Shelesh Agrawal

Technical University of Darmstadt | TU · Department of Civil and Environmental Engineering Sciences (Dept.13)

Background Sequencing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA from wastewater samples has emerged as a valuable tool for detecting the presence and relative abundances of SARS-CoV-2 variants in a community. By analyzing the viral genetic material present in wastewater, researchers and public health authorities can gain e...

Waste stabilization pond (WSP) systems exist in many countries affected by climate change causing increasing demand for irrigation water. There is little long-term experience with WSP in Africa, and thus, this study provides a comprehensive investigation of a WSP in Namibia. One of its treatment trains was upgraded with mechanical and anaerobic pre...

Background Sequencing of SARS-CoV-2 RNA from wastewater samples has emerged as a valuable tool for detecting the presence and relative abundances of SARS-CoV-2 variants in a community. By analyzing the viral genetic material present in wastewater, public health officials can gain early insights into the spread of the virus and inform timely interve...

Tracking SARS-CoV-2 variants in wastewater is primarily performed by detecting characteristic mutations of the variants. Unlike the Delta variant, the emergence of the Omicron variant and its sub-lineages as variants of concern has posed a challenge in using characteristic mutations for wastewater surveillance. In this study, we monitored the tempo...

Wastewater-based SARS-CoV-2 epidemiology (WBE) has been established as an important tool to support individual testing strategies. The Omicron sub-variants BA.4/BA.5 have spread globally, displacing the preceding variants. Due to the severe transmissibility and immune escape potential of BA.4/BA.5, early monitoring was required to assess and implem...

Wastewater-based epidemiology (WBE) has demonstrated its importance to support SARS-CoV-2 epidemiology complementing individual testing strategies. Due to their immune-evasive potential and the resulting significance for public health, close monitoring of SARS-CoV-2 variants of concern (VoC) is required to evaluate the regulation of early local cou...

Waste stabilization ponds (WSP) exist worldwide to treat wastewater, especially in warm climates. They are characterized by simple operation and maintenance and over 50 years many WSP were built in urban communities in Namibia. This study characterized and evaluated nine of these WSP systems in terms of their influent and effluent water quality and...

For community-level monitoring, the European Commission under the EU Sewage Sentinel System recommends wastewater-based SARS-CoV-2 surveillance. Tracking SARS-CoV-2 variants in a community is pivotal for appropriate public health response. Genome sequencing of SARS-CoV-2 in wastewater samples for tracking variants is challenging, often resulting in...

Wastewater-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) surveillance of Frankfurt Airport by genome sequencing was used to detect SARS-CoV-2 variants entering the region. In November 2021, we found all characteristic mutations of Omicron in wastewater originating from Frankfurt Airport before the first confirmed clinical repor...

Assessing the efficacy of thermal hydrolysis of waste activated sludge in terms of boosting specific methane yield by using a normalized solids retention time of the activated sludge process.

Treated wastewater irrigation (TWW) releases antibiotics and antibiotic resistance genes (ARGs) into the environment and might thus promote the dissemination of antibiotic resistance in groundwater (GW). We hypothesized that TWW irrigation increases ARG abundance in GW through two potential mechanisms: the contamination of GW with resistant bacteri...

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemia has been one of the most difficult challenges humankind has recently faced. Wastewater-based epidemiology has emerged as a tool for surveillance and mitigation of potential viral outbreaks, circumventing biases introduced by clinical patient testing. Due to the situation urge...

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemia has been one of the most difficult challenges humankind has recently faced. Wastewater-based epidemiology has emerged as a tool for surveillance and mitigation of potential viral outbreaks, circumventing biases introduced by clinical patient testing. Due to the situation urge...

Wastewater based surveillance employing qPCR has already shown its utility for monitoring SARS-CoV-2 at community level, and consequently the European Commission has recommended the implementation of an EU Sewage Sentinel System. However, using sequencing for the determination of genomic variants in wastewater is not fully established yet. Therefor...

Upcycling wastes into valuable products by mixed microbial communities has recently received considerable attention. Sustainable production of high-value substances from one-carbon (C1) compounds, e.g., methanol supplemented as an external electron donor in bioreactors for wastewater treatment, is a promising application of upcycling. This study un...

We report a sequencing analysis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in wastewater samples collected in the Frankfurt metropolitan area of Germany. The majority of the detected mutations have been identified only in clinical genomes outside Frankfurt, indicating that the sequencing of SARS-CoV-2 RNA in wastewater can...

Wastewater-based epidemiology (WBE) is a great approach that enables us to comprehensively monitor the community to determine the scale and dynamics of infections in a city, particularly in metropolitan cities with a high population density. Therefore, we monitored the time course of the SARS-CoV-2 RNA concentration in raw sewage in the Frankfurt m...

Treated wastewater (TWW) irrigation is a useful counter-measure against the depletion of freshwater (FW) resources. However, TWW contains several contaminants of emerging concern, such as antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs). Thus, TWW irrigation might promote the spread of antimicrobial resistance in soil envir...

This study investigated the potential of Membrane-Aerated Biofilm Reactors (MABRs) for mainstream nitrogen removal via partial nitration / anaerobic ammonium oxidation (anammox). Four laboratory-scale MABRs were operated with real municipal wastewater characterized by low concentrations of nitrogen (varying between 31 – 120 mg-NH4-N L⁻¹) and the pr...

Quantitative PCR (qPCR) is broadly used as the gold standard to quantify microbial community fractions in environmental microbiology and biotechnology. Benchmarking efforts to ensure the comparability of qPCR data for environmental bioprocesses are still scarce. Also, for partial nitritation/anammox (PN/A) systems systematic investigations are stil...

The substantial presence of denitrifiers has already been reported in partial nitritation anammox (PNA) systems using the 16S ribosomal RNA (rRNA) gene, but little is known about the phylogenetic diversity based on denitrification pathway functional genes. Therefore, we performed a metagenomic analysis to determine the distribution of denitrificati...

In the present study, we investigated the impact of treated wastewater (TWW) irrigation on the prevalence of antibiotic resistance genes (ARGs) in subsoil pore-water, a so-far under-appreciated matrix. We hypothesized that TWW irrigation increases ARG prevalence in subsoil pore-water. This hypothesis was tested using a multiphase approach, which co...

Wastewater-based epidemiology (WBE) is a great approach that enables us to comprehensively monitor the community to determine the scale and dynamics of infections in a city, particularly in metropolitan cities with a high population density. Therefore, we monitored the time course of the SARS-CoV-2 RNA concentration in raw sewage in the Frankfurt m...

There are increasing concerns about wastewater treatment plants (WWTPs) acting as hotspots for antibiotic resistance genes (ARG). However, their role largely depends upon the treatment methods and antibiotics in the wastewater. To better understand these influences, we compared the occurrence and fate of ARG between a pond system in a developing co...

Using metagenome sequencing, a nearly complete genome sequence was retrieved for the uncultured Methyloceanibacter sp. strain A49, recovered from an activated sludge system used for landfill leachate treatment at a closed landfill site. The total size and encoded sequences are 3,407,434 bp and 3,280 genes, respectively.

The choice of primer and TaqMan probes to quantify ammonia‐oxidizing bacteria (AOB) in environmental samples is of crucial importance. The re‐evaluation of primer pairs based on current genomic sequences used for quantification of the amoA gene revealed (1) significant misrepresentations of the AOB population in environmental samples, (2) and a lac...

Aerobic and anaerobic oxidations of ammonium are core biological processes driving the nitrogen cycle in natural and engineered microbial ecosystems. These conversions are tailored in mixed-culture biotechnology to propel partial nitritation and anammox (PN/A) for a complete chemolithoautotrophic removal of nitrogen from wastewater at low resource...

Methane-oxidizing bacteria (MOB) possess the metabolic potential to assimilate the highly potent greenhouse gas, CH4, and can also synthesize valuable products. Depending on their distinct and fastidious metabolic pathways, MOB are mainly divided into Type I and Type II; the latter are known as producers of polyhydroxyalkanoate (PHA). Despite the m...

The membrane-aerated biofilm reactor (MABR) is considered promising for partial nitritation anammox (PNA) due to better control over the oxygen flux. Similar to other biofilm reactor configurations, the start-up of MABR depends on the inoculum biomass. The microbial community composition of the two distinctly selected inocula was investigated using...

The hurdles of PCR based methods like primer sets are continuously re-evaluated to ensure comparability and reproducibility, especially with the focus on the choice of the hypervariable region for best coverage of the microbial community either in conventional wastewater treatment plant (WWTP) or in partial nitritation anammox (PNA) systems. Howeve...

The diversity and dynamics of microorganisms in engineered ecosystems have a high impact on performance and operational stability. Nitrogen removal from wastewater is one example of such complex and dynamic ecosystems. Following the microbial community composition and its functional potential is highly valuable information for optimizing performanc...

PCR-based methods have caused a surge for integration of eco-physiological approaches into research on partial nitritation anammox (PNA). However, a lack of rigorous standards for molecular analyses resulted in widespread data misinterpretation and consequently lack of consensus. Data consistency and accuracy strongly depend on the primer selection...

We investigated the impact of wastewater treatment plant effluents on a German river. This river serves as a model area for understanding the impact of wastewater treatment plants because it flows through a water and bird protection area on its way into a bigger river. We performed sequencing of six hypervariable regions of the 16S rRNA gene to det...

Oxygen inhibits anammox, a bioconversion executed by anoxic ammonium oxidizing bacteria (AnAOB). Nonetheless, oxygen is mostly found in the proximity of AnAOB in nitrogen removal applications, being a substrate for nitritation. The experiments performed to date were mostly limited to batch activity tests where AnAOB activity is estimated during oxy...

Twenty years ago, mainstream partial nitritation/anammox (PN/A) was conceptually proposed as pivotal for a more sustainable treatment of municipal wastewater. Its economic potential spurred research, yet practice awaits a comprehensive recipe for microbial resource management. Implementing mainstream PN/A requires transferable and operable ways to...

Implementation of partial nitritation anammox (PNA) in the mainstream (municipal wastewater treatment) is still under investigation. Microbial community structure and reactor type can influence the performance of PNA reactor; yet, little is known about the role of the community composition of the inoculum and the reactor configuration under mainstr...

Partial Nitritation/Anammox (PN/A) is a well-established technology for side-stream nitrogen removal from highly concentrated, warm wastewaters. The focus has now shifted to weakly concentrated municipal wastewaters with much lower concentrations and temperatures. The major challenge is the temperature, which ranges from moderate 20 °C in summer to...

Municipal wastewater collected in areas with moderate climate is subjected to a gradual temperature decrease from around 20°C in summer to about 10°C in winter. A lab-scale moving bed biofilm reactor (MBBR) with carrier material (K3 from AnoxKaldnes) was used to test the tolerance of the overall partial nitritation/anammox process to this temperatu...

The exploitation of a lag phase in nitrate production after anoxic periods is a promising approach to suppress nitrite oxidizing bacteria, which is crucial for implementations of the combined partial nitritation-anammox process. An in depth study of the actual lag phase in nitrate production after short anoxic periods was performed with varied temp...