Table 2:
Disinfection Byproducts (DBPs) and Total Organic Halogen Formed from the Treatment of MC-LRa
| DBP | chlorine | chlorine + Cl− | UV/chlorine | UV/chlorine + Cl− | no treatment |
|---|---|---|---|---|---|
| trichloromethane | 1.7 | 1.4 | ND | 0.8 | ND |
| trichloroacetaldehyde | ND | 0.9 | 0.9 | 0.9 | ND |
| dichloroacetonitrile | <0.75 | <0.75 | 1.3 | <0.75 | ND |
| chloroacetonitrile | 3.2 | 3.6 | 3.3 | 3.5 | ND |
| 1,1-dichloropropanone | 1.0 | <0.25 | 1.0 | 0.9 | ND |
| chloropropanone | 2.2 | 4.6 | 2.2 | 2.1 | ND |
| trichloronitromethane | 0.9 | 0.9 | 0.9 | 0.9 | ND |
| dichloroacetamide | 2.6 | 0.9 | 1.2 | 0.9 | ND |
| trichloroacetamide | 3.2 | 3.7 | 3.3 | 3.2 | ND |
| chloroacetic acid | 0.1 | 0.1 | 0.1 | 0.1 | ND |
| dichloroacetic acid | 0.5 | 0.4 | 0.1 | 0.3 | ND |
| trichloroacetic acid | <0.1 | <0.1 | <0.1 | <0.1 | ND |
| total DBPs | 15.5 | 16.4 | 14.3 | 13.6 | ND |
| TOC1 | 47.2 | 51.2 | 33.4 | 39.7 | ND |
| TOBr | ND | ND | ND | ND | ND |
| TOI | ND | ND | ND | ND | ND |
a
ND: not detected. DBPs that were not present in any of the sample sets are not listed. Results are the mean of 3 replicates. [FAC] = 1.5 mg/L, [Cl−] = 5 mM, UV254 dose 70 mJ/cm2. TOC1 was detected in degradation experiments of MC-LR (1 mg/L) in four tested processes in pure water, with the following trend: Cl2 + Cl− (51.2 μg/L) > Cl2 (47.2 μg/L) > UV/chlorine + Cl− (39.7 μg/L) > UV/chlorine (33.4 μg/L). Thus, when integrating chlorine with UV, lower total concentrations of chlorinated DBPs (TOC1) were produced. No TOBr or TOI was detected (as expected), since bromide and iodide were not added to reactions.