Fate of cyanobacteria in drinking water treatment plant lagoon supernatant and sludge.
In conventional water treatment processes, where the coagulation and flocculation steps are designed to remove particles from drinking water, cyanobacteria are also concentrated into the resultant sludge. As a consequence, cyanobacteria-laden sludge can act as a reservoir for metabolites such as taste and odour compounds and cyanotoxins. This can pose a significant risk to water quality where supernatant from the sludge treatment facility is returned to the inlet to the plant. In this study the complex processes that can take place in a sludge treatment lagoon were investigated. It was shown that cyanobacteria can proliferate in the conditions manifest in a sludge treatment lagoon, and that cyanobacteria can survive and produce metabolites for at least 10days in sludge. The major processes of metabolite release and degradation are very dependent on the physical, chemical and biological environment in the sludge treatment facility and it was not possible to accurately model the net effect. For the first time evidence is provided to suggest that there is a greater risk associated with recycling sludge supernatant than can be estimated from the raw water quality, as metabolite concentrations increased by up to 500% over several days after coagulation, attributed to increased metabolite production and/or cell proliferation in the sludge.
Australian Water Quality Centre, South Australian Water Corporation, Adelaide, SA 5000, Australia.
Carlos J
CJ
Pestana
Australian Water Quality Centre, South Australian Water Corporation, Adelaide, SA 5000, Australia.
Petra J
PJ
Reeve
Australian Water Quality Centre, South Australian Water Corporation, Adelaide, SA 5000, Australia.
Emma
E
Sawade
Australian Water Quality Centre, South Australian Water Corporation, Adelaide, SA 5000, Australia; École Européenne de Chimie, Polymères et Matériaux (ECPM), Strasbourg 67087, France.
Camille F
CF
Voldoire
Australian Water Quality Centre, South Australian Water Corporation, Adelaide, SA 5000, Australia.
Kelly
K
Newton
Australian Water Quality Centre, South Australian Water Corporation, Adelaide, SA 5000, Australia.
Radisti
R
Praptiwi
Australian Water Quality Centre, South Australian Water Corporation, Adelaide, SA 5000, Australia; École Européenne de Chimie, Polymères et Matériaux (ECPM), Strasbourg 67087, France.
Lea
L
Collingnon
Allwater, Adelaide Services Alliance, Wakefield St, Adelaide, SA 5001, Australia.
Jennifer
J
Dreyfus
Australian Water Quality Centre, South Australian Water Corporation, Adelaide, SA 5000, Australia.
Peter
P
Hobson
University of Adelaide, Ecology and Environmental Sciences, School of Biological Sciences, Adelaide, SA 5005, Australia.
Virginie
V
Gaget
Australian Water Quality Centre, South Australian Water Corporation, Adelaide, SA 5000, Australia. Electronic address: gayle.newcombe@sawater.com.au.
Gayle
G
Newcombe
D000458:Cyanobacteria / Q000502:physiology*; D060766:Drinking Water / Q000737:chemistry* / Q000382:microbiology*; D005427:Flocculation; D059027:Recycling; D013021:South Australia; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification; D014881:Water Supply
D060766:Drinking Water; D014874:Water Pollutants, Chemical
Cyanobacteria; Geosmin; MIB; Microcystin; Sludge; Water treatment