WATER TREATMENT PLANT

Gral. San Martín

The companyAySA provides essential water and sanitation services to more than 13.000.000 inhabitants in the City of Buenos Aires and its surrounding area.

In order to provide these services, it operates 3

treatment plants (General San Martín, Ge- neral Belgrano, and Juan Manuel de Rosas), 1

groundwater treatment plant that uses

reverse osmosis (Virrey del Pino), and 16

wastewater treatment plants (Del Bicente-nario, Lanús, Fiorito, Norte, Sudoeste, El Ja- güel, Hurlingham, Barrio Uno, Santa Catalina, Escobar, Garín, Bella Vista, Guernica, Merlo-Fe-rrari, Merlo-Norte, and Florencio Varela).

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 Tigre, San Fernando, San Isidro, Vicente López, San Martín, Tres de Febrero, Morón, Ituzaingo, Hurlingham, part of La Ma- tanza, and all of the City of Buenos Aires. It has a production capacity of 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

Filth

Nozzles (air)Sand

layers

PUMPINGSTATION

CATCHMENTTOWER

Coagulants(Aluminum Sulfate

or Aluminum Polychloride)

+ Flocculation adjuvant

(Polyelectrolyte)Inletchamber

HOUSEHOLDS

Flocculants

Sludge

RESERVOIRS

Flocks

Chlorine Lime

De La PlataRiverThe treatment

processThe water treatment process of the General San Martín Plant is based on a concept of consecutive barriers, including the following steps:

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 effect established by the laboratory.

FLOCCULATIONIt 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.

DECANTINGThe 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 effect. 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 (62 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 (68 units): these are old but ef�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 DISTRIBUTION8ALKALINIZATION7FILTERING5CATCHMENT 1

16PUMPINGSTATIONS

13LIFTINGPUMPS

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 OF

3.500.000LITERS OF WATER

PER DAY

Vacuumchamber

Pipelines for rawwater distribution

Sludgeoutlet

Sludgeoutlet

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.

QUALITY CONTROL

AySA controls the distribution system at all times through 288 �ow pressure measuring points in the network, 16 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 TREATMENTPLANTS

16 PUMPINGSTATIONS

288FLOW PRESSURE MEASURING POINTS IN THE NETWORK

11/2017

www.aysa.com.ar