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Tertiary Pond Algae Issues

Last Post 7/12/2019 1:02:50 PM by Brendan Guiney. 1 reply.
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Tertiary Pond Algae Issues

03-12-2019 09:20 AM
 
dtynan@singleton.nsw.gov.au
by dtynan@singleton.nsw.gov.au
Joined 21-03-2018 08:40 AM
Posts 1
Singleton Council are experiencing issues with algae in the tertiary lagoons of the STP. As the STP uses IDEA treatment Council still have high levels of phosphorous in the effluent which causes the algae to come on in the warmer months. Currently there is surface aeration and ultrasonic systems in place but these seemed to only slow down the formation of the algae, and as it warms up there is algae starting to form
Has anyone had similar experiences with algae and what method were used to deal with the problem? EPA are not allowing the use of alum which is making things particularly difficult.
Thanks

Re: Tertiary Pond Algae Issues

07-12-2019 01:02 PM
 
Brendan Guiney
by Brendan Guiney
Joined 02-08-2019 03:32 PM
Posts 2
Algae in wastewater lagoons is a really common problem, especially with hot weather, shallow lagoons with plenty of sunlight and slow flow. Sounds like you are already trying some of the known solutions, such as aeration, mixing and ultrasonics. Smaller ponds might be able to be shaded. Alum would probably need to be combined with tertiary filtration to remove the precipitate, and if dosed into the preliminary or secondary treatment areas, may need pH correction. Obviously tertiary treatment is a capital intensive solution with ongoing chemcial and energy costs. Minimising storage/retention time of the effluent is another option if you can create a smaller compartment in your storage. A more natural solution where storage times are longer, say, in the order of weeks, and flow/velocity is minimal, is the growth of duckweed on the pond surface to shade out the light for algae growth, but this needs careful attention to pH and likes to have some ammonia. Many Councils have modest treatment and then 'restricted' reuse on nearby agricultural land whilst meeting recycled water guidelines to beneficially reuse the water and nutrient. Agricultural reuse has been found to be cheaper on a whole-of-life cost basis. Regards, Brendan Guiney | Executive Officer | Water Directorate
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