Wise Wastewater Management
From the trickle of water we use at home to brush our teeth to the millions of gallons consumed daily by the resource sectors, agriculture, and manufacturing, every drop is precious. Fortunately, water is far from being a single-use commodity. Depending on contamination, water can be cleaned, recycled, and re-used. From industrial laundromats running their grey water through pipes to heat facilities, to homeowners using dishwater to flush toilets or irrigate gardens, water can be used far more efficiently than we may think.
On a household level, the amount of water we consume is staggering. In the United States, estimates range from 80 to 100 gallons (302 to 378 liters) per person every day for indoor purposes such as showering and laundry. Canada is second behind the U.S. on a per capita basis, consuming about 329 liters, or 87 gallons, day in and day out. And while many of us are changing our mindset about the environment and conserving water through means such as low-flush toilets and low-flow showerheads and faucets, we still use over twice the amount of water as Europeans.
More than ‘just water’
Tasteless, colourless and odourless, water is essential to all life – and industry – on Earth. While we are aware of drinkable waters like tap, sparkling, spring, purified, distilled, glacier and well water, uses for water vary depending on industry, and contamination varies a great deal.
Although it is of referred to simply as ‘wastewater’ once used, its composition can be complex and varied. Grey water – previously clean, drinkable water we use to wash our bodies, dishes and clothes that’s disappeared down showers, kitchen drains and laundry tubs – contains some bacteria and low levels of contaminants, but can be processed and re-used for watering lawns and other purposes. In parts of the world prone to drought, like Australia, grey water is recycled to flush toilets, significantly reducing household water consumption.
Not all water can be safely re-purposed, such as black water. Sometimes called brown water, black water is water contaminated from human waste and flushing toilets. Containing high amounts of bacteria and pathogens, it requires chemical treatment and strict adherence to environmental regulations before it can be re-introduced into the environment.
Water use by sector
Every industry on Earth uses water for everything from growing crops to wide-scale manufacturing and processing, with some sectors being more dependent on water than others. According to the U.S. Geological Survey (USGS) – which has gathered and analyzed water use data for over 70 years – the United States and territories use 322 billion gallons of water per day (Bgal/day). The biggest water consumer is farming, followed by thermoelectric power and public supply at 133 Bgal/day and 39 Bgal/day.
In resource sector industries like mining and oil and gas, water is a necessity. In mining, mineral extraction is just one of many uses for water. Other purposes include dampening roads to suppress dust, processing, and filling massive tailings dams with water and mining waste like chemicals and rock particles. Among the biggest man-made structures on earth, some of the estimated 3,500 tailings dams are the size of natural lakes.
The very large amount of water used by the resources sector – and the fact that water in tailings dams contains sulfuric acid, lead, mercury, dissolved iron and a myriad of other contaminants – means it requires extensive treatment before it can be released into rivers, lakes, and streams. And in the oil and gas sector, it is not unusual for millions of gallons of water, mixed with fracking fluids, to be used for just one well. In mining, water management is essential to ensure water used for purposes such as mineral processing is properly treated, reused, and recycled before it is re-introduced back into the environment.
While many of us in North America are keenly aware of the need to protect and preserve our streams, lakes, and oceans, the same awareness is not universal. This was the subject of a World Bank blog post written soon after the 8th World Water Forum, staged in Brazil and organized through the World Water Council (WWC) in 2018. Held every three years, the purpose of the Forum is “to promote awareness, build political commitment and trigger action on critical water issues at all levels,” according to The World Bank, and “to facilitate the efficient conservation, protection, development, planning, management and use of water in all its dimensions on an environmentally sustainable basis for the benefit of all life on Earth.”
Titled Wastewater treatment: A critical component of a circular economy, author Diego Juan Rodriguez’s post addressed the irony of holding a Forum on water in a city of three million persons itself wrestling with an urgent water shortage. Upon arriving at his hotel, Rodriguez found a government notice making guests aware of the water situation, and suggested ways to conserve.
The circular economy of water
While traditional water management methods have their benefits, some believe the current systems are not sustainable in the long run. The tragic reality is, much of the planet’s wastewater is not collected; according to World Bank Group estimates, this is as high as 80 percent. “Wastewater is a valuable resource, but it is often seen as a burden to be disposed of,” states the organization, which works toward sustainable solutions to reduce poverty. “This perception needs to change.”
Indeed, our collective attitude toward reducing and preserving the water we use needs an adjustment. Cleaning and repurposing water benefits the environment, and transitioning from the traditional linear model to a circular one brings many benefits – including waste in water being removed and repurposed as fuel or fertilizer. For the energy, industrial and mining sectors, treated water is used to cool power plants, in the production of paper and textiles, and as process water for mines. Other purposes include water for recreational use, irrigation, and human consumption.
Processing used water through anaerobic digesters – sealed vessels using bacteria to break down manure, food waste, crop residue and other organic materials – results in biogas and “digestate,” solid and liquid sludge also called biosolids. Composed of various gases including highly flammable methane, carbon dioxide and hydrogen sulfide, biogas has many uses, including generating electricity, heating and cooling systems, and even as an alternative to traditional gasoline for vehicles.
Since they are composed of organic materials, digestates/biosolids are full of macro- and micro-nutrients like nitrogen, phosphorus, and potassium. Depending on processing and treatment, these materials are no longer waste to be dumped or incinerated, but become the foundation of bioplastics, bedding for animals, or organic fertilizer for plants and crops.
Another benefit of anaerobic digestion is economic. Since they are generating renewable energy, wastewater treatment plants (WWTPs) can apply for carbon credits. According to the World Bank Group, “Improved wastewater management¬ offers a double value proposition if, in addition to the environmental and health benefits of wastewater treatment, financial returns are also possible. Resource recovery from these facilities in the form of energy, nutrients, reusable water, and biosolids represent an economic and financial benefit that contributes to the sustainability of these systems and of the water utilities operating them.”
Fortunately, the issue of how we can best manage our water resources is meeting with growing awareness. For the momentum to continue, we need to view “wastewater” as water – not something used once and dumped back into waterways, but as something to be treated and repurposed. While many of us in the west take water for granted, the fact is we are running out of clean water, and can ill afford to mistreat lakes and oceans. If Microsoft magnate and philanthropist Bill Gates and his wife can fund through their Foundation the Janicki Omni Processor (J-OP) – a revolutionary waste treatment system that not only transforms feces-infested water into drinkable water while generating electricity and heat – anything on Earth is possible.