Cassava peels & extracts: Performance in a single chamber air cathode microbial fuel cell
Bibliographic record
Abstract
Microbial fuel cells (MFC) are gaining popularity because of their unique ability to produce electricity from the activity of bacteria on a diverse range of substrates. Several studies have investigated the use of domestic wastewater, winery waste, sewage sludge, starch, and chocolate as substrates in MFCs, with varying degrees of success. While this technology has shown considerable promise for the future of energy production and waste management, much still has to be done with respect to its scaling-up for practical applications. Advances in the optimization of power outputs, MFC construction materials, and in predicting power outputs for scale-up projects further buoy this positive outlook.Cassava (Manihot esculenta Crantz) is a common root crop in the tropics and an important source of sustenance for many people around the world. The processing of this root crop involves, amongst many other steps, the removal of the peel, which is then discarded. More often than not, these peels are left to rot in open spaces close to the processing factories and constitute a nuisance to the environment.In a bid to find a use for this abundant waste, the possibility of serving as substrate to produce electricity in a single chamber MFC with an air cathode was examined. An examination of the microbes present on cassava peels identified rod-shaped gram-positive and cocci-shaped gram-negative bacteria as the dominant microbes growing indigenously on the cassava peels. The exoelectrogenicity of these organisms was determined in a tubular single chamber MFC, operating at an optimal anode-cathode distance of 2.54 cm (1 in). The anode consisted of carbon graphite brushes, while the cathode was a membrane electrode assembly (MEA) carbon cloth assembly, consisting of a gas diffusion layer coated with 60% PtC at 0.5 mg/cm2, with an active area of 10 cm ×10 cm. The maximum output and power density recorded over a 35-day cycle were 450 ± 20 mV and 29 mW/m3 of reactor volume, respectively. Peaking after about 96 h of operation, the system’s power density steadily decreased thereafter. The information and experience gained through this study allowed for the conceptualization of a new, cleaner and more maneuverable system design. Extracts squeezed from cassava peels bearing a 65% moisture content were used for subsequent experiments. At other times, cassava peels or extracts were subjected to different pre-treatments before being loaded into the MFC. In this latter portion of the study, the maximum voltage output recorded was 687 ± 21mV, while the highest calculated power density was 155 mW/m3 of reactor volume after 96 hrs. This was coupled with a high coulombic efficiency (77%). These values were recorded for an extract of 7-day fermented cassava peels, adjusted to pH = 7.63 with Na2CO3. This project is fundamental to further scholarship on the usage of cassava peels or similar agricultural wastes in a microbial fuel cell. It is believed that there are inferences to be taken from this project for the design of a more efficient and scalable process for the usage of such wastes in generating electricity, all in a bid to reduce the damage to the environment that may arise from their indiscriminate disposal.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".