2. Disinfection by-products Precursors + oxidant → DBPs DBPs can be reduced by: the precursors (organic materials present in the sourcewater) the reactants (chlorine, chlorine dioxide, chloramine, ozone…) the REACTION (pH, temperature, time) the products (DPB removal through Granular Activated Carbon)

3. H H C C H H H H H H Methane CH 4 Cl C C H H Chloroform CHCl 3 Tri chloro methane Tri halo methanes DBPs Image from Wikipedia

4. Cl H H C C H H H H H H Methane CH 4 C C H H Cl Chloroform CHCl 3 Tri chloro methane Tri halo methanes DBPs Br C C H H Cl CHCl 2 Br Dichloro bromo methane

5. Cl H H C C H H H H H H Methane CH 4 C C H H Cl Chloroform CHCl 3 Tri chloro methane Tri halo methanes DBPs Br C C H H Cl CHCl 2 Br Dichloro bromo methane Br C C H H Cl Br CHClBr 2 Chloro di bromo methane

6. Cl H H C C H H H H H H Methane CH 4 C C H H Cl Chloroform CHCl 3 Tri chloro methane Tri halo methanes DBPs Br C C H H Cl CHCl 2 Br Dichloro bromo methane Br C C H H Cl Br CHClBr 2 Chloro di bromo methane Br C C H H Bromoform CHBr 3 Tri bromo methane

7. Haloacetic Acids (HAA5) Chloroacetic acid Dichloroacetic acid Trichloroacetic acid Bromoacetic acid Dibromacetic acid Br ClCH 2 CO 2 H

8. Disinfection by-products Precursors + oxidants reaction DBPs pH, time, Temp DBPs can be reduced by: the REACTION (pH, temperature, time) – pH ↑ increases THM reaction – Time ↑ increases THM reaction – Temperature ↑ increases THM reaction