M. E. Tumbleson

Characterization of dairy waste streams, current treatment practices, and potential for biological nutrient removal

Abstract Fifteen milk processing plants in the Upper Midwest of the United States participated in a study to obtain information on general process operation, waste generation and treatment practices, chemical usage, and wastewater characteristics. Long term data on wastewater characteristics were obtained for 8 of the 15 dairy plants, and a 24-h composite wastewater sample was characterized in detail for each plant. Wastewater flow rates and characteristics varied greatly among and within plants and were not easily predictable even when detailed information on processing operations was available. In addition, the contribution of milk and milk products to the waste streams was underestimated by plant operators. The use of caustic soda, phosphoric acid, and nitric acid for cleaning had a significant impact on wastewater characteristics, despite the implementation of changes in chemical usage practices during recent years. In particular, the use of phosphoric acid based cleaning products has been reduced to eliminate or decrease discharge fines. It was determined that most of the on site treatment facilities require renovations and/or operational changes to comply with current and future discharge regulations, especially with respect to nutrient (nitrogen and phosphorus) levels in their waste streams. It was concluded that biological nutrient removal of dairy wastewaters should be feasible given the relatively high concentrations of easily degradable organics, the generally favorable organic matter to total phosphorus ratio, and the very favorable organic matter to nitrogen ratio.

Comparison of modified dry-grind corn processes for fermentation characteristics and DDGS composition.

ABSTRACT Three different modified dry-grind corn processes, quick germ (QG), quick germ and quick fiber (QGQF), and enzymatic milling (E-Mill) were compared with the conventional dry-grind corn process for fermentation characteristics and distillers dried grains with solubles (DDGS) composition. Significant effects were observed on fermentation characteristics and DDGS composition with these modified dry-grind processes. The QG, QGQF, and E-Mill processes increased ethanol concentration by 8–27% relative to the conventional dry-grind process. These process modifications reduced the fiber content of DDGS from 11 to 2% and increased the protein content of DDGS from 28 to 58%.

Comparison of Enzymatic (E-Mill) and Conventional Dry-Grind Corn Processes Using a Granular Starch Hydrolyzing Enzyme

ABSTRACT A new low temperature liquefaction and saccharification enzyme STARGEN 001 (Genencor International, Palo Alto, CA) with high granular starch hydrolyzing activity was used in enzymatic dry-grind corn process to improve recovery of germ and pericarp fiber before fermentation. Enzymatic dry-grind corn process was compared with conventional dry-grind corn process using STARGEN 001 with same process parameters of dry solid content, pH, temperature, enzyme and yeast usage, and time. Sugar, ethanol, glycerol and organic acid profiles, fermentation rate, ethanol and coproducts yields were investigated. Final ethanol concentration of enzymatic dry-grind corn process was 15.5 ± 0.2% (v/v), which was 9.2% higher than conventional process. Fermentation rate was also higher for enzymatic dry-grind corn process. Ethanol yields of enzymatic and conventional dry-grind corn processes were 0.395 ± 0.006 and 0.417 ± 0.002 L/kg (2.65 ± 0.04 and 2.80 ± 0.01 gal/bu), respectively. Three additional coproducts, germ 8.0...

Comparison of Raw Starch Hydrolyzing Enzyme with Conventional Liquefaction and Saccharification Enzymes in Dry-Grind Corn Processing

ABSTRACT In a conventional dry-grind corn process, starch is converted into dextrins using liquefaction enzymes at high temperatures (90–120°C) during a liquefaction step. Dextrins are hydrolyzed into sugars using saccharification enzymes during a simultaneous saccharification and fermentation (SSF) step. Recently, a raw starch hydrolyzing enzyme (RSH), Stargen 001, was developed that converts starch into dextrins at low temperatures (<48°C) and hydrolyzes dextrins into sugars during SSF. In this study, a dry-grind corn process using RSH enzyme was compared with two combinations (DG1 and DG2) of commercial liquefaction and saccharification enzymes. Dry-grind corn processes for all enzyme treatments were performed at the same process conditions except for the liquefaction step. For RSH and DG1 and DG2 treatments, ethanol concentrations at 72 hr of fermentation were 14.1–14.2% (v/v). All three enzyme treatments resulted in comparable ethanol conversion efficiencies, ethanol yields, and DDGS yields. Sugar pr...

Separation of Fiber from Distillers Dried Grains with Solubles (DDGS) Using Sieving and Elutriation

ABSTRACT A process was developed to separate fiber from distillers dried grains with solubles (DDGS) in a dry-grind corn process. Separation of fiber from DDGS would provide two valuable coproducts: 1) DDGS with reduced fiber, increased fat, and increased protein contents; and 2) fiber. The process, called elusieve process, used two separation methods, sieving and elutriation, to separate the fiber. Material carried by air to the top of the elutriation column was called the lighter fraction and material that settled to the bottom of the column was called the heavier fraction. We evaluated the compositions of fractions produced from sieving and elutriation. Two commercial samples of DDGS were obtained from two dry-grind corn plants. Sieving over four screens (869, 582, 447, and 234 μm openings) created five size categories. The two smallest size categories contained >40% (w/w) of the original DDGS and had reduced fiber and increased protein and fat contents relative to the original DDGS. Elutriation of the...

Variability in the nutritional quality of distillers solubles

Abstract Use of ethanol in fuels has led to increased production of industrial ethanol, and consequently of a coproduct, distillers solubles (DS). While DS from beverage ethanol processing have been shown to be valuable as animal foods, there are few data on the nutritional value of DS from industrial ethanol. The purpose of this study was to obtain nutritional data on the latter. Samples of DS were obtained from a corn wet milling/ethanol plant during five periods of 5–6 days each and analysed for nutrient content. Nutritional value varied with periods. Available energy in DS was lower than for corn. Most amino acids were in high concentrations, relative to many feeds, but digestibilities of several essential amino acids were low. DS have potential as food for non ruminants, but high nutrient variability, low amino acid digestibility and dewatering difficulties have to be addressed. Feeding trials will be necessary to establish practical dietary limits.

Development of Fumonisin-Induced Hepatotoxicity and Pulmonary Edema in Orally Dosed Swine: Morphological and Biochemical Alterations:

The fumonisin (FB) mycotoxins induce liver injury in all species but induce fatal pulmonary edema (PE) only in pigs. They inhibit ceramide synthase in the sphingolipid biosynthetic pathway. To study the pathogenesis of PE, we examined the early events in the development of FB-induced PE and hepatotoxicity in pigs. Pigs were fed FB-contaminated culture material at 20 mg fumonsin B1 (FB 1)/kg body weight/day. Groups of 4 pigs were to be euthanatized on 0, 1, 2, 3, 4, or 5 days after initial exposure to FB or when PE developed. Pigs developed PE beginning on day 3; none survived beyond day 4. Progressive elevations in hepatic parameters, including serum enzymes, bile acids, total bilirubin, and histologic changes, began on day 2. Early histologic changes in the lung (day 2) consisted of perivascular edema followed by interlobular and peribronchial edema. Ultrastructurally, alveolar endothelial cells contained unique accumulations of membranous material in the cytocavitary network beginning on day 2. Marked elevations in sphinganine, sphingosine, and their ratio began on day 1 for all tissues whether affected morphologically (lung, liver) or not (kidney, pancreas). The membranous material in endothelial cells may be accumulations of sphingoid bases with damage to the cytocavitary network. Thus, FB induces early elevations in sphingolipids and hepatic injury, followed by alveolar endothelial damage, which may be the critical event in the pathogenesis of PE in pigs.

Effects of ground corn particle size on ethanol yield and thin stillage soluble solids.

ABSTRACT The effects of ground corn particle size on ethanol yield and soluble solids in thin stillage was evaluated using a 2-L laboratory dry-grind procedure. The procedure was optimized for grinding, liquefaction, sacchari-fication, and fermentation parameters. The optimized procedure was reproducible with a coefficient of variation of 3.6% in ethanol yield. Five particle size distributions of ground corn were obtained using a cross-beater mill equipped with five screens (0.5, 2, 3, 4, and 5 mm). Particle size had an effect on ethanol yield and on soluble solids concentration in thin stillage. The highest ethanol yield of 12.6 mL/100 mL of beer was achieved using a 0.5-mm screen in the cross-beater mill. Treatment using the 0.5-mm mill screen resulted in soluble solids concentration of 25.1 g/L and was higher than soluble solids concentrations obtained with other screens. No differences in soluble solid concentrations were observed in samples of thin stillage obtained from 2, 3, 4, and 5-mm screens whi...

Evaluation and strategies to improve fermentation characteristics of modified dry-grind corn processes.

ABSTRACT New corn fractionation technologies that produce higher value coproducts from dry-grind processing have been developed. Wet fractionation technologies involve a short soaking of corn followed by milling to recover germ and pericarp fiber in an aqueous medium before fermentation of degermed defibered slurry. In dry fractionation technologies, a dry degerm defiber (3D) process (similar to conventional corn dry-milling) is used to separate germ and pericarp fiber before fermentation of the endosperm fraction. The effect of dry and wet fractionation technologies on the fermentation rates and ethanol yields were studied and compared with the conventional dry-grind process. The wet process had the highest fermentation rate. The endosperm fraction obtained from 3D process had lowest fermentation rate and highest residual sugars at the end of fermentation. Strategies to improve the fermentation characteristics of endosperm fraction from 3D process were evaluated using two saccharification and fermentatio...

Economics of Fiber Separation from Distillers Dried Grains with Solubles (DDGS) Using Sieving and Elutriation

ABSTRACT Separation of fiber from distillers dried grains with solubles (DDGS) provides two valuable coproducts: 1) enhanced DDGS with reduced fiber, increased fat and increased protein contents and 2) fiber. Recently, the elusieve process, a combination of sieving and elutriation was found to be effective in separating fiber from two commercial samples of DDGS (DDGS-1 and DDGS-2). Separation of fiber decreased the quantity of DDGS, but increased the value of DDGS by increasing protein content and produced a new coproduct with higher fiber content. Economic analysis was conducted to determine the payback period, net present value (NPV), and internal rate of return (IRR) of the elusieve process. The dependence of animal foodstuff prices on their protein content was determined. Equipment prices were obtained from industrial manufacturers. Relative to crude protein content of original DDGS, crude protein content of enhanced DDGS was higher by 8.0% for DDGS-1 and by 6.3% for DDGS-2. For a dry-grind plant proc...