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Table 2

Comparison of the water quality parameters used in the evaluation of TW and PW

ParameterTWPWRequirements for mixing water for concrete (ABNT 2009 a)
pH 6.8–7.9 7.2 ≥5 
Total alkalinity (mg CaCO3 L−1313.6 21.7 ≤2,422b 
Conductivity (μS cm−11,193 54.9 – 
Dissolved oxygen (mg O2 L−14.4 8.1 – 
Turbidity (uT) 10 0.19 – 
Total solids (mg L−1519 55.2 ≤50,000 
Chemical oxygen demand (mg L−185 – – 
Total N (mg L−1188 1.10 – 
Nitrite (mg NO2N L−14.9 <0.005 – 
Nitrate (mg NO3N L−142.5 0.63 ≤500 
Total P (mg P L−12,74 0.12 ≤44c 
Sulfate (mg SO42− L−150 3.99 ≤2,000 
Chloride (mg Cl L−1113 0.36 ≤500 
Total coliforms (NMP/100 mL) 1.0 – 
Escherichia coli (NMP/100 mL) <1.0 – 
Lead (mg Pb2+ L−1<0.1 <0.1 ≤100 
Zinc (mg Zn2+ L−1<0.1 <0.1 ≤100 
ParameterTWPWRequirements for mixing water for concrete (ABNT 2009 a)
pH 6.8–7.9 7.2 ≥5 
Total alkalinity (mg CaCO3 L−1313.6 21.7 ≤2,422b 
Conductivity (μS cm−11,193 54.9 – 
Dissolved oxygen (mg O2 L−14.4 8.1 – 
Turbidity (uT) 10 0.19 – 
Total solids (mg L−1519 55.2 ≤50,000 
Chemical oxygen demand (mg L−185 – – 
Total N (mg L−1188 1.10 – 
Nitrite (mg NO2N L−14.9 <0.005 – 
Nitrate (mg NO3N L−142.5 0.63 ≤500 
Total P (mg P L−12,74 0.12 ≤44c 
Sulfate (mg SO42− L−150 3.99 ≤2,000 
Chloride (mg Cl L−1113 0.36 ≤500 
Total coliforms (NMP/100 mL) 1.0 – 
Escherichia coli (NMP/100 mL) <1.0 – 
Lead (mg Pb2+ L−1<0.1 <0.1 ≤100 
Zinc (mg Zn2+ L−1<0.1 <0.1 ≤100 

aThis regulation states that TW should not be used for concrete production.

bAccording to ABNT (2009), the alkalis content in mixing water must not exceed 1,500 mg Na2O L−1, which is equivalent to 2,422 mg CaCO3 L−1.

cAccording to ABNT (2009), the phosphate content in mixing water must not exceed 100 mg P2O5 L−1, which is equivalent to 44 mg P L−1.

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