WATER TREATMENT PLANT. Gral. San Martín

Transcription

1 WATER TREATMENT PLANT Gral. San Martín

2 The company AySA provides essential water and sanitation services to more than 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, General Belgrano, and Juan Manuel de Rosas), 1 groundwater treatment plant that uses reverse osmosis (Virrey del Pino), and 16 wastewater treatment plants (Del Bicentenario, Lanús, Fiorito, Norte, Sudoeste, El Jagüel, Hurlingham, Barrio Uno, Santa Catalina, Escobar, Garín, Bella Vista, Guernica, Merlo-Ferrari, Merlo-Norte, and Florencio Varela).

3 WATER TREATMENT PLANT General San Martín 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 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 Matanza, and all of the City of Buenos Aires. It has a production capacity of m 3 /day, and is one of the largest plants in the region, not only in size but in production capacity as well.

4 1 2 CATCHMENT 3 DOSIFICACIÓN COAGULATION DE COAGULANTES 4 5 FLOCULACIÓN / DECANTING FLOCCULATION 6 FILTERING DISINFECTION 7 ALKALINIZATION 8 DISTRIBUTION Vacuum chamber STATION Thick grills to keep coarse solids from going through CATCHMENT TOWER CAPACITY OF LITERS OF WATER PER DAY Sludge outlet (Aluminum Sulfate or Aluminum Polychloride) + Located m from the shore Inlet chamber Chlorine Lime (Polyelectrolyte) It pumps water to a height of 10 m Pipeline of 4,6 meters in diameter Flocculants Water with coagulants and polyelectrolytes process The water treatment process of the General San Martín Plant is based on a concept of consecutive barriers, including the following steps: Sludge outlet Pipelines for raw water distribution Flocculation adjuvant De La Plata River The treatment PULSATOR DECANTERS Coagulants UNDERGROUND RIVERS Filth Sludge Pipeline of 5,4 meters in diameter Octagonal shape CHAMBER STATIC DECANTERS Sand layers 16 Nozzles (air) STATIONS 13 LIFTING PUMPS 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 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. The catchment tower is 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. This lifting process allows the liquid in the plant to flow by gravity. The water entering the catchment tower gets to the plant by means of a pipe of 5,4 meters in diameter. Flocks HOUSEHOLDS RESERVOIRS 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 flocks. The addition of a polyelectrolyte increases cohesiveness or resistance to flocks. FLOCCULATION It is meant to facilitate the crash of micro-flocks, 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 flocculation 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, flowing slowly, which allows for the precipitation of the flocks. 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 flow. The water flows through the 100 m of the decanter, exiting through the outlets that drive it to the collector channel towards the filters. This circuit takes approximately 2 hours. Pulsator Decanters: these are of vertical flow, 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 filtering 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 filters 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 filters. They operate at a speed between 8,5 and 12 m/hour, with a filtering bed between 1 m and 1,2 m high. They are washed with air and water, counter-flow. 2. Water-wash (68 units): these are old but efficient. They have a supporting layer of gravel, and a filtering homogenous sand layer. Washing is performed with water, counter-flow. 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. 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. 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.

5 QUALITY CONTROL AySA controls the distribution system at all times through 288 flow pressure measuring points in the network, 16 pumping stations and 3 water treatment plants FLOW PRESSURE MEASURING POINTS IN THE NETWORK STATIONS 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 flow, 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.

6 11/2017