USEPA Stage 2 Disinfection By-product Rule Compliance Monitoring with the Aqualog® from HORIBA

By: Adam M. GILMORE

February 1, 2019


Excitation-emission contours for PARAFAC model components c1(A), c2(B)and c3(C). The data set included n=1484 samples with duplicate daily measurements for each raw and finished sample. The model accounted for 97.3% of the variance, the split-half validation match was 98.6% and the core consistency was 94%.

Author Information: HORIBA Instruments Inc.

This application note describes the use of the Aqualog for monitoring regulated Dissolved Organic Matter (DOM) and disinfection by-product issues for drinking water treatment.  The Aqualog was used to simultaneously measure the UV-VIS absorbance spectrum and fluorescence Excitation Emission Matrix (EEM) and monitor DOM pertaining to EPA Stage2 Disinfection By-product Rule (DBPR2) compliance in a typical surface water source drinking water treatment plant (defined as Subpart H).  The method enabled near real-time monitoring of the EPA regulated parameters of Total Dissolved Organic Carbon (TOC), absorbance at 254 nm (UVA) and the Specific UV Absorbance (SUVA-TOC) as well as the Simulated Distribution System Trihalomethane (THM) Formation Potential (SDS-THMFP).  The parameters were reported as a function of compliance rules associated with required % removals of TOC (as a function of alkalinity) and predicted maximum contaminant levels (MCL) of THMs.  The single instrument method, which is compatible with continuous flow monitoring or grab sampling, provides a rapid (2-3 minute) and precise indicator of drinking water disinfectant treatability without the need for separate UV photometric and TOC meter measurements or independent THM determinations. SUVA100×UVAcm1/TOCmg/L

NoteFull paper of the same content in Japanese is in Readout No.48-Japanese edition.


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