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Compared with conventionally collected sewage, source-diverted greywater has a higher potential for on-site treatment and reuse due to its lower contaminant levels and large volume. A new design of granular activated carbon (GAC) biofilters was developed by incorporating unsaturated and saturated zones in a single stage to introduce an efficient, passive, and easy-to-operate technology for greywater on-site treatment at the household scale. The design was customized for its intended application considering various aspects including the reactor’s configuration, packing media, and feeding strategy. With the highest hydraulic and organic loadings of 1.2 m3 m−2 d−1 and 3.5 kg COD m−2 d−1, respectively, and the shortest retention time of 2.4 h, the system maintained an average total chemical oxygen demand removal rate of 94% with almost complete removal of nutrients throughout its 253 days of operation. The system showed a range of reduction efficacy towards five surrogates representing viruses, bacteria, and Cryptosporidium and Giardia (oo)cysts. A well-functioning biofilm was successfully developed, and its mass and activity increased over time with the highest values observed at the top layers. The key microbes within the biofilter were revealed. Feasibility of the proposed technology was investigated, and implications for design and operation were discussed.
Ahmed Sharaf; Bing Guo; David Shoults; Nicholas Ashbolt; Yang Liu. Viability of a Single-Stage Unsaturated-Saturated Granular Activated Carbon Biofilter for Greywater Treatment. Sustainability 2020, 12, 8847 .
AMA StyleAhmed Sharaf, Bing Guo, David Shoults, Nicholas Ashbolt, Yang Liu. Viability of a Single-Stage Unsaturated-Saturated Granular Activated Carbon Biofilter for Greywater Treatment. Sustainability. 2020; 12 (21):8847.
Chicago/Turabian StyleAhmed Sharaf; Bing Guo; David Shoults; Nicholas Ashbolt; Yang Liu. 2020. "Viability of a Single-Stage Unsaturated-Saturated Granular Activated Carbon Biofilter for Greywater Treatment." Sustainability 12, no. 21: 8847.
Capsid-integrity quantitative PCR (qPCR), a molecular detection method for infectious viruses combining azo-dye pretreatment with qPCR, has been widely used in recent years; however, variations in pretreatment conditions for various virus types can limit the efficacy of specific protocols. By identifying and critically synthesizing forty-two recent peer-reviewed studies employing capsid-integrity qPCR for viruses in the last decade (2009 to 2019) in the fields of food safety and environmental virology, we aimed to establish recommendations for the detection of infectious viruses. Intercalating dyes are effective measures of viability in PCR assays provided the viral capsid is damaged; viruses that have been inactivated by other causes, such as loss of attachment or genomic damage, are less well detected using this approach. Although optimizing specific protocols for each virus is recommended, we identify a framework for general assay conditions. These include concentrations of ethidium monoazide, propidium monoazide or its derivates between 10 and 200 µM; incubation on ice or at room temperature (20 - 25°C) for 5 to 120 min; and dye activation using LED or high light (500 – 800 Watts) exposure for periods ranging from 5 to 20 min. These simple steps can benefit the investigation of infectious virus transmission in routine (water) monitoring settings and during viral outbreaks such as the current COVID-19 pandemic or endemic diseases like dengue fever. Graphical abstract
Mats Leifels; Cheng Dan; Emanuele Sozzi; David C. Shoults; Stefan Wuertz; Skorn Mongkolsuk; Kwanrawee Sirikanchana. Capsid integrity quantitative PCR to determine virus infectivity in environmental and food applications – a systematic review. 2020, 1 .
AMA StyleMats Leifels, Cheng Dan, Emanuele Sozzi, David C. Shoults, Stefan Wuertz, Skorn Mongkolsuk, Kwanrawee Sirikanchana. Capsid integrity quantitative PCR to determine virus infectivity in environmental and food applications – a systematic review. . 2020; ():1.
Chicago/Turabian StyleMats Leifels; Cheng Dan; Emanuele Sozzi; David C. Shoults; Stefan Wuertz; Skorn Mongkolsuk; Kwanrawee Sirikanchana. 2020. "Capsid integrity quantitative PCR to determine virus infectivity in environmental and food applications – a systematic review." , no. : 1.
Recreational, reclaimed and drinking source waters worldwide are under increasing anthropogenic pressure, and often contain waterborne enteric bacterial, protozoan, and viral pathogens originating from non-point source fecal contamination. Recently, the capsid integrity (ci)-qPCR, utilizing the azo-dyes propidium monoazide (PMA) or ethidium monoazide (EMA), has been shown to reduce false-positive signals under laboratory conditions as well as in food safety applications, thus improving the qPCR estimation of virions of public health significance. The compatibility of two widely used human adenovirus (HAdV) qPCR protocols was evaluated with the addition of a PMA/EMA pretreatment using a range of spiked and environmental samples. Stock suspensions of HAdV were inactivated using heat, UV, and chlorine before being quantified by cell culture, qPCR, and ci-qPCR. Apparent inactivation of virions was detected for heat and chlorine treated HAdV while there was no significant difference between ci-qPCR and qPCR protocols after disinfection by UV. In a follow-up comparative analysis under more complex matrix conditions, 51 surface and 24 wastewater samples pre/post UV treatment were assessed for enteric waterborne HAdV to evaluate the ability of ci-qPCR to reduce the number of false-positive results when compared to conventional qPCR and cell culture. Azo-dye pretreatment of non-UV inactivated samples was shown to improve the ability of molecular HAdV quantification by reducing signals from virions with an accessible genome, thereby increasing the relevance of qPCR results for public health purposes, particularly suited to resource-limited low and middle-income settings.
Mats Leifels; David Shoults; Alyssa Wiedemeyer; Nicholas J. Ashbolt; Emanuele Sozzi; Angela Hagemeier; Lars Jurzik. Capsid Integrity qPCR—An Azo-Dye Based and Culture-Independent Approach to Estimate Adenovirus Infectivity after Disinfection and in the Aquatic Environment. Water 2019, 11, 1196 .
AMA StyleMats Leifels, David Shoults, Alyssa Wiedemeyer, Nicholas J. Ashbolt, Emanuele Sozzi, Angela Hagemeier, Lars Jurzik. Capsid Integrity qPCR—An Azo-Dye Based and Culture-Independent Approach to Estimate Adenovirus Infectivity after Disinfection and in the Aquatic Environment. Water. 2019; 11 (6):1196.
Chicago/Turabian StyleMats Leifels; David Shoults; Alyssa Wiedemeyer; Nicholas J. Ashbolt; Emanuele Sozzi; Angela Hagemeier; Lars Jurzik. 2019. "Capsid Integrity qPCR—An Azo-Dye Based and Culture-Independent Approach to Estimate Adenovirus Infectivity after Disinfection and in the Aquatic Environment." Water 11, no. 6: 1196.
UV disinfection is a relatively simple and cost-efficient disinfection method, especially for in-home greywater treatment. In this study, a bench scale experiment was performed using a LED collimated UV-C beam with a peak wavelength of 256 nm to determine if potentially pathogenic bacteria such as Staphylococcus aureus may become enriched in a semi-recirculating greywater system with UV as the sole disinfection step. A statistically significant (P < 0.001) decreasing trend in UV-C efficacy was observed between the 1st and 6th UV exposure-growth cycles of S. aureus (ATCC 25923), resulting in a 1.5 decrease in log10 removal (P < 0.00000) by the 5th iteration. An eleven-point dose-response curve of the 7th iteration of S. aureus was estimated and compared to the dose-response curve of the original strain; due to a longer apparent shoulder period and a decay constant of lesser degree, the dose required for a 4-log reduction of the enriched S. aureus was estimated to be ∼1.9 times greater (22.0 mJ⋅cm−2 versus 11.8 mJ⋅cm−2). However, experimental results with S. epidermidis (ATCC 12228) and two wild strains, S. aureus and S. warneri, exhibited no trend of increased resistance. UV doses exceeding 20 mJ⋅cm−2 are generally sufficient in achieving a 4-log reduction of bacteria in drinking water systems; however, the results exhibited in this study suggest that when recirculation is involved, there may be a need for UV doses exceeding what is necessary for a 4-log reduction to suppress the enrichment of strains which could pose a public health risk.
David C. Shoults; Nicholas Ashbolt. Decreased efficacy of UV inactivation of Staphylococcus aureus after multiple exposure and growth cycles. International Journal of Hygiene and Environmental Health 2018, 222, 111 -116.
AMA StyleDavid C. Shoults, Nicholas Ashbolt. Decreased efficacy of UV inactivation of Staphylococcus aureus after multiple exposure and growth cycles. International Journal of Hygiene and Environmental Health. 2018; 222 (1):111-116.
Chicago/Turabian StyleDavid C. Shoults; Nicholas Ashbolt. 2018. "Decreased efficacy of UV inactivation of Staphylococcus aureus after multiple exposure and growth cycles." International Journal of Hygiene and Environmental Health 222, no. 1: 111-116.
Greywater reuse is a feasible solution for decreasing raw water extraction in urban and rural settings. However, pathogen-specific performance guidelines and regulations have only recently been recommended; practical means to assess performance are missing. Here we examine the efficacy of Staphylococcus spp. as an endogenous surrogate for greywater pathogen reduction performance testing, by evaluating UV-C irradiation of hand-rinse greywater, and the variability in UV resistance between different wild Staphylococcus species. Hand-rinse greywater samples were collected from five participants, and a collimated UV-C beam (256 nm) was used to assess log10 reductions. Assays of colony-forming units on tryptic soy agar (TSA) were compared to mannitol salt agar (MSA) using LysostaphinTM to confirm Staphylococcus spp. After irradiating raw hand-rinse samples to a dose of 220 mJ·cm−2, log10 reductions of Staphylococcus spp. were similar (2.1 and 2.2, respectively, p = 0.112). The similarity of the reduction based on TSA and Staphylococcus-specific culture assays following UV irradiation and the dominating presence of Staphylococcus spp. suggests that Staphylococcus spp. could be used as an endogenous performance surrogate group for greywater treatment testing. Suspended wild Staphylococcus isolates were irradiated with 256 nm UV-C to compare the variability of different Staphylococcus species. Staphylococcus isolates exhibited significant variance in log10 reduction values when exposed to 11 mJ·cm−2 of UV-C. Staphylococcus hominis subsp. hominis exhibited surprising resistance to UV-C, with only a 1.6-log10 reduction when exposed to 11 mJ·cm−2 of UV-C (most other isolates exhibited > 5-log10 reduction). The efficacy of UV-C was also significantly reduced when the sunscreen oxybenzone was present at a possible endogenous greywater concentration.
David C. Shoults; Nicholas J. Ashbolt. UV Disinfection of Hand-Rinse Greywater and Performance Testing Using Indigenous Staphylococcus spp. Water 2017, 9, 963 .
AMA StyleDavid C. Shoults, Nicholas J. Ashbolt. UV Disinfection of Hand-Rinse Greywater and Performance Testing Using Indigenous Staphylococcus spp. Water. 2017; 9 (12):963.
Chicago/Turabian StyleDavid C. Shoults; Nicholas J. Ashbolt. 2017. "UV Disinfection of Hand-Rinse Greywater and Performance Testing Using Indigenous Staphylococcus spp." Water 9, no. 12: 963.
Faecal indicator bacteria (FIB) are commonly used as water quality indicators; implying faecal contamination and therefore the potential presence of pathogenic enteric bacteria, viruses, and protozoa. Hence in wastewater treatment, the most commonly used treatment process measures (surrogates) are total coliforms, faecal coliforms, Escherichia coli (E. coli), and enterococci. However, greywater potentially contains skin pathogens unrelated to faecal load, and E. coli and other FIB may grow within greywater unrelated to pathogens. Overall, FIB occurs at fluctuating and relatively low concentrations compared to other endogenous greywater bacteria affecting their ability as surrogates for pathogen reduction. Therefore, unlike municipal sewage, FIB provides a very limited and unreliable log-reduction surrogate measure for on-site greywater treatment systems. Based on our recent metagenomic study of laundry greywater, skin-associated bacteria such as Staphylococcus, Corynebacterium, and Propionibacterium spp. dominate and may result in more consistent treatment surrogates than traditional FIB. Here, we investigated various Staphylococcus spp. as potential surrogates to reliably assay over 4-log10 reduction by the final-stage UV disinfection step commonly used for on-site greywater reuse, and compare them to various FIB/phage surrogates. A collimated UV beam was used to determine the efficacy of UV inactivation (255, 265 and 285 nm) against E. coli, Enterococcus faecalis, E. faecium, E. casseliflavus, Staphylococcus aureus, and S. epidermidis. Staphylococcus spp. was estimated by combining the bi-linear dose-response curves for S. aureus and S. epidermidis and was shown to be less resistant to UV irradiation than the other surrogates examined. Hence, a relative inactivation credit is suggested; whereas, the doses required to achieve a 4 and 5-log10 reduction of Staphylococcus spp. (13.0 and 20.9 mJ cm−2, respectively) were used to determine the relative inactivation of the other microorganisms investigated. The doses required to achieve a 4 and 5-log10 reduction of Staphylococcus spp. resulted in a log10 reduction of 1.4 and 4.1 for E. coli, 0.8 and 2.8 for E. faecalis, 0.8 and 3.6 for E. casseliflavus and 0.8 and 1.2 for MS2 coliphage, respectively. Given the concentration difference of Staphylococcus spp. and FIB (3 to 5-log10 higher), we propose the use of Staphylococcus spp. as a novel endogenous performance surrogate to demonstrate greywater treatment performance given its relatively high and consistent concentration and therefore ability to demonstrate over 5-log10 reductions.
David C. Shoults; Nicholas Ashbolt. Total staphylococci as performance surrogate for greywater treatment. Environmental Science and Pollution Research 2017, 25, 32894 -32900.
AMA StyleDavid C. Shoults, Nicholas Ashbolt. Total staphylococci as performance surrogate for greywater treatment. Environmental Science and Pollution Research. 2017; 25 (33):32894-32900.
Chicago/Turabian StyleDavid C. Shoults; Nicholas Ashbolt. 2017. "Total staphylococci as performance surrogate for greywater treatment." Environmental Science and Pollution Research 25, no. 33: 32894-32900.