Vol.:(0123456789) 1 3 Environmental Science and Pollution Research https://doi.org/10.1007/s11356-022-24058-6 RESEARCH ARTICLE Nutrient recovery from yellow water to soil‑crop systems Toyin Dunsin Saliu 1  · Olusegun Olutope Olaniyi 2  · Yetunde Irinyemi Bulu 2  · Segun Oladele 3  · Isaac Ayodele Ololade 4  · Nurudeen Abiola Oladoja 1 Received: 25 November 2021 / Accepted: 2 November 2022 © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2022 Abstract The potentials of the nutrient recovered (NRM), via a facile green and sustainable approach from human urine, as a fertilizer in soil-crop system was studied. Nutrient was recovered using a highly decentralized modular reactor, with packed bed of granular gastropod shell. The cultivations of Zea mays (maize) and Solanum lycopersicum (tomato) were the cases studied. The total nutrient composition, the P-speciation, and the safety-risk assessment of the NRM were determined. Using NPK as the standard fertilizer, and a non-fertilized soil as the control, the fertilizing potential of the NRM was evaluated. The infuence of the diferent fertilizer application regimes on the wet and dry biomass nutrient composition, after-harvest soil nutrient composition, and pH values was studied. The NRM contained 106 mg/g of TN and 374.6 mg/g of TP, and the P species identifed were Ca 2 -P (31.66%), Ca 8 -P (14.99%), and Ca 10 -P (53.32%). The growth rate of the NRM crops were lower than that of the NPK crops until the 17th day, when the NRM crops grew faster than that of the NPK and control (p < 0.05). The NRM is benefcial to acidic soils and also acts as a slow nutrient releasing fertilizer. Keywords Yellow water · Recovered nutrient · Green fertilizer · Nutrient recovery · NPK fertilizer · Plant growth Introduction The energy-intensive approach that is required for the production nitrogen-based fertilizer and the non-renewa- ble nature of phosphorus ore has made fertilizers highly expensive and inaccessible to rural farmers. Thus, creating a circular economy from the use of nutrient-rich wastewater for green and sustainable agricultural practice is the new hopeful. For example, the high concentration of nutrient fractions (i.e., phosphorus (P) and nitrogen (N)) in human urine (known as yellow water) makes it a valuable fertilizer resource. On average, individuals excrete about 550 L urine/ year, which is equal to 0.4 kg of P, 4 kg of N, and 0.9 kg of potassium (K) per year (Pradhan et al. 2017). The direct application of human urine, to enhance crop productions, has been practiced, but the potential risks of contamination from extraneous constituents (e.g., microorganisms, phar- maceuticals, hormone residues, and other micro-pollutants fraction) have been an issue of concern (Bischel et al. 2016; Amoah et al. 2017; Bonvin et al. 2015). In order to cir- cumvent these challenges, diferent methods have been developed to isolate the nutrient fractions for fertilizer applications. These methods include ammonia recovery by air stripping (Antonini et al. 2012), P and N recov- ery by struvite precipitation (Pradhan et al. 2019; Udert et al. 2015), and N (as NH 4 + ) recovery by ion exchange (Nagy et al. 2019; Tarpeh et al. 2018). A comprehensive review that evaluated the prevailing technologies for nutri- ent recovery from yellow water was provided by Chipako and Randall (2020). The successful recovery of nutrient fractions on solid aggregates has also been reported (Gong et al. 2019; Saliu et al. 2019; Saliu and Oladoja 2020; Han et al. 2021; Zin and Kim 2021). Despite the array of methods that have been developed for nutrient recovery from yellow water, only few studies have Communicated by Philippe Garrigues * Nurudeen Abiola Oladoja bioladoja@yahoo.com 1 Hydrochemistry Research Laboratory, Department of Chemical Sciences, Adekunle Ajasin University, Akungba Akoko, Nigeria 2 Department of Plant Science and Biotechnology, Adekunle Ajasin University, Akungba Akoko, Nigeria 3 Department of Agronomy, Adekunle Ajasin University, Akungba Akoko, Nigeria 4 Department of Chemical Sciences, Adekunle Ajasin University, Akungba Akoko, Nigeria