Improving the energy efficiency of UV water disinfection systems

Symmary

The performance of a number of ultraviolet water disinfection systems available on the market is analyzed in comparison with systems of the maximum capacity reached as a result of theoretical studies, at the same energy consumption. It is demonstrated that the maximum performance values declared by the system manufacturers are 1.1–2 times less than could be obtained for the same designs, provided the irradiation uniformity of the treated flow is ensured. A technical solution is proposed that provides for the uniform exposure due to the flow velocity distribution that decreases with the distance from the lamp in proportion to a decrease in the average irradiation intensity along the length of the lamp. This solution allows approaching significantly the maximum design performance with the minimal cost and minor changes in the design. The distribution of treated water flows in a system with diaphragms-spreaders that ensure the required flow direction, is investigated. It is demonstrated that for a reactor vessel up to 50 cm long one diaphragm is enough, whereas for larger vessels installing additional flow spreaders can solve the problem. Possible use of the proposed solution for any systems with a longitudinal flow relative to the location of the UV lamps is shown.

Key words

ultraviolet , water disinfection , flow rate , irradiation dose , UV-lamp , flow spreader