Nitrogen Recovery With Source Separation of Human Urine—Preliminary Results of Its Fertiliser Potential and Use in Agriculture

Abstract

The growing demand for food and the increasing costs of cultivation are posing a challenge for agriculture. Diminishing phosphorus reserves, as well as the energy intensive method of producing nitrogen fertilisers are drivers for more intensive reuse of different organic fertilisers, such as manures and excreta. Source separation and fertilisation with human urine can be one option for nutrient reuse. Urine contains all the main nutrients as well as micronutrients in soluble form, but it also contains chemicals, like pharmaceuticals and hormones. The aim of this study was to examine the efficiency and safety of the use of source separated human urine as a fertiliser for barley (Hordeum vulgare). The fertiliser efficiency of source-separated urine was examined in field-scale experiments for the first time in Finland. Two separate cultivation experiments in two fields and barley varieties were conducted. The efficiency of urine as a fertiliser was compared to corresponding amount of mineral fertiliser. No fertiliser was applied to one plot in order to create a reference treatment. The two experiments were conducted using variety Wolmari with 54 kg N ha −1 and variety Harbinger with 100 kg N ha −1. The barley grain and straw yield grown with urine fertiliser was equivalent to the yield in mineral fertilised plots. The growth of barley in both fertiliser treatments was slightly faster, compared to non-fertilised treatment. There were no significant differences between the treatments in terms of protein content of the grain although the results varied in terms of the thousand grain weight (TGW) and germination. The urine analyses indicated that there were no pathogen indicators, nor heavy metal concentrations, exceeding the limit values set by legislation. The main nutrient concentrations (N, P, K) would also meet the requirements for a fertiliser product according to Finnish legislation. Pharmaceuticals and hormones were found from the urine, but apart from progesterone, all of them presented extractable values in soil below the detection limits, and they were not detected in measurable amounts in barley grain at the end of the growing season. These results suggest that source separated urine could be an efficient fertiliser in crop cultivation.

The role of source separation in nutrient recovery – Comparison of alternative wastewater treatment systems

“…More information is needed about the existence of harmful substances and micropollutants in the end products as well as their behavior in water and soil. According to Viskari et al (2018), human urine stored according to WHO guidelines (WHO, 2006) fulfilled the criteria of the Finnish legislation (Ministry of Agriculture and Forestry Finland, 2011b), including pathogen indicators and heavy metals. In addition to the requirements of the legislation, the amounts of pharmaceuticals and hormones were analyzed from urine as well as soil and grains after the growing season.…”

“…Blackwater separation systems were included in the comparison as well, since the technology and logistics applied are simpler. In addition to theoretical calculations, including life cycle assessment (LCA) and nutrient potential evaluation, presented in this paper, field demonstrations and fertilizer tests were made in the two farms in Southern Finland (Viskari et al, 2018). In this part of the study, amounts of pharmaceuticals and hormones in the urine used as fertilizer were analyzed (total of 55 pharmaceuticals) as well as their presence in grains and soil after the growing season.…”

Discrimination of Tomato Plants (Solanum lycopersicum) Grown under Anaerobic Baffled Reactor Effluent, Nitrified Urine Concentrates and Commercial Hydroponic Fertilizer Regimes Using Simulated Sensor Spectral Settings

“…The red-edge section of the electromagnetic spectrum is very sensitive to high chlorophyll, leaf angle distribution, leaf area index levels associated with plants grown in more nutritious environments such as the those exhibited by ABR. As aforementioned, HEDM have a high turnover of N P K plant nutrients which is comparable to that of commercial soluble fertilizers [46][47][48]. In this regard, the high turnover of plant nutrients such as nitrogen facilitates an increase in biomass, LAD, LAI which in turn makes the canopy spectral signature of those plants treated with HEDM to be discriminable from other plants especially in the red-edge and the NIR sections of the electromagnetic spectrum [49,50].…”

Field Testing a Pilot-Scale System for Alkaline Dehydration of Source-Separated Human Urine: A Case Study in Finland

“…Yet, wastewater treatment plants only partially eliminate these compounds, as evidenced by their detection in urban drinking water reservoirs (Levén et al, 2016). The current best practice is to apply pharmaceutical residues in soil where there is higher likelihood for their degradation (Viskari et al, 2018;Simha et al, 2020b). In the current study, we detected very few (8 out of 126) pharmaceutical compounds in the urine and their concentrations after urine dehydration were low.…”