Combination treatment of ultrasound and ozone for improving solubilization and anaerobic biodegradability of waste activated sludge.
The hydrolysis is known to be the rate-limiting step of biological sludge anaerobic degradation. The disruptions of sludge flocs and microbial cell walls by ultrasound combined with ozone treatment (US/O(3)) were investigated in laboratory-scale experiments. The results showed that temperature, O(3) dose, US energy density and pH had a positive effect on the disintegration of sludge. The organic substrates were released into the liquor, which induced the increases of soluble chemical oxygen demand (COD(S)) and turbidity in the aqueous phase. Accordingly, the biodegradability of sludge was improved. The COD(S) increased from 1821 to 2513 mg/l after reaction for 30 min when NaHCO(3) was added, which indicated that the ozone molecule played a major role in the disintegration of waste activated sludge. The COD(S) was 2483 mg/l after 60 min O(3) treatment followed by 60 min US treatment, and it changed into 3040 mg/l after 60 min US/O(3) treatment, which proved that US/O(3) induced a synergetic effect. The pH-drop of sludge from 6.8 to 5.21 might be attributed to the increase of volatile fatty acid from 61.35 to 111.96 mg/l during the US/O(3) treatment process.
Xu
Guihua
G
Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Chen
Shaohua
S
Shi
Jianwen
J
Wang
Shumei
S
Zhu
Gefu
G
D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D010126:Ozone / Q000737:chemistry*; D010316:Particle Size; D012722:Sewage; D017693:Sodium Bicarbonate / Q000737:chemistry; D012995:Solubility; D013696:Temperature; D014465:Ultrasonics
D012722:Sewage; D010126:Ozone; D017693:Sodium Bicarbonate