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Municipal Wastewater Quality Control: Heavy Metal Comparative Analysis—Case Study

Wiktor Halecki
Wiktor Halecki
, 
Tomasz Sionkowski
Tomasz Sionkowski
, 
Krzysztof Chmielowski
Krzysztof Chmielowski
, 
Agnieszka Kowalczyk
Agnieszka Kowalczyk
 oraz 
Konrad Kalarus
Konrad Kalarus
   | 31 gru 2023
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Data publikacji: 31 gru 2023
Zakres stron: 127 - 134
DOI: https://doi.org/10.2478/oszn-2023-0023
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© 2023 Wiktor Halecki et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1.

The heavy metal content in raw and treated wastewater. The means with 95% confidence intervals. Grey bars represent raw wastewater and white bars represent treated wastewater
The heavy metal content in raw and treated wastewater. The means with 95% confidence intervals. Grey bars represent raw wastewater and white bars represent treated wastewater

Figure 2.

The heavy metal content in sewage sludge from municipal wastewater treatment. The means with 95% confidence intervals. If the upper limit of the confidence interval is below the value of the standard, it means that the standard is met, if the confidence interval overlaps the value of the standard, it means that the standard is not met, but the metal content is close to the standard, in the situation when the lower limit of the confidence interval is above the value of the standard, it means that the metal content significantly exceeds the standard. The upper bound of the confidence interval falls below the standard (red line), indicating that the metal content in the sludge is statistically significantly lower than the maximum permissible content
The heavy metal content in sewage sludge from municipal wastewater treatment. The means with 95% confidence intervals. If the upper limit of the confidence interval is below the value of the standard, it means that the standard is met, if the confidence interval overlaps the value of the standard, it means that the standard is not met, but the metal content is close to the standard, in the situation when the lower limit of the confidence interval is above the value of the standard, it means that the metal content significantly exceeds the standard. The upper bound of the confidence interval falls below the standard (red line), indicating that the metal content in the sludge is statistically significantly lower than the maximum permissible content

Figure 3.

PCA analysis results. Ordination diagrams showing the first and second ordination axes: (a) for wastewater, (b) sewage sludge. For diagram (a), circles represent raw wastewater and squares represent treated wastewater
PCA analysis results. Ordination diagrams showing the first and second ordination axes: (a) for wastewater, (b) sewage sludge. For diagram (a), circles represent raw wastewater and squares represent treated wastewater

The results of the repeated measures, analysis of variance. “R1” represents the wastewater treatment effect, and “quarter” refers to the quarter of the year. Significant effects are bolded. Following symbols denote: df – degrees of freedom, F – F-statistic, p – p-value

Effect df F p
Zn (N = 138) Intercept 1 948.19 <0.001
Quarter 3 1.23 0.302
Error 133 - -
R1 1 7.07 0.009
R1*Quarter 3 4.32 0.006
Error 133 - -
Pb (N = 123) Intercept 1 708.47 <0.001
Quarter 3 1.88 0.138
Error 118 - -
R1 1 2.09 0.151
R1*Quarter 3 0.19 0.905
Error 118 - -
Cd (N = 88) Intercept 1 411.53 <0.001
Quarter 3 0.96 0.414
Error 83 - -
R1 1 2.78 0.099
R1*Quarter 3 1.87 0.141
Error 83 - -
Cu (N = 137) Intercept 1 969.36 <0.001
Quarter 3 0.26 0.857
Error 132 - -
R1 1 14.19 <0.001
R1*Quarter 3 0.10 0.960
Error 132 - -
Cr (N = 121) Intercept 1 707.04 <0.001
Quarter 3 0.34 0.794
Error 116 - -
R1 1 1.80 0.183
R1*Quarter 3 2.18 0.095
Error 116 - -
Ni (N = 125) Intercept 1 635.60 <0.001
Quarter 3 1.48 0.222
Error 120 - -
R1 1 17.16 <0.001
R1*Quarter 3 0.47 0.707
Error 120 - -
Mn (N = 138) Intercept 1 1600.64 <0.001
Quarter 3 0.16 0.923
Error 133 - -
R1 1 61.15 <0.001
R1*Quarter 3 1.28 0.285
Error 133 - -

Compliance with the heavy metal content standard in sewage sludge originating from municipal wastewater treatment. Results of the one-sample t-test relative to a constant reference value – the norm. N denotes sample size. SE denotes Standard error, t indicates t-statistic, and p indicates p-value

Mean [mg/l] SE Reference value [mg/l] N t p
Zn 1,148.97 42.39 2,500 70 31.87 <0.001
Pb 68.86 3.90 750 70 174.48 <0.001
Cd 4.06 1.45 20 70 11.03 <<.001
Cu 170.82 7.95 1,100 70 104.35 <0.001
Cr 81.46 11.37 500 70 36.82 <0.001
Ni 34.12 2.33 300 70 113.89 <0.001
Hg 0.98 0.06 16 70 261.84 <0.001
eISSN:
2353-8589
Język:
Angielski
Częstotliwość wydawania:
4 razy w roku
Dziedziny czasopisma:
Life Sciences, Ecology
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