https://github.com/jmalonso55/Sewage-sludge-characteristics This repository contains the R script and part of the data from Alonso, J.M., Ph.D. Thesis (Alonso, J.M., 2019. Caracterização de Biossólidos para a Produção de Mudas de Espécies Arbóreas da Mata Atlântica [Thesis]. Universidade Federal Rural do Rio de Janeiro, Seropédica, Brasil). Published as a paper with the reference: Alonso, J.M., Abreu, A.H.M., Andreoli, C.V. et al. Chemical characteristics and valuation of sewage sludge from four different wastewater treatment plants. Environ Monit Assess 196, 34 (2024). https://doi.org/10.1007/s10661-023-12211-8 The data in this particular repository are from samples of 19 sewage sludge batches. The samples were collected in January, May, August, December 2016, February, June, September, and December 2017 from four wastewater treatment plants (WWTP). At WWTP Ilha do Governador, samples were collected in all eight seasons. Due to various reasons, it was not always possible to collect samples from the other WWTPs. The WWTP Alegria had five collections, while Barra and Sarapuí had three. The chemical characterization of the sludges was conducted based on the parameters required by Resolution nº 498/2020 of the National Council for the Environment (BRASIL, 2020). The elements P, K, Ca, Mg, Fe, Al, Na, Co, Mn, As, Ba, Cd, Cr, Cu, Ni, Se, Pb, and Zn were determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The dry combustion method determined the C and N contents using a CHN-600 elemental autoanalyzer. The organic matter content was determined by multiplying the total carbon present in each sample by the “van Bemmelen” conversion factor of 1.724. The pH and electrical conductivity (EC) were determined by taking 5 g of each sample and diluting it in 50 mL of deionized water. The mixture was stirred for 30 minutes and then measured using a bench pH and conductivity meter. The valorization of the sludge batches was performed using the substitute goods method, which compares the prices of products well-established in the market with the good to be valued. The sludge was valued for its N, P, and K contents. The inputs quoted as sources of these nutrients were the mineral fertilizers urea (N), triple superphosphate (P), and potassium chloride (K). The fertilizers' megagram prices were divided by the percentage of nutrients they contain to calculate each nutrient's value. Fertilizer prices were consulted in: CONAB. Companhia Nacional de Abastecimento. Relatório de Insumos Agropecuários, Grupo Fertilizante, Sub-Grupo Químico, UF PR, Ano 2023. Brasília: CONAB, 2023. Available from: https://consultaweb.conab.gov.br/consultas/consultaInsumo.do?method=acao CarregarConsulta (accessed 26 July 2023). A manuscript has been prepared with the results of the data analysis presented in this repository. Currently, the manuscript is under consideration for publication in a scientific journal.