ABSTRACT
The new coronavirus 2 (SARS-CoV-2) is known to be also shed through feces, which makes wastewater-based surveillance possible, independent of symptomatic cases and unbiased by any testing strategies and frequencies. We investigated the entire population of the Principality of Liechtenstein with samples from the wastewater treatment plant Bendern (serving all 39,000 inhabitants). Twenty-four-hour composite samples were taken once or twice a week over a period of 6 months from September 2020 to March 2021. Viral RNA was concentrated using the PEG centrifugation method followed by reverse transcription quantitative PCR. The aim of this research was to assess the suitability of SARS-CoV-2 fragments to relate the viral wastewater signal to the incidences and assess the impact of the emerging B.1.1.7. variant. The viral load in the wastewater peaked at almost 9 × 108 viral fragments per person equivalent (PE) and day on October 25, and showed a second peak on December 22 reaching a viral load of approximately 2 × 108 PE-1d-1. Individual testing showed a lag of 4 days and a distinct underestimation of cases at the first peak when testing frequency was low. The wastewater signal showed an immediate response to the implementation of non-pharmaceutical interventions. The new virus variant B.1.1.7. was first detected in wastewater on December 23, while it was first observed with individual testing on January 13, 2021. Further, our data indicate that the emergence of new virus variant may change the wastewater signal, probably due to different shedding patterns, which should be considered in future models.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Liechtenstein , Prevalence , WastewaterABSTRACT
A 750,000litre fermenter was studied throughout one entire year by investigating the concentrations of volatile fatty acids (acetic, butyric, i-butyric, propionic, valeric and i-valeric acids), pH, concentrations of total C, N, S and NH(4)(+)-N, amounts of chemical and biological oxygen demand, and abundance of acetogenic microorganisms. Additionally several process parameters such as temperature, retention time, dry weight and input of substrate and liquids, and the concentrations and amounts of CH(4), H(2), CO(2) and H(2)S within the biogas were monitored continuously. Various volatile fatty acids and the ratio of acetic to propionic acid were shown to allow a rough indication on the fermentation but were not sufficiently precise to describe the fermenter performance. Nutrient compounds and special fractions, such as easily extractable carbohydrates or the concentration of total fats were more strongly correlated to the gas production of the fermenter. Results of an MPN-method for the determination of acetogenic microorganisms point to an important role of these microorganisms during the phase of restoration of the fermenter performance.
