Banca de DEFESA: Sávio Henrique de Barros Holanda

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Sávio Henrique de Barros Holanda
DATE: 14/12/2022
TIME: 15:00
LOCAL: Pós-Graduação em Engenharia Civil
TITLE:

The Application of Microbial Consortium to Waste Management: A Biotechnological Alternative to Accelerate Anaerobic Biodegradation and Bbiogas and Methane Generation from Solid Organic Waste

KEY WORDS:

Biomass. Solid waste. Anaerobic digestion. Bioenergy. Biotechnology. Biogas

PAGES: 112
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

The world economy generates, annually, around 2.01 billion tons of municipal solid waste (MSW). Of these, 46% (924.6 million tons) correspond to the amount of organic waste, which, if not treated correctly, represent a potential agent of soil, air and water pollution. Among the various existing technologies for waste treatment, the Anaerobic Digestion (AD) stands out for its low or zero emission of greenhouse gases, the ability to treat both solid waste and liquid effluents, but especially for generating two by-products of high economic and ecological interest: biogas and biofertilizer. In short, Anaerobic Digestion consists of the biochemical process of synthesizing large polymeric conglomerates of high molecular weight to oligomers and monomers, with low molecular weight, in an oxygen-free environment. This process consists of four well-defined stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Among these, the hydrolytic phase is characterized by the degradation of complex polymers with high molecular weight (carbohydrates, proteins and lipids), which gives this stage a high hydraulic detention time, due to the recalcitrance of the organic substances present. Aiming to speed up the anaerobic fermentation, and the consequent reduction of the hydraulic detention time, this research adopted the biotechnological technique of bioaugmentation, which consists in adding microorganisms capable of providing benefits to the biochemical system to a pre-existing biological process, optimizing it and reducing the biodegradation time. For this, a microbial consortium composed of Bacillus subtilis (T9) and Alcaligenes faecalis (T19) strains was used, with the objective of promoting an improvement in the degradation of residual biomass and the consequent production of biogas and methane. Eleven BMP digesters were used, in borosilicate flasks (250 mL), with brass connections, and analogic manometer (scale of 0-1 kgf/cm² and interval of 0.02), inside which varied amounts of substrate (dry and triturated solid residues) and inoculum (digestate from a biogas plant and microbial consortium) were inserted. Adopting the Experimental Planning tool (DCCR - 2³), with the central composite design consisting of sequential experimentation (factorial with central, axial and curvature points), this allows an "economy" in experimentation, with replication only in the central points. Totaling eleven experiments, the aforementioned anaerobic fermentation batch was developed using the following configurations: 3.0 g RO + 7.27 mLDG + 42.73 mLC; 3.0 g RO + 42.73 mLDG + 7.27 mLC; 7.0 g RO + 7.27 mLDG + 42.73 mLC; 7.0 g RO + 42.73 mLDG + 7.27 mLC; 2.18 g RO + 25 mLDG + 25 mLC; 7.82 g RO + 25 mLDG + 25 mLC, respectively, the points (-1.0, -1.0; -1.0, 1.0; 1.0, -1.0; 1.0, 1.0; -1.41, 0; 1.41, 0; 0, -1.41; 0, 1.41), with the triplicate experiments (5 g RO + 25 mLDG + 25 mLC) concentrating on the central point (0.0, 0.0). Composed predominantly of fruits (89.71%), with trace amounts of leafy vegetables (6.75%) and legumes (3.54%), the organic waste studied had a moisture content (%W) of 85.56%, a pH of 3.5, a BOD5/D COD ratio of 0.936, a volatile solids content of 0.93 g*gST-1 and a C/N ratio of 12.3. These data point to an acid and biodegradable waste, despite the C/N ratio not being favorable for anaerobic fermentation. In turn, the digestate, which initially presented pH, BOD5/ COD ratio and volatile solids values of, respectively, 7.1, 0.23 mg*L-1 and 0.56 g*gST-1 was submitted to a 6-month acclimation/incubation process (t ≈ 180 days), with the purpose of allowing the self-depuration of the intrinsic organic load of the effluent, as well as stabilizing physical and biochemical parameters, presenting, at the end of the incubation, the values of pH, BOD5/D COD ratio and volatile solids of, respectively, 7.6, 0.02 mg*L-1 and 0.41 g*gST-1. The use of the acclimated effluent was necessary in order to promote improvements and fluidity to the anaerobic biochemical process, especially in favor of raising/correcting the pH of the system. After the anaerobic fermentation, the highest Accumulated Potential of biogas was observed in Experiment 1, which was composed of 3.0 g RO + 7.27 mLDG + 42.73 mLC, recording 113.26 NmLbiogas/gSV, followed by Experiment 5, which was composed of 2.5 g RO + 25 mLDG + 25 mLC, recording 53.13 NmLbiogas/gSV. Regarding the Potentials of methane gas present in the biogas, such Experiments 1 and 5 reached 62.57 NmLCH4/gSV and 37.76 NmLCH4/gSV, respectively, being also the Experiments that obtained better methane yields. The other experiments (2, 4, 8 and 9) presented the respective values: 20.21, 0.77, 15.76, 1.19 NmLCH4/gSV. Experiments 3, 6 and 7 presented high amounts of volatile solids, having high organic load, inhibiting anaerobic digestion. Therefore, it is possible to observe, through concrete data, that Solid Waste Management or residual biomass can reach higher levels of efficiency and improvement of the quality of the anaerobic biodegradative process, with the adoption of tools originating from Environmental and Industrial Biotechnology, such as the application of consortia of microorganisms to socio-environmental problems. 

COMMITTEE MEMBERS:
Presidente - 3199298 - MAURICIO ALVES DA MOTTA SOBRINHO
Externo ao Programa - 1742969 - JORGE VINICIUS FERNANDES LIMA CAVALCANTI - UFPEExterna à Instituição - ALESSANDRA LEE BARBOSA FIRMO - IFPE
Externo à Instituição - ARMANDO BORGES DE CASTILHOS JUNIOR - UFSC
Externa à Instituição - LAIS ROBERTA GALDINO DE OLIVEIRA - UFG