Impacts of Anaerobic Thermophilic Fermentation on Physicochemical Characteristics of Effluents Derived from Diverse Organic Feedstocks

Abstract

The study primarily investigates the chemical and physical properties of effluent produced via anaerobic thermophilic fermentation, aimed at addressing critical agricultural issues such as low soil fertility, diminished crop yields, and soil cover degradation. Raw materials, specifically cattle manure and vegetable food waste, were subjected to anaerobic thermophilic fermentation in a bioreactor. Potentiometric methods were employed to ascertain the acidity index, while the quantification of total nitrogen content was achieved through the wet oxidation of the test sample's organic substances, facilitated by heated sulfuric acid in the presence of catalysts. A widely accepted flotation method was utilized to detect helminth eggs, followed by a quantitative counting process. The study strived to determine the most effective ratios of organic waste components and other factors, thereby ensuring the production of an organic fertilizer with superior physicochemical and microbiological properties. During the thermophilic fermentation process, the total content of major nutritional elements and humus-forming substances remained stable. The outcomes revealed that the anaerobic thermophilic process significantly amplified the concentration of ammonium nitrogen in the fermented biomass (by 40-60%), while the total carbon content decreased (by 15-30%). Furthermore, a decline was observed in dry and organic matter content, and the C/N ratio reduced. An inverse relationship between the effluent's acidity and the content of ammonium nitrogen was noticed. Anaerobic treatment also enhanced the rheological properties of the fertilizers. Compared to pre-fermentation effluent, post-fermentation effluent exhibited a lower total content of suspended solids, fewer large particles, and reduced biomass density. The resulting product, an organic fertilizer, was characterized by high nitrogen and carbon content, absence of pathogenic microflora, and was deemed ready for use.