Biotransformation of Sewage Sludge by Bacillus subtilis and Ecotoxicological Analysis to Obtain Sustainable Biofertilizer

• Grant number: 24/19198-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2025
• End date: March 31, 2026
• Field of knowledge: Biological Sciences - Ecology - Ecosystems Ecology
• Principal Investigator: Dânia Elisa Christofoletti Mazzeo Morales
• Grantee: Ana Carolina Nunes Moreno
• Host Institution: Centro de Ciências Agrárias (CCA). Universidade Federal de São Carlos (UFSCAR). Araras , SP, Brazil

Abstract

Sewage sludge, a semi-solid urban waste derived from wastewater treatment, has proven to be a very interesting material due to its high bioavailability of nutrients, making it suitable for use as a fertilizer and/or soil conditioner. However, the presence of toxic components in its composition complicates its direct application due to the potential ecotoxicological risks it may pose to the environment. Therefore, to detoxify the sludge, this project aims to employ the process of bioremediation using the bioaugmentation technique with Bacillus subtilis, seeking to eliminate its harmful effects. It is expected that bioaugmentation will optimize the process due to the beneficial characteristics of the B. subtilis bacteria. For the project, mixtures containing sewage sludge, soil, and/or B. subtilis will be placed in glass containers, maintained at a room temperature, and will undergo a bioremediation process for 0, 3, and 5 months. After each period, the mixtures in each container will be evaluated for their ecotoxicogenetic potential using the Allium cepa bioassay. The following parameters will be analyzed: germination index, changes in the mitotic index (cytotoxic effects), chromosomal alterations and nuclear abnormalities (genotoxic effects) in meristematic cells, and the presence of micronuclei in F1 region cells (mutagenic effects). Thus, the study aims to investigate the role of B. subtilis in the detoxification process of sewage sludge, contributing to the development of an environmentally safe, sustainable, and cost-effective agricultural fertilizer.