(602bg) Evaluating the Potentials of Paper Mill Sludge (PMS) As Feedstock for Biofuels Production

Heightened concerns over escalating greenhouse gas emissions as well as the depletion of petroleum oil and the continuing rise of its prices have resulted in focus on obtaining energy, traditionally produced from the combustion of fossil fuels, from renewable sources. One such renewable source of energy is biomass, in particular lignocellulosic biomass which is rich in lignin, cellulose, and hemicellulose. These carbon-containing components can be converted to liquid fuels by biochemical approaches, thermochemical approaches, or the combination of biochemical and thermochemical approaches.  

The ideal biomass materials for energy production are those that are readily available and do not require a lot of energy to produce and collect. More importantly, the biomass materials should not be produced on fertile lands used for growing food crops. Such biomass materials are commonly readily available in the forms of what are considered wastes. These materials are produced from agriculture, forestry, household, or manufacturing activities. Examples of the materials include wheat straws, wood chips, spent mushroom substrate, municipal solid waste (MSW) and paper mill sludge (PMS). This study is focused on PMS materials.   

As byproduct of paper making, PMS is produced in the order of 15 to 50 tons per day for a typical paper mill. It is estimated that five million tons of PMS are produced annually in the United States alone. Currently there are not many uses PMS, that most of PMS is disposed to landfills, a financial burden for paper mills. The decline of the landfill space availability has caused the cost of disposing PMS to increase rapidly to the point where the cost of PMS disposal now is about 60% of paper mill’s operating costs. Therefore, there is growing interest in the paper industry to research possible uses of PMS, instead of just disposing them.

Thus, the purpose of this study is to show the viability of PMS as a feedstock for the production of liquid biofuels. Exploring the viability first requires characterization of the PMS samples. Characterization by way of Induced Coupled Plasma (ICP), Thermogravimetric Analysis (TGA), Differential Scanning Calorimeter (DSC), Fourier Transform Infrared Spectroscopy (FTIR), and Fiber Analysis will provide information on the physicochemical properties of PMS. The ash content and the mineral composition of the ash material in PMS will be determined. Functional groups and heat capacities will also be determined as well as the amount of lignin, hemicellulose, and cellulose in PMS. The characterization will determine whether PMS is within the optimal specifications as feedstock for biofuel production.

In addition to characterization study, a study on converting PMS to fuels will also be conducted. In order to convert the PMS into a liquid fuel, this study will utilize a method called fast pyrolysis. Fast pyrolysis is a thermochemical conversion technology that rapidly heats organic material to temperatures of 450°C to 600°C in the absence of air which results in rapid decomposition of the material to produce a liquid product typically called bio-crude oil which can be used as a heat source or an intermediate feedstock for producing gasoline or diesel fuels. The fast pyrolysis experiments will be performed by using a micropyrolyzer/GC-MS system. To be reported in this presentation are the results of these characterization and fast pyrolysis studies.