Source: VIRGINIA POLYTECHNIC INSTITUTE submitted to
BIOFUELS PRODUCTION FROM COTTON GIN WASTE AND RECYCLED PAPER SLUDGE
 
PROJECT DIRECTOR: Agblevor, F. A.
 
PERFORMING ORGANIZATION
BIOLOGICAL SYSTEMS ENGINEERING
VIRGINIA POLYTECHNIC INSTITUTE
BLACKSBURG,VA 24061
 
NON TECHNICAL SUMMARY: Renewable energy sources can provide the United States with a stable reliable domestic energy supply, contribute very little, if any, net carbon dioxide into the atmosphere, reduce the demand for fossil fuels and hence reduction in NOx, SOx, carbon monoxide, and hydrocarbon emissions into the atmosphere. It can revitalize rural agricultural economies and thus create new jobs. USDA estimated that a 100 million gallon bioethanol plant could create 2,250 local jobs (temporary and/or permanent) in the United States. Cotton gin waste (CGW) is an agro-industrial residue, which could be potentially used for ethanol production. Unlike other lignocellulosic feedstocks, this material is concentrated at the processing sites and therefore harvesting and transportation costs could be considerably less than those for agricultural and forestry residues and dedicated biomass feedstocks. Recycled paper sludge is a short fiber cellulosic feedstock, which could also be potentially used for ethanol production. Similar to the CGW, this material is concentrated at processing sites and therefore transportation cost could be considerably reduced. By combining these feedstocks, ethanol in high yields can be produced for fuel applications and waste disposal problems in these industries can be solved simultaneously. The purpose of this project is to develop an in situ detoxification process for the bioconversion of cotton gin waste and recycled paper sludge mixtures into ethanol in high yields.
 
OBJECTIVES: Our previous studies on cotton gin waste showed that we could produce ethanol at very good yields at one-liter scale level if the pretreated material is properly detoxified. However, the process was not been demonstrated for the cotton gin waste/recycled paper sludge combination. The overall goal of this project is to develop an in situ detoxification process for the bioconversion of cotton gin waste and recycled paper sludge mixtures into ethanol using steam explosion, enzyme hydrolysis, and fermentation technologies. The process has the potential of solving a waste disposal problem while simultaneously generating a new product stream for the cotton and paper and pulp industries. The specific objectives of this project are: 1. Collect and fractionate cotton gin waste from cotton gins in five states to access the impact of harvesting method on the quality of the feedstock. 2. Characterize recycled paper sludge and cotton gin waste from various states to assess impact of ginning on feedstock composition. 3. Investigate the in situ detoxification of cotton gin waste/recycled paper sludge during steam explosion pretreatment. 4. Investigate the bioconversion of steam exploded cotton gin waste/recycled paper sludge mixture to ethanol. 5. Analyze biomass-to-ethanol fermentation residue to assess the nature of the unhydrolyzed residual cellulose. This technology could be applied to other biomass feedstocks and thus eliminate the extra processing step required for the bioconversion of biomass to fuels and chemicals. This will obviously improve the biomass-to-ethanol process economics. The conversion of RPS and CGW to fuel ethanol has other potential advantages. It will solve waste disposal problem in two industries, it will create new jobs in rural America and further it will stimulate both paper recycling and increase processing of cotton. Increased processing of cotton will of course impact USA agriculture, which is one of the goals of the Hatch Program. The processing of cotton gin waste and recycled paper sludge to ethanol will reduce greenhouse gas emission, and replace petroleum products. It cannot be overemphasized that this proposal fits the objectives of this program because it will assist in implementing new ethanol production capacity and it has a potential for near-term applicability and replication in Southern United States.
 
APPROACH: Objective 1. Collect and fractionate cotton gin waste from cotton gins in five states to access the impact of harvesting method on the quality of the feedstock. a) Collection of cotton gin waste. Cotton gin waste samples will be collected from five cotton gins in Virginia, Mississippi, Texas, Georgia, and North Carolina, and the RPS will be collected from the International Paper recycling facility in Franklin, Virginia. Samples will be collected every year for three years during the project. b) Fractionation of cotton gin waste. About 1 kg dry CGW samples from the five gins will be shipped to the USDA-ARS Cotton Ginning Laboratory, (Stoneville, MS) to be fractionated into clean lint, hulls, sticks/stems, grass, seeds, small leaf, and pin trash. Additionally, some cotton gin waste fractions will be generated from the pilot scale ginning machine for the studies. Objective 2. Characterize recycled paper sludge and cotton gin waste from various states to assess impact of ginning on feedstock composition. The CGW, RPS, and CGW/RPS samples will be analyzed for their summative composition (cellulose, lignin, hemicellulose, ash, and extractives) using ASTM standard methodologies. In addition, the RPS will also be analyzed for elemental composition. Objective 3. In situ detoxification of cotton gin waste/recycled paper sludge during steam explosion pretreatment. a) Steam explosion of cotton gin waste and recycled paper sludge. We will steam explode CGW and RPS mixtures at various CGW to RPS ratios, moisture contents, and severity parameters in the batch steam explosion unit. The CGW and RPS will be steam exploded as received without any milling or presoaking. b) Enzyme hydrolysis of steam exploded material. Steam exploded CGW and RPS will be hydrolyzed independently to determine their hydrolysis rates and their fermentable sugar yields. The hydrolysis will be carried out for 72 h at 50 deg. C using commercial cellulase enzyme preparation such as Spezyme CP. We will investigate various CGW/RPS ratios and the influence of potential heavy metal content of the RPS on the sugar yield. Objective 4. Investigate the bioconversion of steam exploded cotton gin waste/recycled paper sludge mixture to ethanol. a) Fermentation of hydrolysates. We will use both Saccharomyces cerevisiae, and E. coli KO11 for the fermentation. We will investigate the effect of the following parameters on ethanol yield: severity of steam explosion, CGW/RPS ratio, degree of enzyme hydrolysis, composition of CGW, feedstock source, temperature, pH and additives content of RPS. b) Optimization of in situ detoxification process. Factorial designs and response surface methodology will be used to determine the best operating parameters for in situ detoxification and ethanol production. c) Scale-up of process to 1-liter scale. We will scale-up the process from shaker flask level to one-liter scale after the optimization of the process parameters.
 
CRIS NUMBER: 0205429 SUBFILE: CRIS
PROJECT NUMBER: VA-135747 SPONSOR AGENCY: NIFA
PROJECT TYPE: HATCH PROJECT STATUS: TERMINATED MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: Oct 1, 2005 TERMINATION DATE: Sep 30, 2010

GRANT PROGRAM: (N/A)
GRANT PROGRAM AREA: (N/A)

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
511171920202.125%
403171920206.225%
511066020202.125%
403066020206.225%

CLASSIFICATION HEADINGS
KA511 - New and Improved Non-Food Products and Processes
KA403 - Waste Disposal, Recycling, and Reuse
S0660 - Paper and pulp derived products
S1719 - Cotton, other
F2020 - Engineering
G6.2 - Enhance Soil Quality for Productive Working Lands
G2.1 - Expand Domestic Market Opportunities


RESEARCH EFFORT CATEGORIES
BASIC 50%
APPLIED 50%
DEVELOPMENTAL (N/A)%

KEYWORDS: biomas,; cotton gin waste; ethanol; recycled paper sludge; steam explosion; enzyme hydrolysis; detoxification; fermentation

PROGRESS: Oct 1, 2008 TO Sep 30, 2009
OUTPUTS: During the reporting period, we worked on the experimental verification of the previous enzyme hydrolysis models developed for bioethanol production from cotton gin waste and recycled paper sludge. Microcrystalline cellulose hydrolysis and fermentation was investigated. Both the model and experimental data showed that the cell growth was the rate limiting step at the initial fermentation period in the reaction series from cellulose to ethanol. At the later stages of the fermentation, cellulose to cellobiose reaction step controlled the process. The batch model was extended to the continuous and fed-batch operating models. For the continuous simultaneous saccharification and fermentation (SSF) operation, the ethanol productivities increased with increasing dilution rate until a maximum value was attained and then rapidly decreased as the dilution rate approached the washout point. The model predicted a relatively high ethanol yield for the fed-batch operation mode compared to the batch operation mode. PARTICIPANTS: Shen, J. Graduate student. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

IMPACT: 2008-10-01 TO 2009-09-30 The results from this work will enable us to design more efficient reactors for the production of bioethanol from cotton gin waste and recycled paper sludge. It will also enable us to accelerate the scale-up of the process development for commercialization. The successful commercialization of this technology will solve a dual problem of providing new product stream to the cotton industry as well as disposing of industrial waste efficiently.

PUBLICATION INFORMATION: 2008-10-01 TO 2009-09-30
Shen, J., Agblevor, F.A. 2009. Operable modeling of simultaneous saccharification and fermentation of ethanol production from cellulose. Applied Biochemistry and Biotechnology. Published on line DOI 10.1007/s12010-009-8650-8.

PROJECT CONTACT INFORMATION
NAME: Agblevor, F. A.
PHONE: 540-231-2578
FAX: 540-231-3199