Water, a Precious Resource under Threat
Only 2.5% of all water on Earth is freshwater, and 70% of it is frozen. Despite this, world water usage continues to grow rapidly, due to an increasing global population and expanding industrial and agricultural activities. It is estimated that by 2025, 1.8 billion people will be living in regions of absolute water scarcity, and 2/3 of the population could be under water stress conditions.
In addition to freshwater supply limitations, an additional concern is the deteriorating quality of available freshwater resources, due to increasing contamination by discharged effluent. There is a growing realization that traditional wastewater treatment approaches are not entirely successful. Biological treatment is unable to treat some wastewaters and is incapable of removing some contaminants, including pharmaceuticals and personal care products (PPCPs) and priority pollutants from industrial and agricultural activities. Some of these contaminants find their way back into our drinking water, and can result in eutrophication of surface bodies of water.
These water challenges are leading to strong interest in new approaches to:
- Reduce freshwater consumption
- Effectively treat wastewater
Terragon’s innovative WETTTM technologies offer the potential to do just that, and are capable of removing harmful nutrients and degrading refractory compounds that remain untouched by many other approaches.
Water recycling and reuse, once of interest primarily for arid regions, is now a priority issue in many cities and industrial environments, and in specific situations such as ships, remote camps, hotels, islands, and isolated communities.
The most complex situation arises when it is desired to convert heavily contaminated wastewater (for example, sewage or industrial effluent) into potable or drinking-quality water that poses no health risks due to pathogens or contaminants.
Typically multiple filtration, oxidation, disinfection, and polishing stages are required. The treatment train may be simplified if either the wastewater is not highly contaminated (for example, greywater) and/or the end use does not require potable water (for example, irrigation).
A few definitions can be helpful to understand some of the many options that are being adopted around the world today. In all of these water reuse scenarios, the concept of treating wastewater to the extent required to make it fit-for-purpose is at play.
Water from bathing and laundry activities which is reused again with or without treatment is called recycled greywater. Potential uses include toilet flushing, irrigation, cleaning, and in some cases showering and laundry, but not potable water. Recycled greywater is typically considered for homes, apartment buildings, hotels, camps and sometimes schools or governmental institutions (e.g. prisons). Toilet and kitchen waters are not greywater and are referred to as blackwater (or sewage). Any stream containing any toilet water becomes by definition sewage. Greywater reuse scenarios require separate plumbing for blackwater and greywater.
Wastewater (sewage) that is collected from a community’s homes, businesses and/or industries and sent to a centralized treatment facility is called reclaimed water. It can be treated to a level consistent with its intended reuse, for example irrigation, cooling, building, mining, recharge of groundwater aquifers, supply to commercial and industrial facilities, and even use as potable water.
Direct Potable Reuse
Reclaimed water that is used to supply in whole or in part a community’s potable water needs is called direct potable reuse (DPR). The reclaimed water is blended into the drinking water distribution system for a community (or it may be the only source of drinking water for a community).
Indirect Potable Reuse
Reclaimed water that will eventually be used as potable water but is indirectly supplied by blending it with source water used for producing potable water is called indirect potable reuse (IPR). The reclaimed water is used for recharging or replenishment of aquifers (groundwater) and surface waters, and water from these sources goes through additional treatment in a potable water treatment plant prior to distribution to the community.
Wasting Our GHG Savings Potential
The materials Canadians throw in the trash every day are impacting greenhouse gas (GHG) emissions in a colossal way. Every year, 54 Mt of GHGs are emitted from the waste sector, mainly due to the release of methane from landfills. Methane has a global warming potential 21 times greater than carbon dioxide. At the 2015 Paris Climate conference, Canada endorsed the goal of holding global warming to no more than 1.5°C, a very ambitious objective. Meaning, at the very least, that Canada must surpass the late Conservative government’s target of 30% below 2005 carbon dioxide equivalent levels by 2030. The result: a drop from today’s 726 Mt of GHG emissions to at least 512 Mt of GHG in 14 years.
Basically, if Canada removed every single car and truck from the road, every train from the track, and every plane from the sky, we would still be about 25% away from the targeted goal. Clearly, each area of Canada’s economy is going to have to cut back drastically; one can practically hear the “what about our economy” groans. However, there is one area where we can significantly affect GHG reductions almost immediately and benefit economically in the short term. It is an area where we are literally throwing away GHG savings potential: the waste sector. If Canada applied a TRU, Total Resource Utilization, model to its waste sector, whereby each waste stream is treated according to maximum recovery potential within the community where it is generated, meaning local reuse, composting, recycling and energy recovery, the entirety of GHG emissions released by landfills could be avoided completely, representing 25% of the current GHG reduction goal.
Local energy recovery from waste is possible through multi-fuel energy generating appliances. Terragon’s Micro-Auto Gasification System (MAGSTM) offers the possibility of zero discharge, or TRU habitats, playing a complimentary role to reuse, composting and recycling of materials. Even if MAGSTM simply replaced every Canadian landfill, it would account for 13% of Canada’s GHG reduction goal. This amount is equivalent to 51% of emissions from the total GHGs generated by the entire waste sector. MAGSTM alone improves Canada’s GHG footprint in a significant way, but more is needed in the form of a total waste revolution. Other reusable resources Canadians dispose of every day include water; technologies such as WETTTM allow us to reuse grey water in our homes reducing potable water consumption by up to 85%. We need to take ownership of all our resources to reduce Canada’s carbon footprint, water and waste included; it’s time to quit throwing away our carbon savings!