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Table 1

Analysis results of raw wastewater and wetland treated wastewater with the pollutant removal efficiency and mechanism observed in existing natural wetland

Constituents (pollutants)Raw wastewater (wetland inlet)Wetland treated wastewater (wetland outlet)Percent reductionRemoval mechanisms
Ionic strength 
 EC (μS/cm) 2,640 1,460 44.69% Precipitation and Evapotranspiration 
Organic contents 
 BOD 60 13 78.33% Aeration, addition of oxygen by Photosynthesis, Bacterial release of oxygen 
 COD 184 44 76.08% 
 DO 0.15 3.34 Added 22 folds 
Nutrients (mg/L) 
 NO3 as N 142 97.18% Sedimentation, Denitrification, Reduction and Plant assimilation 
 SO4−2 305 68 77.70% Reduction by SRB, Heterotrophic consumption, Adsorption, Sedimentation and Precipitation. 
 PO4−2 8.30 1.45 82.53% Matrix Sorption, Precipitation and Plant uptake 
 Na+ 234 151 35.47 Sedimentation, Flocculation, Adsorption, Cation and anion exchange, Complexation, Redox reactions, Precipitation, Plant uptake, etc. 
 K+ −100%a 
 Ca+2 80 80 0% 
 Mg+2 151 49 67.54% 
 Cl 500 210 58.00% 
 F 1.64 1.38 15.85% 
 HCO3 250 272 −8.08%a 
Trace elements (μg/L) 
 Al 146.60 14.30 90.24% Adsorption and cation exchange, Complexation, Precipitation, Plant uptake, Microbial oxidation/ reduction. Bound to articulate matters, deposited on the beds of water bodies, and sorbed onto the sediments 
 Si 8.47 15.07 −44.64% 
 V 4.60 3.30 28.26% 
 Cr 7.60 6.30 17.10% 
 Mn 72.70 83.90 −13.34a 
 Fe 155.20 73.60 52.57% 
 Ni 6.30 7.40 10.81% 
 Co 0.61 0.56 8.19% 
 Cu 7.70 11.20 −31.25%a 
 As 1.30 0.60 53.84% 
 Se 17.60 18.75 6.13% 
 Rb 7.60 0.40 94.73% 
 Sr 279.90 462.80 −39.52%a 
 Mo 0.16 0.50 −68.00%a 
 Ag 0.02 0.01 50.00% 
 Cd 0.52 0.04 92.30% 
 Sb 0.05 0.02 60.00% 
 Ba 37.50 29.10 22.40%  
 Ti 0.02 0.015 25.00%  
 Pb 3.10 1.30 58.06%  
Agriculture suitability parameters of water 
 TH as CaCO3 820 400 51.22%  
 SAR 3.55 3.27 7.88%  
Microbial contamination 
 Sulphite reducing bacteria (/100 ml) Present Present – Sedimentation/filtration, UV radiation, Excretion of antibiotics from roots of macrophytes 
 Total plate count (CFU/ml) 7.27 × 106 1,000 99.99% 
 Coliforms (CFU/ml) 110 × 103 17 99.98% 
 Faecal coliforms (/100 ml) 1,600 99.56% 
E. coli O157:H7 (/g) Not detected Not detected – 
Salmonella (per 250 ml) Absent Absent – 
Shigella (per 250 ml) Absent Absent – 
Campylobacter (CFU/ml) Not detected Absent –  
Constituents (pollutants)Raw wastewater (wetland inlet)Wetland treated wastewater (wetland outlet)Percent reductionRemoval mechanisms
Ionic strength 
 EC (μS/cm) 2,640 1,460 44.69% Precipitation and Evapotranspiration 
Organic contents 
 BOD 60 13 78.33% Aeration, addition of oxygen by Photosynthesis, Bacterial release of oxygen 
 COD 184 44 76.08% 
 DO 0.15 3.34 Added 22 folds 
Nutrients (mg/L) 
 NO3 as N 142 97.18% Sedimentation, Denitrification, Reduction and Plant assimilation 
 SO4−2 305 68 77.70% Reduction by SRB, Heterotrophic consumption, Adsorption, Sedimentation and Precipitation. 
 PO4−2 8.30 1.45 82.53% Matrix Sorption, Precipitation and Plant uptake 
 Na+ 234 151 35.47 Sedimentation, Flocculation, Adsorption, Cation and anion exchange, Complexation, Redox reactions, Precipitation, Plant uptake, etc. 
 K+ −100%a 
 Ca+2 80 80 0% 
 Mg+2 151 49 67.54% 
 Cl 500 210 58.00% 
 F 1.64 1.38 15.85% 
 HCO3 250 272 −8.08%a 
Trace elements (μg/L) 
 Al 146.60 14.30 90.24% Adsorption and cation exchange, Complexation, Precipitation, Plant uptake, Microbial oxidation/ reduction. Bound to articulate matters, deposited on the beds of water bodies, and sorbed onto the sediments 
 Si 8.47 15.07 −44.64% 
 V 4.60 3.30 28.26% 
 Cr 7.60 6.30 17.10% 
 Mn 72.70 83.90 −13.34a 
 Fe 155.20 73.60 52.57% 
 Ni 6.30 7.40 10.81% 
 Co 0.61 0.56 8.19% 
 Cu 7.70 11.20 −31.25%a 
 As 1.30 0.60 53.84% 
 Se 17.60 18.75 6.13% 
 Rb 7.60 0.40 94.73% 
 Sr 279.90 462.80 −39.52%a 
 Mo 0.16 0.50 −68.00%a 
 Ag 0.02 0.01 50.00% 
 Cd 0.52 0.04 92.30% 
 Sb 0.05 0.02 60.00% 
 Ba 37.50 29.10 22.40%  
 Ti 0.02 0.015 25.00%  
 Pb 3.10 1.30 58.06%  
Agriculture suitability parameters of water 
 TH as CaCO3 820 400 51.22%  
 SAR 3.55 3.27 7.88%  
Microbial contamination 
 Sulphite reducing bacteria (/100 ml) Present Present – Sedimentation/filtration, UV radiation, Excretion of antibiotics from roots of macrophytes 
 Total plate count (CFU/ml) 7.27 × 106 1,000 99.99% 
 Coliforms (CFU/ml) 110 × 103 17 99.98% 
 Faecal coliforms (/100 ml) 1,600 99.56% 
E. coli O157:H7 (/g) Not detected Not detected – 
Salmonella (per 250 ml) Absent Absent – 
Shigella (per 250 ml) Absent Absent – 
Campylobacter (CFU/ml) Not detected Absent –  

TH: Total hardness as CaCO3; SAR: Sodium adsorption ratio for agriculture suitability (categorized as Excellent 0–10, Good 10–18, Doubtful 18–26, Unsuitable >26 (Richards 1954).

aIncrease % of pollutant in wetland).

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