefore, using whey as a major raw material for an environmentally friendly ice/snow melting agent production can be very beneficial to the environment, as well as to the dairy industry. A combined anaerobic fermentation is developed to produce potassium acetate from cheese whey permeate by employing a free-cell or immobilized coculture. Using the immobilized cell fermentation technique the
yield of PA was increased by one and half fold compared to the batch/fed-batch fermentation (PA yield, 2-3 %). The recovery of acetic acid from the whey permeate fermentation broth was carried out using a liquid-liquid reactive extraction method using Alamine 336 and 2-octanol. The effects of various conditions, such as pH, ions, ratio of extractant to diluent and ratio of solvent to broth were investigated. The fermentation broth was filtered through an ultra filter first before being adjusted to different pH and treated with the extraction solvent. pH 3.5 and equal ration of Alamin 336 and 2-octanol to broth, extracted the best amount of acetic acid. We have been able to produce the desired PA at a concentration of 3.5% by the immobilized cell procedure. However, currently we are exploring some new methods in order to further increase the PA yield in the broth.
The results of the whey based environmentally safe deicer research will be beneficial to the environment, the dairy industry, and the highway systems in Vermont and the nation.
- Alam, M., J. Li, and M.R. Guo. 2006. Production of potassium acetate from cheese whey by fermentation. J. Dairy Science (Supplement 1) 89:180.
Progress 10/01/04 to 09/30/05
Conventional deicing salts such as sodium chloride and calcium chloride are causing serious corrosion and major environmental problems. The objective of this project is to use cheese whey as a renewable resource for production of potassium acetate (PA) - a noncorrosive environment-friendly road deicer. A cocultured strain containing lactate/acetate tolerant Lactococcus lactis and Clostridium formicoaceticum was used to produce PA from nutrient-supplemented whey permeate by fermentation in a bioreactor. Previous studies showed that application of fed-batch fermentation in conjunction with continuous flow cell-recycle fermentation in coculture system produced 3.5-4.2% of acetic acid in the fermentation broth, which is equivalent to 5.7-6.9% of PA. We further explored the possibility of using cell immobilization technique in improving the acetate yield. A jacketed glass column (5 cm I.D.) packed with fibrous matrix (cotton cloth) was connected to a 5-L stirred-tank
fermentor through a recirculation line. A positive pressure (3-5 psi) of N2 gas was applied to the fermentor head to maintain anaerobic condition in the system. The experiment was carried out with single inoculation of L. lactis (10%) followed by C. formicoaceticum (10%) into the media in the 5-L vessel and maintained the temperature at 37 C and pH at 7.5 by adding 5 M potassium hydroxide. The fermentation was carried out first in the vessel for 40 h, after which the circulation started through the fibrous-bed bioreactor for another 40-50 h. During this time the bacterial cells were accumulated and trapped onto the cotton cloth. The yield of PA using the immobilized fermentation process was found to range between 4 to 5%. We are now working on a two-step process in an effect to further improve the acetate production. The lactose in the whey permeate will be converted into glucose first, then the fermentation will be carried out using a strain of Clostridium thermoaceticum, a well
known anaerobic thermophile which produces higher concentration of acetic acid. By using C. thermoaceticum (acts only on glucose), we can avoid using C. formicoaceticum (a slow-growing and oxygen-sensitive strain) and hopefully further increase the yield of acetate in the fermentation broth.
This project explores the use of agricultural byproduct cheese whey in the production of an environment-friendly substitute deicer (potassium acetate) by fermentation. If successful, it will be beneficial not only to the environment and highway systems, but also to the dairy industry.
- No publications reported this period
Progress 10/01/03 to 09/30/04
The application of sodium chloride and calcium chloride deicing salts to roadways has increased dramatically in recent years due to public demand for safer winter driving conditions. Unfortunately, these salts create adverse effects such as corrosion-related damage to the highway infrastructure and environmental damage to water supplies and soils. The objective of this project is to utilize lactose from milk permeate, an important byproduct of the cheese industry, as a renewable resource for production of potassium acetate (PA) - a noncorrosive environmentally friendly road deicer. A cocultured stain containing lactate/acetate tolerant Lactococcus lactis and Clostridium formicoaceticum was used to produce PA from nutrient-supplemented whey permeate in a bioreactor. The optimum conditions for the homofermentative process were achieved by inoculating 10% of the coculture under 37C and maintaining the pH at 7.35 by adding 4M potassium hydroxide. The acetic acid
production was 3.5-4.2%, which is equivalent to 5.7-6.9% of acetate. Three processing technologies have been explored for the recovery and drying of the PA from the fermentation broth: (1) PA was obtained directly from the fermentation broth by atmospheric water evaporation; (2) A liquid-liquid reactive extraction method, using alamine 336 (extractant) dissolved in equal volume of 2-octanol (diluent) as the extraction solvent, was used to extract the acetic acid (AA) from the fermentation broth first, then the organic layer (containing AA) obtained was subjected to distillation under 117C in an automatic distillation system for AA recovery. The distilled AA was then reacted with an appropriate amount of potassium hydroxide and dried at 105C for 1 h to produce the PA; (3) PA was obtained by back extraction of the above organic layer after neutralizing with 5M potassium hydroxide and drying under the oven at 105C for 1 h. Currently, a larger scale production of PA based on the methods
described above is underway. We are in the process of investigating the effects of these prototype deicer products on ice/snow in the laboratory and its performance on road application will also be tested accordingly.
Conventional snow/ice melting agents are the cause of serious corrosion and major environmental problems. This project explores the use of cheesemaking byproduct - whey, in the production of an environmentally friendly substitute deicer (potassium acetate) by fermentation. If successful, it will be a win-win-win situation for dairy industry, highway systems, and environmental protection.
- 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.
Progress 01/01/03 to 12/31/03
Currently used deicers cause extensive corrosion-related damage to the highway infrastructure and environmental damage to water supplies and soils. This proposed research explores the use of cheese whey in the production of an environmentally friendly substitute deicer (potassium acetate) by fermentation. In order to improve the acetate yield (up to 4.16% and 5.32% of acetate concentration by using batch fermentation and fed-batch fermentation, respectively) from our previous studies, fed-batch fermentation in conjunction with continuous flow cell-recycle fermentation in coculture system was adopted. A nutrient-supplemented whey permeate substrate (5%) was inoculated with 10% mixed culture containing lactate/acetate tolerant Lactococcus lactis and Clostridium formicoaceticum. The homofermentative process was carried out under 37?C and a constant pH at 7.45 (by adding 5N KOH) in a 5-L fermentor with agitation (100 rpm). Anaerobic condition was maintained by controlling
a positive N2 gas pressure at 1-2 psi inside the fermentor. When the concentration of acetic acid (AA) reached maximum (after 72 h), continuous supply of sterilized substrate was carried out at a flow rate of 40-120 ml/h. At the same time, the fermentation broth was pumped out at the same flow rate through a hollow fiber ultrafiltration membrane, where the filtrate was collected and the retentate (containing coculture bacteria) was recycled to the fermentor. The AA concentration in the fermentation broth maintained at 3.5 to 4.2% (equivalent to 5.71 to 6.85% of acetate) during the extended fermentation period from 84 h to 200 h. The results suggest that this cocultured fermentation process could be used to improve the acetate yield and to produce a low-cost acetate deicer from whey permeate and acid whey. Further experiments with a fibrous-bed bioreactor and a two-stage fermentation process will be compared. Development of a processing technology for the recovery and drying of the
deicer from the fermentation broth is underway. Meanwhile, formulations of the prototype deicing/snow melting products for road application will be prepared and its performance will be tested accordingly.
The massive use of chloride salts as snow/ice melting agents is the cause of serious corrosion and major environmental problems. The objective of this study is to utilize lactose from milk permeate, an important byproduct of the cheese industry, as a renewable resource for production of potassium acetate - a noncorrosive environmentally friendly road deicer. If successful, use of the alternative deicer for road maintenance will be beneficial to the environment, highway systems, and the dairy industry.
- There was no publication in this period (01/01/2003 to 12/31/2003)