Urine

Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellular metabolism generates many by-products that are rich in nitrogen and must be cleared from the bloodstream, such as urea, uric acid, and creatinine. These by-products are expelled from the body during urination, which is the primary method for excreting water-soluble chemicals from the body. A urinalysis can detect nitrogenous wastes of the mammalian body. Urine plays an important role in the earth's nitrogen cycle. In balanced ecosystems, urine fertilizes the soil and thus helps plants to grow. Therefore, urine can be used as a fertilizer. Some animals use it to mark their territories. Historically, aged or fermented urine (known as lant) was also used for gunpowder production, household cleaning, tanning of leather and dyeing of textiles. Human u

Investigation of the Electrochemical Destruction of X-ray Contrast Media using Boron-‐Doped Diamond Electrodes (BDD)

Guillaume Tissot

Iodinated X-ray contrast media (ICM) are persistent micropollutants in wastewater, which come mainly from hospital activities. Currently, there is no efficient method of treatment for this class of compounds, which leads to their increased presence in surface water and drinking water. In this work we propose to treat directly ICM in urine, meaning at high concentration, by electrochemical oxidation process using BDD electrodes. In a first step of the project, determination of the reactivity of Iohexol towards electrochemical oxidation in inactive electrolyte was performed. In subsequent iohexol electrolysis experiment the electrolyte composition was gradually modified until electrolysis of Iohexol in fresh urine. Obtained results were compared with those predicted by adjusted kinetic model of COD elimination. Model is based on the kinetic of the electrochemical oxidation is controlled by diffusion, and it was demonstrated, in this work, that this is also the case for the electrochemical oxidation of Iohexol. This methodology permits to determine interference that urine components such as chloride and ammonia have on the electrochemical oxidation. The obtained results showed that 99% of Iohexol present in the electrolyte and at least 85% of the initial COD elimination can be achieved with an efficiency close to 100%, even in fresh urine. Investigation of the main constituents of urine showed that chloride has a positive effect on the process efficiency due to both catalytic and no‐catalytic action (oxidation of organics compounds, via electrogenereted active chlorine, close to the electrode or in the bulk). On the contrary ammonia has no effect on the efficiency if it is present alone, and negative effect if chloride is also present (certainly due to chloramine formation). Nevertheless, at high concentration of ICM, the effect of chloride and ammonia is negligible as experiment in fresh urine demonstrated. As expected, the reaction of hydroxyl radical with Iohexol is non-specific. Preliminary identifications of transformation products by UPLC-MS showed that electrochemical oxidation can lead to nucleus attack (deiodination) or side chain attack unselectively. In addition, deiodination by cathodic reduction under mass transfer control is also possible according to these UPLC‐MS results, and by the kinetic of Iohexol elimination. At an elimination of 85% COD in treated urine only a very low concentration of pollutant remain. Ecotoxicity and biodegradability analyses were performed with the treated urine at this point. Toxicity assays showed some ecological toxicity towards environment; biodegradability test didn’t show clear biodegradation. Finally, operating cost analysis for a possible installation using electrochemical oxidation process with BDD electrodes showed that even if other advanced oxidation process (AOPs), such as processes such as ozonation or UV/H2O2, demonstrate the same efficiency as electrochemical oxidation in the future, electrochemical oxydation using BDD electrode remains strongly competitive economically.

2012

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

Bastian Etter, Tamar Kohn, Linda Strande, Kai Udert

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.

2015

Fate of parasites and viruses in calcium hydroxide-treated urine in relation to temperature and moisture content

Loïc Decrey, Tamar Kohn

Human urine can be used as fertilizer and technologies, such as alkaline-urine treatment, are being developed to enable easier re-use. There is, however, a risk of pathogens being present in the urine. This hygiene assessment examined inactivation of three model organisms, one parasite (Ascaris suum) and two viruses (coliphages MS2 and ΦX174), during (1) alkaline-urine treatment and (2) drying of the alkalized-urine (A. suum only). Fresh human urine was mixed with calcium hydroxide (10 g Ca(OH)2 L-1 urine) and divided into three fractions (Mixed liquor, Supernate, Precipitates). The factions were inoculated with the model organisms and then subjected to three treatments (Drying-storage, Stored and Thermal treatment) at temperatures between 20 and 50 °C. For Ascaris, drying (moisture content (MC) 13-33%) the alkaline-urine proved effective in shortening the time required for a 3 log10 reduction in viable eggs at 20 °C, but only Partially drying (MC 73-82%) the urine led to longer inactivation times compared with Wet (MC >90%) or Dry conditions. While virus inactivation took place during the initial addition of Ca(OH)2, the viruses that were embedded in feces survived longer compared to the free viruses. At pH 11.5, contact times of 1.5 and 90.7 min were required to achieve a 4 log10 decay of phages in solution and phages embedded in feces respectively. In areas prone to parasites, Thermal treatment (≥42 °C) and/or Storage (111 days at 20 °C or 79 days at 35 °C) is recommended in order to meet the WHO and USEPA guidelines for unrestricted fertilizer use. Drying (MC 73-82%) can also be used in combination with thermal treatment and/or storage, to accelerate the process.

2022

Investigation of the Electrochemical Destruction of X-ray Contrast Media using Boron-‐Doped Diamond Electrodes (BDD)

Guillaume Tissot

2012

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

Bastian Etter, Tamar Kohn, Linda Strande, Kai Udert

2015

Investigation of the Electrochemical Destruction of X-­ray Contrast Media using Boron-­‐Doped Diamond Electrodes (BDD)

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

Fate of parasites and viruses in calcium hydroxide-treated urine in relation to temperature and moisture content

Investigation of the Electrochemical Destruction of X-­ray Contrast Media using Boron-­‐Doped Diamond Electrodes (BDD)

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

Fate of parasites and viruses in calcium hydroxide-treated urine in relation to temperature and moisture content

Investigation of the Electrochemical Destruction of X-ray Contrast Media using Boron-‐Doped Diamond Electrodes (BDD)

Investigation of the Electrochemical Destruction of X-ray Contrast Media using Boron-‐Doped Diamond Electrodes (BDD)