& Publication] [Guest
of wastewater recycling system to Architectural Services Department
public toilet at Sai Wan Village
Engineering Co. Ltd. was commissioned by the Architectural
Services Department in November 2007 to supply and install
wastewater recycling systems for public toilets at Chek King,
Ham Tin and Sai Wan of Saikung District. Due to the remote
locations of the toilets, no public sewer has been connected
in the past. In other words, they are still aqua privies,
the appearance and smell of which can hardly meet the needs
of modern lifestyle. From the environmental perspective, aqua
privies are far from making the best use of wastewater which
can be reused for flushing after being treated and disinfected.
wastewater recycling system to be installed will initially
remove the coarse solids from wastewater, followed by the
removal of suspended solids upon sedimentation. Since a considerable
amount of organic matters remain in the wastewater, micro
organisms in the aeration tank will convert the organic matters
into non-polluting carbon dioxide and water.
the process in the aeration tank, small amount of organic
matters still exist in the semi-treated water which will enter
another system called bio-filter. The semi-treated water will
spread from the top of bio-filter and pass through the bio
media where micro organism on its surface will consume the
remaining organic matters and achieve the water re-use standard.
to discharge or re-use in flushing, the biological treated
water will pass through the UV system to remove the bacteria
inside the treated water.