1：Experimental Design and Method Selection:

The study used batch experiments for chlorination, direct photolytic, and UV/chlorine processes. UV irradiation was conducted using semi-collimated beam apparatus with LPUV (254 nm) and UV-LEDs (275 and 310 nm). The kinetics followed pseudo-first-order models, and various analytical methods were employed to measure degradation and by-products.

2：Sample Selection and Data Sources:

Humic acid (HA) from Suwannee River was used as the model compound. Solutions were prepared with ultra-pure water, and initial concentrations were set at DOC 3.0 mg-C/L and chlorine 200 μM. pH was adjusted from 5.0 to 9.0 using phosphate buffer.

3：0 mg-C/L and chlorine 200 μM. pH was adjusted from 0 to 0 using phosphate buffer. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included TOC-VCSH analyzer, spectrophotometer, fluorescence spectrophotometer, ion chromatography system, pH meter, fiber optic spectrophotometer, gas chromatography with ECD, and semi-collimated beam apparatus. Materials included HA, chlorine, bromide, buffers, and DBP standards.

4：Experimental Procedures:

Experiments involved adding chlorine to HA solutions, adjusting pH, irradiating with UV at specific wavelengths, sampling at intervals, quenching reactions, and analyzing for chlorine, DOC, UV254, DBPs, bromide, bromate, and fluorescence.

5：Data Analysis Methods:

Data were analyzed using pseudo-first-order kinetics, ANOVA for significance (p < 0.05), and calculations for bromine utilization factor and theoretical cytotoxicity based on LC50 values.