(1) Some domestically unqualified ultraviolet lamps cannot provide the remaining disinfection capacity. When the treated water leaves the reactor, some microorganisms killed by ultraviolet rays will repair the damaged DNA molecules under the photo-resurrection mechanism to regenerate the bacteria. Therefore, it is necessary to further study the principles and conditions of photoresurrection and determine the minimum ultraviolet irradiation intensity, time or dose to avoid photoresurrection.

(2) The cleaning of the outer wall of the quartz sleeve is the key to operation and maintenance. When the sewage flows through the ultraviolet sterilizer, many of the inorganic impurities will precipitate and adhere to the outer wall of the casing. Especially when the content of organic matter in the sewage is high, it is easier to form a dirt film, and microorganisms are easy to grow to form a biofilm, which will inhibit the transmission of ultraviolet rays and affect the disinfection effect. Therefore, it is necessary to adopt reasonable anti-scaling measures and cleaning devices according to different water qualities, and develop and develop ultraviolet sterilizers with automatic cleaning functions.

(3) Domestic UV lamps implement the national industry standard for straight-tube quartz ultraviolet low-pressure mercury disinfection lamps. The maximum power of the lamp is 4W, and the effective life is generally 1000-3000h, while the effective operating time of imported low-pressure lamps can reach 8000- 12000h, the medium-pressure lamp can also reach 5000 ～ 6000h. In contrast, the use of domestic lamps will increase maintenance costs. Therefore, the development of long-life UV lamps or the direct introduction of foreign advanced UV lamp production technology is an urgent problem to be solved.

(4) In the tender for the ultraviolet disinfection system of sewage plants in our country, some sewage plants have deepened the chromaticity of the discharged sewage due to the introduction of a large amount of industrial sewage, but the ultraviolet transmittance parameters of the sewage in the tender documents still use the values provided by foreign countries The actual situation of domestic sewage varies greatly, which leaves insurmountable obstacles for the future operation of ultraviolet equipment to achieve disinfection requirements.