ORIGINAL PAPER Effect of biosolid hydrochar on toxicity to earthworms and brine shrimp Tatiane Medeiros Melo . Michael Bottlinger . Elke Schulz . Wilson Mozena Leandro . Adelmo Menezes de Aguiar Filho . Yong Sik Ok . Jo ¨rg Rinklebe Received: 16 December 2016 / Accepted: 1 June 2017 Ó Springer Science+Business Media B.V. 2017 Abstract The hydrothermal carbonization of sew- age sludge has been studied as an alternative technique for the conversion of sewage sludge into value-added products, such as soil amendments. We tested the toxicity of biosolid hydrochar (Sewchar) to earth- worms. Additionally, the toxicity of Sewchar process water filtrate with and without pH adjustment was assessed, using brine shrimps as a model organism. For a Sewchar application of 40 Mg ha -1 , the earth- worms significantly preferred the side of the vessel with the reference soil (control) over side of the vessel with the Sewchar treatments. There was no acute toxicity of Sewchar to earthworms within the studied concentration range (up to 80 Mg ha -1 ). Regarding the Sewchar process water filtrate, the median lethal concentration (LC50) to the shrimps was 8.1% for the treatments in which the pH was not adjusted and 54.8% for the treatments in which the pH was adjusted to 8.5. The lethality to the shrimps significantly increased as the amount of Sewchar process water T. M. Melo (&) Institute of Foundation Engineering, Water- and Waste-Management, School of Architecture and Civil Engineering, Soil and Groundwater Management, University of Wuppertal, Pauluskichstraße 7, 42285 Wuppertal, Germany e-mail: txmmelo@yahoo.com.br M. Bottlinger Department of Hydrothermal Carbonization, Trier University of Applied Sciences, Environmental Campus Birkenfeld, 55761 Birkenfeld, Germany e-mail: m.bottlinger@umwelt-campus.de E. Schulz Department of Soil Ecology, Helmholtz Centre for Environmental Research (UFZ), 06120 Halle, Germany e-mail: elke.schulz@ufz.de W. M. Leandro Department of Agronomy, Federal University of Goia ´s (UFG), 74690-900 Goia ˆnia, Brazil e-mail: wilsonufg@gmail.com A. M. de Aguiar Filho Department of Chemical Engineering, Federal University of Bahia (UFBA), 40210-630 Salvador, Brazil e-mail: adelmo.aguiar.filho@gmail.com Y. S. Ok Á J. Rinklebe Soil and Groundwater Management, University of Wuppertal, Pauluskichstraße 7, 42285 Wuppertal, Germany e-mail: soilok@kangwon.ac.kr J. Rinklebe e-mail: rinklebe@uni-wuppertal.de Y. S. Ok Korea Biochar Research Center, School of Natural Resources and Environmental Science, Kangwon National University, Chuncheon, South Korea J. Rinklebe Department of Environment and Energy, Sejong University, 98 Gunja-Dong, Guangjin-Gu, Seoul, South Korea 123 Environ Geochem Health DOI 10.1007/s10653-017-9995-5