Field application of cost-effective sensors for the monitoring of NH₃, H₂S, and TVOC in environmental treatment facilities and the estimation of odor intensity

Figures & data

Table 1. Specification of odor sensors used in this study.

	H2S sensor	NH3 sensor	TVOC sensor
Principal	Electrochemical (EC)	Electrochemical (EC)	Photoionization detection (PID)
Model	Model #SO1198	Model #SO1N8	MinPID
Manufacture	Senko LTD. (Korea)	Senko LTD. (Korea)	Base-Mocon LTD. (USA)
Temperature	−10∼50℃	−10∼50℃	−20∼60℃
Humidity	15∼90%)	15∼90%)	0∼90%)
Measurement range	5∼5000(ppb)	100∼5000(ppb)	5∼5000(ppb)
T90 response time	<90 seconds to 90% RH	<30 seconds to 90% RH	<30 seconds to 90% RH
Weakness	Long initial running time	Low Selectivity	high cost, Short lifetime

Table 2. Information on three environmental treatment facilities and their odor treatment plants.

	O-MWT	Y-LWT	S-FWC
Treatment media	Municipal wastewater	Piggery wastewater	Food waste
Treatment method	DeNiPho	Natural purification + HCR	Aerobic composting
Treatment capacity	5,180 m^3/d (wastewater)	141 m^3/d (wastewater)	37 ton/d (food waste)
Data periods of sensor monitoring	Oct. 18 to Dec. 12, 2019	Oct. 23 to Dec. 25, 2019	Nov. 22 to Dec. 26, 2019
Odor treatment process	Scrubber + Biofilter	Biofilter + Activated carbon	Scrubber + Biofilter
Odor treatment capacity	80 m^3/min	140 m^3/min	450 m^3/min

Figure 1. Customized environmental monitoring system including odor sensors to measure ammonia, hydrogen sulfide and TVOC.

Table 3. Summary of performance tests for the three sensors used in this study (Han et al. 2019).

		H2S sensor	NH3 sensor	TVOC sensor
Linearity	R^2	0.999	0.986	0.985
	Range	0–1000 ppb	0–1300 ppb	0–300 ppb
Lower detection limit		22.3 ppb	18.6 ppb	26.7 ppb
Accuracy		0.09%	5.2%	5.7%
Repeatability		0.3%	0.1%	0.03%
Response time		120 s	540 720 s	60 s

Figure 2. Sensor measurement data at a municipal wastewater treatment facility (black solid line: In-OTP, and brown dotted line: Out-OTP).

Table 4. Sensor monitoring data from a municipal wastewater treatment facility.

	In-OTP					Out-OTP
	NH3 (ppb)	H2S (ppb)	TVOC (ppb)	Temp. (°C)	RH (%)	NH3 (ppb)	H2S (ppb)	TVOC (ppb)	Temp. (°C)	RH (%)
Mean ± SD	383 ± 90	828 ± 363	29 ± 8	26 ± 4	39 ± 7	24 ± 27	35 ± 20	210 ± 54	17 ± 5	46 ± 13
Max./Min.	960 / 221	1,904 / 253	43 / 10	33 / 17	57 / 27	148 / 0	201 / 0	395 / 37	30 / 6	70 / 18
Expressed data (n)	1,217	1,217	1,217	1,217	1,217	1,089	1,100	932	1,100	1,100
Data expression ratio (%)	91	91	91	91	91	82	83	70	83	83

Figure 3. Sensor measurement data at a livestock wastewater treatment facility (black solid line: In-OTP, and brown dotted line: Out-OTP).

Table 5. Sensor monitoring data from a livestock wastewater treatment facility.

	In-OTP					Out-OTP
	NH3 (ppb)	H2S (ppb)	TVOC (ppb)	Temp. (°C)	RH (%)	NH3 (ppb)	H2S (ppb)	TVOC (ppb)	Temp. (°C)	RH (%)
Mean ± SD	10,059 ± 3,237	2,258 ± 3,159	1,889 ± 2,719	16 ± 6	56 ± 14	314 ± 204	484 ± 686	823 ± 445	13 ± 6	62 ± 13
Max./Min.	24,472 / 3,089	27,271 / 116	14,222 / 42	31 / 0	91 / 19	2,334 / 120	5,135 / 1	4,371 / 166	34 / 0	96 / 31
Expressed data (n)	945	972	442	932	932	1,468	1,468	1,468	1,468	1,468
Data expression ratio (%)	62	64	29	61	61	97	97	97	97	97

Figure 4. Sensor measurement data at a food waste composting facility (black solid line: In-OTP, and brown dotted line: Out-OTP).

Table 6. Sensor monitoring data from a food waste composting facility.

	In-OTP					Out-OTP
	NH3 (ppb)	H2S (ppb)	TVOC (ppb)	Temp. (°C)	RH (%)	NH3 (ppb)	H2S (ppb)	TVOC (ppb)	Temp. (°C)	RH (%)
Mean ± SD	930 ± 657	151 ± 16	3,669 ± 2,069	17 ± 6	57 ± 10	954 ± 652	119 ± 10	1,004 ± 286	17 ± 6	49 ± 9
Max. / Min.	2,833 / 222	210 / 117	11,954 / 1,190	29 / 6	71 / 35	2,853 / 269	142 / 93	1,911 / 603	29 / 6	68 / 31
Expressed data (n)	758	758	758	743	748	758	758	758	742	747
Data expression ratio (%)	100	100	100	98	99	100	100	100	98	99

Figure 5. Correlation between odor by ADOM and each sensor measurement concentrations of NH₃ (black), H₂S (brown), TVOC (blue) in MWT (a), LWT (b), FWC (c), respectively.

Table 7. Multivariate linear regression between complex odor (dependent variable) measured by ADOM and sensor measurement data.

Regression	Independent variables	B (coefficients for independent variables)	T (coefficient /standard error)
R = 0.821 p value = 0.000	Intercept	228.444	0.373
	NH3	0.153	1.094
	H2S	1.339	2.051
	TVOC	0.789	2.994

Figure 6. Correlation comparison between odor by odor estimated by sensor data (a) and ADOM and odor divided by the odor threshold values (b) and (black: MWT, brown: LWT, blue: FWC).

Figure 7. Correlation between odor estimated by correlation equation (eq.1) and odor divided by threshold (black: MWT, brown: LWT, blue: FWC).

Figure 8. Estimated odor unit from sensor measurement data and removal efficiency at a MWT (a), LWT (b), FWC (c), respectively (black solid line: In-OTP, and brown dotted line: Out-OTP, blue solid line: removal efficiency).

Table 8. Odor intensity generated by the linear regression using sensor measurement data.

	MWT		LWT		FWC
	In-OTP	Out-OTP	In-OTP	Out-OTP	In-OTP	Out-OTP
Mean ± SD (O.U)	2,039 (±518)	419 (±93)	5,557 (±5,392)	1,573 (±1,220)	3,468 (±1,664)	1,326 (±281)
Removal ratio ± SD (%)	78 (± 8)		60 (± 25)		58 (± 12)
Max./min. (O.U.)	4,280 / 1,025	686 / 0	45,358 / 455	10,380 / 0	10,077 / 1,444	2,167 / 970
Expressed data (n)	1,217	1,088	972	1,469	748	748
Data expression ratio (%)	91	82	64	97	99	99

Figure 9. Suggested protocol for field application of sensor monitoring and odor data estimation.

Han, S. W., C. S. Lee, H. S. Joo, K. C. Kim, S. Y. Kim, H. J. Ryu, J. M. Lee, H. S. Kim, and J. S. Han. 2019. Performance assessment of H2S, NH3, and VOCs sensors for field application. J Odor Indoor Environ 18 (3):261–71.

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Data availability statement

The data that support the findings of this study are available from the first author,[HSJ], corresponding author, [JSH], upon reasonable request.