The old processes can take a toll on the ecosystem
Environmental responsibility is a growing imperative for the water sector as it grapples with climate change-associated drought, pollution, and depletion of natural water resources that once seemed limitless ─ and regulators and ESG investors are making sure no one forgets it. How can water systems adapt their operations in such a way that treatment is not just another in a long list of harmful human activities? There are many answers to that question.
The traditional water treatment paradigm needs an update. Legacy processes often take a heavy environmental toll through high energy consumption, chemical use, and greenhouse gas emissions. The large-footprint centralized plants that disrupt ecosystems, demand great amounts of energy, and require miles of invasive pipelines can be avoided entirely. Decentralized systems with smaller plants placed strategically have been outperforming the lumbering water and wastewater treatment giants.
Making the Most of Energy
Innovative technologies such as the membrane aerated bioreactor (MBR) and new-generation reverse osmosis (RO) have slashed energy requirements. Decentralization also greatly increases energy efficiency. Instead of pumping water for miles through extensive pipe networks, decentralization sites smaller plants directly where they are needed. Smaller plants tailored to finite service areas also can be much more efficient.
Water treatment processes and pumping are not the only energy hogs at treatment facilities. The sites, including offices, require power for lighting, computers, and other needs, but energy to power them can be generated onsite. Solar arrays at plants or turbines fueled by biogas from the anaerobic digestion treatment process can slash a plant’s energy requirement.
Trimming the Use of Chemicals
Minimizing chemicals and adopting less harmful treatments can soften the environmental impact of treatment facilities. Processes such as electrocoagulation, electro-oxidation, advanced oxidation processes, adsorption, and ion exchange can cut chemical use.
Using biological treatment approaches goes a long way toward reducing chemical discharges. Those treatments include activated sludge or advanced membrane processes such as nanofiltration (NF), ultrafiltration (UF), microfiltration (MF), and RO. The newer MBR process combines biological treatment with membrane technology, increasing volumetric loading rates and abbreviating hydraulic retention times.
Updating the disinfection stage with ozone or ultraviolet disinfection also allows plants to destroy pathogens without chlorine or other disinfectant chemicals.
Embracing water reuse is a powerful way to maximize water resources and reduce the burden of human activities on natural sources. By providing treated wastewater for industrial use, agricultural and landscaping irrigation, and other applications that do not require potable water, a great deal of fresh ground and surface water can remain in the environment.
Environmental Impact Assessment
Conducting thorough assessments to understand the ecological effects of water treatment projects can significantly minimize impacts on ecosystems. Consider the discharge of a stream of concentrated brine from a desalination plant. Public concern over environmental impacts from brine has stopped many a planned desalination plant because the brine can harm ocean-floor ecosystems. Water intakes also can destroy sea life, from tiny organisms to giant sea turtles.
In many cases, a thoughtful environmental impact study can inform the placement of desalination plants to avoid areas with a great deal of vulnerable sea life. It can also suggest the siting and design of intakes and outfalls for the best environmental outcomes.
Environmental Responsibility in Water Treatment: A Pipe Dream?
Are these strategies for environmental responsibility in water treatment just pipe dreams? The strategies outlined are fully mature and broadening into the market, with many entities in all sectors adopting environmentally responsible practices.
One company that puts it all together is Tampa-based Seven Seas Water Group. A profile of its operations shows environmentally conscious practices, starting with a special focus on decentralized systems, with established protocols and a fleet of smaller modular units to extend wastewater treatment far from grids.
Seven Seas sited its Trinidad and Tobago desalination plant near less sensitive waters after a painstaking environmental impact study, and instituted an innovative third-party brine monitoring program at the plant along with engineering unique seawater intakes to protect sea life. In the Bahamas, it operates a desalination plant and a wastewater reclamation plant at the same location for water reuse efficiency. It is phasing in solar arrays for its plants, many of which also treat wastewater for return to the environment to support ecosystems.
Environmental responsibility in wastewater treatment can be achieved today with mature technologies. It is encouraged at an institutional level by regulators and the ESG investment community, but individual operators who explore many relatively new approaches still drive much of the adoption. There is a great deal of technology and energy among the experts, scientists, engineers, and operators who devote themselves to realizing the water infrastructure of the future.