By Jennifer Cisneros
By 2027, the world’s population is predicted to double, meaning millions more people will be denied access to clean water. Scientists from around the world are urging an immediate adoption of clean waste-processing technologies, along with the development of infrastructures to protect water resources and areas with delicately balanced ecosystems. Even in countries like Canada, having access to clean, fresh water is too precious to take for granted.
While onsite wastewater treatment systems (e.g. septic systems) are nothing new, the idea of recycling water generated on properties is becoming very popular. Onsite septic systems are called by many different industry terms, including:
- advanced, wastewater treatment systems;
- scalable, distributed sewer systems;
- residential blackwater/greywater treatment systems; and
- decentralized water/wastewater management systems, etc.
Regardless of the terminology, they can help resolve the many issues concerning infrastructure alternatives, budget constraints, and site planning. Most national and international environmental protection agencies’ policy literature identifies finding a viable distributed approach to achieving a water management solution as an issue of economic, legislative, and institutional importance.
Water recycling is a key component of sustainable water engineering. However, water and wastewater treatment are two separate and broad fields, involving a number of technical disciplines for best practices. Water treatment standards are mainly guidelines involving finer filtration (e.g. reverse osmosis [RO]) or disinfection (e.g. chlorine or ultraviolet [UV]); they are rarely included in water recycling or reuse schemes involving wastewater treatment, have any legal basis, or are subject to enforcement.
Significant potential with the urban core
While municipal treatment plants tend to be perceived to be the best option available, there are many other methods communities can adopt. The layout, engineering, and integrated design allows smaller systems to treat wastewater and stormwater at its source, while reducing the need for large piping, site disruption, or enormous amounts of energy to pump untreated or partially treated water through kilometres of a sewer network, never to be sent the water back to its original source.
Additionally, utilities are beginning to recognize the benefits of these technologies for overloaded plants. While not yet common practice, they have been installed on commercial properties to pretreat the wastewater, screen it, and remove most of the organics prior to the municipal treatment plant. These systems can address compliance issues for small communities and/or remote areas, and can be designed for varying levels of wastewater treatment, depending on the discharge location and requirements.
Residential onsite water-recycling can have significant potential benefits beyond utility bills for homeowners. For example, compared to conventional water-efficient homes built using low-flow fixtures, residences with water recycling systems could use almost half as much water (due to treated greywater being circulated to the toilets), while generating only one-sixth the peak sewage.
For municipal systems, the decrease in loading caused by pretreatment with onsite systems on commercial properties may mean more effective treatment for undersized wastewater treatment plants. Water reuse enables municipalities to decrease displacement and discharge into surface waters, decreasing demand on the local potable watershed. This could lead to lower fees for water rights and sewer tie-in fees for builders, while significantly stretching allocations for reduced water.
Ecological water management systems and both decentralized residential and commercial wastewater (i.e. blackwater/greywater) treatment technologies can satisfy project goals and provide more options for using treated water. With a long, proven history, these systems perform exceptionally well in achieving the new higher levels of nitrogen removal, net-zero water goals, and optimal effluent quality with automated, energy efficiency.
What are the specific challenges of water recycling?
Some companies are actively involved in the stewardship of the wastewater and sewage treatment industry, working with provincial and national regulatory health authorities to advance technologies safeguarding public health and protect fresh water resources.
The largest potential source of onsite water in homes is greywater drained from showers, laundry rooms, and sinks. Typically, two-thirds of indoor water is greywater, with the remaining one-third blackwater from the toilet. It is believed “adoption of off-the-shelf residential technologies could reduce indoor water use from approximately 200 L per day to 89 L [53 to 24 gal] per day.” (For more, see Elizabeth Hendriks and Sarah Wolfe’s article in ForesterDailyNews online here, retrieved 07/21/2016.) Some septic homeowners’ guides suggest the typical single-family home indoor water use average can be about 1000 L (264 gal) daily, with leaky toilets wasting as much as 900 L (238 gal). (This comes from Waste Water Nova Scotia Society [WWNS] and Nova Scotia Environment’s [NSE’s] A Homeowner’s Guide to Septic Systems, published in November 2009. For more, click here.) Greywater composes 50 to 80 per cent of residential wastewater generated from all of a household’s sanitation uses. (For more, see Alberta WaterSmart’s 2011 “Greywater Recycling and Reuse in Alberta Report,” which was posted online at www.albertawatersmart.com.)