Impact of temperature and residence time on sewage sludge pyrolysis for combined carbon sequestration and energy production

Environmental challenges related to sewage sludge call for urgent sustainable management of this resource. Sludge pyrolysis might be considered as a sustainable technology and is anticipated to support measures for mitigating climate change through carbon sequestration. The end products of the process have various applications, including the agricultural utilization of biochar, as well as the energy exploitation of bio-oil and syngas. In this research, sewage sludge was pyrolyzed at 500 °C, 600 °C, 750 °C, and 850 °C. At each temperature, pyrolysis was explored at 1hr, 2hrs, and 3hrs residence times. The ratio (H/Corg)at was tapped to imply organic carbon stability and carbon sequestration potential. Optimum operating conditions were achieved at 750 °C and 2hrs residence time. Produced biochar had (H/Corg)at ratio of 0.54, while nutrients' contents based on dry weight were 3.99%, 3.2%, and 0.6% for total nitrogen (TN), total phosphorus (TP), and total potassium (TK), respectively. Electrical conductivity of biochar was lesser than the feed sludge. Heavy metals in biochar aligned with the recommended values of the International Biochar Initiative. Heat content of condensable and non-condensable volatiles was sufficient to maintain the temperature of the furnace provided that PYREG process is considered. However, additional energy source is demanded for sludge drying.

Manufacturing Processes of a Purified Microbiome Therapeutic Reduce Risk of Transmission of Potential Bacterial Pathogens in Donor Stool

BACKGROUND

Although fecal microbiota transplant has been used to prevent recurrent Clostridioides difficile infection (rCDI), documented pathogen transmissions highlight inherent safety risks of minimally processed stool. We describe manufacturing processes for fecal microbiota spores, live (VOWST; VOS, formerly SER-109), a microbiota-based oral therapeutic of Firmicutes spores.

METHODS

Bacterial inactivation kill curves were obtained after ethanol exposure for 4 model organisms spiked into process intermediates.

RESULTS

Bacterial log reduction factors ranged from 6.5 log10 to 7.4 log10 and lysis of spiked organisms occurred rapidly within 30 seconds.

CONCLUSIONS

These experiments demonstrate substantial and rapid inactivation of representative organisms, supporting the potential benefit of VOS manufacturing processes to mitigate risk.

1035. Manufacturing Processes of SER-109, a Purified Investigational Microbiome Therapeutic, Reduce Risk of Transmission of Emerging and Undetected Infections in Donor Stool

Background

Fecal microbiota transplantation (FMT) is vulnerable to emerging pathogens due to reliance on donor screening for risk mitigation. These concerns were highlighted by dual FDA safety alerts regarding FMT transmission of bacterial pathogens, which were recognized in hindsight only after hospitalizations and deaths. The FDA also warned of potential risk of SARS-CoV-2 transmission, leading to quarantine of FMT in March 2020, two months after COVID-19 was reported on US soil. Conversely, our development program for SER-109, an oral investigational microbiome therapeutic, was prospectively designed to inactivate organisms of concern, while purifying the hardy Firmicutes spores. We evaluated whether the manufacturing processes for SER-109 inactivate model organisms, including a coronavirus with gastrointestinal tropism, and a representative Gram-negative bacterium.

Methods

Model organisms were selected based on biologic suitability, detectability, and laboratory safety. Porcine Epidemic Diarrhea Virus (PEDV, a coronavirus) was selected to model SARS-CoV-2. Quantitation used a Vero cell tissue culture infectious dose (TCID50) assay. For E. coli, a rifampicin-tolerant Salmonella enterica was selected and quantified with MacConkey lactose agar plus rifampicin. Spiking experiments into representative fecal suspensions were completed to measure inactivation of model organisms. Log-reduction factors (LRF) were calculated based on the drop in organism titer during inactivation. Hold controls in non-ethanolic test matrices were used to confirm specificity of the ethanol inactivation.

Results

In 70% v/v ethanol, PEDV was inactivated by more than 4.2 log10 (to limit of detection, LOD) within 4 minutes (Fig1). In 50% v/v ethanol, S. enterica was inactivated by more than 6.5 log10 (to LOD) within 30 seconds (Fig2).

Figure 1. Inactivation of Porcine Epidemic Diarrhea Virus (PEDV), log10 reduction factor (LRF) versus time

Conclusion

These experiments demonstrate substantial inactivation of the model organisms and support the potential benefit of SER-109 manufacturing process to mitigate risks of undetected or emerging pathogens for which reliable screening is limited. Ethanol exposure leads to a purified investigational product of beneficial Firmicutes spores while affording a safety net beyond donor screening alone.

Disclosures

Christopher McChalicher, n/a, Seres Therapeutics (Employee, Shareholder) Ahmad Abdulaziz, MS, Seres Therapeutics Inc. (Employee, Shareholder) Elizabeth Halvorsen, PhD, Seres Therapeutics (Employee, Shareholder) Mary-Jane Lombardo, PhD, Seres Therapeutics (Employee, Shareholder) Jonathan Winkler, PhD, Seres Therapeutics (Employee, Shareholder) Barbara McGovern, MD, Seres Therapeutics (Employee, Shareholder) Gregory McKenzie, PhD, Prolacta Bioscience (Employee) David Ege, PhD, Merck & Co., Inc. (Shareholder)Seres Therapeutics (Employee, Shareholder) John Aunins, PhD, Seres Therapeutics, Inc. (Employee)