Fecal Malodor Detection Using Low-Cost Electrochemical Sensors
"> Figure 1
<p>Schematic of the experimental setup for odor generation and collection (<b>top left</b>), and odor analysis (<b>top right</b>), and pictures of the sensor box (<b>bottom left</b>) and of the overall test system (<b>bottom right</b>).</p> "> Figure 2
<p>Typical dose response vs. time for Membrapor formaldehyde sensor when exposed to air containing fecal odor. The green bands indicate exposure to malodor. The values above the graph indicate the concentration with respect to the original odor sample (i.e., 100% is undiluted, 71% means 71% odor sample, and 29% odorless air).</p> "> Figure 3
<p>Dilution to threshold (D/T) (<b>A</b> and <b>B</b> panels) and odor intensity (<b>C</b> and <b>D</b> panels) of fecal odor samples tested with the low-cost sensors as a function of their concentration with respect to the original odor sample (i.e., 100% is undiluted). See the Methods section for details.</p> "> Figure 4
<p>Heatmap showing the signal to noise (S/N) ratios to 64 odorant exposures for the 10 sensors tested. The horizontal dashed lines separate the different odor intensity levels.</p> "> Figure 5
<p>Dose response to three fecal malodor specimens by four sensors, two Membrapor (CH<sub>2</sub>O and NH<sub>3</sub>, <b>A</b>,<b>B</b>), and two SGX sensors (<b>C</b>,<b>D</b>). The dose (%) represents the concentration with respect to the original odor sample. The olfactometry data of each sample (reported as dilution to threshold, or D/T) is indicated by the marker type. Error bars represent the standard deviation.</p> "> Figure 6
<p>S/N ratios for three malodors specimen by four sensors (same as <a href="#sensors-20-02888-f005" class="html-fig">Figure 5</a>) as a function of the odor intensity. Error bars represent the standard deviation.</p> ">
Abstract
:1. Introduction
2. Materials and Methods
2.1. Gas Sensors Selection and Characteristics
2.2. Sensor Assembly Device
2.3. Odor Generation and Collection
2.4. Experimental Setup and Protocol for Odor Sensing Experiments
2.5. Data Analysis
2.6. Analytical Methods
3. Results
3.1. Electrochemical Sensors Response
3.2. Olfactometry Results
3.3. Relationship of Sensor Responses and Olfactometry
4. Conclusions
Supplementary Materials
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Compound | Concentration in Odorous Latrines (ppbv) | Odor Character | Odor Threshold (ppbv) |
---|---|---|---|
Hydrogen sulfide | 25–55 [7,8] | Rotten egg | 0.5–2 |
Ammonia | 50–60 [8] | Sharp, pungent | 3000–20,000 |
Butyric acid | 36 [7] | Rancid, vomit | 10–500 |
Methyl mercaptan | 2–15 [8] | Rotten egg, fermented cabbage | 1–20 |
Indole | 0.31 [7] | Fecal, musty | 5–20 |
p-cresol | 1.2 [7] | Animal barn, medicinal | 0.05–9 |
Acetic acid | 3–10 [8] | Sour, vinegar | 400–1000 |
Propionaldehyde | 10 [8] | Sweet, ester | 50–200 |
Trimethylamine | 10–100 [7] | Stale urine | 50–200 |
Brand | Sensor | Retail Price (USD) | Gas | LDL 1 (ppmv) | Range (ppmv) | Sensitivity (nA/ppmv) |
---|---|---|---|---|---|---|
SGX | SGX-7H2S | $45 | H2S | <0.1 | 0–50 | 1700 ± 400 |
Membrapor | H2S/C-10 | $87 | H2S | 0.003 | 0–10 | 4500 ± 1000 |
SGX | EC4-20-SO2 | $98 | SO2 | 0.1 | 0–20 | 400–600 |
SGX | SGX-4NH3 | $88 | NH3 | 1 | 0–100 | 100 ± 30 |
Membrapor | NH3/CR-200 | $140 | NH3 | 0.06 | 0–200 | 90 ± 18 |
Membrapor | Alc/C-100 | $130 | MeOH/EtOH | 0.03 | 0–100 | 1600 ± 600 |
Membrapor | CH2O/C-10 | $105 | CH2O | 0.003 | 0–10 | 4600 ± 1200 |
Membrapor | ETO/C-20 | $105 | Ethylene Oxide | 0.006 | 0–20 | 2500 ± 600 |
CityTech | Sensoric TBM 2E 50 | $379 | Mercaptan | <0.14 | 0–14 | 40–100 2 |
CityTech | Sensoric THT 3E 50 | $554 | Tetrahydrothiophene | <0.42 | 0–14 | 500 ± 180 |
Odorant Sample | Number of Runs |
---|---|
Dog feces | 3 |
Human feces | 2 |
Thermally dried feces | 3 |
Popcorn | 2 |
Citrus odor control product | 2 |
Water vapor (effect of relative humidity) | 1 |
Odor Intensity Score | Description | Details |
---|---|---|
0 | No odor | - |
1 | Very faint | Can detect presence of an odor, but unable to assign a character to the odor |
2 | Faint | Can detect an odor and assign character to the odor after some thought |
3 | Easily detectable | Can detect odor and assign character to the odor instantaneously |
4 | Strong | Unpleasant odor. Can withstand it, but would prefer to move away from the odor source |
5 | Very strong | Unacceptable odor. Would move away from the odor source as soon as possible |
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Kawadiya, S.; Welling, C.; Grego, S.; Deshusses, M.A. Fecal Malodor Detection Using Low-Cost Electrochemical Sensors. Sensors 2020, 20, 2888. https://doi.org/10.3390/s20102888
Kawadiya S, Welling C, Grego S, Deshusses MA. Fecal Malodor Detection Using Low-Cost Electrochemical Sensors. Sensors. 2020; 20(10):2888. https://doi.org/10.3390/s20102888
Chicago/Turabian StyleKawadiya, Siddharth, Claire Welling, Sonia Grego, and Marc A. Deshusses. 2020. "Fecal Malodor Detection Using Low-Cost Electrochemical Sensors" Sensors 20, no. 10: 2888. https://doi.org/10.3390/s20102888
APA StyleKawadiya, S., Welling, C., Grego, S., & Deshusses, M. A. (2020). Fecal Malodor Detection Using Low-Cost Electrochemical Sensors. Sensors, 20(10), 2888. https://doi.org/10.3390/s20102888