Co-substrate addition for in-flow acclimation of sulfidogenic bioreactor fed with brewery spent grain as slow release electron donor

• Grant number: 23/16400-0
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: May 06, 2024
• End date: November 05, 2024
• Field of knowledge: Engineering - Sanitary Engineering - Water Supply and Wastewater Treatment
• Principal Investigator: Denise Bevilaqua
• Grantee: Guilherme Salvador Peres Neto
• Supervisor: Piet Lens
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Institution abroad: University Of Galway, Ireland
• Associated to the scholarship: 23/03148-0 - Analysis of the toxicity of Fe, Cu, Ni, Zn e Co metals in sulfidogenic reactors fed with different electrons donors., BP.MS

Abstract

Bioremediation using sulfate reducing bacteria (SRB) is a promisor technology for acid mine drainage (AMD) treatment. Bioprocesses typically offer advantages like low energy consumption, reduced sludge production, and the potential for metal recovery. SRB metabolism generates sulfide, which can be employed to precipitate heavy metals from AMD. While SRB can be utilized in various methods, bioreactors are often considered a superior choice. However, AMD is poor in carbon, and organic electron donor addition is required, leading to increased operational costs. The use of lignocellulosic materials (LM) as slow-release electron donors (SRED) enhances cost-effectiveness and provides favorable conditions for metal sulfide precipitation with efficient settling properties. However, LM may lack sufficient substrate for SRB during the reactor's early days (acclimation period), as lignocellulosic materials are not directly utilized by SRB. Thus, the present work aims to use lactate as co-substrate in sulfate-reducing reactors filled with brewery spent grain (BSG) as SRED to enhance SRB development during in-flow acclimation. The assays will be conducted in two down-flow structured bed reactors (RBSG and Rco-sub), and BSG bundles will work as SRED and support material in both of them, but lactate will be added only to Rco-sub. After acclimation period, the lactate will be omitted from the Rco-sub. After two weeks a mixed metal solution will be added to both reactors to allow whether the start-up strategies influenced reactors resistance to metal toxicity. Metals concentration will increase every two weeks, initially from 1 mg L-1 to 10 mg L-1 and then 50 mg L-1. Sulfate and sulfide concentration, volatile fatty acids, pH, oxi-reduction potential (ORP) and alkalinity will be measured twice a week. Samples will be collected for DNA sequencing and microbial community analysis.