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. 2019 Mar 22;85(7):e02956-18. doi: 10.1128/AEM.02956-18

TABLE 1.

Water quality measurements for influent tap water and BARsa

Water quality parameter Measurements (mean [SD]) for:
Influent tap BAR1 BAR2 BAR3
HPC (log10 CFU ml−1) 2.45 (0.25) 3.58 (0.70) 3.71 (0.73) 3.65 (0.79)
pH 8.35 (0.18) ND ND ND
Temp (°C) 19 (3.5) 20.8 (2.3)b
Total alkalinity (mg liter−1) 70 (22) ND ND ND
Hardness (mg liter−1) 154 (17) ND ND ND
Turbidity (NTU) 0.35 (0.95) ND ND ND
Free Cl2 (mg liter−1) 0.96 (0.18) 0.61 (0.24) 0.62 (0.21) 0.54 (0.23)
Total Cl2 (mg liter−1) 1.07 (0.18) 0.71 (0.24) 0.72 (0.22) 0.64 (0.24)
NO3 (mg liter−1) 0.86 (0.23) ND ND ND
PO4 (mg liter−1) 0.15 (0.07) ND ND ND
TOC (mg liter−1) 0.99 (0.77) 1.11 (1.01) 1.02 (0.81) 1.00 (0.62)
Essential elementsc
 Ca 30.60 (4.80)
 Cu 0.01 (0.01) ND ND ND
 Fe 0.02 (0.04) ND ND ND
 K 2.40 (0.71) ND ND ND
 Mg 9.08 (1.96) ND ND ND
 Total N 0.83 (0.13)
 Na 26.00 (8.69) ND ND ND
 Total P 0.19 (0.08) ND ND ND
 Zn 0.02 (0.01) ND ND ND
Beneficial elementsd
 Si 2.28 (0.69) ND ND ND
Toxic elementse
 Al 0.05 (0.04) ND ND ND
a

Abbreviations: BAR, biofilm annular reactor (three operated in parallel for biofilm development; see Materials and Methods); Cl2, chlorine; HPC, heterotrophic plate count; ND, not detected; NO3, nitrate; NTU, nephelometric turbidity units; PO4, phosphate; SD, standard deviation; TOC, total organic carbon. Other parameters detected, mean mg liter−1 (SD): Ba, 0.04 (0.01); S, 21.18 (4.82); Sr, 0.22 (0.05). Other parameters not detected: Be; NH3, ammonia as N; Sb; and V.

b

Temperature was measured in BAR3.

c

Classifications are based on the World Health Organization criteria (65).

d

Classifications are based on the World Health Organization criteria (65). Mn and Ni were not detected.

e

Classifications are based on the World Health Organization criteria (65). As, Cd, Li, Pb, and Sn were not detected.