Pretreatment of spiramycin fermentation residue using hyperthermophilic digestion: quick startup and performance

Abstract

This study aimed to evaluate the feasibility of hyperthermophilic anaerobic digestion at 70 °C in the pretreatment of spiramycin fermentation residue. By feeding municipal excess sludge under a solid retention time of 5 days, the hyperthermophilic digester was successfully started up within 3 days from mesophilic digestion by a one-step temperature increase from 35 to 70 °C. MiSeq sequencing showed the fast establishment of thermophilic fermenting bacterial communities in 3 days immediately after the temperature increase, with increases in abundance of Coprothermobacter, Spirochaetaceae_uncultured and Fervidobacterium from <0.001%, 1.06% and <0.001% to 33.77%, 11.65% and 3.42%, respectively. The feasibility of hyperthermophilic digestion for spiramycin residue was evaluated in batch experiments for 7 days. Hyperthermophilic digestion considerably reduced antibiotic concentrations, with removal efficiencies of 55.3% and 99.0% for the spiramycin residue alone and its mixture with hyperthermophilic sludge, respectively. At the same time, the abundances of four macrolide-lincosamide-streptogramin resistance genes were also reduced within 7 days, due to the decrease of their corresponding hosts. These results suggest that hyperthermophilic digestion could easily be started up from mesophilic digestion and might be a suitable pretreatment approach for spiramycin residue.

Hydrothermal pretreatment of oxytetracycline fermentation residue: Removal of oxytetracycline and increasing the potential for anaerobic digestion

“…At present, hydrothermal pretreatment has been applied in the treatment of waste mother liquor from the antibiotic fermentation process [10]. Recently, we reported that hyperthermophilic anaerobic digestion process operated at 70°C for 7 d could simultaneously remove antibiotics, reduce antibiotic resistance genes (ARGs) and enhance the solubility of spiramycin fermentation residue [11]. To further improve efficiency and reduce processing time, the thermal hydrolysis process operated at more than 120°C [12,13] has been developed.…”

Integrated nutrient recovery from source-separated domestic wastewaters for application as fertilisers

“…Hygienisation is a prerequisite for the safe agricultural reuse of the anaerobic digestate and its solid or liquid fractions [12,38]. A separate pasteurisation step can be avoided when the anaerobic treatment itself is carried out at thermophilic temperatures at appropriate minimum retention times [12,[39][40][41][42].…”