Supplementary sulfide during inoculation for improved sulfur autotrophic denitrification performance and adaptation to low temperature

Elemental sulfur (S0) autotrophic denitrification (SAD) has been considered an advanced denitrification technology due to its low operating cost and small secondary pollution in wastewater treatment plants. However, the wide application of this technology is still challenged by its low denitrification rate, long start-up time, and poor low-temperature adaptation. This study employed supplementary sulfide to facilitate the conversion of S0 into polysulfide, a critical step in SAD. Batch experiments indicated that more polysulfide could be generated when S0 served as an electron donor and partnered with additional Na2S, leading to greatly increased nitrate removal than the controls. Particularly when the sulfide concentration was relatively high at 160 mg/L, a denitrification rate up to 11.3 mg-N/(L·d) was achieved, 3.8-fold of control group working with solely S0. Sulfide was further applied during inoculation of a packed bed reactor (PBR) with S0 particles and significantly benefit the development of biofilm. Although the feeding of sulfide was stopped after inoculation, the reactor was fast started up in just 2 days and delivered an average denitrification rate of 346.9 mg-N/(L·d), 1.4-fold of the control. In addition, benefit from the thick and well-developed biofilm, the reactor was able to restore its nitrate removal performance, when challenged by a low temperature (15 °C), to a larger rate than the control. Compared to short-term employment of the sulfide which was found a temporary solution addressing declined SAD rate during operating the PBR, applying sulfide for inoculation facilitated the formation of biofilm, leading to sustained improvement of SAD performance and better adaptation to coldness.

A new inoculation method of sulfur autotrophic denitrification reactor for accelerated start-up and better low-temperature adaption

Elemental sulfur (S⁰) autotrophic denitrification (SAD) has been proved feasible for nitrate removal from aquatic environments. The long start-up period up to weeks of the SAD reactor impedes its industrial application. To accelerate the start-up process, this study employed S⁰ powder packed sequencing batch reactor operated for 10 days to obtain a seed biofilm, which was inoculated into a regular S⁰ flake packed bed reactor afterwards. Merely two days after inoculation, the reactor inoculated with seed biofilm was well started up and outperformed the control reactor, which was inoculated with regular anaerobic sludge and operated for more than 10 days, delivering much increased denitrification rate of 126 ± 0.68 mg N/(L·d) and a high nitrate removal efficiency of 93.0%. Batch tests during the start-up period showed that the seed biofilm developed well on S⁰ flakes and delivered improved nitrate removal performance than the control. Extracellular polymeric substance (EPS) analysis revealed an abundant content of protein in tightly bound EPS in the biofilm developed from the seed biofilm, which was recognized as a major contributor to facilitate the biofilm's attachment and growth onto S⁰ flakes. After operating under moderate temperature, the reactors were tested at a reduced temperature of 15 °C. Results indicated that the reactor inoculated with seed biofilm showed stronger adaptation ability towards low temperature and sustained better denitrification performance than the control, which was attributed to increased protein content in tightly bound EPS produced by the microbes against low-temperature. Determination of the microbial communities in tested reactors when the whole experiment was closing found that sulfur-related genera were dominating in the packed-bed reactor inculcated with seed biofilm, which played an important role in the S⁰-based denitrification process.

Accelerated first-in-human clinical trial of EIDD-2801/MK-4482 (molnupiravir), a ribonucleoside analog with potent antiviral activity against SARS-CoV-2

A recently published article described the safety, tolerability, and pharmacokinetic profile of molnupiravir (Painter et al. 2021), a novel antiviral agent with potent activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19). Here, we report an unprecedented collaboration between sponsor, contract research organization (CRO), and regulatory authorities that enabled accelerated generation of these phase I data, including administration of the first-in-human (FIH) dose of molnupiravir within 5 days of receiving regulatory approval in the United Kingdom (UK). Single and multiple ascending dose (SAD and MAD, respectively) cohorts were dosed in randomized, double-blind, and placebo-controlled fashion, with a 6:2 active-to-placebo ratio in each cohort. A food-effect (FE) cohort included 10 subjects who were randomized to receive drug in the fasted or fed state followed by the fed or fasted state to complete a fed and fasted sequence for each subject. Dose escalation decisions were accelerated and MAD cohorts were initiated prior to completion of all SAD cohorts with the provision that the total daily dose in a MAD cohort would not exceed a dose proven to be safe and well-tolerated in a SAD cohort. Dosing in healthy volunteers was completed for eight single ascending dose (SAD) cohorts, seven multiple ascending dose (MAD) cohorts, and one food-effect (FE) cohort within approximately 16 weeks of initial protocol submission to the Research Ethics Committee (REC) and Medicines and Healthcare products Regulatory Agency (MHRA). Working to standard industry timelines, the FIH study would have taken approximately 46 weeks to complete and 33 weeks to enable phase 2 dosing. Data from this study supported submission of a phase 2/3 clinical trial protocol to the US Food and Drug Administration (FDA) within 8 weeks of initial protocol submission, with FDA comments permitting phase 2 study initiation within two additional weeks. In the setting of a global pandemic, this model of collaboration allows for accelerated generation of clinical data compared to standard processes, without compromising safety.

Accelerated start-up for photo-fermentative hydrogen production in biofilm reactor by adding waste effluent

The difficulty and long duration of start-up wastes numerous costs, labors and time and a little fluctuate during the process might fail it. However, studies dealing with the problem hindering accelerated start-up are still insufficient. Current research focused to develop a method for accelerated start-up in an efficient way. This work outlined a novel alternative for accelerated start-up. This joint method, adding waste effluent with applying biofilm reactor, could successfully start up hydrogen production in the first 24 h via increasing ability of hydrogen producers while the control group produced little hydrogen. The two factors, biofilm formation and addition of waste effluent, expressed the combined effects on accelerated start-up. This study suggested that little molecules like quorum sensing system factors and indoles might be the crucial regulating and stimulating factors and express the accelerated start-up ability only in biofilm reactors.

Thermoanaerobacterium sp. Strain RBIITD as a dominant species in accelerating thermophilic dark fermentation start up through pH and substrate concentration regulation

In this work, accelerated start-up of biological hydrogen production system fed with glucose and molasses at 55 °C by regulating pH and COD concentration was investigated in two groups. Then three reactors in each group were compared: controlling pH, controlling pH with COD, and controlling the COD. The reactors in group A presented best hydrogen yield of 1.84 mol H₂/mol glucose·day and worked stably at the 8th day. The highest hydrogen yield in group B was 2.13 mol H₂/mol molasses·day and steadily at the 11th day. It proved that controlling two key parameters of the inflow pH (8.0) and substrate concentration (4000 mg COD/L) could realize fast start-up of hydrogen production reactor. This study demonstrated that Thermoanaerobacterium sp. strain RBIITD could produce hydrogen and provide a new avenue for biological hydrogen production by dark fermentation using cheap substrate towards a more sustainable and feasible technology.