Pathogen and Particle Associations in Wastewater

Abstract

Disinfection guidelines exist for pathogen inactivation in potable water and recycled water, but wastewater with high numbers of particles can be more difficult to disinfect, making compliance with the guidelines problematic. Disinfection guidelines specify that drinking water with turbidity ≥1 Nephelometric Turbidity Units (NTU) is not suitable for disinfection and therefore not fit for purpose. Treated wastewater typically has higher concentrations of particles (1-10NTU for secondary treated effluent). Two processes widely used for disinfecting wastewater are chlorination and ultraviolet radiation. In both cases, particles in wastewater can interfere with disinfection and can significantly increase treatment costs by increasing operational expenditure (chemical demand, power consumption) or infrastructure costs by requiring additional treatment processes to achieve the required levels of pathogen inactivation. Many microorganisms (viruses, bacteria, protozoans) associate with particles, which can allow them to survive disinfection processes and cause a health hazard. Improved understanding of this association will enable development of cost-effective treatment, which will become increasingly important as indirect and direct potable reuse of wastewater becomes more widespread in both developed and developing countries. This review provides an overview of wastewater and associated treatment processes, the pathogens in wastewater, the nature of particles in wastewater and how they interact with pathogens, and how particles can impact disinfection processes.

Co-quantification of crAssphage increases confidence in wastewater-based epidemiology for SARS-CoV-2 in low prevalence areas

“…More sensitive methods, but also improved interpretation of wastewater surveillance data, would be facilitated by a better understanding of the state of both SARS-CoV-2 RNA and surrogate nucleic acids within wastewater and, specifically, what proportion are a) contained within viral particles, b) released and dissolved, or c) released and bound to other particles. While some studies have explored viral associations to various wastewater particles in terms of size and charge ( da Silva et al., 2008 ; Hejkal et al., 1981 ), variability in particle association between different types of viruses ( Chahal et al., 2016 , Chen et al., 2020 , Colosi et al., 2020 , Crits-Christoph et al., 2021 , da Silva et al., 2008 ) suggests that both SARS-CoV-2 and surrogate viral particle associations may require specific study with an additional focus on the state(s) of nucleic acids. If some DNA or RNA is bound, knowing the size and mass of the particles and how they vary over time and across locations would greatly improve the precision of methods based on size (e.g., ultrafiltration), charge (e.g., electropositive filtration), or mass (e.g., ultracentrifugation).…”

Removal of bacterial and viral indicator organisms in full-scale aerobic granular sludge and conventional activated sludge systems

“…The expected concentrations of F-specific RNA bacteriophages in raw wastewater has been reported to range approximately from 10 4 to 10 6 PFU/100 mL (De Luca et al., 2013; McMinn et al., 2017; Thwaites et al., 2018; Zhang and Farahbakhsh, 2007). The concentration of faecal coliforms ( E. coli , TtC and Enterococcus ) in raw wastewater ranges from 10 6 to 10 7 CFU/100 mL (Henze et al., 2008); Chahal et al. (2016) reported for E. coli concentrations of 10 4 to 10 9 CFU/100 mL, and Matthews et al.…”

“…(2017) reported removal efficiencies of faecal indicator organisms (FIOs) such as F-specific RNA bacteriophages and total coliforms of 99.5% and higher. FIOs may be either physically removed, being enmeshed into the flocs during the sedimentation process (Chahal et al., 2016; Fauvel et al., 2017; Guzman et al., 2007), or biologically predated by other high order organisms such as protozoa (Mallory et al., 1983).…”

Potential biofilm control strategies for extended spaceflight missions

“…With increasing drought and human population, a number of regions are now beginning to employ wastewater recycling as a key component of municipal drinking water. Aside from being used for non-potable uses such as crop and parkland irrigation, some recycled water is being used for potable water [ 119 ]. As well, UV light is used in many broad-distribution and also point of use water systems [ 120 ].…”