Growing Diatom Algae and fish in the ponds is a good solution to reduce mosquito problem.

Diatoms will keep the DO high and prevent breeding of most species of mosquitoes.

High DO will enable fish to survive and these will consume the remaining mosquito larva.

The pond size can be smaller when Diatoms are grown, so land required will be less.

It is easier and cheaper to maintain Diatom growth in ponds than to build wetlands, remove weeds from ponds, etc.

The treated water with Diatoms in it can flow into public lakes and rivers, they will be useful in these too and not cause any problems.

Hi,

A couple of years ago I took a training delivered by the Mentor Initiative, an NGO aiming at improving mosquitoe vector borne diseases all over the world. They are certainly a good resource organisation. What I remember from the training confirms the above information, ie, some mosquitoes (malaria) breed in clean water, even in the smallest drops such as condensation from an aircon unit. Other mosquitoes (dengue) breed in dirty and standing water.
In Sumatra, this could be verified by simple observation of open concrete drainage and septic tanks, both of which were full of millions of wiggling larvae.
One solution was to avoid standing water (clean the drainage to allow water flow) which is not a solution for a stabilization pond...
Another solution was to pour liquid insecticide in the gutters and regularly spray close by vegetation with insecticide. It is not an ideal solution but it helped in a region where dengue was endemic.

In France, there is a controversy on the subject of constructed wetlands and mosquitoes. In a few areas, where there have been mostiquoe related diseases, the authorities have restricted the use of constructed wetlands, to avoid mosquitoe breeding. Professionals of constructed wetlands argue on the contrary that the infiltration time is much to short to allow for mosquitoe breeding. Although the wetlands are vegetated, it seems that it does not encourage mosquitoe breeding (ecological balance ?) and there is no water standing because the water flows underneath ground level.
Some wetland systems include one or several ponds (ornemental or recreational)and I understand the bio diversity allows a natural balance which include mosquitoe predators (frogs, birds).
Regards,
cecile

Hi,

something to add to this: These days I spoke to a Malaria specialist and asked him about Mosquito breeding in wastewater treatment facilities. He said, generally speaking, Anopheles don't breed in polluted water, so in princinple WSP shouldn't be a problem for Malaria. Maturation ponds with cleaner water could be, but adding fish that predate in insect larvae would be a good measure in such ponds

However, he also said that various Mosquito species transmitting other diseases (like Dengue) could very well breed in different ponds, and that preferences for breeding of the differen species are quite varable in the different continents and regions. His advice was to always check with local entomolgists or specialists for vector control with experience in the respective regions where wastewater facilities are to be built.
Best wishes, Florian

Mosquito problem in WSP:
Please see here the manual by Duncan Mara who gives main criteria to avoid mosquito breeding:
depth more than 0.9 m and proper O&M such as regular grass cutting
see details here:
www.ircwash.org/sites/default/files/341.1-87WA-2422.pdf

Best regards
Claudia

The issue is a bit complex, as the species of mosquito that actually transmit malaria do not breed in open & muddy water. They like small clear puddles of (rain)water and similar habitats.
Some water plants are known to form pockets of water in their leaves though, that can fill with rain and thus have good conditions for anopheles larvae.

The more quiet muddy waters between the free floating water hyacint for example, can be pretty good habitats for other mosquito species, and it is probably difficult to convince people nearby that these don't cause much issues beyond annoyance (similar to the situation of communities near protection worthy wetlands).

pprasetya wrote: mosquito breeding when vegetation starts growing in the pond

As far as I know, it is exactly like this: to avoid mosquito breeding, the ponds have to be kept free from vegetation. This is best achieved by maintaining a minimum depth of the ponds that discourages plant growth from the bottom and regular maintenance for keeping the pond shore free of vegetation. Floating mataterial and scum should also be removed frequently. The main risk is therefore from lack of good maintenance. WSPs are a well established technology, you should find plenty of literature on this issue with a little research.

I am not sure if your facultiative WSP are meant to be used as component for treating toilet sludge and organic waste. If it is so, you should be careful: liquids from sludge treatment have often a very high ammonia content, which may be toxic to algae in facultative ponds and these ponds thus may not work properly...

Best regards, Florian

Dear all,

My name is Priska, currently a second-year Master student on MSc Urban Environmental Management at Wageningen University. I am currently doing an internship at Safi Sana (www.safisana.org/projects/), a company that collects toilet and organic waste to produce biogas and organic fertilizer. Their current project is based in Ghana (see here on the forum: forum.susana.org/forum/categories/35-bio...ganic-waste-as-input).

I am responsible to assist in the development of their Wastewater Treatment Plant design for their new anaerobic digestion site in Ghana. The proposed plan is to use Waste Stabilization Pond, mainly Facultative pond, as one of the wastewater treatment systems.

However, I hear that the common problem with this system is that it attracts mosquito breeding when vegetation starts growing in the pond, which is a problem considering that Ghana is known to have big issue with Malaria. Nevertheless, there are some people who say mosquito is not a problem, and some people say mosquito is definitely a problem with this system.

For this reason, I am writing this post to ask if anyone is familiar with the issue of mosquito breeding within a waste stabilization pond system, particularly in Ghana. Any recommendations/solutions would also be very much appreciated!

Thank you very much in advance. I look forward to your responds.

Best regards, Priska