Oliveira, VerónicaRodrigues, Manuel ÂngeloArrobas, MargaridaRodrigues, EditeSimões, P.Miguens, FilomenaSantos, Daniela2026-06-162026-06-162023Oliveira, V.; Rodrigues, M.A.; Arrobas, Margarida; Rodrigues, E.; Simões, P.; Miguens, F.; Santos, D. (2023). Chemical evaluation of agro-industrial wastes for composting water hyacinth. In 6th International Conference Wastes: Solutions, Treatments and Opportunities. Coimbra: CRC Press/Balkema, p.289-295. ISBN 978-103238441-2978-103238441-2http://hdl.handle.net/10198/36900Water hyacinth (WH) waste removed from watercourses can be valued through composting. In this study it was determined the elemental composition of WH waste and other local organic residues to prepare suitable mixtures for composting. Rice husk, straw and woodchip showed high C/N ratios (> 80). In turn, farmyard manures and vegetables displayed low C/N ratios (< 20). WH tissues showed increased C/N ratios with the aging process (from 17.4 to 37.1). WH tissues had low P (< 2 g kg-1) and high Fe (>5000 mg kg-1) and Mn (2476.7-- 12885.8 mg kg-1) concentrations. Fe and Mn levels were particularly high in the roots (31706.8 and 38335.2 mg kg-1, respectively). Such high levels of Mn and Fe may impair the composting process and restrict the agricultural use of compost. Thus, the composting piles must be prepared from an optimized combination of organic materials that avoids either of those problems.engFertilizersHistologyIndustrial wastesTissueAgro-industrial wastesC:N ratioChemical evaluationElemental compositionsFarmyard manureLow C/N ratiosOrganic residuesRice huskWater HyacinthWood chipconference paper10.1201/9781003345084-47