Glossary
1. A
AATO: Autorità d’Ambito Territoriale Ottimale (territorial subdivision authority)
ACB: Cost-Benefit Analysis
ACEI: Integrated Electronic Control Centre
Aqueduct: is a water supply or navigable channel (conduit) constructed to convey water. The word is derived from the Latin aqua ("water") and ducere ("to lead")
Active carbon: drinking water treatment of the groundwater to remove unpleasant smells and taste. The active carbon grains, obtained from mineral or plant carbons heated up to a high temperature (over 900°C), have a high internal porosity and acquire the capacity to trap the large molecules of organic compounds like chlorinated solvents and pesticides. They are effective at eliminating volatile and non-volatile compounds. The active carbon soaks up pollutants and therefore progressively saturates, making it ineffective; in the treatment plants active carbon normally lasts from 10 to over 24 months. Ineffective active carbon can be regenerated in special furnaces
Aeration towers: system to make water potable by breaking down the main type of pollutants found in the water from the wells of Milan – chlorinated solvents and volatile organic compounds (V.O.C.). In the towers, the water is sprayed upwards and comes into contact with the clean, filtered air blown up from below by powerful fans. Contaminants move in the air: this treatment is 95 % and more effective. Basically, aeration or stripping is used to transfer the undesired volatile substances from the water to the air. The air pumped into the tower is taken from outside and filtered before it enters the blowing fan. The stripping action of the air is also developed against other substances found in the water, such as carbon dioxide (CO2); the result of this action is a carbon imbalance of the water, which is then followed by the addition of carbon dioxide in order to rebalance the alkalinity.
AI: Air Inlet
ARPA: Agenzia Regionale per la Protezione dell'Ambiente (Lombardy regional environmental protection agency)
Artesian aquifer: a confined aquifer (overlain by a relatively impermeable layer of rock or substrate) containing groundwater under positive pressure
Artesian well: a drilled well cased with pipes; the water gushes up to ground level spontaneously due to the pressure that is higher than if it flowed in open channels on the surface. They were named after the French province of Artois, where this phenomenon was accidently discovered when boring into the ground, afterwards explained clearly through hydraulic science
ASL: Azienda Sanitaria Locale (local health authority)
2. B
B.H.: Blind Hole underground excavation technique
3. C
CBA: Cost-Benefit Analysis
Chlorinated solvents: substances that for the most part have excellent solvent, propellent, refrigerating properties as well as low flammability. They pollute groundwater
C.I.: Crowding Index
Chemical contamination: this can be industrial (organic and non-organic substances), physical (high temperatures, radioactive substances) and agricultural.
Collection: collection of wastewater, synonym of stormwater and sewage collection
Combined sewer systems: is a type of sewer system that collects sanitary sewage and stormwater runoff in a single pipe system
Connection: connection point of the private system (condominium) and the public system of drinking water (drinking water connection) and of wastewater (sewage connection)
4. D
Distribution network: all the plants (pipes, valves and gate valves, hydrants, vent wells, special pieces etc.) used to supply drinking water to the customer.
Drying of purification sludge: activity aimed at reducing the water content in the sludge deriving from the wastewater treatment processes to guarantee suitable disposal of waste
5. E
EE: emergency exit
ET: electrical traction, overhead power supply
ESS: electrical substation
6. F
FA: Fire Authority (access)
7. G
Geothermal water: water produced by cooling of water vapour contained in magma, in turn generated by chemical reactions
8. H
Heat-pump: device that can transfer heat from a liquid at a lower temperature to another at a higher temperature. Its name derives from the fact that it transfers heat from a lower temperature to a higher temperature, reversing the natural flow of heat that in nature flows from a higher temperature to a lower one
9. I
I.a.: Crowding Index
Inverter: an electrical device; when connected to induction motors it can change the power supply frequency and adjust the speed. Consequently, it can be used to adjust the flow of the centrifugal pumps coupled with those motors
IECC: Integrated Electronic Control Centre
10. J
J: junction
11. K
12. L
13. M
Microbiological contamination: microrganisms (invisible to the naked eye) that may be harmful to the health if swallowed with water; in fact, they are pathogens so responsible for disease transmitted through feces and orally.
14. N
Nitrates: salts deriving from nitric acid, highly polluting
15. O
16. P
Pax: passengers
PEF: piano economico finanziario (economic and financial plan)
Permafrost: soil at or below the freezing point of water in arctic regions or at high altitude; overlying permafrost seasonally thaws in summer
PGT: territorial zoning plan
PPHPD: passengers per hour per direction
PUM: piano urbano della mobilità (urban transport plan)
Pumping station: manufactured item that includes a collection tank and sewage and drainwater lifting system
17. Q
18. R
Reverse osmosis: drinking water purification process totally eliminating dissolved salts and compounds present in the water as well as eliminating tiny specks (down to one ten thousandth of a micron, so including viruses, bacteria and impurities in general) to guarantee absolute bacteriological purity. This all occurs thanks to an osmotic membrane, the true heart of the whole system, which can "filter" the water down to molecular sizes. In nature, it is one of the most common phenomena of life: for example, plants take their nourishment from the soil thanks to the osmotic properties of their roots; by the same token, the purification of our blood in our kidneys is also a form of osmosis. Reverse osmosis is, as the name suggests, the reverse procedure to nature, obtains thanks to the action of special high pressure pumps that push the water of the most concentrated solution, so-called "with pollutants" up through the semi-permeable osmotic membrane to produce pure, distilled water that is then remineralised by mixing it with part of the untreated water. This type of desalination treatment is generally used to obtain drinking water from seawater
RH: top of the rail head
RS: revenue speed
19. S
S: siding
Sewage systems: sanitary sewer systems that specifically collect civilian, agricultural and industrial wastewater, in particular human metabolic waste. Sewage and stormwater is separated to make the treatment system more effective and efficient
Siphon: manufactured item used to keep sewage flowing even when there is an obstacle (railway embankment, metro tunnel, natural waterway, artificial hydraulic canal). It is formed of an underground, circular or rectangular closed pipe connected to the canal upstream and downstream of the obstacle so it passes underneath through two wells (entering and exiting). The water flows in the siphon under pressure.
Storage tank: water storage tank
Stormwater systems: storm systems that specifically collect precipitation water and surface runoff or water leftover from non-intensive use of water. Sewage and stormwater is separated to make the treatment system more effective and efficient
Stripping aeration: it is a physical separation process where one or more volatile components dissolved in water are removed by molecular diffusion. A constant flow of air passes through an exchange column (aeration tower) in which the water is sprayed upwards then falls into a tank where air is blown up from below.
20. T
TBM: tunnel boring machine
Total dissolved solids: the parameter that expresses the amount of salts dissolved in the water (mineralisation). The principal components (sometimes called macro-constituents or dissolved salts) in mineral water are: sodium, potassium, calcium, magnesium, chloride, sulphate and bicarbonate
Two-stage water pumping stations: submersible electric pumps draw up the water in the wells and convey it along a network of pipes to the storage tank of the stations; from here it is re-pumped into the distribution network.
21. U
UdT: unit of traction
UVC: ultraviolet irradiation type C, light rays whose frequency is superior to the maximum that the human eye can perceive, which in the solar spectrum appear beyond the violet band. Water treatment with UVC is a germicidal process and has the advantage of not changing and/or damaging the taste of the water. Chemical-free, ultraviolet irradiation is used to purify the water and sterilise the microorganisms. The smell and taste of the water supplied therefore remains the same
22. V
23. W
Wastewater: comprises liquid waste discharged by domestic and industrial human activities. It can be broken down into domestic wastewater that can come from human waste (sewage) and from domestic activities; industrial wastewater discharged from buildings or installations where commercial or manufacturing activities take place; urban wastewater originating from domestic and industrial wastewater and rainfall runoff collected in sanitary sewers.
Water: a chemical substance with the chemical formula H2O. (one oxygen and two hydrogen atoms). It can come in a gaseous, liquid and solid state. Water in nature is one of the main components of ecosystems and is vital for all forms of known life, including humans.
Water hardness: value that expresses the content of calcium and magnesium ions in the water. These ions are found naturally in the environment, in different quantities and they enter the water as it flows along the ground and underground. In general, surface water in rivers and lakes has a lower concentration of these minerals than underground water supplies, which remain in contact with the minerals found in the soil for longer. Particularly hard water is not in itself dangerous or harmful to human health, nor is it an indication of poor quality water. Suffice to say that some bottle mineral waters are extremely hard, in some cases a lot harder than tap water: the more minerals water contains the higher its level of TSD (total dissolved solids). For certain groups (newborn babies, young children and the elderly) highly mineralised water is recommended for increased calcium intake
Water table: groundwater table. Water that flows underground. After precipitation (rainfall, snow, hail), the water flows along the ground and seeps beneath the ground through soil pore spaces, fractures and voids and can flow down very deep under the surface; when these are saturated, the water still or moving underground aquifers depending on the permeability and layering of the soil and on the geometric conformation of the impermeable layers bordering the actual water table