Nitrification and autotrophic denitrification of source-separated urine

Udert, Kai M.; Fux, C.; Münster, M.; Larsen, Tove A.; Siegrist, Hansruedi; Gujer, Willi

doi:10.2166/wst.2003.0031

Cited by 125 publications

(87 citation statements)

References 14 publications

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“…An alternative to struvite production for urine nutrient recovery is the application of biological nitrification to stabilize nutrients in urine (Udert et al, 2003). Recent evaluation of the inactivation of bacterial and viral surrogates during urine nitrification indicates that nitrification is insufficient as a stand-alone technology for pathogen inactivation (Bischel et al, 2015).…”

Section: Urine Nitrification For Nutrient Stabilizationmentioning

confidence: 99%

Pathogens and pharmaceuticals in source-separated urine in eThekwini, South Africa

et al. 2015

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a b s t r a c tIn eThekwini, South Africa, the production of agricultural fertilizers from human urine collected from urine-diverting dry toilets is being evaluated at a municipality scale as a way to help finance a decentralized, dry sanitation system. The present study aimed to assess a range of human and environmental health hazards in source-separated urine, which was presumed to be contaminated with feces, by evaluating the presence of human pathogens, pharmaceuticals, and an antibiotic resistance gene. Composite urine samples from households enrolled in a urine collection trial were obtained from urine storage tanks installed in three regions of eThekwini. Polymerase chain reaction (PCR) assays targeted 9 viral and 10 bacterial human pathogens transmitted by the fecaleoral route. The most frequently detected viral pathogens were JC polyomavirus, rotavirus, and human adenovirus in 100%, 34% and 31% of samples, respectively. Aeromonas spp. and Shigella spp. were frequently detected gram negative bacteria, in 94% and 61% of samples, respectively. The gram positive bacterium, Clostridium perfringens, which is known to survive for extended times in urine, was found in 72% of samples. A screening of 41 trace organic compounds in the urine facilitated selection of 12 priority pharmaceuticals for further evaluation. The antibiotics sulfamethoxazole and trimethoprim, which are frequently prescribed as prophylaxis for HIV-positive patients, were detected in 95% and 85% of samples, reaching maximum concentrations of 6800 mg/L and 1280 mg/L, respectively. The antiretroviral drug emtricitabine was also detected in 40% of urine samples. A sulfonamide antibiotic resistance gene (sul1) was detected in 100% of urine samples. By coupling analysis of pathogens and pharmaceuticals in geographically dispersed samples in eThekwini, this study reveals a range of human and environmental health hazards in urine intended for fertilizer production. Collection of urine offers the benefit of sequestering contaminants from environmental release and allows for targeted treatment of potential health hazards prior to agricultural application. The efficacy of pathogen and pharmaceutical inactivation, transformation or removal during urine nutrient recovery processes is thus briefly reviewed.

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Section: Urine Nitrification For Nutrient Stabilizationmentioning

confidence: 99%

Pathogens and pharmaceuticals in source-separated urine in eThekwini, South Africa

et al. 2015

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“…12,13 A promising nutrient recovery process that yields a chemically stable solution from stored urine is nitrification. 14 In configurations where nitrification is applied in combination with evaporation, a concentrated solution that preserves nearly all nutrients in the urine can be produced. 15 Pilot reactors for combined nitrification/distillation systems are operated at eThekwini Water and Sanitation in Durban, South Africa and at the Swiss Federal Institute of Aquatic Science and Technology (Eawag) in Dübendorf, Switzerland as part of the Valorisation of Urine Nutrients in Africa (VUNA) project.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, it reduces the pH of urine from 9 to around 6, which causes the remaining NH 3 to become protonated to the nonvolatile NH 4 + (pK a = 9.25). 14 Concomitantly to nitrification, heterotrophic bacteria consume biologically degradable organic substances so that malodor is removed as well. Refinement of urine nitrification processes presents several challenges.…”

Section: Introductionmentioning

confidence: 99%

Inactivation kinetics and mechanisms of viral and bacterial pathogen surrogates during urine nitrification

Bischel

Schertenleib

Fumasoli

et al. 2015

Environ. Sci.: Water Res. Technol.

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a This paper assesses the inactivation performance and mechanisms in urine nitrification reactors using bacteria and bacteriophages as surrogates for human pathogens. Two parallel continuous-flow moving bed biofilm reactors (MBBRs) were operated over a two-month period. One MBBR was used to conduct a continuous spike experiment with bacteriophage MS2. The second reactor provided the matrix for a series of batch experiments conducted to investigate the inactivation of Salmonella typhimurium, Enterococcus spp., MS2, Qβ, and ΦX174 during urine nitrification. The roles of aeration, biological activity, and solution composition in inactivation were evaluated. Whereas bacteriophages ΦX174 and MS2 remained infective following urine nitrification, partial inactivation of bacteriophage Qβ was observed. Qβ inactivation was attributed primarily to aeration with a potential additive effect of biological processes, i.e., processes that are attributable to the presence of other microorganisms such as sorption to biomass, predation or enzymatic activity. Tailing of Qβ inactivation to a plateau indicated a protective effect of the solution components in aerated nitrification reactors. In contrast to the bacteriophages, S. typhimurium and Enterococcus spp. were mainly affected by biological processes: they were inactivated in biologically active nitrification reactors while remaining stable in chemically equivalent filtered controls. The tested bacteria could, for example, be out-competed by other microbial communities or sorbed to biomass in the reactor. Microbial communities did not adapt to inactivate bacteriophage MS2 (e.g., via increased prevalence of virus predators) in the experimental time-scale evaluated, with no observed inactivation of MS2 during continuous input for 51 days in the flow-through MBBR. The compilation of these results suggests that biological nitrification as a fertilizer production process remains insufficient as a stand-alone technology for the sanitization of source-separated urine.

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“…During nitrification, half of the total ammonia in urine is oxidised to nitrate, while the pH is lowered to values close to 6. Under such conditions, no considerable ammonia losses occur anymore (Udert et al, 2003b). Nitrate production is limited by the alkalinity in stored urine; after half of the ammonia is oxidised to nitrate, the process stops due to the low pH value.…”

Section: Nitrification and Distillationmentioning

confidence: 99%

Technologies for the treatment of source-separated urine in the eThekwini Municipality

Udert

Buckley

Wächter

et al. 2016

WSA

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In recent years, a large number of urine-diverting dehydration toilets (UDDTs) have been installed in eThekwini to ensure access to adequate sanitation. The initial purpose of these toilets was to facilitate faeces drying, while the urine was diverted into a soak pit. This practice can lead to environmental pollution, since urine contains high amounts of nutrients. Instead of polluting the environment, these nutrients should be recovered and used as fertiliser. In 2010 the international and transdisciplinary research project VUNA was initiated in order to explore technologies and management methods for better urine management in eThekwini. Three treatment technologies have been chosen for the VUNA project. The first is struvite precipitation, a technology which has already been tested in multiple projects on urine treatment. Struvite precipitation is a simple and fast process for phosphorus recovery. Other nutrients, such as nitrogen and potassium, remain in the effluent and pathogens are not completely inactivated. Therefore, struvite precipitation has to be combined with other treatment processes to prevent environmental pollution and hygiene risks. The second process is a combination of nitrification and distillation. This process combination is more complex than struvite precipitation, but it recovers all nutrients in one concentrated solution, ensures safe sanitisation and produces only distilled water and a small amount of sludge as by-products. The third process is electrolysis. This process could be used for very small on-site reactors, because conversion rates are high and the operation is simple, as long as appropriate electrodes and voltages are used. However, nitrogen is removed and not recovered and chlorinated by-products are formed, which can be hazardous for human health. While urine electrolysis requires further research in the laboratory, struvite precipitation and nitrification/distillation have already been operated at pilot scale.

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Nitrification and autotrophic denitrification of source-separated urine

Cited by 125 publications

References 14 publications

Pathogens and pharmaceuticals in source-separated urine in eThekwini, South Africa

Pathogens and pharmaceuticals in source-separated urine in eThekwini, South Africa

Inactivation kinetics and mechanisms of viral and bacterial pathogen surrogates during urine nitrification

Technologies for the treatment of source-separated urine in the eThekwini Municipality

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