Cristina and I have visited one of the three wastewater treatment plants of Milano. This one, the largest, gained full capacity on October 30th, 2004. With an intake of 5 to 15 cubic meter of water per second, depending on the weather, Nosedo plant is treating the waste of 1.250.000  population equivalent.

The idea of the process is to separate sludge from water and water from bacteria and chemicals like nitrates and the phosphorus contained in detergents.

What presently cannot be eliminated, and that is object of intense scrutiny, are pharmaceuticals (like antibiotics) and drugs. Curiously enough, routine testing at the Nosedo plant detects around 40.000 doses of cocaine incoming everyday with the urine of the people of Milano.

Nosedo plant gained full capacity on October 30th, 2004. Nikon D810, 40 mm (24-120 mm ƒ/4) 1/100″ ƒ/6.3 ISO 64

Pretreatment consists of removing all solid materials like trash, tree limbs, leaves, branches plus fabric, plastics and the like from the sewage entering the plant. These materials are collected and sent by truck to incineration. Nikon D810, 24 mm (24-120 mm ƒ/4) 1/100″ ƒ/5 ISO 1600

The affluent liquid is usually a soup containing water, human waste and a few chemicals, along with possible stormwater runoff: soil particles and other sediment, heavy metals, organic compounds, animal waste, oil and grease. Nikon D810, 120 mm (24-120 mm ƒ/4) 1/100″ ƒ/10 ISO 1600

The aerobic biological process consists of injecting air and micro-organisms to purifyi the soup from coli bacteria. Nikon D810, 50 mm (24-120 mm ƒ/4) 1/100″ ƒ/7.1 ISO 1600

The sludge gets separated from water by sedimentation. Nikon D810, 24 mm (24-120 mm ƒ/4) 1/100″ ƒ/9 ISO 64

Part of the compressed mud is dried (right) and sent as fuel to cement factories. The rest (left) is added to organic waste to produce compost. Nikon D810, 55 mm (24-120 mm ƒ/4) 1/100″ ƒ/4.5 ISO 1600

Phosphorus gets eliminated by adding small amounts of peracetic acid to the water. Nikon D810, 120 mm (24-120 mm ƒ/4) 1/100″ ƒ/9 ISO 64

Phosphorus gets eliminated by adding small amounts of peracetic acid to the water. Nikon D810, 120 mm (24-120 mm ƒ/4) 1/100″ ƒ/14 ISO 64

The effluent is released into the water system. Nikon D810, 120 mm (24-120 mm ƒ/4) 1/100″ ƒ/16 ISO 64

Nikon D810, 24 mm (24-120 mm ƒ/4) 1/100″ ƒ/13 ISO 64

The effluent is released into the water system. Nikon D810, 24 mm (24-120 mm ƒ/4) 1/100″ ƒ/11 ISO 64

You would not want to drink it, but the effluent water is pure enough for rural applications, namely irrigation. Nikon D810, 24 mm (24-120 mm ƒ/4) 1/100″ ƒ/11 ISO 64

Nosedo promotes activities by youth associations and schools within the perimeter of the plant. Nikon D810, 24 mm (24-120 mm ƒ/4) 1/100″ ƒ/13 ISO 64

Nosedo promotes activities by youth associations and schools within the perimeter of the plant. Nikon D810, 24 mm (24-120 mm ƒ/4) 1/100″ ƒ/8 ISO 64

Curiously enough, routine testing at the Nosedo plant detects around 40.000 doses of cocaine incoming everyday with the urine of the people of Milano. Nikon D810, 46 mm (24-120 mm ƒ/4) 1/100″ ƒ/9 ISO 1600

Cristina ed io abbiamo visitato uno dei tre impianti di depurazione delle acque di Milano, il maggiore, che raggiunse la piena efficienza il 30 ottobre 2004. Accogliendo dai 5 ai 15 metri cubi d’acqua al secondo, il depuratore di Nosedo processa gli scarti di una popolazione teorica di 1.250.000 abitanti.

Il concetto è la separazione dei fanghi dall’acqua e dell’acqua dai batteri e dai composti chimici, come i nitrati e il fosforo contenuto nei detersivi.

Ciò che al momento non può essere ancora eliminato, e che è oggetto di attenti studi, sono i farmaci e le droghe. Curiosamente, analisi regolari nei laboratori del depuratore rilevano ogni giorno il passaggio di circa 40.000 dosi di cocaina nelle urine dei milanesi.