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Thesis (M.S.) in Plant, Soil, and Environmental Sciences--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves 110-121).

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 107-108). Also available via the Internet.

Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 107-113).

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains vii, 38 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 34-36).

Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisor: Jeffry J. Fuhrmann, Dept. of Plant & Soil Science. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1996. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 308-317).

Large quantities of biosolids are produced from treatment of municipal wastewater and can be processed into a nutrient and organic-rich soil amendment that has great value for agriculture. The drying process involves converting solids at approximately 25-30% solids content to a dry, stable biosolids pellet. The majority of the input material is recycled to the mixing step upstream of the dryer to achieve a more uniform particle size distribution. The objective of this work was to investigate use of polyelectrolyte amendments to promote uniformity in dried biosolids pellet size. Biosolids samples were collected at the New England Fertilizer Company (NEFCO) facility located in Quincy, MA, U.S. The biosolids samples were characterized by scanning electron microscopy (SEM), inductively coupled plasma/mass spectrometry (ICP-MS), dynamic light scattering (DLS) and zeta potential measurements. Five polyelectrolytes, polyethyleneimine (PEI), polydiallyldimethyl-ammonium chloride (PDADMAC), polyallyamine (PAM), polyacrylic acid (PAA) and polyethylene oxide (PEO) were selected as candidate amendments for surface properties modification trials. The results indicated that three cationic polyelectrolytes, PDADMAC, PEI and PAM, reduced the (absolute value) zeta potentials of the biosolids surfaces to near zero. The optimal doses for reducing the zeta potentials were found to be 0.008 mg PEI/mg solids; 0.005 mg PAM/mg solids and 0.03 mg PDADMAC/mg solids, respectively. The anionic polyelectrolyte PAA and nonionic polymer PEO were found to be ineffective for modifying the zeta potential of the biosolids. The changes in particle size distributions of the biosolids using the three cationic polyelectrolytes were determined by dynamic light scattering (DLS) measurements. Of the three cationic polyelectrolytes, only PDADMAC was found to increase the biosolids particle size from average size of 340 nm to 3600 nm with 240 min contact time. This indicates the potential for PDADMAC as an amendment for improving the biosolids drying process as it was able to decrease the number of fines and increase the “green” biosolids pellet size.

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