Configuration optimization of UV reactors for water disinfection with computational fluid dynamics: Feasibility of using particle minimum UV dose as a performance indicator

Abstract

h i g h l i g h t sD min was used as a performance indicator for UV reactor configuration optimization. D min proved to be a qualified alternative to RED for UV reactor optimal design. Reactor with a well-mixed flow dispersed by lamp array had the best performance. Disinfection capability of the optimally designed UV reactor was elevated by 47À100%. t r a c tComputational fluid dynamics is a powerful tool for ultraviolet (UV) reactor performance evaluation, since it allows the reactor configuration optimization by comparing the performance indicator [e.g., reduction equivalent dose (RED)] of various UV reactors. In this study, a new performance indicator independent of the microbial UV dose-response curve, namely particle minimum UV dose (D min ), was introduced, and its feasibility was evaluated in the configuration optimization of 3-lamp UV reactors for water disinfection. Results indicate that the D min could serve as an alternative to the RED in characterizing the UV reactor performance. In general, reactors with a normal (NOR) lamp position pattern (i.e., with one lamp on the top and two at the bottom) had larger D min values (110À193 mW cm À2) than those with a reverse (REV) lamp position pattern (i.e., with two lamps on the top and one at the bottom) (98À160 mW cm ) was obtained in an UV reactor with a lamp relative distance (i.e., the ratio of the distance between the lamp and reactor axes to the reactor radius) of 0.4 and an inlet internal diameter of 75 mm, which could be ascribed to a well-mixed flow resulting from an optimal dispersion of the influent flow by the lamp array. The maximum disinfection flow rate of the UV reactor with the optimal configuration was elevated by 47À100% compared to those of the non-optimally designed reactors, which led to an energy saving efficiency of 32À50%.

Impact of inner-wall reflection on UV reactor performance as evaluated by using computational fluid dynamics: The role of diffuse reflection

“…Parameter FR aa : area-averaged FR (mW cm À2 ); FR max : maximum FR (mW cm À2 ); FR min : minimum FR (mW cm À2 ); and RSD: relative standard deviation. minimum fluence (F min ), which plays a determinant role in the REF (Li et al, 2016), would most probably be found with particles traveling in the near-wall region. Because the FR va increment was a net result of the FR increase in the near-wall region subtracting the FR decrease in the near-lamp region, the degree of increase in the F min was slightly greater than that in the FR va .…”

Computational Fluid Dynamics Modeling of Rotating Annular VUV/UV Photoreactor for Water Treatment

“…Various methods have been developed based on the two mentioned routes. For example, a pipe-type reactor with a small diameter has been explored for maximization of ultraviolet light intensity [17][18][19]22]. However, this method has the disadvantage that the long contact time (residence time) required for the reaction can be only obtained by designing a long reaction pipe, which is normally limited by actual situations.…”

“…The RAVR integrated the flow characteristics of a continuous-flow stirred-tank reactor (CSTR) and a plug flow reactor (PFR). As mentioned in Section 1, the RAVR is an economical reactor with good mixing function compared with long tubular reactors [17][18][19] or reactors with internal baffles [3,20,21]. The rotating flow along the VUV lamp in a RAVR reactor plays the role of mixing and extending the fluid-retention time, and there is thus no dead zone in a RAVR reactor.…”

Optimization of UV-Induced Graft Polymerization of Acrylic Acid on Polypropylene Films Using CdS as Light Sensor

“…Therefore, in this work we researched the effect of the reaction mixture position about light source and the reaction time on the performance of a photograft polymerization. The surface of PP films was modified by using a UV-induced graft polymerization of acrylic acid (AA), selected as a reaction model. ,, It is known that the distance between the light source and reaction mixture is a crucial variable for this kind of reaction . In order to monitor the changes of lamp light intensity against the variables mentioned above, we used a photoconductive cell of CdS as a light sensor. − Benzophenone was used as a radical photoinitiator agent in an aqueous reaction mixture containing AA .…”