@article{wang_cruz_ximenes_barlaz_2015, title={Decomposition and carbon storage of selected paper products in laboratory-scale landfills}, volume={532}, ISSN={["1879-1026"]}, DOI={10.1016/j.scitotenv.2015.05.132}, abstractNote={The objective of this study was to measure the anaerobic biodegradation of different types of paper products in laboratory-scale landfill reactors. The study included (a) measurement of the loss of cellulose, hemicellulose, organic carbon, and (b) measurement of the methane yields for each paper product. The test materials included two samples each of newsprint (NP), copy paper (CP), and magazine paper (MG), and one sample of diaper (DP). The methane yields, carbon storage factors and the extent of cellulose and hemicellulose decomposition all consistently show that papers made from mechanical pulps (e.g., NPs) are less degradable than those made from chemical pulps where essentially all lignin was chemically removed (e.g., CPs). The diaper, which is not only made from chemical pulp but also contains some gel and plastic, exhibited limited biodegradability. The extent of biogenic carbon conversion varied from 21 to 96% among papers, which contrasts with the uniform assumption of 50% by the Intergovernmental Panel on Climate Change (IPCC) for all degradable materials discarded in landfills. Biochemical methane potential tests also showed that the solids to liquid ratio used in the test can influence the results.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, publisher={Elsevier BV}, author={Wang, Xiaoming and Cruz, Florentino B. and Ximenes, Fabiano and Barlaz, Morton A.}, year={2015}, month={Nov}, pages={70–79} }
 @article{de la cruz_dittmar_niggemann_osburn_barlaz_2015, title={Evaluation of Copper Oxide Oxidation for Quantification of Lignin in Municipal Solid Waste}, volume={32}, ISSN={1092-8758 1557-9018}, url={http://dx.doi.org/10.1089/ees.2014.0402}, DOI={10.1089/ees.2014.0402}, abstractNote={Abstract The ability to quantify lignin is an important tool for characterizing the extent of decomposition of municipal solid waste (MSW). Traditionally, acid insoluble Klason lignin (KL) has been used to measure lignin. However, synthetic organic materials such as plastics and rubber present in MSW interfere with the traditional KL method, resulting in artificially high measurements. Another method for lignin analysis is CuO oxidation, in which lignin is oxidatively hydrolyzed into phenolic monomers that are quantified by high-performance liquid chromatography or gas chromatography–mass spectrography. The objective of this study was to evaluate the applicability of CuO oxidation to measure the lignin content of MSW. The study demonstrated that analysis of lignin monomers can be simplified by skipping the ethyl acetate extraction step and that ball milling is not necessary to optimize CuO oxidation. Neither the MSW components (e.g., plastics and metals) nor extractives affected CuO oxidation. The ratio o...}, number={6}, journal={Environmental Engineering Science}, publisher={Mary Ann Liebert Inc}, author={De la Cruz, Florentino Banaag and Dittmar, Thorsten and Niggemann, Jutta and Osburn, Christopher L. and Barlaz, Morton A.}, year={2015}, month={Jun}, pages={486–496} }
 @article{cruz_yelle_gracz_barlaz_2014, title={Chemical Changes during Anaerobic Decomposition of Hardwood, Softwood, and Old Newsprint under Mesophilic and Thermophilic Conditions}, volume={62}, ISSN={["1520-5118"]}, DOI={10.1021/jf501653h}, abstractNote={The anaerobic decomposition of plant biomass is an important aspect of global organic carbon cycling. While the anaerobic metabolism of cellulose and hemicelluloses to methane and carbon dioxide are well-understood, evidence for the initial stages of lignin decomposition is fragmentary. The objective of this study was to look for evidence of chemical transformations of lignin in woody tissues [hardwood (HW), softwood (SW), and old newsprint (ONP)] after anaerobic decomposition using Klason and acid-soluble lignin, CuO oxidation, and 2D NMR. Tests were conducted under mesophilic and thermophilic conditions, and lignin associations with structural carbohydrates are retained. For HW and ONP, the carbon losses could be attributed to cellulose and hemicelluloses, while carbon loss in SW was attributable to an uncharacterized fraction (e.g., extractives etc.). The 2D NMR and chemical degradation methods revealed slight reductions in β-O-4 linkages for HW and ONP, with no depolymerization of lignin in any substrate.}, number={27}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, publisher={American Chemical Society (ACS)}, author={Cruz, Florentino B. and Yelle, Daniel J. and Gracz, Hanna S. and Barlaz, Morton A.}, year={2014}, month={Jul}, pages={6362–6374} }
 @article{cruz_chanton_barlaz_2013, title={Measurement of carbon storage in landfills from the biogenic carbon content of excavated waste samples}, volume={33}, ISSN={["0956-053X"]}, DOI={10.1016/j.wasman.2012.12.012}, abstractNote={Landfills are an anaerobic ecosystem and represent the major disposal alternative for municipal solid waste (MSW) in the U.S. While some fraction of the biogenic carbon, primarily cellulose (Cel) and hemicellulose (H), is converted to carbon dioxide and methane, lignin (L) is essentially recalcitrant. The biogenic carbon that is not mineralized is stored within the landfill. This carbon storage represents a significant component of a landfill carbon balance. The fraction of biogenic carbon that is not reactive in the landfill environment and therefore stored was derived for samples of excavated waste by measurement of the total organic carbon, its biogenic fraction, and the remaining methane potential. The average biogenic carbon content of the excavated samples was 64.6 ± 18.0% (average ± standard deviation), while the average carbon storage factor was 0.09 ± 0.06 g biogenic-C stored per g dry sample or 0.66 ± 0.16 g biogenic-C stored per g biogenic C.}, number={10}, journal={WASTE MANAGEMENT}, publisher={Elsevier BV}, author={Cruz, Florentino B. and Chanton, Jeffrey P. and Barlaz, Morton A.}, year={2013}, month={Oct}, pages={2001–2005} }
 @article{wang_padgett_cruz_barlaz_2011, title={Wood Biodegradation in Laboratory-Scale Landfills}, volume={45}, ISSN={["1520-5851"]}, DOI={10.1021/es201241g}, abstractNote={The objective of this research was to characterize the anaerobic biodegradability of major wood products in municipal waste by measuring methane yields, decay rates, the extent of carbohydrate decomposition, carbon storage, and leachate toxicity. Tests were conducted in triplicate 8 L reactors operated to obtain maximum yields. Measured methane yields for red oak, eucalyptus, spruce, radiata pine, plywood (PW), oriented strand board (OSB) from hardwood (HW) and softwood (SW), particleboard (PB) and medium-density fiberboard (MDF) were 32.5, 0, 7.5, 0.5, 6.3, 84.5, 0, 5.6, and 4.6 mL CH(4) dry g(-1), respectively. The red oak, a HW, exhibited greater decomposition than either SW (spruce and radiata), a trend that was also measured for the OSB-HW relative to OSB-SW. However, the eucalyptus (HW) exhibited toxicity. Thus, wood species have unique methane yields that should be considered in the development of national inventories of methane production and carbon storage. The current assumption of uniform biodegradability is not appropriate. The ammonia release from urea formaldehyde as present in PB and MDF could contribute to ammonia in landfill leachate. Using the extent of carbon conversion measured in this research, 0-19.9%, predicted methane production from a wood mixture using the Intergovernmental Panel for Climate Change waste model is only 7.9% of that predicted using the 50% carbon conversion default.}, number={16}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, publisher={American Chemical Society (ACS)}, author={Wang, Xiaoming and Padgett, Jennifer M. and Cruz, Florentino B. and Barlaz, Morton A.}, year={2011}, month={Aug}, pages={6864–6871} }
 @article{cruz_barlaz_2010, title={Estimation of Waste Component-Specific Landfill Decay Rates Using Laboratory-Scale Decomposition Data}, volume={44}, ISSN={["1520-5851"]}, DOI={10.1021/es100240r}, abstractNote={The current methane generation model used by the U.S. EPA (Landfill Gas Emissions Model) treats municipal solid waste (MSW) as a homogeneous waste with one decay rate. However, component-specific decay rates are required to evaluate the effects of changes in waste composition on methane generation. Laboratory-scale rate constants, k(lab), for the major biodegradable MSW components were used to derive field-scale decay rates (k(field)) for each waste component using the assumption that the average of the field-scale decay rates for each waste component, weighted by its composition, is equal to the bulk MSW decay rate. For an assumed bulk MSW decay rate of 0.04 yr(-1), k(field) was estimated to be 0.298, 0.171, 0.015, 0.144, 0.033, 0.02, 0.122, and 0.029 yr(-1), for grass, leaves, branches, food waste, newsprint, corrugated containers, coated paper, and office paper, respectively. The effect of landfill waste diversion programs on methane production was explored to illustrate the use of component-specific decay rates. One hundred percent diversion of yard waste and food waste reduced the year 20 methane production rate by 45%. When a landfill gas collection schedule was introduced, collectable methane was most influenced by food waste diversion at years 10 and 20 and paper diversion at year 40.}, number={12}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, publisher={American Chemical Society (ACS)}, author={Cruz, Florentino B. and Barlaz, Morton A.}, year={2010}, month={Jun}, pages={4722–4728} }