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Separate collection of urine, which is only 1% of wastewater volume but contains the majority of nitrogen humans excrete, can potentially reduce the costs and energy input of wastewater treatment and facilitate recovery of nitrogen for beneficial use. Ion exchange was investigated for recovery of nitrogen as ammonium from urine for use as a fertilizer or disinfectant. Cation adsorption curves for four adsorbents (clinoptilolite, biochar, Dowex 50, and Dowex Mac 3) were compared in pure salt solutions, synthetic urine, and real stored urine. Competition from sodium and potassium present in synthetic and real urine did not significantly decrease ammonium adsorption for any of the adsorbents. Dowex 50 and Dowex Mac 3 showed nearly 100% regeneration efficiencies. Estimated ion exchange reactor volumes to capture the nitrogen for 1 week from a four-person household were lowest for Dowex Mac 3 (5 L) and highest for biochar (19 L). Although Dowex Mac 3 had the highest adsorption capacity, material costs ($/g N removed) were lower for clinoptilolite and biochar because of their substantially lower unit cost. [ABSTRACT FROM AUTHOR]

Source-separated urine contains most of the excreted nutrients, which can be recovered by using nitrification to stabilize the urine before concentrating the nutrient solution with distillation. The aim of this study was to test this process combination at pilot scale. The nitrification process was efficient in a moving bed biofilm reactor with maximal rates of 930 mg N L-1 d-1. Rates decreased to 120 mg N L-1 d-1 after switching to more concentrated urine. At high nitrification rates (640 mg N L-1 d-1) and low total ammonia concentrations (1,790 mg NH4-N L-1 in influent) distillation caused the main primary energy demand of 71 W cap-1 (nitrification: 13 W cap-1) assuming a nitrogen production of 8.8 g N cap-1 d-1. Possible process failures include the accumulation of the nitrification intermediate nitrite and the selection of acid-tolerant ammonia-oxidizing bacteria. Especially during reactor start-up, the process must therefore be carefully supervised. The concentrate produced by the nitrification/distillation process is low in heavy metals, but high in nutrients, suggesting a good suitability as an integral fertilizer. [ABSTRACT FROM AUTHOR]

The water utility of Durban, eThekwini Water and Sanitation (EWS), installed urine-diverting dry toilets to provide sanitation to under-served communities in rural and peri-urban areas. While faeces was treated by dehydration, urine was discharged into a soak away in the ground. EWS teamed up with the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and other partners in Switzerland and South Africa to valorise this resource. The VUNA project developed a sanitation system which produces a valuable fertiliser from urine, reduces pollution of water resources and promotes the acceptance of dry toilets [ABSTRACT FROM AUTHOR]

The combination of nitritation and autotrophic denitrification (anammox) in a single sequencing batch reactor (SBR) is an energy efficient process for nitrogen removal from high-strength ammonia wastewaters. So far, the process has been successfully applied to digester supernatant. However, the process could also be suitable to treat source-separated urine, which has very high ammonium and organic substrate concentrations (up to 8,200 gN/m³ and 10,000 gCOD/m³). In this study, reactor performance was tested for digester supernatant and diluted source-separated urine. Ammonium concentrations in both solutions were similar (between 611 and 642 gN/m³), thus reactor performance could be directly compared. Differences were mainly due to higher activity of heterotrophic bacteria in urine. Nitrogen removal was slightly higher for sourceseparated urine, because heterotrophic bacteria denitrified the nitrate that was produced by anammox bacteria. In spite of higher heterotrophic growth with source-separated urine, calculated sludge concentrations at steady state were higher with digester supernatant due to accumulation of inert particulate organic matter from the influent. Although the sludge concentrations are less problematic for source-separated urine, process instabilities are more likely, because lower pH values are reached and heterotrophic denitrification can cause sudden increases of nitrite concentrations and/or nitric oxide. Both compounds inhibit aerobic ammonium oxidizing bacteria, heterotrophic bacteria and, most importantly, anammox bacteria. Nitrite and nitric oxide production by heterotrophic denitrification must be better understood to optimize nitritation/anammox for source-separated urine. [ABSTRACT FROM AUTHOR]

In long-term experiments with membrane aerated biofilm reactors we observed complete nitrite oxidation in highly concentrated ammonium nitrite solutions with a contaminant pH decrease to values below 3. The maximum initial concentration for ammonium was 42 mM and for nitrite was 41 mM. We hypothesized that (1) acid-tolerant ammonium oxidizing bacteria were responsible for the pH decrease, and (2) chemical processes caused complete nitrite oxidation at low pH values. To test this hypothesis we set up a mechanistic computer model based on kinetic data from literature and we validated the model with additional experiments. The simulations fitted the measurements very well. Additionally, an experiment with the inhibitor allylthiourea showed that ammonium-oxidizing bacteria were active at pH values far below 5.5. Experiments in a sterile reactor confirmed the chemical nitrite oxidation to nitrate. Nitrogen balances revealed that 8 ± 4% of the initial nitrogen (ammonium, nitrite, and nitrate) were lost during the cycles. On the basis of measurements and simulations we concluded that volatilization was responsible for the significant nitrogen loss. We estimated that about half of the lost nitrogen volatilized as nitrous acid HNO2. The rest mainly volatilized as dinitrogen N2 and nitrous oxide N2O. [ABSTRACT FROM AUTHOR]

Sanitizing human and animal waste (e.g., urine, fecal sludge, or grey water) is a critical step in reducing the spread of disease and ensuring microbially safe reuse of waste materials. Viruses are particularly persistent pathogens and can be transmitted through inadequately sanitized waste. However, adequate storage or digestion of waste can strongly reduce the number of viruses due to increases in pH and uncharged aqueous ammonia (NH3), a known biocide. In this study we investigated the kinetics and mechanisms of inactivation of the single-stranded RNA virus MS2 under temperature, pH and NH3 conditions representative of waste storage. MS2 inactivation was mainly controlled by the activity of NH3 over a pH range of 7.0-9.5 and temperatures lower than 40°C. Other bases (e.g., hydroxide, carbonate) additionally contributed to the observed reduction of infective MS2. The loss in MS2 infectivity could be rationalized by a loss in genome integrity, which was attributed to genome cleavage via alkaline transesterification. The contribution of each base to genome transesterification, and hence inactivation, could be related to the base pKa by means of a Bronsted relationship. The Bronsted relationship in conjunction with the activity of bases in solution enabled an accurate prediction of MS2 inactivation rates. [ABSTRACT FROM AUTHOR]