Aeration method might be the first choice to clean such kind of water.

aeration will re-suspend the nutrients that were locked in the sediment.  It (aeration) can reduce the water clarity and temporarily assist with macrophytic development but because nutrients are available plant growth will manifest in single-celled alga rather than aquatic emergents or subemergent species.  Also, if you start aeration when pond is stratified you risk killing aerobic organisms as anoxic conditions and hydrogen sulfide quickly get introduced into rest of pond.  Ultimately you will need to reduce the availability of nutrients.  If dredging to remove or conservation buffer strips to reduce introduction of new nutrients are not an option you may look into alum treatments which bind some nutrients but need to find out if pond is nitrogen or phosphorus limited.

Before fighting the symptoms (water hyacinth or algae (?), low oxygen content) you should analyse the main pollution and nutrient sources in the catchment. I would use GIS and a GIS-based model for this purpose. In a first approach you could find the necessary maps and inputs on the Internet. Of course, landuse changes or other measures to be taken depend on the results of this study.

Giving recommendations for the pond itself without knowing further details is in my opinion rather difficult. I guess that you have a bigger mud layer in your pond, no inflow and from time to time anaerobic conditions. If this is the case you could clean the pond (remove mud and plants). I would not recommend the use of aluminium compounds (causing fish kills under certain conditions). Some better experiences have been gained in the past with calcium nitrate. Many bacteria use nitrate instead of oxygen and reduce it to N2. This will oxidise the upper mud layer and therefore diminish resolution of nutrients.. But all this does not make sense if the external loads are not reduced.

Would be nice to hear from you later what you have decided and with what success.

First make sure the loading of nutrients to the system is reduced. With septic tank effluents etc. the system can never be stable.

The next step is to remove nutrients from the system. Removing floating waterplants, dredging sediments, fish out bait fish (but not piscivorous fish) from the system can all help. Adding aluminium or iron salts to bind phosphorous is also effective.

Free floating aquatic macrophytes like Eichhornia, Salvinia, Spirodela, Lemna, Wolffia are reported for their great potential for phytoremediation of nutrients from eutrophic waters. They reproduce vegetatively at a very rapid rate and have relatively high rate for uptake of nutrients. Collect some free floating aquatic macrophytes from freshwater bodies wash thoroughly in lab and culture for one week to acclimatize the normal environmental conditions. Now transfer the young individuals to the eutrophic pond and allow them to grow and multiply for at least 15 days.

By removing the rapidly growing plants, absorbing high nutrient contents (different ionic forms) from the pond water, and replacing old with fresh plants at a regular interval, the eutrophic pond can be restored. This is a simple and preliminary method for nutrients (N & P) removal using free floating aquatic macrophytes. These plants show their best potential for phytoremediation of nutrients if the temperature is between 25-35 oC and pH 6.5-7.5.

First make sure the loading of nutrients to the pond is reduced.

Sediment dredging and water exchange.

It depends on the age and size of the eutrified lake. For larger size dredging may not work. In any case nutrient control could be very vital using buffer stripping around the catchment using nutrient efficient indigenous plants/grasses as well as use of macrophytes could help.

Hi Yim Mongtoeun; 

Phytoremediation is the fast and simplest way to  restore ponds from eutrophication.  As Abid Ali Ansari mentioned Eichhornia, Salvinia, Spirodela, Lemna, Wolffia have great potential for phytoremediation of nutrients from eutrophic ponds. Only thing is that the propogation of plants like Eichornia is so fast that after some time it chocked the pond completely and become menace. Even than it is a simplest way in developing countries.

Dear All Freiends,

It would be the great to gather all answer and responses. It is very useful to jopin the research gate. I will try to implement. This pond is in my work place, so most sewage is from cateen and toilet. So detergent is much used which contain alot of P and other nutrient. Many thanks to all scholars.

I think you are looking for a solution for a small pond where canteen and sewage waste is released. If the pond is small better to remove algae by manual method and then go for the remedies suggested. The main problem is to stop releasing sewage in to the pond or reduce its BOD before it is released to pond.

dear Yim Mongtoeun,

You first to control the sewage discharge or any other sources of agricultural runoff to prevent increasing nutrients and aeration is important in this stage.

Regards

I guess reducing/removing the nutrient source is not an option (although it is the obvious and long-term solution). I would try something that doesn't require chemicals or energy input (to drive aeration pumps). I would create a  shallow and wide, slow-flow pre-pond which receives the effluent first. At the effluent receiving end, create some waterfalls which will help with aeration to speed up mineralization of the organic matter. You then need to control the nitrates/phosphates/ammonia from the OM mineralization, so at the tail-end of the pre-pond, create a shallow muddy area. That will turn anaerobic which will stimulate denitrification (turns nitrate to nitrogen gas). Another waterfall before the main pond should re-aerate the effluent as it goes into the main pond. Periodically, you need to replace the mud at the tail end of the pre-pond as it will fill up with phosphate.

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I agree with the solution provided by Vissilis. But at many times all the ponds may not provide the space required for the fountains as well as a muddy area. But it is a good and practical solution. One can also practice boating in the area.

Floating Hydroponic islands or flow through system can grow food etc and utilises nutrients.

Wind driven paddle stirrers can upwell water dissociating gases and reducing concentrations and stratification.  How Large is pond, Depth, Flow? Tropic Hot, Arid Hot? In flow concentration sources?

Yim, certainly would help to know more about the function of this pond.  Are you hoping to keep it for fish production? recreational development?  The list of responses highlight both biotic and habitat based responses.  Most likely you will need to incorporate both to effectively transfer the pond to a more desirable state.  If you are unable to develop a riparian or protective zone outside of the pond then rely on within pond buffering options like Vassilis suggested.  Be cautious on establishing periodic aeration devices as stirring up a pond with an established thermolcline typically leads to anoxic conditions throughout and can cause a fish kill.

Dear All,

Thanks very much for answers and comments. I am so busy that why i could not response to all of you. The function of pond just for recreation for university leazure. If the pond become nice and ....so students can enjoy reading and realxing by looking at the pond with water hycine. Hope i can come back soon. For now the time is contraint so hope see all of you soon. Happy Marry Chrismas.! and Happy New Year!

Prakash Dattatray Raut. Thank you very much.

Yes, I think it is the appropriate way for such condition.

Keith D. Kaupal,

It is just for recreation, especially for student refresh after class. However, fish production is one of our target if it is possible. But sewage from canteen and toilet might bring high load of nutrients. May be the better way is to stop discharge the sewage directly to the pond or BOD need to be reduced before discharging.

Many thanks for everyone.

Yim

Dear Yim Mongtoeun,

As you identified the sources; I think along with aeration by surface spray / paddlewheel / air diffusers, you can also use chemicals like aluminium salts, iron salts, lime or magnesium hydroxides for phosphorus precipitation. In our case, we used chemical precipitation to restore our university pond. Alternatively, you can also try barley straw (considered as an algicide by EPA). This method will remain active for 4-6 months. In all situations, you have to stop boating on the pond. Otherwise, sediment phosphorus will be resuspended.