In the United States alone, billions of gallons of water are treated each day at wastewater treatment facilities. Once the water is clean, a different challenge remains: determining what to do with the solids that are removed during the treatment process. The resulting mixture is often a unique semi-solid blend of organic and inorganic materials, trace elements, chemicals, and even pathogens, so there is no across the board solution for handling and processing the combinations of constituents that may be present.

Because these solids are often rich in nutrients, like nitrogen and phosphorus—which also happen to be the perfect ingredients for promoting healthy soil and plant growth—many facilities have turned to land application. Before these solids can be put to use for things like fertilizing farmland, however, they must undergo rigorous treatment to meet stringent regulations, at which point they become known as biosolids.  

Climate change is already altering the patterns of our natural hydrologic cycle, creating uncertainty when it comes to the quality and quantity of water sources—forcing utilities to rethink practices that have traditionally been effective and seek solutions for more unpredictable conditions. While it is clear that widespread shifts in weather patterns will continue in the foreseeable future, the rate and intensity are not fully known. Even seemingly slight temperature increases can set off a chain of negative effects, such as lower dissolved oxygen levels, higher contaminant loads, reduced stream flows, altered runoff timing, widespread algal blooms, and increased saltwater intrusion. 

Adding to this challenge is the increased frequency of extreme weather, also linked to climate change. From drought to storms to tidal surges, these events can have devastating effects on critical water infrastructure. Because lack of access to clean, safe water is the single biggest threat to human health and economic livelihood, water service providers must be prepared to address these unstable weather conditions. 

Aquatic microscopic algae and cyanobacteria (blue-green algae) occur naturally in most surface waters, however certain nutrient and temperature conditions can lead them to rapidly multiply, leading to “blooms.” Under certain conditions, some species of cyanobacteria can produce toxic secondary metabolites or cyanotoxins, which may pose health risks to humans and animals. Even when algae is not toxic, it can produce unpleasant tastes and odors.

Cyanobacteria continue to be one of the most problematic organisms in our fresh water systems—with nearly a third of the United States reporting blooms. Without clear guidance or consensus regulations in place, many utilities struggle with responding to events. Since 1994, WRF has completed more than 30 research projects on these microscopic organisms and the cyanotoxins they produce, helping facilities detect, monitor, and manage these nuisance organisms—as well as communicate with the public.

The use of strong oxidants to disinfect water has virtually eliminated waterborne diseases like typhoid, cholera, and dysentery in developed countries. However, research has shown that chlorine interacts with natural organic matter present in water supplies to form regulated and non-regulated disinfection byproducts (DBPs).

To minimize the formation of regulated DBPs and comply with existing regulations, water utilities have increasingly been moving away from chlorine to use alternative disinfectants like chloramine, or installing more advanced and costly treatment processes, such as ozone or granular activated carbon to remove DBP precursors. However, while reducing the formation of halogenated DBPs, alternative oxidants have been shown to favor the formation of other DBPs (e.g., ozone producing bromate and halonitromethanes, and chloramines producing N-nitrosodimethylamine and iodinated DBPs). 

For most water facilities, energy is one of the highest costs in their operating budget. Stricter regulations are pushing facilities to use even more advanced—and energy-intensive—treatment technologies. Optimizing energy use can provide huge cost savings and numerous additional benefits, including improving air quality, protecting the environment, and bolstering energy security. WRF has published more than 100 projects that explore ways to not only optimize current energy use, but to generate power as well—setting the course for a self-sufficient water sector.

As with other industries, newly developed technologies drive water utilities to adapt their day-to-day operations. Water networks have been a special focus, with new instrumentation options for water production, transmission, distribution, wastewater collection, and consumer end-points coming to market. Implementing these technologies can improve the efficiency and reliability of water networks, but with myriad options, utilities need guidance on which technologies are most worthwhile and how they should be implemented. 

Control of microbes in water systems is critical to achieving water quality and public health goals. While most microbes are not considered human pathogens, certain microbes can pose health risks or contribute undesirable tastes and odors. 

Since the early 20th century, modern drinking water treatment has made great advancements in the detection, removal, and inactivation of bacteria, viruses, and protozoa. As technologies in the drinking water space continue to progress, new challenges have arisen in the form of opportunistic premise plumbing pathogens. 

Wastewater and stormwater utilities also play an essential role in reducing the pathogen load to receiving waters used for recreation.  Additionally, more recent advancements in water reuse, especially direct potable reuse, demand more understanding of pathogen detection, removal, and inactivation in wastewater. 

In recent decades, the wastewater sector has moved away from the idea of wastewater treatment plants as waste disposal facilities, instead envisioning these plants as water resource recovery facilities (WRRFs). WRRFs can produce clean water, recover nutrients (such as phosphorus and nitrogen), and potentially reduce fossil fuel consumption through the production and use of renewable energy.