2003 Progress Report: Conversion of Paper Sludge to Ethanol

EPA Grant Number: R829479C006
Subproject: this is subproject number 006 , established and managed by the Center Director under grant R829479
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: The Consortium for Plant Biotechnology Research, Inc., Environmental Research and Technology Transfer Program
Center Director: Schumacher, Dorin
Title: Conversion of Paper Sludge to Ethanol
Investigators: Lynd, Lee
Institution: Dartmouth College
EPA Project Officer: Lasat, Mitch
Project Period: July 1, 2002 through June 30, 2004
Project Period Covered by this Report: July 1, 2002 through June 30, 2003
RFA: The Consortium for Plant Biotechnology Research, Inc., Environmental Research and Technology Transfer Program (2001) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Targeted Research

Objective:

This research project has two major objectives: (1) to characterize and improve the performance of semicontinuous solid-state fermentation (SSF) reactors and optimize the operational conditions; and (2) to build a reactor and a process model.

Progress Summary:

We have successfully converted paper sludge to ethanol in a semicontinuous, solid-fed reactor system using a 4-day residence time, 20 filter paper units (FPU)/g cellulose loading, and 60 international units (IU)/g cellulose ß-glucosidase addition. A 92 percent conversion rate was achieved, and more than 40 g/L ethanol was produced using the above conditions. Saccharomyces cerevisiae was the microorganism used for SSF (Fan, et al., 2003). It fermented the cellulose portion of the paper sludge very well, but left the xylan portion untouched. Our further process optimization goals include converting the xylan portion of paper sludge to ethanol and decreasing cellulose loading.

In this reporting period, we evaluated the viability of Klebsiella oxytoca P2 as the alternative microorganism to convert paper sludge to ethanol. K. oxytoca P2 is a recombinant bacteria that inherently can metabolize cellobiose and xylose. K. oxytoca P2 could ferment both cellobiose and xylose and produce more than 40 g/L ethanol in the batch SSF in a rich medium (LB medium).

In this reporting period, we evaluated the conversion of paper sludge to ethanol in more industrial-like conditions. A lean medium (Martinez, et al., 1999) instead of a rich medium was used for the SSF. It was found that K. oxytoca P2 lost the ability to ferment xylose in the lean medium (result not shown). Results of the SSF experiment on avicel showed that K. oxytoca P2 stopped growing before ethanol concentration in the fermentation broth reached 20 g/L.

K. oxytoca P2 did not use xylose in the lean medium. This, together with its poor ethanol tolerance ability, made us believe that K. oxytoca P2 may not be the ideal candidate microorganism to convert the xylan portion of paper sludge.

In this reporting period, we also modified an existing continuously stirred tank reactor SSF model built in 1995 by a former laboratory member, Colin South, to a discrete-feeding SSF model. The reformulated model using the same parameters Colin used in his model predicted that conversion can be improved by reducing the feeding frequency while keeping the residence time unchanged.

We have done some experimental work on optimizing the feeding frequency enlightened by the model prediction. Preliminary results were consistent with the prediction. When feeding frequency was reduced from 2 to 1.33, the conversion improved from 91.5 percent to 93.4 percent using 10 FPU/g cellulose loading and 60 IU/g cellulose ß-glucosidase loading. Table 1 shows the material balance data of the run adopting a feeding frequency of 1.33.

Table 1. Material Balance of the Run With Feeding Frequency of 1.33

Material Balance of the Run
Cellulose In-g 50.54
Cellulose Out-g 3.34
Conversion: percent 93.4
Xylan In-g 7.35
Xylan Out in solid-g 0.26
Xylose out-g 3.33
Xylan Oligomer out-g 3.22
recovery rate-percent 92.7
glucose-g 3.46
Ethanol yield-percent 47.9

(g = gram)

Future Activities:

The future work includes testing new microorganisms to convert the xylose portion of the paper sludge, optimization of operational conditions, and completing development of the process model for the semicontinuous paper sludge SSF.

The strains we plan to test include Escherichia coli KO11, recombinant S. cerevisiae with an engineered xylose utilization pathway, and recombinant S. cerevisiae expressing cellobiase. We will optimize feeding frequency and test lower cellulose loading using found optimized feeding frequency. We will experimentally measure the adoption parameters and kinetics parameters of the paper sludge SSF to provide inputs to the new formulated model and verify the model by batch and semicontinuous experimental results.

Journal Articles:

No journal articles submitted with this report: View all 6 publications for this subproject

Supplemental Keywords:

paper sludge, ethanol, Saccharomyces cerevisiae, Escherichia coli cellulose, xylan, Klebsiella oxytoca P2, ferment, microorganism, ?-glucosidase, feeding frequency., Scientific Discipline, Waste, TREATMENT/CONTROL, Sustainable Industry/Business, Treatment Technologies, Geochemistry, Technology, New/Innovative technologies, Bioremediation, Environmental Engineering, Agricultural Engineering, bioengineering, paper sludge, biodegradation, ethanol, biotechnology, plant biotechnology, remediation, semicontinuous solid state fermentation

Relevant Websites:

http://www.cpbr.org Exit

Progress and Final Reports:

Original Abstract
  • Final Report

  • Main Center Abstract and Reports:

    R829479    The Consortium for Plant Biotechnology Research, Inc., Environmental Research and Technology Transfer Program

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R829479C001 Plant Genes and Agrobacterium T-DNA Integration
    R829479C002 Designing Promoters for Precision Targeting of Gene Expression
    R829479C003 aka R829479C011 Biological Effects of Epoxy Fatty Acids
    R829479C004 Negative Sense Viral Vectors for Improved Expression of Foreign Genes in Insects and Plants
    R829479C005 Development of Novel Plastics From Agricultural Oils
    R829479C006 Conversion of Paper Sludge to Ethanol
    R829479C007 Enhanced Production of Biodegradable Plastics in Plants
    R829479C008 Engineering Design of Stable Immobilized Enzymes for the Hydrolysis and Transesterification of Triglycerides
    R829479C009 Discovery and Evaluation of SNP Variation in Resistance-Gene Analogs and Other Candidate Genes in Cotton
    R829479C010 Woody Biomass Crops for Bioremediating Hydrocarbons and Metals
    R829479C011 Biological Effects of Epoxy Fatty Acids
    R829479C012 High Strength Degradable Plastics From Starch and Poly(lactic acid)
    R829479C013 Development of Herbicide-Tolerant Energy and Biomass Crops
    R829479C014 Identification of Receptors of Bacillus Thuringiensis Toxins in Midguts of the European Corn Borer
    R829479C015 Coordinated Expression of Multiple Anti-Pest Proteins
    R829479C016 A Novel Fermentation Process for Butyric Acid and Butanol Production from Plant Biomass
    R829479C017 Molecular Improvement of an Environmentally Friendly Turfgrass
    R829479C018 Woody Biomass Crops for Bioremediating Hydrocarbons and Metals. II.
    R829479C019 Transgenic Plants for Bioremediation of Atrazine and Related Herbicides
    R829479C020 Root Exudate Biostimulation for Polyaromatic Hydrocarbon Phytoremediation
    R829479C021 Phytoremediation of Heavy Metal Contamination by Metallohistins, a New Class of Plant Metal-Binding Proteins
    R829479C022 Development of Herbicide-Tolerant Energy and Biomass Crops
    R829479C023 A Novel Fermentation Process for Butyric Acid and Butanol Production from Plant Biomass
    R829479C024 Development of Vectors for the Stoichiometric Accumulation of Multiple Proteins in Transgenic Crops
    R829479C025 Chemical Induction of Disease Resistance in Trees
    R829479C026 Development of Herbicide-Tolerant Hardwoods
    R829479C027 Environmentally Superior Soybean Genome Development
    R829479C028 Development of Efficient Methods for the Genetic Transformation of Willow and Cottonwood for Increased Remediation of Pollutants
    R829479C029 Development of Tightly Regulated Ecdysone Receptor-Based Gene Switches for Use in Agriculture
    R829479C030 Engineered Plant Virus Proteins for Biotechnology