The test lab
Metropolitana Milanese has qualified specialist staff that carries out daily chemical, chemical-physical and microbiological testing on water samples using specific methods. The drinking water monitoring programme had been defined with the Milan health authority (ASL) and was approved by the Health Institute and by the internationally recognized bodies, in compliance with the AATO provisions.
The Metropolitana Milanese internal laboratory tests water samples taken daily. It reports the quarterly results of its 28,000 tests to its clients on their bills and publishes them on the Company website. Considering the characteristics of the water distributed, they differ slightly from place to place, with the test results summarised according to the four macro-areas of the City – North-West, North-East, South-West and South-East – and the Municipality of Corsico.
How the water sampling is carried out
Water samples are taken at specific points:
- at the water table wells to monitor the quality at the water supply source;
- at the inlets and outlets of the purification plants located upstream of the pumping stations, to check the efficiency of the purification systems;
- at the pumping station outlets that supply the network, to monitor the supplied water quality;
- at the drinking fountains throughout the City, to verify that the water maintains its quality even there.
The collected water samples are tested on a daily basis in the MM test laboratory.
The laboratory tests about 180,000 parameters a year and the results are reported quarter to the clients by printing them on the bills and publishing on the website.
Considering that the characteristics of the distributed water differ slightly depending on the four macro-areas of the city – North-West, North-East, South-West and South-East – and for the Municipality of Corsico, the reports differ for the users in those areas.
The Laboratory normally carries out:
- microbiological tests: coliform bacteria at 37°C (99 degF), escherichia coli, enterococcus, pseudomonas aeruginosa, total mesophilic bacteria at 37°C (99 degF), total thermophilic bacteria at 22°C (72 degF);
- chemical-physical tests: total dissolved solids, hydraulic conductivity, colour, turbidity, hardness and pH level;
- chemical tests: residual free chlorine, pesticides, volatile organic compounds (VOC), aromatic hydrocarbons, metals, polycyclic aromatic hydrocarbons, chromium, anions and cations.
Monitoring the water table
Apart from ensuring that all parameters meet the legal limits set by the laws, the laboratory constantly monitors the flow of micro-organic and inorganic pollutants that may be found in the water table. If the parameter level exceeds 60% then they are internally reported as a warning status, if it exceeds 80% then it is upgraded to the alarm status. Following these tests, preventive action ids undertaken to reduce the possibility of degradation of the water quality.
The laboratory instrumentaton
The laboratory is equipped with a number of testing instruments, such as:
- 1 automatic titration system for chemical and physical tests,
- 2 UV-VIS spectrophotometers,
- 2 organic pollutant concentration systems,
- 1 ionic chromatograph,
- 1 HPLC (high performance liquid chromatograph),
- 1 gas chromatograph with FID and ECD detectors,
- 1 gas chromatograph with FID and ECD detectors, Purge and Trap system,
- 1 gas chromatograph coupled with quadrupole mass analyser (GC/MS),
- 1 gas chromatograph coupled with a triple quadrupole mass spectrometer (GC/MS),
- 1 ICP-MS (plasma optic spectrometer with mass detector and collision cell),
- 1 ICP-EOS (plasma optic spectrometer),
- 7 microbiological incubators,
- 1 PCR with gradient,
- 1 fluorescent optic microscope.
The gas chromatograph coupled with a triple quadrupole mass spectrometer is a sophisticated, recently acquired new-generation instrument for specific and accurate detection of organic substances listed in the parameter table. By breaking down the compounds, this instrument provides high selectivity and sensitivity and accurate data.
The laboratory has been equipped with other new instruments to carry out periodic tests on the water wells located near the two wastewater treatment plants of Nosedo and San Rocco.
The laboratory has fine-tuned specific testing methods for the treatment plants to ensure their efficiency and optimize operations even further.