The role of inorganic nitrogen in successful formation of granular biofilms for wastewater treatment that support cyanobacteria and bacteria

Recently, the use of phototrophs for wastewater treatment has been revisited because of new approaches to separate them from effluent streams. One manifestation uses oxygenic photogranules (OPGs) which are dense, easily-settleable granular biofilms of cyanobacteria, which surrounding populations of heterotrophs, autotrophs, and microalgae. OPGs can remove COD and nitrogenous compounds without external aeration. To better grow and maintain biomass in the proposed wastewater process, this study seeks to understand the factors that contribute to successful granulation. Availability of initial inorganic nitrogen, particularly ammonium, was associated with successful cultivation of OPGs. In the first days of granulation, a decrease in ammonium coupled with an increase in a cyanobacterial-specific 16S rRNA gene, may suggest that ammonium was assimilated in cyanobacteria offering a competitive environment for growth. Though both successful and unsuccessful OPG formation demonstrated a shift from non-phototrophic bacterial dominated communities on day 0 to cyanobacterial dominated communities on day 42, the successful community had a greater relative abundance (46%) of OTUs associated with genera Oscillatoria and Geitlernema than the unsuccessful community (27%), supporting that filamentous cyanobacteria are essential for successful OPG formation. A greater concentration of chlorophyll b in the unsuccessful OPG formation suggested a greater abundance of algal species. This study offers indicators of granulation success, notably availability of inorganic nitrogen and chlorophyll a and b concentrations for monitoring the health and growth of biomass for a potential OPG process

Wastewater Surveillance for SARS-CoV-2 on College Campuses: Initial Efforts, Lessons Learned, and Research Needs

Wastewater surveillance for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging approach to help identify the risk of a coronavirus disease (COVID-19) outbreak. This tool can contribute to public health surveillance at both community (wastewater treatment system) and institutional (e.g., colleges, prisons, and nursing homes) scales. This paper explores the successes, challenges, and lessons learned from initial wastewater surveillance efforts at colleges and university systems to inform future research, development and implementation. We present the experiences of 25 college and university systems in the United States that monitored campus wastewater for SARS-CoV-2 during the fall 2020 academic period. We describe the broad range of approaches, findings, resources, and impacts from these initial efforts. These institutions range in size, social and political geographies, and include both public and private institutions. Our analysis suggests that wastewater monitoring at colleges requires consideration of local information needs, sewage infrastructure, resources for sampling and analysis, college and community dynamics, approaches to interpretation and communication of results, and follow-up actions. Most colleges reported that a learning process of experimentation, evaluation, and adaptation was key to progress. This process requires ongoing collaboration among diverse stakeholders including decision-makers, researchers, faculty, facilities staff, students, and community members

Ecological and Transcriptional Responses of Anode-Respiring Communities to Nitrate in a Microbial Fuel Cell

A poorly understood phenomenon with a potentially significant impact on electron recovery is competition in microbial fuel cells (MFC) between anode-respiring bacteria and microorganisms that use other electron acceptors. Nitrate is a constituent of different wastewaters and can act as a competing electron acceptor in the anode. Studies investigating the impact of competition on population dynamics in mixed communities in the anode are lacking. Here, we investigated the impact of nitrate at different C/N ratios of 1.8, 3.7, and 7.4 mg C/mg N on the electrochemical performance and the biofilm community in mixed-culture chemostat MFCs. The electrochemical performance of the MFC was not affected under electron donor non-limiting conditions, 7.4 mg C/mg N. At lower C/N, electron donor limiting and ratio electron recovery were significantly affected. The electrochemical performance recovered upon removal of nitrate at 3.7 mg C/mg N but did not at 1.8 mg C/mg N. Microbial community analysis showed a decrease in <i>Deltaproteobacteria</i> accompanied by an increase in <i>Betaproteobacteria</i> in response to nitrate at low C/N ratios and no significant changes at 7.4 mg C/mg N. Transcriptional analysis showed increased transcription of <i>nirK</i> and <i>nirS</i> genes during nitrate flux, suggesting that denitrification to N₂ and not facultative nitrate reduction by <i>Geobacter</i> spp. might be the primary response to perturbation with nitrate

Quantifying the Relationship between SARS-CoV-2 Wastewater Concentrations and Building-Level COVID-19 Prevalence at an Isolation Residence: A Passive Sampling Approach

SARS-CoV-2 RNA loads can be detected in the excreta of individuals with COVID-19 and have demonstrated positive correlations with clinical infection trends. Consequently, wastewater-based epidemiology (WBE) approaches have been implemented globally as a public health surveillance tool to monitor community-level prevalence of infections. The majority of wastewater specimens are gathered as either composite samples via automatic samplers (autosamplers) or grab samples. However, autosamplers are expensive and can be challenging to maintain in cold weather, while grab samples are particularly susceptible to temporal variation when sampling sewage directly from complex matrices outside residential buildings. Passive sampling can provide an affordable, practical, and scalable sampling system while maintaining a reproducible SARS-CoV-2 signal. In this regard, we deployed tampons as passive samplers outside of a COVID-19 isolation unit (a segregated residence hall) at a university campus from 1 February 2021&ndash;21 May 2021. Samples (n = 64) were collected 3&ndash;5 times weekly and remained within the sewer for a median duration of 24 h. SARS-CoV-2 RNA was quantified using reverse-transcription quantitative polymerase chain reaction (RT-qPCR) targeting the N1 and N2 gene fragments. We quantified the mean viral load captured per individual and the association between the daily viral load and total persons, adjusting for covariates using multivariable models to provide a baseline estimate of viral shedding. Samples were processed through two distinct laboratory pipelines on campus, yielding highly correlated N2 concentrations. Data obtained here highlight the success of passive sampling utilizing tampons to capture SARS-CoV-2 in wastewater coming from a COVID-19 isolation residence, indicating that this method can help inform building-level public health responses

Bioelectrochemical perchlorate reduction in a microbial fuel cell

Perchlorate is an emerging surface water and groundwater contaminant, and it is of concern because of its mobility in the environment and its inhibitory effect on thyroid function. Microbial fuel cells (MFCs) may be a suitable method for its treatment We investigated a MFC with a denitrifying biocathode for perchlorate reduction and utilized the system to identify putative biocathode-utilizing perchlorate-reducing bacteria (PCRB). Perchlorate reduction in the MFC was established by increasing the perchlorate loading to the biocathode, while decreasing nitrate loading. Perchlorate reduction was obtained without the need for exogenous electron shuttles or fixed electrode potentials, achieving a maximum perchlorate removal of 24 mg/L-d and cathodic conversion efficiency of 84%. The perchlorate-reducing biocathode bacterial community, which contained putative denitrifying Betaproteobacteria, shared little overlap with a purely denitrifying biocathode community, and was composed primarily of putative iron-oxidizing genera. Despite differences in cathodic function, the anode communities from the perchlorate-reducing MFC and the denitrifying MFC were similar to each other but different than their corresponding biocathode community. These data indicate that PCRB can utilize a cathode as an electron donor, and that this process can be harnessed to treat perchlorate while producing usable electrical power

The Oxygenic Photogranule Process for Aeration-Free Wastewater Treatment

This study presents the oxygenic photogranule (OPG) process, a light-driven process for wastewater treatment, developed based on photogranulation of filamentous cyanobacteria, nonphototrophic bacteria, and microalgae. Unlike other biogranular processes requiring airlift or upflow-based mixing, the OPG process was operated in stirred-tank reactors without aeration. Reactors were seeded with hydrostatically grown photogranules and operated in a sequencing-batch mode for five months to treat wastewater. The new reactor biomass propagated with progression of photogranulation under periodic light/dark cycles. Due to effective biomass separation from water, the system was operated with short settling time (10 min) with effective decoupling of hydraulic and solids retention times (0.75 d vs 21–42 d). During quasi-steady state, the diameter of the OPGs ranged between 0.1 and 4.5 mm. The reactors produced effluents with average total chemical oxygen demand less than 30 mg/L. Nitrogen removal (28–71%) was achieved by bioassimilation and nitrification/denitrification pathways. Oxygen needed for the oxidation of organic matter and nitrification was produced by OPGs at a rate of 12.6 ± 2.4 mg O₂/g biomass-h. The OPG system presents a new biogranule process, which can potentially use simple mixing and natural light to treat wastewater

Wastewater Surveillance for SARS-CoV-2 on College Campuses: Initial Efforts, Lessons Learned, and Research Needs.

Wastewater surveillance for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging approach to help identify the risk of a coronavirus disease (COVID-19) outbreak. This tool can contribute to public health surveillance at both community (wastewater treatment system) and institutional (e.g., colleges, prisons, and nursing homes) scales. This paper explores the successes, challenges, and lessons learned from initial wastewater surveillance efforts at colleges and university systems to inform future research, development and implementation. We present the experiences of 25 college and university systems in the United States that monitored campus wastewater for SARS-CoV-2 during the fall 2020 academic period. We describe the broad range of approaches, findings, resources, and impacts from these initial efforts. These institutions range in size, social and political geographies, and include both public and private institutions. Our analysis suggests that wastewater monitoring at colleges requires consideration of local information needs, sewage infrastructure, resources for sampling and analysis, college and community dynamics, approaches to interpretation and communication of results, and follow-up actions. Most colleges reported that a learning process of experimentation, evaluation, and adaptation was key to progress. This process requires ongoing collaboration among diverse stakeholders including decision-makers, researchers, faculty, facilities staff, students, and community members