Influence of diffuser design on selected operating variables for wastewater flotation systems: a review

Abstract

Air diffusers or spargers have since been used in separation processes that include conventional wastewater treatment. Over the years, there has been advancements in diffuser design in terms of shape, pore size, orientation and materials of construction as a way of mitigating challenges such as fouling, clogging, energy consumption and poor system efficiency. Some of the available air diffusers are inadequate to solve most of these challenges due to reduced quality and increased quantity of wastewater being treated. Additionally, there is a paucity of information regarding air diffuser design and their effect on operational parameters in wastewater treatment. This review seeks to address the advancement in diffuser design and also the effects of design factors including parameters of air diffusers with a focus of their use in a column flotation system for wastewater treatment.

The electrochemical microbial tree: A new concept for wastewater treatment

“…In the current context of compulsory energy saving, reducing the energy cost of aeration in WWTPs has become a key challenge. Intensive research is being carried out in various ways, such as improving the aeration equipment [10], refining the strategies of dissolved oxygen control [11] and even replacing air by pure oxygen [4]. Nevertheless, it is difficult to expect huge energy saving to be achieved simply by improving the existing set-ups, because the basic barrier is the low solubility of oxygen in aqueous systems.…”

Common Issues in Aeration System Choice for Flotation Wastewater Treatment

“…A wastewater treatment is, as a rule, a multistage process. Flotation is considered to be the main stage in many cases, especially for the treatment of wastewater that contains fats, grease and oil; for example, wastewater from meat processing plants and petrochemical refineries [3]. The process of flotation is based on the effect of wettability: wastewater is aerated with gas bubbles, and particles of hydrophobic contamination become attached to the bubbles and float, forming a froth layer on the surface [4].…”

“…Vacuum flotation in wastewater treatment systems was first used in the 1920s, and then the technology was developed to include dissolved air flotation (DAF) in the 1960s. At that time, it started to be widely used in the pulp and paper industry, in drinking water production, and in wastewater treatment [3].…”

Induced Pre-Saturation Tower: A Technological Innovation for Oily Water Treatment in Semi-Industrial Scale

“…Important operational and structural parameters of a bench scale IPST were determined [6] and used as the primary strategy for generating the scale-up criteria for a semi-industrial IPST project. The main parameters and strategies were: (i) kinetic constants of oil and grease removal [7]; (ii) hydraulic detection time [8]; (iii) flotation chamber dimensions [8][9][10]; (iv) siphon diameter and level [11]; (v) use of scraper for oily foam collection [12]; (vi) individual pumps for the stages [13,14]; and (vii) use of biosurfactant [15,16]. Based on this premise and the physical arrangement used in distillation towers, the purpose of this work was to reproduce adequate conditions on a semi-industrial scale water-oil separation in flotation equipment in the form of a tower with stages from a bench-scale prototype [5].…”