Dissolved air flotation separation for pretreatment of membrane bioreactor in domestic wastewater treatment

Abstract

Due to requiring higher water quality standards over time, new technologies are being employed for wastewater treatment. Dissolved air flotation (DAF) and membrane bioreactor (MBR) technologies are widely employed as new technologies in wastewater treatment. DAF is used due to its excellent separation capability of suspended solids as well as oily material. MBR is used because it may provide a high level of mixed liquor suspended solids in a biological system and excellent separation capability too. In the investigation, separation by DAF, without addition of coagulant, could remove chemical oxygen demand by potassium dicromate (COD cr ) up to over 70%, biochemical oxygen demand (BOD 5 ) 73%, suspended solids (SS) 83%, total nitrogen (T-N) 55%, and total phosphorus (T-P) 65% in influent of municipal wastewater. Average overall removal rates of water quality parameters by the DAF-MBR system were very high such as COD cr 95.9%, BOD 5 99.7%, chemical oxygen demand by potassium permanganate) 93.6%, T-N 69.8%, NH 4 -N 98.5%, T-P 78.2%, and SS 99.5%, which satisfy effluent water quality standards. Membrane separation in the MBR system produced a very low SS concentration of 1.27 mg/ℓ in the final effluent. It was proven that DAF separation is an excellent technology for pretreatment of wastewater treatment, especially for an MBR system.

Effect of coagulation and sonication on the dissolved air flotation (DAF) process for thickening of biological sludge in wastewater treatment

“…The effect of coagulant on the DAF efficiency has been evaluated in several studies by adding a variety of polymers, alum, ferric chloride, etc (34)(35)(36). In a study by Kim et al, the addition of coagulant increased the removal efficiency of suspended solids from 82% to 99% (37). In the present study, the process showed an acceptable efficiency (69.27%) without coagulation.…”

Membrane Technologies in Wastewater Treatment: A Review

“…Other forms of pretreatment include the use of dissolved air flotation [172,173] and biological pretreatment methods [174][175][176].…”

The Role of Nanobubbles in the Precipitation and Recovery of Organic-Phosphine-Containing Beneficiation Wastewater

“…DAF is a novel flotation technique reported by Calgaroto et al to remove decyl-trimethyl-ether-amine (collector employed in Brazilian iron mines) from water, and reached 80% of amine removal . DAF has served as the most promising method in recent years for removing organic phosphine and nitrogen in wastewater, especially in beneficiation wastewater. − It is found that micro- and nanobubbles can flocculate the fine particles effectively. ,− However, those studies have primarily concentrated on applications, whereas the interactions in DAF processed and its mechanisms, such as the interaction of nanobubbles and nanoparticles, were rarely discussed. The role of bulk nanobubbles in the interaction with gold nanoparticles has been studied by Zhang and Seddon using dynamic light scattering (DLS) and nanoparticle tracking analysis .…”