Ceramic diffuser production for dissolved air flotation (DAF) applications

Nowadays, dissolved air flotation (DAF) method is widely used in the treatment of industrial wastewater. While DAF provides advantages in terms of installation cost, separation capacity and operating life compared to other systems, the production of micro air bubbles used in the solid-liquid separation process creates a major disadvantage in terms of energy consumption. In DAF systems, air bubble production is generally achieved by using high-pressure pumps and additional special equipment. At the same time, since some of the separated water is used again in air bubble production, the system efficiency is negatively affected. Within the scope of this study, the production of ceramic diffusers that can produce micro-sized air bubbles at low pressures suitable for ÇHF processes and do not require purified water for process continuity was studied. The produced ceramic diffusers consist of substrate and coating layers. The substrate layer was produced with alumina having an average grain size of 53 µm and various ratios of clay and flux additions and the average pore size was 13 µm. The coating layers were produced with alumina having average grain sizes of 12, 8, 1 and 0.3 µm and various ratios of flux additions. The average pore sizes of the coating layers were 1.95, 1, 0.54 and 0.2 µm, respectively. The average diameters of the air bubbles obtained with the produced ceramic diffusers were 450, 350, 260 and 210 µm, respectively. As a result of the study, 2 macro-sized and 2 micro-sized ceramic air bubble diffusers that can be used in ÇHF systems were produced.