Search Results (8)

Source-separated, nitrified, and decontaminated human urine constitutes a promising plant fertilizer that contains a large share of the nitrogen and phosphorus in household wastewater, and other plant nutrients. However, human urine contains high levels of sodium and chloride that can affect salt-sensitive greenhouse crops. Replacing mineral fertilizer with nitrified urine fertilizer could reduce the environmental impact of lettuce production in hydroponic systems, if marketable yield, appearance, and produce quality are not affected. In the present study, a treatment combination of a nitrified urine fertilizer and mineral fertilizers was used to grow lettuce through the nutrient film technique. This was compared to a conventionally fertilized control treatment. No significant differences were observed regarding yield, phenotype, and contents of nitrate, heavy metals, phenolic acids, and chlorophyll in leaf tissue. Calcium content was significantly reduced and sodium was elevated in nitrified urine treatment. For the elements nitrogen, phosphorous, and potassium, a saving of 48%, 13%, and 15% was calculated, respectively. The calculated carbon footprint from the total fertilizer production was reduced by 20.52%, caused by the nitrified urine treatment. Based on these results, a nutrient solution composed of nitrified urine fertilizer combined with mineral fertilizer may be a promising alternative for growers to produce lettuce with a reduced environmental impact without loss of plant quantity and quality. Full article

Water and nutrient deficiencies in soil are becoming a serious threat to crop production. Therefore, usable water and nutrient recovery from wastewater, such as urine and grey water, should be considered. In this work, we showed the possibility of using grey water and urine after processing in an aerobic reactor with activated sludge in which the nitrification process takes place. The resulting liquid (nitrified urine and grey water, NUG) contains three potential factors that can adversely affect plant growth in a hydroponic system: anionic surfactants, nutrient deficits, and salinity. After dilution and supplementation with small amounts of macro- and micro-elements, NUG was suitable for cucumber cultivation. Plant growth on this modified medium (enriched nitrified urine and grey water, NUGE) was similar to that of plants cultivated on Hoagland solution (HS) and reference commercial fertilizer (RCF). The modified medium (NUGE) contained a significant amount of sodium (Na) ions. Therefore, typical effects of salt stress were observed in cucumber plants, including reduced chlorophyll levels, slightly weaker photosynthesis parameters, increased H₂O₂ levels, lipid peroxidation, ascorbate peroxidase (APX) activity, and proline content in the leaves. In addition, reduced protein levels were observed in plants treated with recycled medium. At the same time, lower nitrate content in tissues was found, which may have resulted from their intensive use by nitrate reductase (NR), the activity of which significantly increased. Although cucumber is a glycophyte, it grew very well in this recycled medium. Interestingly, salt stress and possibly anionic surfactants promoted flower formation, which in turn could positively affect plant yield. Full article

Urea present in cattle urine contributes large amounts of nitrogen (N) to grazed pastures, which can be the equivalent to approximately 1000 kg N ha⁻¹. However, there are no studies in volcanic soils of southern Chile on the effect of different concentrations of urinary N deposited in the soil, nor of the effect different wetting and drying conditions mimicking the variation in weather conditions on the nitrification process from urea to NH₄⁺ and total oxidized nitrogen (TON) over time. In addition, the inhibition of nitrification driven by the accumulation of NH₃ at high rates of N applied to Andisol has not been evaluated. Fresh cattle urine was applied at three different rates of N equivalent to 247 kg N ha⁻¹ (Low N), 461 kg N ha⁻¹ (Medium N), and 921 kg N ha⁻¹ (High N), as well as deionized water as a control. Further, three moisture conditions were imposed: constant moisture (CM), drying–rewetting (DRW) cycles at 7-day intervals, and soil drying (SD). Destructive soil core samples were evaluated for top and bottom halves individually every 7 days over a 36-day period to measure changes on inorganic N and pH. There were no interaction effects for N rates and soil moisture. The main effect of the different rates of N on mineralization was significant throughout the incubation period, while the effect of the different moisture conditions was variable over time. High N was associated with elevated NH₃ concentrations and could explain why total N mineralization was partially inhibited. These results suggest that the presence of different nitrifying microorganisms in soil under different chemical and physical conditions determines nitrification, and thus, the oxidation of ammonia should be studied in more detail as the first step of nitrification, specifically in volcanic soils. Full article

Sustainability has been a concern of survival for future long-term manned space missions. Therefore, the wastewater generated by the crew members, containing urine and hygiene wastewater, should be treated with appropriate biological processes to promote recycling efficiency. In this study, we developed a membrane-aerated biofilm reactor (MABR) that could achieve up to 96% total organic carbon (TOC) removal efficiency and up to 82% denitrification efficiency for an influent with 370–390 mg/L TOC and 500–600 mg/L total nitrogen (TN) without additional carbon source or sludge discharge. The nitrogen removal rate was about 100 mg N L⁻¹ d⁻¹. Metagenomic analysis indicated the presence of a variety of nitrifying, denitrifying, and anammox bacteria in the microbial community and existence of functional genes in nitrification, denitrification, and anammox pathways. Full article

The application of hydroponic cultivation fertilized with biologically nitrified synthetic urine can produce nitrate-rich fertilizer for lettuce (Lactuca sativa var. capitata L.). The mounting water crisis and depletion of natural resources makes nitrogen recovery from human urine a practical option. Nitrified urine can be used in indoor vertical hydroponic cultivation and is characterized by a high degree of element recovery. Because of its high ammonium content, hydrolyzed fresh urine may be toxic. A nitrification sequencing batch reactor with suspended activated sludge biomass ensured urine stabilization and biological conversion into nitrate-rich fertilizer. The diluted nitrate-rich fertilizer was then supplied for soilless cultivation. The results show that diluted nitrified urine is an excellent source of bioavailable nitrogen and phosphorus and, with proper enrichment with microelements, could replace commercial fertilizers in hydroponic systems. The yield and quality parameters of lettuce cultivated with enriched urine were comparable to those obtained with a commercial fertilizer. The mass balance calculation showed that industry-scale lettuce production can be based on urine fertilizer collected from a few hundred people for a single unit. Full article

We assess the discriminative strength of three different satellite spectral settings (HyspIRI, the forthcoming Landsat 9 and Sentinel 2-MSI), in mapping tomato (Solanum lycopersicum Linnaeus) plants grown under hydroponic system, using human-excreta derived materials (HEDM), namely, anaerobic baffled reactor (ABR) effluent and nitrified urine concentrate (NUC) and commercial hydroponic fertilizer mix (CHFM) as main sources of nutrients. Simulated spectral settings of HyspIRI, Landsat 9 and Sentinel 2-MSI were resampled from spectrometric proximally sensed data. Discriminant analysis (DA) was applied in discriminating tomatoes grown under these different nutrient sources. Results showed that the simulated spectral settings of HyspIRI sensor better discriminate tomatoes grown under different fertilizer regimes when compared to Landsat 9 OLI and Sentinel-2 MSI spectral configurations. Using the DA algorithm, HyspIRI exhibited high overall accuracy (OA) of 0.99 and a kappa statistic of 0.99 whereas Landsat OLI and Sentinel-2 MSI exhibited OA of 0.94 and 0.95 and 0.79 and 0.85 kappa statistics, respectively. Simulated HyspIRI wavebands 710, 720, 690, 840, 1370 and 2110 nm, Sentinel 2-MSI bands 7 (783 nm), 6 (740 nm), 5 (705 nm) and 8a (865 nm) as well as Landsat bands 5 (865 nm), 6 (1610 nm), 7 (2200 nm) and 8 (590 nm), in order of importance, were selected as the most suitable bands for discriminating tomatoes grown under different fertilizer regimes. Overall, the performance of simulated HyspIRI, Landsat 9 OLI-2 and Sentinel-2 MSI spectral bands seem to bring new opportunities for crop monitoring. Full article

Sustainable smallholder farming is contingent on fertilizer access. Soils across Africa are typically nutrient deficient, a condition exacerbated by long-term nutrient mining. Nitrified urine fertilizer is a nutrient-rich and hygienically safe solution derived from human urine. It has the potential to provide a sustainable source of soil nutrients to low and middle-income countries struggling with food insecurity challenges. This study presents findings of a survey that assessed public acceptance within Msunduzi, Kwazulu-Natal, South Africa towards the use of nitrified urine fertilizer. Results indicate that in general attitudes were much more positive towards the use of nitrified urine fertilizer than raw urine as a soil amendment. Residents living within rural zones of the municipality (78.5%), as opposed to urban (65.7%) and peri-urban (65.2%), and younger individuals within the sampled population were found to be the most receptive to the use of nitrified urine fertilizer. Our findings also underscore the complex set of factors that shape attitudes towards a topic such as the use of human waste as a fertilizer, which are crucial in shaping the legitimacy of an emerging technology such as urine nitrification. Full article