Engineering Commons^™

Upcycling Dairy Manure Fine Solids Captured By Dissolved Air Flotation As Part Of A Phosphorus Recovery And Reuse Strategy, Katherine Keith Porterfield

Graduate College Dissertations and Theses

Dissolved air flotation (DAF) has shown potential to substantially improve phosphorus (P) mass balance on dairy farms by capturing P associated with fine solids from liquid manure, enabling new management options. However, at < 25% total solids, further dewatering and other upcycling is necessary to facilitate export of recovered fine solids off farm for use in bagged or bulk products. I generated plant foods using DAF-captured dairy manure fine solids thermally dried to 45% total solids blended with other organic residuals. Dry biomass of tomato and marigold seedlings amended with 6% v/v plant food was six-times greater than the unamended control and not significantly different from a market alternative treatment. Because thermal dewatering can be prohibitively costly, I generated a second batch of plant foods using DAF-captured dairy manure fine solids conditioned with 3, 4.5 and 6% (w/w) quicklime or lime kiln dust (LKD) and dewatered using a benchtop press for comparison with thermally dried fine solids. Tomato seedling biomass was similar for thermally dried and LKD plant foods, but quicklime plant foods had no effect compared to the unamended control. Quicklime and LKD conditioned fine solids contained approximately 30 and 10 times less plant-available P than thermally dried fine solids, respectively—likely due to precipitation of Ca-P minerals. These studies indicate that DAF-captured dairy manure fine solids could be upcycled to bagged horticultural products with substantial agronomic value, however sustainable materials drying remains a key challenge to realizing this potential.

The Food-Energy-Water Nexus, Embodied Injustices, And Transboundary Sustainability, Sonya Ahamed

Graduate College Dissertations and Theses

Intersections of food, energy, and water systems (the FEW nexus) pose many sustainability and governance challenges, including risks to ecosystems, inequitable distribution of benefits and harms across populations, and reliance on distant sources for food, energy, and water. Nexus-based approaches can offer more holistic pathways for societal transitions to FEW systems that are just and sustainable, but tend to focus narrowly on inputs (e.g. water ‘for’ energy) in ways that do little to address the historical roots and structural underpinnings of current system inadequacies, thus risking their perpetuation.

This dissertation widens the FEW nexus in two contexts in which the …