Journal of Environmental Management 272 (2020) 111072 Available online 17 July 2020 0301-4797/© 2020 Elsevier Ltd. All rights reserved. Research article Synthesis and characterization of struvite derived from poultry manure as a mineral fertilizer Ion� a Rech a, * , Marcos Y. Kamogawa a , Davey L. Jones b, c , Paulo S. Pavinato a a College of Agriculture Luiz de Queiroz, S~ ao Paulo University - ESALQ-USP, Av. P� adua Dias, 11, 13418-900, Piracicaba, SP, Brazil b School of Natural Sciences, Bangor University, Bangor, Gwynedd, LL57 2UW, United Kingdom c SoilsWest, UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA, 6009, Australia A R T I C L E INFO Keywords: Slow release fertilizer Manure P recovery Sustainable nutrient use Struvite precipitation ABSTRACT Animal manure is an important source of nutrients for crop production, but environmental issues can restrict its direct use. Thermochemical processing these manures may be an alternative to concentrate nutrients and reduce the final volume for agriculture application. We aimed here to evaluate the viability of extracting nutrients from chicken manure using a thermochemical process which reduces the volume of transported nutrients, targeting phosphorus (P) recovery as precipitated struvite, without add external source of P. The extraction of nutrients from poultry manure was performed in water, followed by a thermochemical treatment of the solid phase by incineration and acidulation of the resulting ash. Struvite was produced from the acidified ash extract after supplementation with Mg and regulating the pH (~8.5) by KOH addition. The recovery efficiency of P from the poultry manure and incorporation into struvite was 90%. The final product was a multi-nutrient fertilizer with high macronutrient levels (P, K, Mg and S) and low micronutrient content when compared to fresh manure, as well as lower levels of heavy metals, potentially harmful for the environment. The precipitated product obtained here is composed of struvite-NH 4 and struvite-K, alongside appreciable quantities of potassium sulphate and hydroxyapatite carbonate. Overall, we conclude that poultry manure represents a viable source of P and N for struvite production resulting in a nutrient-rich, pathogen-free inorganic fertiliser suitable for widespread use in agriculture. 1. Introduction The continued global increase in human population and, conse- quently, the need to increase agricultural productivity to cover the de- mand for food, are accompanied by an increased need for fertilizers (Nicolodelli et al., 2016). However, there are increasing concerns about the long-term sustainability of non-renewable mineral sources for fer- tilizer production, especially phosphate (P) (Schoumans et al., 2015). Whether these concerns are justified, however, remains controversial. According to the United States Geological Survey (USGS, 2020), the world phosphate rock reserves are more than 300 billion tons, and no imminent shortages are expected. Even if the reserves of phosphate rock for fertilizer production are far from exhaustion, we should not neglect that they are a non-renewable resource, and that the costs of P fertilizers are increasing annually. In addition, as high-quality sources of rock-phosphate are declining, there is an urgent need to identify alter- native and renewable sources of P (Peng et al., 2018). In this context, reducing our dependence on fertilizers from primary mineral sources becomes a strategic issue, since most countries lack reserves of phosphate rock and market pressures can be a serious obstacle to the sustainability of agricultural systems. Thus, the recycling of P from animal waste and even human’s excreta becomes a promising alternative for the production of phosphate fertilizers (Cabeza et al., 2011; Shashvatt et al., 2018). Poultry manure is frequently used as a fertilizer to promote plant productivity (Ravindran et al., 2017), and studies have indicated that repeated application has the potential to improve soil quality (Lin et al., 2018). It is noteworthy that in addition to the search for alternative sources of P for fertilizer production, there are also concerns associated with the environmental impacts of manure application directly to soil. The overuse of these residues directly to the soil can lead to soil contamination with heavy metals or harmful organic compounds of anthropogenic origin like antibiotics, hormones, and plant and human pathogens (Fijalkowski et al., 2017). Moreover, contamination of aquatic environments either by nutrient * Corresponding author. E-mail addresses: agr.rech@gmail.com, rech@alumni.usp.br (I. Rech). Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: http://www.elsevier.com/locate/jenvman https://doi.org/10.1016/j.jenvman.2020.111072 Received 14 April 2020; Received in revised form 17 June 2020; Accepted 8 July 2020