Desalination vs Water Recycling: Differences, & A Comparison

In the guide below, we compare desalination vs water recycling.

We consider the main differences, some of the similarities, and which might be better across several different indicators.

 

Firstly, What Is Desalination, & What Is Water Recycling?

We put together two separate guides where we describe what each one is, and discuss key aspects of each:

Desalination: What It Is, & Other Key Aspects

Water Recycling: What It Is, & Other Key Aspects

 

Desalination vs Water Recycling – Main Differences

The main differences between desalination and water recycling are:

– The Type Of Water Used As An Input

Desalination mainly uses saltwater and water with a high salt content as a water input. It can also use brackish water.

Water recycling on the other hand mainly uses different types of waste water as an input, which come from a range of different parts of society

 

– The Processes, Methods & Technology Used To Process Or Treat Water

Desalination uses the desalination process, which removes salt and other unwanted impurities from the water

It also uses various different types of desalination methods and technologies, with membrane based desalination being used frequently over the last decade or so

Water recycling on the other hand can use a range of different processes, methods, and technology to ‘treat’ or manage waste water in different ways, in order to get it to a water quality that is adequate for the end use it’s being used for (whether that’s a potable, or non potable end use)

There’s also variations of waste water recycling, such as ‘Resource Recovery’, which can recover specific resources and nutrients from waste water to reuse

 

– Price To Produce Water

mercurynews.com provides a set of figures that show the price to product water from different water sources

The price to produce water from seawater desalination is more expensive than both indirect potable reuse and non potable reuse, with brackish desalination the cheapest of the four option

 

nas-sites.org confirms that (paraphrased) in general, water reuse is less expensive than seawater desalination

 

Beyond that, there’s variables that can make both water sources more expensive, such as dedicated pipes for recycled water, and long transport distances can increase the price to produce water for both water recycling and desalination.

In this guide, we list some of the other factors that can impact water recycling costs and prices.

 

– Sustainability & Environmental Impact

Desalination can be energy intensive, and older, more inefficient plants can produce a brine by-product from the desalination process, which is essentially a form of highly concentrated salt

Some reports indicate there’s ways to manage or reuse the brine product

Water recycling also relies on energy to operate, and can also sometimes discharge treated wastewater with residual pollutants/contaminants (that can’t be removed from the wastewater) into surface water sources, which essentially is a form of water pollution

At least one report indicates that recycling wastewater requires less energy than the treatment of seawater with desalination

Additionally, wastewater recycling may have sustainable benefits when recovering or reusing nutrients found in the water as a fertilizer

 

– Use On The Individual Level

Small and/or portable desalination filters, hand pumps, kits and similar products are available for personal/individual use

However, there are not yet similar small waste water recycling devices for individual use

 

– Other Differences

There might be a number of other differences between the two, including but not limited to the regulations that apply to each type of water process/treatment, the cost of each, efficiency, and more

 

Desalination vs Water Recycling – Main Similarities

Potential similarities between desalination and water recycling might include:

– Both Are Man Made Water Sources

Natural water sources might mainly include surface water sources like lakes and rivers, as well as groundwater sources in the form of aquifers.

Both desalination and water recycling on the other hand might be considered as man made water sources.

 

– Both Are Used Widely On A Global Scale

Several reports indicate that there may currently be between 18,000 and to 21,000 desalination plants in the world in over 100 countries

One database indicates that there may be around 58,502 wastewater treatment plants in operation worldwide

 

– Both Can Produce Both Potable & Non Potable Water

Both desalination and water recycling are capable of generating both potable water (drinking water), and non potable water

 

– Both Can Be Costly From A Capital/Set-Up Perspective

The cost of capital and set up of both water sources can cost millions, and sometimes billions of dollars, depending on the type of plant, technology, generation capacity, and other factors

 

– Both Are Amongst The Most Expensive Water Sources In Terms Of Price To Produce Water

Referencing the mercurynews.com report again, seawater desalination, indirect potable reuse, non potable reuse, brackish desalination, and stormwater capture are the most expensive water sources to produce water from

Surface water and ground water are the cheapest

 

– Both May Have Large Potential For Production When Considering The Type Of Water Inputs They Use

Desalination can use seawater as a water input, and roughly 96.5% of the water on Earth’s surface is covered by ocean

Additionally, water recycling uses various types of waste water as a water input, and up to 80% of wastewater worldwide might currently be discharged without being treated or recycled

 

– Both Might Be Considered As ‘Climate Independent’ Water Sources

Surface water sources and groundwater sources generally need rainfall in order to replenish (although, there’s exceptions, such as ground water replenishment schemes)

Desalination and water recycling on the other hand do not rely on rainfall or the climate to produce water (this might make both sets of technology beneficial for water scarce or water stressed countries and regions) 

They do however rely on having water input, and rely on energy in order to operate

 

Desalination vs Water Recycling – Which Is Better?

Which one is better can depend on a range of factors and variables that will ultimately differ between individual cities or town, and what might be best for the potential water issues they face, and their overall water supply strategy.

From a ‘price to produce water’ perspective, seawater desalination might rank as the worst if it leads to businesses and consumers paying more for their water.

However, there’s a range of other factors to consider, such as:

The cost to set up and operate each water source

How much seawater, brackish water, or waste water each city or town has access to 

What the laws and regulations are in the area

The knowledge and expertise available to utilize and operate each type of water technology

Plus, other factors

 

There are cities around the world that use both desalination and water recycling as part of their overall water supply strategy. Perth in Western Australia might be an example of this.

 

Potential Pros & Cons Of Desalination, & Water Recycling 

Potential Pros & Cons Of Desalination

Potential Pros & Cons Of Water Recycling

 

 

Sources

1. Various ‘Better Meets Reality’ guides

2. https://www.mercurynews.com/2019/09/27/100-million-desalination-project-to-be-led-by-lawrence-berkeley-national-lab

3. http://nas-sites.org/waterreuse/cost-of-water-reuse-projects/

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