How Wastewater Can Drive Us Toward a Circular Economy
- Jan 5, 2021 7:34 pm GMT
In today’s world, many people are working hard to find worthwhile solutions that contribute to a circular economy. Instead of facilitating methods that lead to rapidly growing amounts of waste, they search for techniques that foster regeneration and recycling.
Researchers are also interested in using wastewater as a resource with these efforts. Domestic, agricultural and industrial activities all cause wastewater. Ceasing them is an impossible goal. However, a feasible solution is to invest in opportunities that turn wastewater into something new, practical and useful.
Tapping Into the Sun to Obtain Hydrogen From Wastewater
Scientists and sustainability enthusiasts often tout hydrogen’s potential to power cleaner-running cars. It’s already an ingredient in thousands of products. One frequently encountered issue is that pure hydrogen production is a costly, energy-intensive process.
A team of researchers at Princeton University recently engineered a process that uses sunlight to isolate hydrogen from industrial wastewater. They tested the approach at breweries and made exciting conclusions. More specifically, their process doubled the commonly accepted rate for scalable technologies that produce hydrogen by splitting water.
This new approach also splits water, but it uses a Swiss cheese-like black silicone interface, plus a bacterium that generates an electrical current when consuming organic compounds in the liquid. The group believes this technique could prove especially advantageous to refineries and chemical plants. Those facilities generally produce hydrogen in-house from fossil fuels and maintain large wastewater cleaning budgets.
Promoting a Circular Water Economy With Data-Driven Methods
The linear economic model currently prevails throughout the world today. It involves a multistep process of harvesting and extracting resources and using them to produce products that consumers use and eventually throw away. People often call it the Take-Make-Dispose model. In the water treatment sector, the linear model changes to a Take-Use-Discharge approach.
Then, any unconsumed water goes back into river basins, either with direct methods or at wastewater treatment facilities. Moving ahead with the circular water economy could include reducing water usage to recovering biogas from sewage treatment plants. Using a data-based approach can make these efforts more successful, especially when information sheds light on problems and trends.
In one case, officials managing algae growth in a German lake installed five monitoring stations that limit the nutrients entering the lake. In the summer, a foam caused by dead algae limits swimming and fishing opportunities. Tracking systems collect data automatically and trigger alarms when necessary. Elsewhere, Singapore’s public utility authorities will install 300,000 smart meters in domestic, commercial and industrial premises by 2023. Those gadgets will track consumption and highlight patterns.
Increasing Freshwater Resources for Residents
People often discuss the need to address food scarcity in urban areas, but water shortages pose problems, too. Researchers recently built a model that investigated how to bring more potable water to residents of Houston, Texas.
In one scenario, they discovered a potential 28% reduction in surface water dependence by recycling wastewater to make it drinkable. Besides upping the resources for residents, the team that developed the model mentioned that this approach boosts sustainability by cutting the amount of freshwater shipped from elsewhere to cover the lack of potable water.
While the group recognized the expenses associated with advanced purification to clean the wastewater, they said the savings linked to bringing water from elsewhere would more than make up for the new costs. The researchers ultimately want to address previously unanswered questions about the specifics of next-generation water supply systems. For example, what’s the ideal number and location of water sources?
Creating More Durable Concrete
Steel slag is a byproduct of steel production that serves multiple purposes. Firstly, it’s often a substitute aggregate used when making concrete. Steel slag can also absorb wastewater contaminants, such as phosphate, iron and aluminum. It loses its effectiveness over time, however.
Researchers wondered if steel slag could take care of both needs in its lifetime. More specifically, could a company use the byproduct at a wastewater treatment plant, then recycle it as a concrete aggregate? Their results showed that the so-called sewage-enhanced slag caused a 17% increase in the strength of concrete versus options containing conventional aggregates.
Dr. Biplob Pramanik, a project engineer, said, “The global steelmaking industry produces over 130 million tons of steel slag every year. A lot of this byproduct already goes into concrete, but we’re missing the opportunity to wring out the full benefits of this material.” He continued, “While there are technical challenges to overcome, we hope this research moves us one step closer to the ultimate goal of an integrated, no-waste approach to all our raw materials and byproducts.”
Making Fertilizer From Wastewater
Using wastewater as a resource could also entail creating recycled fertilizer. A process developed at Finland’s Aalto University called NPHarvest extracts nitrogen and phosphorus from the liquid to create a clean ammonium sulfate solution suitable for fertilizing. That process also makes a slurry rich in phosphorus and calcium.
The people behind this option noted that it offers several perks. People already associate some of them with sustainability and the circular water economy. For example, it reduces nutrient discharges into waterways and limits the chemicals and energy required by aeration and wastewater treatment processes.
Another advantage of this option is that people can tweak it to produce nitrogen as a general fertilizer in the form of ammonium phosphate or ammonium nitrate, an industrial chemical. Anna Mikola, a professor of practice working the project, said, “The customizability and adaptability of the process are important factors in the shift toward circular economy thinking, where one person's waste is raw material for another.”
Promising Possibilities for a Circular Economy
The coverage here focused on circular water options. However, parties in various other industries are working on innovations to support a circular economy, too. Many of them showcase what’s possible and urge people to broaden their viewpoints.
For example, a Dutch company called DyeCoo revolutionized a fabric-dyeing process that uses no water and no chemicals other than the products that color the material. Then, a company called Miniwiz created a portable machine that turns plastic bottles into a building material.
People don’t ordinarily envision wastewater as a resource. But, as the examples here prove, it’s time to change this mindset and realize it could be more valuable than they initially believed.
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