Erratum: Porterfield, K.K., et al. Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers. Sustainability 2020, 12, 1139

The authors would like to make the following correction for the published paper [...]

Optimizing Photoperiodism, Growth Media Dilution, and Frequency of Inoculum Addition in Microalgae (Chlorella vulgaris) Culture Using Bi-oslurry (ADDMW) as Growth Media

In biogas production using dairy manure, an anaerobic digestion process also produced a by product bioslurry, also known as Anaerobically Digested Dairy Manure Wastewater (ADDMW), which is rich in ammonium and ortophosphate. ADDMW is potentially to be used as growth media to grow autotrophic organism, including microalgae. Furthermore, microalgae potential-ly could reduce organic content in ADDMW, thus play a role as phycoremediator to organic wastewater. In this study we used ADDMW medium for the growth of microalgae, determining its growth kinetics and level of reduction in ammonium and or-thophosphate content in ADDMW. In addition, we also analysed protein content in microalgae biomass for potential use as animal feed. The experiment was conducted using some variations in photoperiodism, i.e., 16:8; 12:12; and 8:16 and medium dilution factor of 2.5 and 5 times. Furthermore, frequency of inoculum addition was also examined i.e., a) 80 mL on day 0 (once); b) 26.67 mL on day 0 to 2 (first 3 days); and c) 8 mL on days 0 to 9 (every day). The results showed that 16:8 photo-period and 5 times medium dilution produced the highest biomass growth and productivity kinetics. Variation in frequency of inoculum addition showed no significant effect to a decrease in ammonium levels but indicated some effect to orthophosphate level. It can be concluded that microalgae can be grown in ADDMW media and can reduce its ammonium and ortophosphate content, as a phycoremediator, before the wastewater is dumped to the river.

Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers

Dissolved air flotation (DAF) separates phosphorus (P)-rich fine solids from anaerobically digested dairy manure, creating opportunities to export surplus P to the marketplace as a bagged plant food product. Seedlings of tomato and marigold were amended at various volume per volume (v/v) ratios with plant foods consisting of fine solids upcycled (i.e., transformed into a higher quality product) by drying and blending with other organic residuals. A plate competition assay was conducted to assess the fine solids’ potential to suppress the plant pathogen Rhizoctonia solani. Plant foods were comprised of 2.0–2.1% N, 0.8–0.9% P and 0.6–0.8% K. Extractions indicated that plant foods contained a mixture of plant-available and slow-release P. At 6% v/v plant food, dry biomass of marigold and tomato were six-times greater than the unamended control and not significantly different from a market alternative treatment. Fine solids exhibited negligible potential to suppress R. solani. This study indicates that DAF-separated fine solids could be used to support horticulture, providing information for design of a circular economy approach to dairy manure nutrient management. Life cycle assessment and business model development for this nutrient recovery strategy are necessary next steps to further guide sustainability efforts.