The Modified Primary Swirl Sedimentation Tanks in Waste Liquids Treatment Plant: Liquid Viscosity Effect

Abstract

This paper discusses design, evaluation, and application for the use of swirl/vortex technologies as liquid purifi cation system. A study was performed using modifi ed swirl sedimentation tanks. The vortex separators containing baffl e have been studied under laboratory conditions at hydraulic load from 21 to 64 [m3/(m2·h)]. Analyzed disperser phases were municipal water and glycerol solutions of varying concentration. The pressure drop and the effi ciency of purifi cation of liquid stream were analyzed. The suspended particles of diff erent diameters were successfully removed from liquid with the application of swirl chambers of proposed constructions. It was found that damming of liquid in the tank increases alongside liquid stream at the inlet and depends on the tank construction. The effi ciency of the sedimentation tanks increases alongside the diameters of solid particles and decrease in the liquid fl ow rate. The best construction proved to be the one where baffl e is located in the middle of inand outlet due to the highest effi ciency of the purifi cation liquid stream for solid particles of the smallest diameter. The proposed solution is an alternative to the constructions of heavy fraction separators. The Modifi ed Primary Swirl Sedimentation Tanks in Waste Liquids Treatment Plant: Liquid Viscosity Effect 43 petroleum derivatives. Oil and water dividing is proceed due to the phenomenon of gravitational separation, which is enhanced by the phenomenon of coalescence (Ecol-Unicon 2018, Szulc 2018). Hydrodynamic settling tanks are used at small gross covered area with wastewater fl ow containing a lot amount of sand. Their construction uses drainage catch pit, usually made of polyethylene that eff ects on blocking out smaller particles inside the vertical part (EcoBlue 2013, Wavin 2015). Horizontal tanks are simple constructed devices made of modular reinforced concrete retention tanks or can be installed as separate chambers with pre-treatment system. Liquid purifi cation occurs as the eff ect of holding the sewers conditions of slower fl ow rate. They can operate as a single device or be a part of pre-treatment system. Horizontal settling tanks can be used in overrun areas, like roads or car parkings (Ecol-Unicon 2016, Nixor 2018, Pur Aqua System 2018). Relatively new type of separator is swirl settling tank, where despite of gravity force presence, there is also a centrifugal force. They are characterized by high effi ciency of suspension separation at high hydraulic load. In addition, they have smaller sizes than other types of settling tank, and with circular, narrow body comes gross covered area arrangement, which is an advantage. Directional defl ector or tangential placement of inlet port aff ects the rotary movement of liquid inside the device. The purpose of swirling fl ow is to gain longer way for particles to precipitate with relatively small tank construction need (Ecol-Unicon 2016, Ecol-Unicon 2018, Pur Aqua System 2018). As we can see, there is a tendency to develop constructions that already exist and to obtain new ones to provide higher effi ciency of water purifi cation. The aim of the study In the literature there are many articles describing sedimentation tanks working in the water-solid particle and water-polluting liquid systems, but there is a paucity of literature on the purifi cation of high-viscosity liquid streams (Wang et al. 2014). The goal of this work was to construct and analyze selected modifi ed designs of swirl sedimentation tank in terms of purifying Newtonian liquids from solid contamination with density greater than the liquid’s, also in relation to liquid’s viscosity. Modifi cations of the settling tank pertained to variable location of applied baffl e inside the device and two diff erent locations of inlet pipe also. The studies included analysis of dependencies of separator effi ciency and liquid damming on the hydraulic load. Two constructions with the highest effi ciency of separation heavy contamination and possibly lowest liquid damming level were distinguished by comparison all obtained and analyzed swirl settling tanks, also with conventional type of swirl settling tank that exists on the market.