Nitrogen loads at wastewater treatment plants grow due to excessive consumption of protein
The nitrogen load received by wastewater treatment plants in the Helsinki Metropolitan Area has grown steadily over several decades.
The figure has grown by 50% from the year 1999 to 2019. In 2019, the growth continued, and the final figure ended up being the largest since 1999. One reason for the growth of nitrogen load is the growing consumption of protein.Excess protein not needed in the body is expelled, for example, as nitrogen in urine, and ends up in the wastewater. In the metropolitan area, the Viikinmäki wastewater treatment plant removes almost 90% of the nitrogen, but nevertheless some of the nitrogen is released to the Baltic Sea where it causes eutrophication.
The wastewater from the Helsinki Metropolitan Area is currently treated in the Viikinmäki and Suomenoja plants. The limits of the Suomenoja wastewater treatment plant will soon be reached due to the growing nutrient load and population growth in the Helsinki Metropolitan Area, and this is the reason HSY is building a new wastewater treatment plant in Blominmäki, Espoo. The Blominmäki wastewater treatment plant, planned to be finished in 2022, increases the treatment efficiency and capacity, ensuring efficient treatment of wastewater also in the future.
In September 2019, we ordered a survey to map out what the residents of the Helsinki Metropolitan Area know about protein intake and sources. The survey was conducted by Nepa.
According to the results, the sufficient amount of protein is unclear to the residents of the Helsinki Metropolitan Area. About a quarter (24%) of women and every tenth man consider they consume less protein than they need. A little more than every third person (36%) was able to tell the suitable amount of protein, which is approximately 1–1.4 grams per kg bodyweight.
More than every fifth (22%) person in the Helsinki Metropolitan Area assumes the excess protein is stored in the body and transformed into muscle tissue. In reality, excess protein is removed with urine into wastewater as nitrogen, among others. The more sufficient protein intake is exceeded, the more nitrogen there is in the wastewater and eventually, in the Baltic Sea, causing eutrophication. According to the survey, the effects of excess protein are not in common knowledge, because half of the respondents do not believe or know that consuming too much protein affects wastewater or the Baltic Sea.
Health effects
In the usual diet of Finnish people there is enough protein, and most of us consume more protein than we need daily. In Finland, protein deficiency is seen in chronically ill patients and elderly people with poor appetite. 1)
Protein is often pictured belonging to a healthy, athletic lifestyle. However, excess protein that the body is unable to use is transformed into sugar and then stored in the body as fat. Excess nitrogen is mostly removed with urine. This means the excess protein does not turn into muscle mass.
Proteins contain nitrogen, which is harmful to the body and normally leaves the body with urine. If the diet includes a significant amount of proteins, sufficient hydration is important for the body to expel the unnecessary nitrogen.
Recommended protein intake
The recommended proportion of proteins in daily energy intake is 10–20 per cent. The recommended protein intake per kg of bodyweight is 1.1–1.3 grams. A physically active lifestyle and old age increase the need for protein. For people over 65, the recommended protein intake is 1.2–1.4 grams per kg of bodyweight per day. 2)
There is no need for a healthy individual to be measuring the food by the gram in order to receive all the nutrients. You get a suitable amount of protein by eating versatile meals according to a healthy eating plate. If meat is not a part of your diet, you should eat different legumes, nuts, seeds and wholegrain products.
Exercise increases the need for protein slightly
Light exercise does not increase the need for protein. People who exercise often or are professional athletes require a bit more protein than others to maintain balance in nitrogen. Fulfilling the protein needs of a professional athlete usually does not require any special measures aside from increasing the amount of food, because consuming more food means consuming more protein. Even the people who exercise often will do fine with a normal, healthy diet without protein supplements. 1)
Where do you get protein?
Great sources of plant-based protein are beans, lentils, peas, nuts, soy products and quorn, for example. Also, grain products are rather good sources of protein. The best animal product protein sources are low-fat milk products, eggs, fish, chicken and lean meat. It is recommended for a vegan to eat legumes, wholegrains and nuts and seeds, to create a complete profile of amino acids. 3)
Protein is most often received from animal products, usually meat, and meat consumption has continually risen in Finland.
Sources:
1) Finnish Institute for Health and Welfare THL: https://thl.fi/web/elintavat-ja-ravitsemus/ravitsemus/mita-ruoka-sisaltaa/proteiinit
2) Finfood - Finnish Food Information: https://www.ruokatieto.fi/ruokakasvatus/ruokaketju-ruuan-matka-pellolta-poytaan/ravitsemus-ja-ruuan-valinta/energiaravintoaineet/proteiinit
3) Finnish Heart Association Sydänliitto: https://sydan.fi/fakta/proteiinia-sopivasti/
Effects on the Baltic Sea
The greatest problem for the Baltic Sea is eutrophication. For decades, too many nutrients, especially phosphorus and nitrogen, have been released in the sea. The main source of nutrients is agriculture and forestry, but other sources are industry and household wastewater and traffic. The Baltic Sea is a delicate area – it is shallow and has low salinity as well as limited water exchange into the North Sea. Also the Baltic Sea catchment area is large.
Phosphorus removal of the wastewater treatment plants in Finland is efficient, but almost a fifth of the nitrogen ending up in the Baltic Sea comes from community wastewater. In the Helsinki Metropolitan Area, the Viikinmäki wastewater treatment plant removes almost all of phosphorus, and manages to remove 90% of nitrogen. As the population grows and protein consumption increases, also the nitrogen load entering the sea grows.
https://www.ymparisto.fi/fi-FI/Meri/Mika_on_Itameren_tila/Rehevoityminen
https://wwf.fi/alueet/itameri/rehevoityminen/
Wastewater treatment process
The residents and companies of the Helsinki Metropolitan Area produce about 130 million cubic metres of wastewater yearly. The sewer network directs the wastewater to the treatment plant for processing before it is returned to the water system.
The process is a combination of biological and chemical procedures, with sludge and biogas as side products. The sludge is refined into soil and the gas is utilised as an energy source. The treated wastewater is led in a tunnel to the open sea.
Wastewater treatment is an important part of protecting the coastal water and the Baltic Sea, because the great amount of phosphorus and nitrogen contained in the incoming wastewater would increase eutrophication significantly if led directly to the sea.
Both EU directives and Finnish legislation have restrictions for wastewater treatment. Also, wastewater treatment plants are required to fulfil their individual environmental licences overseen by the Uusimaa Centre of Economic Development, Transport and the Environment.
Nitrogen removal is a biological process
The main part of nitrogen removal is done with an activated sludge process. The bacteria of the activated sludge use nitrogen as they grow. Most of the nitrogen is removed when the bacteria turn it into nitrogen gas.
In Viikinmäki, the treatment is continued by biological nitrogen removal filters, and the result of the Viikinmäki plant is significantly more efficient in nitrogen removal than its environmental licence requires.