Pathogen Reduction Potential in Anaerobic Digestion of Organic Fraction of Municipal Solid Waste and Food Waste

Abstract

Anaerobic digestion (AD) is a commonly used method of processing waste. Regardless of the type of the used digestate (fertilizer, feedstock in case of solid-state fermentation, raw-material in case of thermal treatment) effective pathogen risk elimination, even in the case of high pathogen concentration is essential. An investigation of the survival time and inactivation rate of the Salmonella Senftenberg W775, Enterococcus spp., and Ascaris suum eggs during thermophilic anaerobic digestion performed on laboratory scale and confirmation of hygienization in full-scale operation were performed in this study. Except for sanitization efficiency, the AD process performance and stability were also verified based on determination of pH value, dry matter content, acidity, alkalinity, and content of fatty acids. The elimination of pathogen was met within 6.06 h, 5.5 h, and about 10 h for the Salmonella Senftenberg W775, Enterococcus spp., and Ascaris suum, respectively in the laboratory trials. The obtained results were confirmed in full-scale tests, using 1500 m3 Kompogas® reactors, operating in MBT Plant located in Poland. Sanitization of the digestate was achieved. Furthermore, the process was stable. The pH value, suspended solids, and ammonium content remained stable at 8.5, 35%, and 3.8 g/kg, respectively. The acetic acid content was noted between almost 0.8 and over 1.1 g/kg, while the concentration of propionic acid was noted at maximum level of about 100 mg/kg. The AD conditions could positively affect the pathogen elimination. Based on these results it can be found that anaerobic digestion under thermophilic conditions results in high sanitation efficiency.

Physicochemical, microbiological characterization and phytotoxicity of digestates produced on single-stage and two-stage anaerobic digestion of food waste

“…The infectious properties of HE can be preserved between 20 months and 6 yr [41]. In this study, D1 reported a higher level of HE than D2 (60% reduction) and D3 (total inactivation).…”

Separate Collected Versus Mechanical Segregated Organic Fractions in Terms of Fertilizers Suitability

“…These requirements were applied in the EU regulation of fertilizers. The AD in thermophilic conditions ensures the proper sanitization of OFMSW [14].…”

“…Thus, it can be stated that waste biological treatment can bring environmental gains. AD brings more benefits than single composting, mainly due to the possibility of energy recovery from waste [33], despite the digestate and its proper sanitization [14]. Some researchers have confirmed the soil amendment effect of a digestate [17,34].…”

“…Considering the potential negative effects of using a digestate from agricultural waste, providing a safety assurance for the digestate is essential in the organic fraction of municipal waste. Hence, the thermophilic aerobic digestate treatment should ensure the sanitization of OFMSW [14], and as a second step, the aerobic digestate treatment should provide higherquality compost.…”

“…The two main byproducts: the digestate (semi-solid residue) and the effluents (together with liquid digestate) occur from AD and must be adequately managed. The digested residue might be used as a fertilizer and must, therefore, be hygienically safe [14]. The AD might also be followed by composting.…”