Water treatment plant

Gral. San Martín

AySA provides essential drinking water and sewerage collection services to our users in the City of Buenos Aires and its metropolitan area.

Drinking water production and sewerage sanitation require a huge infrastructure to be able to ensure quality during production, distribution and treatment. To deliver these services, AySA owns waste treatment and water treatment plants at di�erent locations within the concession area.

The company

GeneralSan Martín

Water treatment plant

The General San Martín water treatment plant, located in the neighborhood of Palermo in the City of Buenos Aires, was partially inaugurated in 1913 and became completely operational in 1928. It currently serves 5.8 million inhabitants in the districts of San Isidro, Vicente López, San Martín, Tres de Febrero, Morón, Ituzaingó, Hurlingham, part of La Matanza, and all of the City of Buenos Aires. It has a production capacity greater than 3,100,000 m3/day, and is one of the largest plants in the region, not only in size but in production capacity as well.

UNDERGROUNDRIVERS

pipeline of4.6 metersin diameter

pipeline of5.4 meters

in diameter

�lth

nozzles (air)sand

layers

PUMPINGSTATION

CATCHMENTTOWER

coagulants(aluminum sulfate

or aluminum polychloride)+

�occulation adjuvant(polyelectrolyte)

INLETCHAMBER

HOUSEHOLDS

�occulants

sludge

RESERVOIRS

�ocks

chlorine lime

De La PlataRiver

This is the process through which water is collected from the De La Plata River. It is worth mentioning that, of the two existing catchment towers, the one more recently built is the one being used.

The catchment tower is 1,200 meters from the shore, is of octagonal shape, and each of its 8 windows is protected by thick grills in order to keep coarse solids out.

The water entering the catchment tower gets to the plant by means of a pipe of 5.4 meters in diameter.

The plant has 13 lifting pumps (8 vertical and 5 horizontal) that work on demand, and have the capacity to lift more than 3.5 million liters per day to a height of 10 m above the river water level.

This lifting process allows the liquid in the plant to �ow by gravity.

The coagulant dosage is determined based on the tests performed in the plant’s laboratory.

The clay in the river is in its colloidal state and has a negative charge. That’s why by adding a coagulant that has a positive charge, colloids are destabilized, which results in clots called �ocks. The addition of a polyelectrolyte increases cohesiveness or resistance to �ocks.

Once the drinking water goes out of the reservoir, it is ready to be distributed for consumption.

Drinking water is sent through underground rivers. These are pipelines of up to a 4.6 meters in diameter that carry water towards the pumping stations by gravity.

The General San Martín water treatment plant has a pumping station called Main Impellers.

The added coagulant increases water acidity, and therefore lime is added to balance it out. The amount of lime varies according to the results of the tests performed in the laboratory. This chemical aggregate is essential in order to lower acidity and preserve the metallic networks of distribution.

To disinfect the water, a dose of chlorine is added to the reservoirs in order to eliminate the bacteria that might have gotten through to this part of the process, and also to achieve a residual concentration that will foresee contamination in the networks, as per the quality standards in e�ect established by the laboratory.

FLOCCULATION: It is meant to facilitate the crash of micro-�ocks, initially formed to be able to increase their size. In order to accomplish this, a gentle agitation is necessary, generated by means of a vane agitator installed in the �occulation chambers located either at the inlet of the static decanters, or of the sludge bed in Pulsator decanters.

DECANTING: The water mixed with the coagulant goes into the decanters, �owing slowly, which allows for the precipitation of the �ocks. There are two types of decanters, namely Static and Pulsator. Both types remove approximately 90% of the clay and 95% of bacteria.

Static decanters: these are of horizontal �ow. The water �ows through the 100 m of the decanter, exiting through the outlets that drive it to the collector channel towards the �lters. This circuit takes approximately 2 hours.

Pulsator decanters: these are of vertical �ow, with a suspended sludge bed. The water with coagulant and polyelectrolyte comes in through the bottom of the equipment and makes contact with the suspended sludge bed, which acts as a �ltering layer. The particles that go through are stopped by this sludge layer. The pulsation causes the layer to have a homogenous consistence in order to avoid the chimney e�ect. They are faster and more compact than static decanters.

There are 130 �lters that retain the particles that manage to get through the decanting stage.

Two types exist: 1. Water and air wash (82 units): these are high-tech sand �lters. They operate at a speed between 8.5 and 12 m/hour, with a �ltering bed between 1 m and 1.2 m high. They are washed with air and water, counter-�ow. 2. Water-wash (48 units): these are old but e�cient. They have a supporting layer of gravel, and a �ltering homogenous sand layer. Washing is performed with water, counter-�ow.

PUMPING2 FLOCULACIÓN4DOSIFICACIÓN DE COAGULANTES3 FLOCCULATION / DECANTING4COAGULATION3 DISINFECTION6 DISTRIBUTION8ALKALINIZATION7FILTERING5CATCHMENT1

18PUMPINGSTATIONS13

LIFTINGPUMPS

PULSATORDECANTERS

STATIC DECANTERS

located 1,200 m

from the shoreit pumps water to a height of10 m

thick grills to keep coarse solids from going through

octagonalshape

CHAMBER

water with coagulantsand polyelectrolytes

PUMPINGCAPACITY OF3,500,000

M3 OF WATERPER DAY

vacuumchamber

pipelines for rawwater distribution

sludgeoutlet

sludgeoutlet

The treatment process

QUALITY CONTROL

AySA controls the distribution system at all times through 288 �ow pressure measuring points in the network, 18 pumping stations and 3 water treatment plants.

The Central Lab is equipped with cutting-edge technology and it is one of the most renowned labs in Latin America.

Through the lab, the company controls parameters in connection with �ow, pressure and quality of the water at diverse measuring points in the drinking water supply system.

In addition, the company performs all the physical, chemical and biological tests from the time the water enters the plant until it gets to the households for human consumption.

3 Water treatment plants

18 Pumping stations

288 Flow and pressure measuring points in the network

Water treatment plantGral. San MartínAv. de los Ombúes 209

Ciudad Autónoma de Buenos Aires - Argentina

01/2021

www.aysa.com.ar