Ultraviolet radiation water treatment system

A water treatment system for causing input raw water to flow sequentially through a plurality of basins arranged in series along a flow route of the raw water, and performing a predetermined water treatment to the basins while the raw water is caused to flow through the basins, thereby supplying the input raw water as drinkable purified water, the system comprising:

• a front stage injection and radiation control unit which controls an injection amount of sodium hypochlorite and a radiation amount of ultraviolet with respect to treatment water in a water basin positioned at the front stage among the respective basins arranged in series in the flow route of the raw water;
• a middle stage injection and radiation control unit which controls an injection amount of sodium hypochlorite and a radiation amount of ultraviolet with respect to treatment water in a sedimentation basin positioned at the middle stage among the respective basins arranged in series in the flow route of the raw water;
• a rear stage injection and radiation control unit which controls an injection amount of sodium hypochlorite and a radiation amount of ultraviolet with respect to treatment water in a chlorine mixing basin positioned at the rear stage among the respective basins arranged in series in the flow route of the raw water;
• turbidity measuring means for measuring turbidity of the water upstream of the front stage, between the front stage and the middle stage, and between the middle stage and the rear stage, respectively;
• high turbidity pattern control means for, when the raw water turbidity measured by the turbidity measuring unit is a high turbidity over a predetermined upper reference value, instructing the front stage injection and radiation control unit to only inject sodium hypochlorite, instructing the middle stage injection and radiation control unit to only inject sodium hypochlorite, and instructing the rear stage injection and radiation control unit to inject sodium hypochlorite and radiate ultraviolet;
• middle turbidity pattern control means for, when the raw water turbidity measured by the turbidity measuring unit is a middle turbidity below the predetermined upper reference value and over a predetermined lower reference value, instructing the front stage injection and radiation control unit to inject sodium hypochlorite and radiate ultraviolet, instructing the middle stage injection and radiation control unit to only radiate ultraviolet, and instructing the rear stage injection and radiation control unit to only inject sodium hypochlorite;
• and
• low turbidity pattern control means for, when the raw water turbidity measured by the turbidity measuring unit is a low turbidity below the predetermined lower reference value, instructing the front stage injection and radiation control unit to only inject sodium hypochlorite, instructing the middle stage injection and radiation control unit to only radiate ultraviolet, and instructing the rear stage injection and radiation control unit to inject sodium hypochlorite and radiate ultraviolet;
• flow rate input amount means for measuring flow rates upstream of the front stage, between the front stage and the middle stage, and between the middle stage and the rear stage, respectively;
• wherein each of the high turbidity pattern control means, the middle turbidity pattern control means, and the low turbidity pattern control means instructs the front stage, middle stage, and rear stage injection and radiation control units in accordance with, respectively, a first product of the first flow rate and a value associated with the first turbidity, a second product of the second flow rate and a value associated with the third turbidity, and a third product of the third flow rate and a value associated with the third turbidity.