Description
Unintentional nitrification occurs in nearly 67% of all utilities practicing chloramination.Nitrification has been linked to distribution systems and storage tanks with long detention times.Excess ammonia during chloramination promotes ammonia-oxidizing bacteria that emit nitriteand form biofilms within distribution systems.Utilities can control nitrification in two ways. First, they can increase the chlorine toammonia molar ratio (Cl<sub>2</sub>:NH<sub>3</sub>) to reduce free ammonia in the distribution system. Second, theycan practice breakpoint chlorination to leave a free chlorine residual that hinders biofilm growthand then reapply chloramines downstream. The former strategy increases the formation ofdichloramine (NHCl<sub>2</sub>), while the latter forms a series of reactive intermediates. The effect ofboth strategies on the formation of nitrogenous byproducts has not been examined.We conducted experiments to study the impact of Cl<sub>2</sub>:NH<sub>3</sub> molar ratios > 1 on theformation of three toxic nitrogenous disinfection byproduct families, nitriles (e.g., cyanogenchloride), nitramines (dimethylnitramine) and nitrosamines (e.g., NDMA). For theseexperiments, we used dimethylcyanamide as a model nitrile, dimethylnitramine as a modelnitramine, and NDMA as a model nitrosamine. Includes 5 references, figures.
Product Details
- Edition:
- Vol. – No.
- Published:
- 11/01/2007
- Number of Pages:
- 7
- File Size:
- 1 file , 170 KB
- Note:
- This product is unavailable in Ukraine, Russia, Belarus
