Improving aeration systems in saline water (part II): effect of different salts and diffuser type on oxygen transfer of fine-bubble aeration systems.

The objective of the present study is to investigate the different effects on the oxygen transfer of fine-bubble aeration systems in saline water. Compared to tap water, oxygen transfer increases due to the inhibition of bubble coalescence. In Part I of the present study, we investigated in laboratory-scale experiments the effect of design of diffuser membrane.

Improving aeration systems in saline water: measurement of local bubble size and volumetric mass transfer coefficient of conventional membrane diffusers.

In this study, for the first time, the influence of the design of conventional membrane diffusers on the volumetric mass transfer coefficient (ka) and bubble size in tap water (TW) and saline water (SW) was investigated (up to 15 g/L NaCl). By using a new analytical approach, ka and the bubble size along the ascent of the bubble swarm were measured simultaneously and in real time. The results show that in TW, after collision bubbles merge into larger bubbles by coalescence.

Fouling mitigation in anaerobic membrane bioreactors using fluidized resin beads.

This study focuses on the use of fluidized resin beads to mitigate fouling during ultrafiltration (UF) of the effluent of an anaerobic bioreactor. Two different module configurations were tested: A fluidized bed of resin beads was generated in a tubular UF membrane, and a hollow fiber (HF) UF membrane was submerged into a fluidized bed, respectively. During filtration of anaerobically treated synthetic wastewater using the tubular module, fluidized resin beads with a diameter of 0.

Design of fine-bubble aeration systems for municipal WWTPs with high sea salt concentrations.

The impact of sea salt on the aeration coefficient ka of fine-bubble aeration systems was investigated in clean water and in a model substance for simulating activated sludge. The investigations were carried out at laboratory and pilot scale. Sea salt was dosed in the form of artificial seawater, real seawater or simplified, by adding NaCl.

Energy, cost and design aspects of coarse- and fine-bubble aeration systems in the MBBR IFAS process.

With the MBBR IFAS (moving bed biofilm reactor integrated fixed-film activated sludge) process, the biomass required for biological wastewater treatment is either suspended or fixed on free-moving plastic carriers in the reactor. Coarse- or fine-bubble aeration systems are used in the MBBR IFAS process. In this study, the oxygen transfer efficiency (OTE) of a coarse-bubble aeration system was improved significantly by the addition of the investigated carriers, even in-process (∼1% per vol-% of added carrier material).