SARS-CoV-2 wastewater surveillance for public health action

Wastewater surveillance for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has garnered extensive public attention during the coronavirus disease pandemic as a proposed complement to existing disease surveillance systems. Over the past year, methods for detection and quantifi cation of SARS-CoV-2 viral RNA in untreated sewage have advanced, and concentrations in wastewater have been shown to correlate with trends in reported cases. Despite the promise of wastewater surveillance, for these measurements to translate into useful public health tools, bridging the communication and knowledge gaps between researchers and public health responders is needed. We describe the key uses, barriers, and applicability of SARS-CoV-2 wastewater surveillance for supporting public health decisions and actions, including establishing ethics consideration for monitoring. Although wastewater surveillance to assess community infections is not a new idea, the coronavirus disease pandemic might be the initiating event to make this emerging public health tool a sustainable nationwide surveillance system, provided that these barriers are addressed

Comparison of bench scale testing methods for nitrifier growth rate measurement

The maximum specific nitrifier growth rate was determined for two wastewater treatment plants (WWTPs) using sequencing batch reactors (SBRs) and high F/M exponential growth batch tests. Higher nitrifier growth rates were obtained from the exponential growth batch tests. Operating SRT and aeration mode (fully aerobic versus anoxic/aerobic) significantly impacted the nitrifier's growth rate in the SBRs with lower SRT and anoxic/aerobic operation resulting in higher specific nitrifier growth rates.</jats:p

Treatment costs of ammonia recovery from biogas digestate by air stripping analyzed by process simulation

Ammonia can be recovered from liquid biogas digestate as ammonium sulfate by air stripping. A full-scale plant treating 30,000 kg h−1 of digestate was simulated in Aspen Plus.The classical sequence stripper–absorber was modified by introducing a flash drum to reduce the buffer capacity. The stripped digestate was mixed with NaOH up to a pH value of 9 and fed to the stripping column using air at 90 °C. The air flow rate was optimized considering the possible recycle from the absorption column. The complete process was modeled using the process simulator Aspen Plus considering a recovery of ammonia equal to 95%. The total capital investment was evaluated by means of Aspen Plus Process Economic Analyzer in about 5.5 million US$, and the costs of energy and chemicals were quantified in less than 1 million US$ year−1. A benefit of 1.6 US$for m3 of digestate was obtained considering an ammonium sulfate price of 522 US$ ton−1.</p