The influence of compaction and amendment type on biological activity during biosolids co-composting

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Chen, Hongtu
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During windrow composting, compressive settlement causes a decrease in the free air space inside the composting pile. The objectives of this research were to study the extent that compressive settlement affects the free air space (FAS) and biological activity. Two experimental phases were done: Phase I characterized the physical and chemical properties of the biosolids, the potential amendments, and various combinations of the two. The physical and chemical properties investigated include moisture content (MC), total solids content (TS), volatile solids content (VS), fixed solids content (FS), Total Kjeldahl Nitrogen (TKN), dry bulk density (D$\sb{\rm db}$), wet bulk density (D$\sb{\rm wb}$), and particle density (D$\sb{\rm p}$), Phase II measured the effect of loading and amendment type on FAS and the biological activity. The composting biological activity was measured using the composting temperature, the oxygen utilization rate (OUR), and the final volatile solids reduction. Four bench-scale 2.6 L compost reactors were used in Phase II. In Phase II five experimental stages of 15 days each were completed. In each of the first four stages, two replicates of loaded and unloaded reactors were run. In the fifth stage two different types of amendment were used. Each amendment was mixed with biosolids individually and put into two reactors, one loaded and another one unloaded. (Abstract shortened by UMI.)