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Improving Settling Characteristics of Pure Oxygen Activated Sludge by Stripping of Carbon Dioxide
Author(s) -
Kundral Somshekhar,
Mudragada Ratnaji,
Coro Ernesto,
Moncholi Manny,
Mora Nelson,
Laha Shonali,
Tansel Berrin
Publication year - 2015
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143015x14212658614595
Subject(s) - settling , aeration , stripping (fiber) , carbon dioxide , chemistry , volume (thermodynamics) , mixed liquor suspended solids , pulp and paper industry , activated sludge , waste management , air stripping , environmental engineering , environmental science , environmental chemistry , sewage treatment , wastewater , materials science , physics , organic chemistry , quantum mechanics , engineering , composite material
Increased microbial activity at high ambient temperatures can be problematic for secondary clarifiers and gravity concentrators due to carbon dioxide (CO 2 ) production. Production of CO 2 in gravity concentrators leads to septic conditions and poor solids separation. The CO 2 production can also be corrosive for the concrete surfaces. Effectiveness of CO 2 stripping to improve solids settling was investigated using the sludge volume index (SVI) as the indicator parameter. Carbon dioxide was stripped by aeration from the sludge samples. Results from the study show that aeration also increased the pH values in the mixed liquor while removing CO 2 and improving sludge settling. After 10 minutes of aeration at a rate of 0.37 m 3 air/m 3 water/min, 90% CO 2 stripping was achieved. Based on the 30 min settling tests, the SVI increased by 26±1 % after CO 2 stripping while the pH increased by 0.8±0.1 pH units.