Evaluation of granular sludge for secondary treatment of saline municipal sewage.
J Environ Manage
; 157: 139-45, 2015 Jul 01.
Article
in En
| MEDLINE
| ID: mdl-25897508
ABSTRACT
This study examined the impact of chemical oxygen demand (COD) loading and dissolved oxygen (DO) concentration on the stability and performance of granular sludge treating high saline municipal sewage. Under high DO concentrations of 4.0-7.0 mg/L, and COD loading rates of 0.98 and 1.55 kg/m(3)/d, rapid settling granules were established within four weeks of start-up. Under the highest COD load, a reduction in DO lead to the rapid deterioration of the sludge volume index (SVI) and washout of granules due to prolific growth of the filament Thiothrix Type 021N. Conversely, when operated under a lower COD load, a reduction in DO concentration had no adverse impact on the stability of SVI and granules. A decrease in DO also improved nitrogen removal performance, where simultaneous removal of ammonium (98%), total nitrogen (86%) and BOD5 (98%) were achieved when median DO concentrations were between 1.0 and 1.5 mg/L. Phosphate removal was lower than expected, however the level of biological phosphate removal activity observed appeared sufficient to maintain granule stability, even under low DO concentrations. Nitrous oxide emissions were also characterised, which ranged between 2.3 and 6.8% of the total nitrogen load. Our results confirmed that granular sludge is a viable option for the treatment of saline sewage.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Oxygen
/
Sewage
/
Waste Disposal, Fluid
/
Bioreactors
/
Biological Oxygen Demand Analysis
Type of study:
Evaluation_studies
Limits:
Humans
Country/Region as subject:
Oceania
Language:
En
Journal:
J Environ Manage
Year:
2015
Document type:
Article