Dissecting ISO 37120: How clean is your city’s water?

Tue, 2014-11-25 15:24 -- SCC Staff

By George Karayannis, LEED AP

We continue our series on the new ISO 37120 Smart City standard with a look at the 16th of 17 themes defined in the standard: wastewater collection and treatment.  As previously described, ISO 37120 includes 46 ‘Core’ (must report) and 54 ‘Supporting’ (should report) indicators.  The wastewater theme has five core indicators.

Wastewater treatment has had a dramatic and measurable impact on public health, and there’s no question that worldwide much remains to be done. Dirty water leads to a variety of diseases, including typhoid fever, typhoid fever, cholera, and dysentery, which each year kill millions and sicken tens of millions more in developing nations, but affect very few in developed countries.

For instance, about 21.5 million people worldwide become ill with typhoid fever each year, but very few of those cases are in industrialized areas, such as the United States, Canada, Western Europe, Japan, and Australia. In fact, in the U.S. there are fewer than 6,000 cases of typhoid fever, and by far the vast majority of them – 75% – involve people who recently returned from countries where the sanitation is poor.

Even cities that have done a great job addressing public health issues still have more to do. Untreated runoff and discharge from factories are still causing significant environmental damage.

A recent study of France’s Dore River found that as many as 80% of the fish downstream from a pharmaceutical factory showed both male and female sex characteristics. That not only prevents those fish from breeding, but could also cause other wildlife populations to plummet as the fish – their food source – vanishes from the river. Similar problems have been found in other parts of the world.

But serious pollution also comes from smaller, but more numerous sources. Runoff from fertilized lawns, farms and from factories that use corrosion inhibitors fill rivers with nitrates, which promotes algae and aquatic plant growth. That growth chokes the river, depleting oxygen and making the water toxic.

The ISO smart city wastewater standard attempts to capture all the risk to the water supply with five core indicators designed to measure the availability of wastewater treatment, the number of people who have access to it and the quality of their treatment.

Core Indicators

1.     Percentage of city population served by wastewater collection

This indicator only reflects the extent to which the city population is served by wastewater collection; it does not address the quality of the service or how well the wastewater is treated. The calculation itself is very simple: the number of households served by wastewater collection divided by the total number of households. A household is counted as having wastewater service only if it’s connect to a public network; households that treat their wastewater with their own septic systems, for example, are not counted as being served.

In major cities in developed countries, such as Sydney, this number is often very close to a perfect 100%. It’s very rare for cities of this type to be below 95%. But there are very large cities that fall at the complete opposite end of the scale. Jakarta is one of them.

According to the United Nations, only about 3% of Jakarta’s nine million residents are connected to public wastewater systems. While many of the other residents who aren’t connected use septic tanks, most of those tanks are poorly maintained and have contaminated the groundwater with fecal coliform bacteria. Further, when the tanks are emptied, many are done so illegally, dumping the untreated waste straight into waterways. This is likely one reason why septic tanks do not count toward the smart city standard.

This core indicator also just measures the population whose wastewater is collected. It does not matter whether or not that wastewater is treated. It all counts toward this indicator.

2.     Percentage of the city’s wastewater that has received no treatment

In the ISO 37120 wastewater standard, this is the first of four indicators that attempt to qualify the wastewater collection. This indicator compares the amount of wastewater that gets no treatment at all against the total amount of wastewater in a city. A perfect score is 0%.

In developed cities in industrialized nations, there may not be much of a difference between the amount of wastewater collected and the amount that is treated, but in others, there can be a sizeable gap.

The UN tracks both numbers on a country-by-country basis. In Greece, for example, the percentage of residents whose wastewater is collected and treated is both 87%. In Malta, on the other hand, 98% of the residents are served by wastewater collection, but less than half that wastewater is treated.

Worldwide, the lack of wastewater treatment is a critical problem. The latest figures from the UN show that as much 90% of the wastewater in developing nations flows untreated into rivers, lakes and highly productive coastal zones. That is a major public health issue.

3.     Percentage of the city’s wastewater receiving primary treatment

Primary treatment is the most basic wastewater treatment, and in highly developed cities, it’s only the first of a three-step treatment process. It’s no coincidence that this and the next two indicators are the three steps of a comprehensive wastewater treatment program.

Primary treatment is mostly a mechanical treatment. It typically involves using filters and screens to remove floating and suspended matter from raw sewage, though chemicals are frequently added to help the process along. According to the World Bank, this process can remove about a quarter of the biodegradable organics from wastewater, although it’s more effective with suspended solids, removing up to 60% of those.

Just as this is a starting point in a comprehensive treatment plan, this can also be a starting point for a city that’s just starting to treat its wastewater. Primary treatment is better than nothing, and a city can start with this type of treatment and add on more advanced treatment as it is able.

4.     Percentage of the city’s wastewater receiving secondary treatment

Secondary treatment is a biological treatment that uses microbes to devour the organic matter that slipped through the primary treatment. Combined with primary treatment, this step removes up to 85% of the organic matter and suspended solids. In very developed areas, there is often very little wastewater that gets primary treatment, but not secondary treatment.

Relatively few countries make a distinction about the treatment levels when reporting how much of their wastewater is treated, but the European Environment Agency has tracked the usage of all three treatment types on a country-level for decades. With the exception of southeastern Europe, approximately 90% of wastewater has received at least secondary-level treatment for the past decade.

5.     Percentage of the city’s wastewater receiving tertiary treatment

Tertiary treatment removes up to 99% of impurities, bringing it up to irrigation quality. But it can also be expensive. In Santa Barbara, Calif., bringing wastewater treatment facilities up to the tertiary-level required tens of millions of dollars in capital investments for most of its facilities, and added several million dollars in ongoing costs each year.

Still, as populations grow and areas become more urban, more cities find they need to make that investment. Northern and central European cities have been pioneers in this area. In Finland, 94% of its wastewater has received tertiary level treatment since 1980, and nearly all of it has since 1990. Sweden, Germany and Austria haven’t been far behind.


George Karayannis  has over 25 years of emerging technology and complex solutions sales, business development and marketing experience. He is currently Director Utility Sales, Trimble Energy and has held leadership positions at Schneider Electric, Lockheed Martin Energy Solutions, AT&T and wireless sensor startups.  He has also served as a city councilman and is restoring a 100-year old opera house to LEED Gold status. @gkarayannis

Next in the series – Water and sanitation indicators

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