TENERIFE’S REGENERATED WASTEWATER REUSE SYSTEM
Main facilities of Tenerife’s WW Reuse System
Costs distribution of Tenerife’s Wastewater Reuse System (by BALTEN)
Tertiary Treatment for wastewater regeneration implemented by BALTEN at
Pumping Station of Santa Cruz.
System description:
The Reclaimed Wastewater Reuse
System of South Tenerife, operated since
1993, enables to reuse reclaimed
wastewater from the metropolitan area of
the city of Santa Cruz for crop irrigation in
the South of the island.
The Wastewater Treatment Plant of
Santa Cruz receives an average flow of 20,000
m3/day. The plant consists of a pretreatment, a
primary treatment, and a conventional
activated sludge system. The pretreatment
includes the removal of gross solids, sand, and
fat, oil and grease. The primary sedimentation
is carried out in two circular settlers, where
approximately 40% of the organic matter is
removed. The secondary treatment consists of
a conventional activated sludge system, carried
out in two aeration tanks. The average solids
retention time is 6 days, which justifies the non existence of nitrification during the
secondary treatment. After the secondary settlers (two units) a whole organic matter
removal of 90% is normally achieved.
The effluent from the plant is
transported to a pumping station situated
next to the treatment plant that enables
to control the flow-rate from the plant to
the zone of reuse. Water is then pumped
to El Tablero Gravity Transportation
Reservoir, whose capacity is 15,000 m3. A
gravity pipeline, starting at El Tablero
Reservoir, transports water to the South of
the island. The connection system
between the reservoir and the pipe
induces water aeration, so that the dissolved oxygen (DO) concentration is of about 3
to 4 mg/l at the pipe inlet.
The gravity pipe, 0.6 m in diameter and 61 km long, in cast iron with concrete
inside coating, has been permanently operated during the period of study with an
average flow-rate of 525 m3/h, corresponding to a water velocity of 0.5 m/s and 33
hour mean residence time. The pipe is completely filled, with no possibility of reoxygenation after DO consumption.
The pipe ends at Valle de San Lorenzo Reservoir
(250,000 m3), adjacent to which there is a complex of
tertiary treatment facilities where water is treated by sand
filtration, desalination (reverse electrodialysis) and final
chlorination.
As a whole, eighty-five percent of the reclaimed
water from treatment plants of the metropolitan capital
area (Santa Cruz-La Laguna) and the main tourist resort area
(Adeje-Arona) is reused in the South of the island, in crop
and golf-course irrigation.