Apparatus for measuring hydroxyl radicals and liquid treatment apparatus

A liquid treatment apparatus, comprising:

• a water flowing barrel connected to an external pipe and forming a main channel through which a liquid introduced from the external pipe flows;
• an ultraviolet irradiation unit provided in the water flowing barrel and including an ultraviolet lamp configured to irradiate the liquid with ultraviolet rays;
• a diverting unit including a divergent channel, that is made of a UV transmitting material, diverging from the main channel such that a part of the liquid flowing in the water flowing barrel is diverted from the main channel for hydroxyl radicals measurement, the divergent channel including a portion extending into the water flowing barrel and extending back out of the water flowing barrel such that the part of the liquid is irradiated with an ultraviolet ray from the ultraviolet lamp and the irradiated liquid is guided outside of the water flowing barrel;
• a reagent adder placed in the divergent channel upstream of the portion, the reagent adder configured to add a hydroxyl radical measuring reagent to the part of the liquid before the ultraviolet ray irradiation;
• and
• an analyzer placed in the divergent channel downstream of where the divergent channel exits the water flowing barrel, the analyzer configured to measure an amount of hydroxyl radicals produced from the part of the liquid by the ultraviolet ray irradiation, based on a change in the hydroxyl radical measuring reagent before and after the ultraviolet ray irradiation.