Experimental studies on flotation of waste activated sludge using carbon dioxide and thermal treatment
1. IV MIĘDZYNARODOWA KONFERENCJA IV INTERNATIONAL CONFERENCE
„ZAOPATRZENIE W WODĘ JAKOŚĆ I OCHRONA WÓD” „ WATER SUPPLY AND WATER QUALITY”
KRAKÓW– POLAND 11-13 WRZEŚNIA 2000 KRAKÓW – POLAND, SEPTEMBER 11-13,2000
Medhat El_zahar1, Masato Takanishi1, Mamdouh Salih2, Kazuhiro Fujisaki1
and Ibrahim El_hattab3
Civil Engineering Department1
Kyushu Institute of Technology1
Tobata, Kitakyushu, 804-8550, JAPAN1
Faculty of Engineering2
University of Suez Canal2
Port Fouad, Port Said, Egypt2
Faculty of Engineering3
University of Cairo3
Giza, Egypt3
EXPERIMENTAL STUDIES ON FLOTATION OF
WASTE ACTIVATED SLUDGE USING CARBON
DIOXIDE WITH THERMAL TREATMENT
The sewage sludge forms more than 40 % of waste in Japan and also in other countries, therefore its
efficient treatment is urgent object. The paper presents a group of experimental studies on using
dissolved gas flotation by micro bubbles of CO2 gas instead of air. CO2 which has a (20-30) times
larger solubility in water than air, tends to be collected from burning gases to prevent the earth green
house effects. The theoretical base of the research is that waste activated sludge contains low density
particles such as algae which has a tendency to float, thus producing micro bubbles of CO2 gas will
give continuous flotation for the sludge. To promote the micro bubbles generation, some indirect
heating for the sludge in water bath is used to warm the flotation column and aid the flotation process.
Using these properties of CO2 and waste activated sludge, pressurized gas flotation experiments with
thermal treatment were executed. The obtained results show that the flotation due to dissolved carbon
dioxide gives almost the same or better efficiency than dissolved air flotation specially with thermal
treatment.
