Ecological Pond




















Ÿ             The ecological pond is located at the backyard of the school.  It is constructed by remodeling part of the flower bed of the backyard.  (Link to construction process)

Ÿ             A pond is a miniature of an aquatic ecosystem.  Pond lives require both oxygen and nutrients for survival.  Therefore, to maintain a stable pond ecosystem, the pond has to maintain a continuous recycling of these materials.



Recycling of oxygen



With the absorption of carbon dioxide released by pond lives (both plants and fish), during respiration, aquatic plants like Nymphea sp. produce oxygen by photosynthesis to support the pond lives. 







Recycling of nutrients


Aquatic plants produce food by photosynthesis.  However, to support their growth and food production, they require inorganic nutrients released by decomposing the organic wastes from the pond lives by bacteria.



The design of the ecological pond











Ÿ         In nature, the oxygen in pond water comes from both aquatic plants and dissolved atmospheric oxygen.  In order to raise the oxygen content of the water, both pumping system and waterfall are installed.

Ÿ         As the pond fish may produce large amount of organic wastes which are beyond the capacity of the pond bacteria to remove, a digester tank with aerobic bacteria is installed to decompose the massive organic wastes.  The treated water will be sterilized by UV lamp before returning to the pond.



Integrated farming


The first part of digester tank is a chamber that allows the organic wastes of the pond water to settle.  The effluent can be collected through a pipe to serve as fertilizer for the orchard plants. 




Digester tank – the rightmost compartment allows the settlement of organic waste


Collection of effluent