Traditional crop production faces a significant challenge due to overapplication, mining, and decreased supply of mineral nutrients. In addition to this, the urgent need to address global food waste has become increasingly apparent, as discarded food scraps in landfills contribute to harmful greenhouse gas emissions. A promising solution that addresses both of these critical challenges includes the innovative utilization of food waste anaerobic digestate as a fertilizer for crop production. This study investigated whether using anaerobically digested food waste as fertilizer can fully replace or reduce the use of chemical fertilizer in vegetable and ornamental crop production. The seeds of lettuce (Lactuca sativa) ‘Nancy’ and petunia (Petunia × hybrida) ‘Easy Wave Velour Berry’ were sown into a soilless medium and grown in the indoor vertical farm at 22℃ under sole-source lighting at a photosynthetic photon flux density of 180 µmol∙m–2∙s–1 with a 20-h photoperiod. Four weeks after sowing, seedlings were transplanted and grown for three weeks in a greenhouse with an average daily temperature of 20 °C under ambient sunlight with an average daily light integral of 22 mol∙m–2∙d–1. The plants were fertilized using tap water mixed with different fertilizers, including a chemical fertilizer (15N-2.2P-16.6K), an organic fertilizer derived from anaerobically digested food waste (0.06N-0.026P-0.1191K), or a blend containing 50% chemical fertilizer and 50% food waste-based fertilizer, at the electrical conductivity of 0.7 mS·cm-1 during the young plant stage and 2.1 mS·cm-1 after transplant. At the young plant stage, lettuce and petunia have similar growth characteristics, including leaf number, SPAD index, and shoot and root fresh mass, when treated with either chemical or chemical + food waste fertilizer. In contrast, in both species, leaf area was 93-152% larger and fresh mass was 82-141% greater in plants treated with chemical or chemical + food waste fertilizer compared to food waste fertilizer. At the finishing stage, lettuce and petunia also showed similar growth and flowering characteristics under chemical or chemical + food waste fertilizer. However, in the lettuce finishing plants, fresh mass was 127-199% larger when supplied with chemical or chemical + food waste fertilizer compared to food waste fertilizer. In petunia, the number of flowers was 123-190% greater in chemical and chemical + food waste fertilizer compared to food waste fertilizer. In both lettuce and petunia at the finishing stage, the SPAD index, leaf number, root fresh mass, and root dry mass were similar among all treatments. These results suggest that food waste fertilizer applied as the sole source of plant nutrition is insufficient in comparison to chemical fertilizer at the same electrical conductivity. However, partially substituting some food waste fertilizer for chemical fertilizer reaps similar plant yield to chemical fertilizer on its own.

As the world’s population exponentially grows, more food production is required. This increasing food production currently has led to the un-sustainable production of chemical fertilizers and resultant overuse. A more sustainable option to enhance food production could be the use of fertilizer derived from food waste. To address this, we investigated the possibility of utilizing a fertilizer derived from food waste to grow hydroponic vegetables. Arugula (Eruca sativa) ‘Slow Bolt’ and lettuce (Lactuca sativa) ‘Cherokee’ and ‘Rex’ were cultivated using indoor deep-flow hydroponic systems at 23 ºC under a photosynthetic photon flux density of 170 µmol∙m−2∙s−1 with an 18-hour photoperiod. Plant nutrient solutions were provided by food waste fertilizer or commercial 15:5:20 NPK fertilizer at the identical electrical conductivity (EC) of 2.3 mS·cm–1. At the EC of 2.3 mS·cm–1, chemical fertilizer contained 150 ppm N, 50 ppm P, and 200 ppm K, while food waste fertilizer had 60 ppm N, 26 ppm P, and 119 ppm K. Four weeks after the nutrient treatments were implemented, compared to plants grown with chemical fertilizer, lettuce ‘Rex’ grown with food waste fertilizer had four less leaves, 27.1% shorter leaves, 68.2% and 23.1% less shoot and root fresh weight, respectively. Lettuce ‘Cherokee’ and arugula grown with food waste fertilizer followed a similar trend with fresh shoot weights that were 80.1% and 95.6% less compared to the chemical fertilizer, respectively. In general, the magnitude of reduction in the plant growth was greatest in arugula. These results suggest that both fertilizers were able to successfully grow lettuce and arugula, although the reduced plant growth with the food waste fertilizer in our study is likely from a lower concentration of nutrients when we considered EC as an indicator of nutrient concentration equivalency of the two fertilizer types.

Conventional functional assays (FAs), which are used to describe the behaviors and assess the impacts of engineered nanomaterials (ENMs), have extensive human factor related errors (i.e. extraction process errors due to human laboratory skills), and consume considerable amounts of laboratory material. Consequently, there is a need and opportunity to improve conventional FAs by minimizing the potential for human factor related errors, reducing the usage of ENMs and reagents, and increase experimental reproducibility. The goal of this study was to simplify the conventional FAs and evaluate the feasibility and reproducibility of the simplified FAs. The underlying hypothesis implies that simplified FAs could quickly quantify the partitioning of nanoparticles between immiscible phases with minimum human factor related errors, low usage of ENMs, and high experimental reproducibility. Three different FAs were studied for this project: octanol-water assay, distribution to sediment assay, and cloud point extraction (CPE) assay. Three widely applied ENMs were selected: silver nanoparticles (AgNPs) coated with citrate, magnetite nanoparticles (Fe3O4) capped with polyvinyl pyrrolidone (PVP), and multiwall carbon nanotubes (MWCNTS) dispersed in an organic solution. Removal efficiency was the selected parameter used to describe the distribution of ENMs. Based on the variability and the t-tests on the removal efficiencies of conventional and simplified FAs, it is conclusive that the conventional octanol-water FAs on Fe3O4, the sediment FAs on Fe3O4, and the CPE FAs on MWCNTs and Fe3O4 can be simplified. The conventional octanol-water on AgNPs and the sediment FAs on AgNPs and MWCNTs cannot be simplified. It is inconclusive that the conventional octanol-water FAs on MWCNTs and the CPE FAs on AgNPs can be simplified, due to the uncertain causes and consistency of the differences on the removal efficiencies.