title: Evaluation of granular sludge for secondary treatment of saline municipal sewage.
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.
authors.affiliation: Australian Water Quality Centre, SA Water Corporation, Adelaide, 5000 South Australia, Australia; Health and Environment Group, School of the Environment, Flinders University, Bedford Park, 5042 South Australia, Australia; Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, Mawson Lakes, 5095 South Australia, Australia. Electronic address: ben.vandenakker@sawater.com.au.
authors.forename: Ben
authors.initials: B
authors.lastname: van den Akker
authors.affiliation: Australian Water Quality Centre, SA Water Corporation, Adelaide, 5000 South Australia, Australia.
authors.forename: Katherine
authors.initials: K
authors.lastname: Reid
authors.affiliation: Australian Water Quality Centre, SA Water Corporation, Adelaide, 5000 South Australia, Australia.
authors.forename: Kyra
authors.initials: K
authors.lastname: Middlemiss
authors.affiliation: Institute for Water Quality, Resource and Waste Management, Vienna University of Technology, Karlsplatz, 1040 Vienna, Austria.
authors.forename: Joerg
authors.initials: J
authors.lastname: Krampe
mesh_terms: D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D006801:Humans; D010100:Oxygen / Q000737:chemistry*; D054712:Salinity; D012722:Sewage / Q000737:chemistry*; D013021:South Australia; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D012722:Sewage; D010100:Oxygen
keywords: COD; Dissolved oxygen; Granular sludge; Nitrous oxide; Salinity