Treating wastewater and reducing emissions – green solutions needed

How to save more than $15.6 billion in 40 years. And avoid nearly 30 million tons of carbon dioxide emissions? Implement more nature-based green solutions in wastewater treatment.

A few words about wastewater

According to a study by researchers at Colorado State University, USA, reducing the expansion of large municipal facilities in favor of wetland development and reforestation can not only improve the quality of the water environment, but also reduce carbon emissions in real terms and save money. The report is based on data collected from more than 22,000. facilities and examines the relationship between basic wastewater treatment rates, emissions, and the cost of implementing and maintaining solutions.

In the future, requirements for the quality of treated wastewater will continue to increase, in addition, it is necessary to reduce emissions from facilities. About 380 billion^{cubic meters (bcm} ) of wastewater is generated annually worldwide, and global production is expected to increase from current levels by 24 percent. By 2030, and by 51 percent. By 2050.

Wastewater is the fifth largest source of anthropogenic methane emissions (more than 19 percent), primarily from leaks in anaerobic digestion plants and chambers, and the sixth of nitrous oxide (about 13 percent), which is generated by more than 90 percent in biological chambers. In addition, carbon dioxide emissions at the facilities are primarily due to energy consumption for aeration of the biological chambers (about 60-70 percent of the entire facility’s demand), if that comes from fossil fuels.

Challenges faced by wastewater treatment plants

Traditionally, wastewater treatment plants have been designed to remove nitrogen and phosphorus compounds, but in recent decades our awareness of the number and variety of chemical compounds that go into wastewater has increased significantly. They pose significant challenges to biological treatment processes. Persistent organics, micro- and nanoplastics, and antibiotic resistance are currently the main problems of water environmental quality.

To meet the new challenges, it is necessary to implement more technologically advanced solutions. However, they can increase energy consumption and thus generate additional emissions. In addition, climate change can significantly reduce treatment efficiency and increase emissions from biological processes. We are also struggling with a large number of so-called non-point sources of emissions, primarily from agriculture, whose negative impact on water resources is compounded by climate change.

Currently in Europe, only 38 percent of surface waters are considered to have good chemical status. The European Environment Agency is sounding the alarm that in more than 20 percent. of all monitored surface waters, at least one pesticide was detected at concentrations of concern.

Green solutions in the US

In the U.S., further costly upgrades to wastewater treatment plants can currently be avoided through a program that provides for investment in green infrastructure(Water Quality Trading – WQT), including. Reclamation of coastal areas, flood plains and wetlands. The program enables water quality trading and the transfer of requirements from a point source to the restoration and maintenance of freshwater ecosystems. One of the barriers to implementing such solutions is the inability to directly monitor the water quality performance of green infrastructure. In addition, green infrastructure, to be effective, must be in locations that need repair or protection and are in close proximity to the pollution-generating facility.

In a recent publication in Communications Earth & Environment, researchers published calculations that confirm that nitrogen removal can be increased by 31.7 to 36.8 percent using green infrastructure in the US. (i.e., for 36.8 percent – nearly 404,000 tons of nitrogen per year) and 20.8 to 21.1 percent. (i.e., 52,500 tons of phosphorus per year). It is estimated that conventional wastewater treatment technologies would emit 11.9 to 29.8 _MtCO2e(megatons of carbon dioxide equivalent) annually, while green technologies would emit 3.8 to 4.2 _MtCO2e. The cost of implementing nature-based solutions, which researchers forecast at $13.6 billion, is also lower. per year, while it was 28.5 billion for conventional treatment plants.

The prospect of U.S. solutions in Europe

The main obstacle to improving these indicators is the limited number of locations where green infrastructure can be used. Nor will this type of technology generate lower costs everywhere. For the 222 water bodies analyzed, only or as much as 70 percent. green solutions generated lower costs in terms of emissions. Although nature-based solutions can remove less than 40 percent. Nitrogen and 25%. phosphorus produced with wastewater in the U.S., this data is promising and we can use it as an argument for initiating such solutions in Europe.

In addition to pollution removal, lower costs and emissions, a very important aspect is the creation of jobs that do not require expertise in environmental innovation. The share of disadvantaged communities due to the water and climate crisis is growing. Analyses show that for every million investment in green infrastructure, 20 new jobs are created, but investment in reforestation or wetland restoration also increases profits in local economic activity by 1.7 to 2.6 times. Also, the implementation of a system of financial compensation for farmers (more than half of the total cost of green infrastructure) who own land for nature-based solutions does not offset the benefits they bring.

This information is particularly important in the context of discussions on the provisions of the European Green Deal and the implementation of the complementary Nature Restoration Law. Low-carbon wastewater treatment plants with increased resource recovery envisioned under the Green Deal demands must be accompanied by an increase in the proportion of land excluded from intensive agricultural use and the implementation of nature-based solutions (such as artificial wetlands) in the buffer strip of wastewater treatment plants.

Dr.-Ing. Edyta Łaskawiec – water and wastewater technologist, scientist at the Zabrze Institute of Fuel and Energy Technology, science popularizer, author of an educational profile on Instagram platform: wastewater_based.doctor.