The Future of Resource Recovery is Closer Than You Think
Have you ever wondered how a wastewater system of the future might transform an ordinary city into a thriving metropolis? Want to know how you could apply today’s cutting-edge treatment technology with tomorrow’s resource recovery innovations to help your city prosper?
Join us on a journey through the possibilities as we explore a water utility of the future. Scroll down to start exploring.
Welcome
Picture this: a city with roughly 200,000 residents. It's a bustling center of commercial, agricultural and industrial production, enjoying steady population gains. But predictions prove that all this growth might soon affect the availability of key resources like water, power and nutrients.
So, this city's utility managers have chosen to combat its impending resource demand by finding new ways to drive net-zero. The secret to success is a closed-loop water resource recovery facility, a powerful infrastructure network that transforms wastewater into valuable resources. Let’s see how the magic happens.
Let the Magic Begin
Where it Starts
In the developed world, when water makes its way down toilets and shower drains, the nutrients, carbon and good old H2O in that water stream are considered waste. But this city is finding a way to recover those resources.
Welcome to the Water Utility of the Future
Once conveyed to the treatment facility, wastewater is ready to begin its treatment journey. But will this wastewater be transformed into drinkable water, fertilizer or energy? The choice is yours! Keep scrolling to find out more.
Screening
Wastewater's first stop is the headworks system, where bar screens first remove large debris and collected materials are washed, compacted and disposed of.
Can you imagine?
It's possible that utilities of the future will be able to use robotic waste sorters—strapped with metal sensors, 3D laser scanners and spectroscopic cameras—to extract recyclables from the screened debris and eliminate wasted resources.
It's possible that utilities of the future will be able to use robotic waste sorters—strapped with metal sensors, 3D laser scanners and spectroscopic cameras—to extract recyclables from the screened debris and eliminate wasted resources.
Grit Removal
Secondly, grit (small particles like eggshells, sand and coffee grounds) is removed and washed to help reduce the maintenance costs of downstream equipment.
Can you imagine?
Here's some egg-cellent news! Soon, cities might be able to repurpose inorganic material that's been removed by grit systems and use it as backfill, pipe bedding or roadway aggregate.
Here's some egg-cellent news! Soon, cities might be able to repurpose inorganic material that's been removed by grit systems and use it as backfill, pipe bedding or roadway aggregate.
What's Next?
Now that we've covered the basic steps of preliminary treatment, let's dive into where things really get interesting! Want to see how water is being used to balance an entire city's ecosystem?
Keep scrolling to find out!
Recovering Water
Primary Clarification
Welcome to primary clarification, the first step in the sophisticated potable water recovery process. Here, suspended solids and organic matter are removed using the powers of sedimentation (thank you, gravity).
Let's Hear it For the Bugs
Bioreactors kick off the secondary treatment process by creating an ideal environment for microorganisms (we call them “bugs”) with as much or as little oxygen as they desire. An operations team takes close care of their ecosystem of bugs, making sure they’re happy so they’ll cooperate when called on to assist later in the nutrient recovery journey.
Final Settling
Our bugs now begin their descent to the bottom of the tank. With them are nanoparticles like titanium dioxide (a whitening agent found in toothpaste and sunscreen) and silver (found in antimicrobial AKA no-stink fabrics), which also accumulate in settled solids.
Can you imagine?
In the future, nanobots will be used to prospect tiny particles that could add up to BIG resources. In fact, studies indicate that nearly $13 million of metals (gold, silver, copper and platinum) could be recovered from sewage every year. Talk about a goldmine!
In the future, nanobots will be used to prospect tiny particles that could add up to BIG resources. In fact, studies indicate that nearly $13 million of metals (gold, silver, copper and platinum) could be recovered from sewage every year. Talk about a goldmine!
Filtration
Even though final settling tanks do a bang-up job removing most of the solids, it's now up to the filters to remove any remaining particles left lurking in the wastewater.
Disinfection
In this city's preferred method of disinfection, ultraviolet (UV) light penetrates deep into wastewater, deactivating microorganisms by absorbing UV into their DNA and destroying their reproductive abilities. This level of disinfection produces a near-potable water product that is now ready to be reused in multiple ways.
Can you imagine?
One day, utilities like this one will be able to use just the power of the sun to disinfect wastewater. Titanium dioxide—previously nanoprospected from the biosolids—can be used as a photocatalyst, maximizing the strength of the sun's UV rays and zapping away recalcitrant organic molecules like pharmaceuticals.
One day, utilities like this one will be able to use just the power of the sun to disinfect wastewater. Titanium dioxide—previously nanoprospected from the biosolids—can be used as a photocatalyst, maximizing the strength of the sun's UV rays and zapping away recalcitrant organic molecules like pharmaceuticals.
Putting it to use
Drinking Water
Wastewater that's been adequately treated is sent directly to a drinking water treatment plant where it will be further processed and eventually distributed as potable water.
Waterbody Discharge
This modern city reserves some of its high-quality effluent for the aquatic habitat! By discharging EPA-regulated quality effluent into the nearby reservoir, the city does its part to keep the ecosystem in balance.
Irrigation
If there are any nutrients still left in the treated wastewater, they can now be land-applied to irrigate the city’s farms and lawns where they'll distribute nitrogen and phosphorus back into the earth. That also means a drastic decrease in potable water use and reduction in the amount of agriculture fertilizer needed. Talk about a win-win.
Cooling
A local power plant receives some of the plant’s treated effluent to cool down equipment, dramatically reducing the amount of fresh water used in the cooling cycle.
What's Next?
Now that we've explored all the ways water recovery is revolutionizing everything from lawn irrigation to aquatic restoration, let's move onto another path and learn how carbon is becoming the new go-to super fuel.
Recovering Carbon
Primary Clarification's Carbon Capture
Primary clarification is where the process of carbon recovery begins—using high-rate clarification to transform wastewater into the energy-efficient power that will provide for all sorts of community needs.
Primary Clarification's FOGgy Business
Skimmers scrape the top of the tank for fats, oils and greases (FOGs), which are then mixed with residential and commercial food waste and introduced to the bioenergy digesters to increase energy production.
Anaerobic Digestion
All that energy-rich organic waste is now mixed with primary- and waste-activated sludge along with primary clarification solids to recover bio-energy—better known as biogas.
See it in action!
When the Des Moines Metropolitan Water Reclamation Authority (WRA) found out it was quite literally burning money by producing more biogas than its digesters could handle, the utility decided to jump into the RINs program and cash in on this valuable fuel.
When the Des Moines Metropolitan Water Reclamation Authority (WRA) found out it was quite literally burning money by producing more biogas than its digesters could handle, the utility decided to jump into the RINs program and cash in on this valuable fuel.
At the city's CHP plant, biogas is converted into energy and used to power bioreactors and other equipment, dry solids and heat the facility.
A CHP system at the Greater Lawrence Sanitary District (GLSD) allows this Massachusetts utility to generate over 3 megawatts of clean, renewable power and bring a new meaning to the phrase "driving net-zero."
Organics to Energy
As a waste-source receiver of organic commercial and agricultural byproducts to enhance gas production, the city enjoys some multi-pronged benefits: reduced energy costs, decreased landfill space usage and an increased revenue stream.
Renewable Natural Gas (RNG)
Thanks to experimentation with renewable natural gas for gas and diesel vehicles, the city is discovering how alternative fuel sources can create a new standard in fuel independence. Aside from cutting greenhouse gas emissions and improving air quality, this switch to RNG is also attracting interest from private investors looking for a commercial return.
What's Next?
Now that we've explored all the ways water recovery is revolutionizing everything from lawn irrigation to aquatic restoration, let's move onto another path and learn how carbon is becoming the new go-to super fuel.
Recovering Nutrients
Primary Clarification
At primary clarification, we begin a journey along the nutrient track. Here, we'll discover how settled solids are captured and sent on to recover beneficial nutrients for agriculture.
Bug Action
In the bioreactor, an operations team creates three tailored zones to persuade certain microorganisms (AKA "bugs") to perform designed tasks. Zone 1 deprives the bugs of oxygen and triggers a release of phosphorus which can later be harvested for further use. In Zone 2, our bugs are fed some much-needed oxygen and in response, they grow and convert nitrogen into nitrite and nitrate. In Zone 3, another team of special organisms called denitrifiers produce energy and nitrogen gas that bubble up to the surface and are released into the atmosphere.
Can you imagine?
Just think: today's toxic algae blooms could be tomorrow's recovered energy source. Scientists and researchers are exploring how LED light can optimize algae growth in controlled environments. They'll then be able to use the harvested algae to extract phosphorus and nitrogen from wastewater.
Just think: today's toxic algae blooms could be tomorrow's recovered energy source. Scientists and researchers are exploring how LED light can optimize algae growth in controlled environments. They'll then be able to use the harvested algae to extract phosphorus and nitrogen from wastewater.
Final Settling
Some unlucky bugs meet their doom in the final settling tank, destined to become waste-activated sludge for the anaerobic digester. Other more fortunate ones are sent back to the bioreactor as return-activated sludge, where they’ll be put back to work.
Thermal Hydrolysis
In addition to the settled solids from primary clarification and final settling, FOG and nutrient-dense food waste from local homes and restaurants can be fed to a high-heat, high-pressure process called thermal hydrolysis. This process uses steam to break down cell walls, yielding a sterilized sludge that lends itself to more efficient and smaller digesters in the next step.
Anaerobic Digester
Teaming up with waste-activated sludge is nutrient-dense food waste from local homes and restaurants, which is added to the process and fermented via anaerobic digestion. This process creates biosolids, a solid organic byproduct of treated wastewater.
See it in action?
CDM Smith's resident biosolids expert Peter Loomis and his team are helping the Trinity River Authority set a higher bar for biosolids in Texas. Check out how!
CDM Smith's resident biosolids expert Peter Loomis and his team are helping the Trinity River Authority set a higher bar for biosolids in Texas. Check out how!
Because biosolids are great at improving soil health and simulating plant growth, they can easily be land-applied as an all-natural, environmentally friendly fertilizer at the nearby farm or landfill and recycling center. But that’s not all! Commercial businesses (like sod farms, gold courses and agricultural centers) and residential homes can also purchase man-made biosolids pellets as an all-natural alternative to chemical fertilizer.
Sludge Products
Biosolids from the digester can now be dewatered and used as a natural fertilizer or further processed to be used as organic compost, dried out and turned into a pelleted fertilizer, or brought to a manufacturer to become Grade A fertilizer.
We bet you didn't realize that wastewater contained so many beneficial nutrients that were once wasted before this future-focused city closed the loop on nutrient recovery.
the future
Closer Than You Think
While a city that so perfectly incorporates water, carbon and nutrient recovery might seem like science fiction, the future is closer than you think. Utilities around the world are constantly developing new solutions that promote sustainability amidst the threat of dwindling resources. And one thing is for sure—a resource recovery system is part of that solution.
Eager to see how your utility can start incorporating some next-generation technology into its processes and systems?
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