## 1 Introduction
### Focus of This Study--Decaying, EMs, Sterilization, Anaerobic Digestion, and Their Combinations  
In summary, biological methods such as EM composting and anaerobic digestion are crucial for organic waste management, with anaerobic digestion gaining prominence due to its efficiency and ability to produce valuable byproducts. Technological advancements over the past two decades have optimized fermentation processes, making them reliable for producing high-quality digestate. The primary goal of this paper is to evaluate whether anaerobic digestion or treatment with effective microorganisms (EMs) enhances kitchen waste's potential as a fertilizer. Specifically, this research investigates the effects of various treatments of kitchen waste on ryegrass growth, biomass yield, and nitrogen uptake. Ryegrass (_Lolium_) is a pollutant-resistant and fast-growing plant, which can be effectively used from early spring to late autumn in central and northern European regions, e.g., for urban green areas, which do not generate any food for consumers. The choice of the ryegrass was due to two main reasons: (1) rapid growth and high biomass yield: (1a) ryegrass grows quickly and produces a substantial amount of biomass, allowing researchers to assess the effectiveness of fertilizers within a short period, (1b) its fast growth makes it an ideal candidate for repeated measurements, offering consistent and reliable data; and (2) high nutrient uptake: ryegrass is efficient in taking up nutrients such as nitrogen (N), phosphorus (P), and potassium (K), which are often present in processed waste fertilizers. This allows researchers to evaluate the nutrient availability and potential environmental impacts, such as leaching or runoff, from waste fertilizers. That is why it was decided to use this crop in the current study. The Monod model kinetics, a well-established framework in biological and ecological studies, could be later employed to describe biomass growth [38; 39]. Moreover, this paper proposes a comprehensive quantitative utilization model based on a literature review, establishing a closed-loop resource chain to achieve efficient management and complete nutrient consumption. While previous studies primarily focused on the effects of EM in composting, this research presents an alternative approach to valorizing kitchen waste without a composting step. By utilizing decaying EMs, thermal sterilization, and anaerobic digestion, this study aims to produce solid organic fertilizers that are non-toxic and environmentally friendly. Of course, generating extra energy, if it comes from fossil fuels for sterilization, may not be considered as an environmentally friendly process, but in this case, this process would be considered as an obligatory step in meeting the national and international regulations on organic and organic-mineral fertilizer production. The production of high-quality organic fertilizers and the use of unpolluted natural resources are critical for achieving a sustainable and clean environment. Ultimately, this paper seeks to demonstrate the potential of effective microorganisms and anaerobic digestion in producing solid organic fertilizers, promoting sustainable resource use and agricultural productivity. Fertilizers' agronomic properties are evaluated through plant testing, with germination tests being the most common. These tests measure germination strength, germination index (percentage of seeds that germinate), and phytotoxicity, providing insight into fertilizer effects during the early stages of plant growth. Pot tests allow for the assessment of later growth phases (e.g., up to the third leaf stage in cucumbers) under controlled conditions in a phytotron or greenhouse. Germination tests have the benefit of near-real conditions and enable the evaluation of the transfer factor, or nutrient uptake within the soil-plant system. Various model plants, such as ryegrass, are used in pot trials [40; 41; 42] as in the present study.