One of the system dont have algal removal facility and the main treatment unit is slow sand filter . within a week we were observed floating slime and afterwards surface of the water fully covered by the slime and greenish algae, treated water also showing diurnal variation. how to control the algae without any alteration in the system ? system capacity is around 2000m3/day.
Copper ionizationoworks very well against algae or what munis do is they add copper sulfate but the ionization works well at 0.40 ppm
well of course you can poison, butthat is usually not really appreciated.. - Is it a possibility to cover the installation and prevent light penetration?
the other possibility is prevent admission of nutirents e.g. by upstrem nitrification and denitrification.
Pasteurize the water. I have a system that can take the water to 95°C for 60 seconds and recover all but 2°C of the heat used.
Dear Colleague,
There are various methods that are applied for removal algae from the water. The most practical of these is the use of UV for me. However, the type of algae is important here. For example, a study on Chlorella vulgaris and some other green algae reported that a lethal dose of 30,000 μwatt-sec / cm2 of UV 254 nm was provided at 0.93 and 1.22 seconds, respectively. However I understand that surface area of your tanks that you collect the water is very large. In these conditions, chlorination or ozonation methods are logical for you.
Kind Regards.
Mr.Aymer MAturana, and Mr.Olcayto treatment system is slow sand filter, and the slow sand filter tanks are very large, i feel UV applications in difficult and costly. same time we cant apply prechlorination to prevent algal growth in slow sand filter.
and Pasteurization is definitely not possible because water quantity is around 2000 M3 per day
Dear Saravanan,
I understand that your problem is exist after sand filter. Prechlorination is not useful because inlet water may have nutrients and when inlet water pass the sand filter algae can grow in your nutrient rich tanks (because tank is open system). So you should apply chlorination process after sand filter I think. Am I right?
Additionally,
In order to full control of algae you should prevent diurnal existence of nutrient in inlet water. Sand filters can not remove dissolved nutrients from water. You can use activated carbon colons to prevent nutrient entrance to water.
Dear
Mr. Olcayto Keskinkan, Yes we are doing the post chlorination in distribution system, my requirement is control the algal growth in the slow sand filter. Activated carbon colons may prevent, we have to try.. some one recommend floating wet lands is it worth ?
Dear Saravanan,
As far as I understand you are talking about the growth of algae in the water that passes through the sand filter. So you are trying to prevent the growth of algae by using a sand filter and this is not possible. Because the sand filter can not keep algae well and can not keep nutrients. Therefore, after the sand filtration, algae will be produced in an open system.
The second possibility is that you are talking about the growth of algae on the surface of the sand filter. In this case, closing the surface of the sand filter will prevent algal growth. If the surface is too large, you can use Lemna specimens to operate a process such as a wetland. This is possible. But in cold climates such plants grow harder. Water plants can also grow well in season when the algae can grow. Lemna minor and Lemna gibba may be ideal for this job. However, carrying out the process can be complicated. Therefore, it seems logical to close the top of the filter with a tarpaulin.
I wanna to suggest cover the tanks and limitate the Nutrients quantity present in the inlet water
Dear Francisco, how to control the nutrient quantity in raw water, we are getting water from a canal, this is 2-3km long and feeding by a large tank
Dear Colleague,
Please draw the flow diagram of your system. On the diagram, show the location of the channels, sand filter, and other components. On the diagram, mark where you have chlorinated and where the algae is growing. In addition, are the algae growing in the form of suspended solids or floating heaps? Please inform us.
I suggest that if you are using transparent tank for storage, you change to dark/black storage tank because it does not favor the growth of organism responding to photosynthesis. And of course we don't know which of the point in your flow chat you are encountering these problem from except you let us know.
Dear Saravanan , if the canal is open you should cover it because maybe there is cross pollution for another sources. And if the water is raw you should implement actions to protect the water source and as a consecuence you will improve the water quality before the slow sand filter
You can add a blue cover on the top of your slow sand tank. It will help reduce the photosynthesis rate.
Dear Mr. Suntharalingam,
After a long time, when another commenter answered your question, I looked again at the old correspondence. Honestly, I'm wondering if you solved the problem, and if so, how did you do it? We will be glad if you provide information.
Kind regards
Dear Mr. Olcayto
Yes, we controlled a certain level, as you said we covered the slow sand tanks with black color net and we are practicing regular flash flushing of the channels.
Dear Mr. Suntharalingam
Thank you for your feedback and information.
Kind regards
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