Influence of Moringa oleifera seed extract on the specific methanogenic activity of anaerobic sludge

Author(s)

Izabela Paiva Martins

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Agrícola
• Defense date: 2024-01-19

Examining board members

Gustavo Mockaitis; Guilherme Peixoto; Juliana Martins Valença; Maria Paula Cardeal Volpi; Oscar Fernando Herrera Adarme

• Advisor: Ariovaldo José da Silva; Gustavo Mockaitis

Abstract

Moringa oleifera is a tree considered an excellent nutritional and coagulant source, with its seed used as an aqueous extract to aid anaerobic effluent treatments. Anaerobic digestion is a process carried out by groups of microorganisms that act in the absence of oxygen, converting complex organic compounds into biogas. To enhance methane production in anaerobic tretments, specific methanogenic activity (Sma) testes can be carried out in order to convert organic compounds into methane. The present study aimed to evaluate the effect of different concentrations of Moringa oleifera seed extract in an anaerobic sludge. The way specific methanogenic activity assays are carried out was reviewed in order to determine a protocol and the most interfering variables. The select variables were tested to obtain the best Sma values, acetic acid, a mix of acetic, propionic and butyric acids, at concentrations of 500, 1000 and 2000 mgO2 L-1, different substrate/microorganisms in the range of 0.2 to 4 gO2 gVST-1, pH in the range of 4 to 10 and agitation of 0, 40, 70 and 100 rpm. Subsequently, an extract of 2.5 mg of Moringa oleifera seed powder was applied per liter of distilled water at concentrations of 0.5, 1 e 2 mL L-1 to analyze its interference with Sma. Two control trials were also conducted concomitantly, one with the addition of nutrient medium and without Moringa oleifera extract and the other without nutritional medium and without extract. Acetic acid was considered as substrate at a concentration of 1000 mgO2 L-1, at a substrate/microorganism ratio of 0.5 gO2 gVST-1, pH 8 and agitation at 40 rpm. The results showed that, despite there being no significant difference between the differet concentrations the concentration of 1.0 mL L-1 of extract benefits the reaction speed of the reactors as well as the degradation of organic matter, and excess extract can inhibit microbial metabolism. Moringa oleifera extract can be used as a nutritional source for anaerobic digestion, replacing high-cost chemical nutrient sources. Failure to use a nutrient medium can affect the anaerobic digestion process, inhibiting methane production (AU)

• FAPESP's process: 18/18802-0 - Influence of concentration of the seed extract of Moringa oleifera in anaerobic digestion
• Grantee: Izabela Paiva Martins
• Support Opportunities: Scholarships in Brazil - Doctorate