Caribbean Environment Programme - UNEP

UNEP(DEC)/CAR WG.18/6
Anexo V
Apéndice 2
Página 15
In the Caribbean, there has been a lot of development in handling and treating
wastewater. Therefore, Bonaire has chosen to make optimal use of the experiences of others.
Curaçao, as mentioned a sister island of Bonaire, has developed in the past 20 years vast
experiences and expertise in wastewater management. They have constructed and managed three
different sewage treatment plants and they will share their experiences with Bonaire.
These treatments systems are:
1. The Imhoff tank.
This is an anaerobic system. It is a combination of physical and biological processes. The
main feature of the physical process is separation of solids and gases from the fluids. That
of the biological process is degradation of decomposable organic matters under anaerobic
conditions.
2. The trickling aerobic system.
This system consists of the water line and the sludge line. The wastewater is flowing
through trickling filters, from the top to the bottom and trickles down through the filter
material. During the passage soluble compounds are removed and some solids are taken
up into the bio-film that is adhered to the carrier material. This treated water has to stay
several days in ponds to be polished. Afterwards this water is ready to deliver to be used
for horticulture, landscaping and irrigation of golf courses. The other part of this process
is the treatment of the sludge. This delivers gas and compost as byproducts.
3. The activated sludge treatment system. The Caroussel.
This system consists also of a water line and a sludge line. The wastewater is brought into
an aeration tank where air is provided by surface aerators. The bacterial growth within
the aeration tank has to remain as high as possible by returning sludge from the sludge
line. The treated water is infiltrated by means of wells in the ground and is pumped up for
delivery to horticulture and for landscaping. The other part of this process is the treatment
of the sludge. This delivers compost as byproduct.
The project “Sewerage Kralendijk Bonaire” consists of two phases:
Phase 1:
Phase 2:
The short-term action plan consists of the implementation of a system of wastewater
collection and treatment for the hotel area “Playa Lechi”.
The long-term action plan consists of the implementation of a system of wastewater
collection and treatment for the households of Kralendijk and surroundings.
For the treatment of the wastewater the activated sludge treatment system will be used in
combination with infiltration ponds.