In this module, we will look at the importance of understanding the water matrix, types of industrial processes and different types of water, so that you can identify the kind of water treatment and water quality requirements for the water reuse system.

Before we talk about Industrial water reuse processes, let’s briefly discuss water treatment. Water treatment describes processes to make water suitable for a desired end use. These can be for drinking water, industrial processes, medical purposes and many more.

Water treatment involves content removal and adding content, depending on the given and the required water quality. All else is water transfer – meaning the water intake before treatment, and water distribution after treatment.

If you wish to find out more, please go to the ECADEMY course ‘Industrial water treatment’ for a general introduction to water treatment in industrial processes, including a more detailed survey of the different process steps.

For any industry, there are a number of important aspects to consider when designing a water reuse process. These include:

* Available technology: does the applied treatment process produce reuse water with quality fit for purpose?

* Safety and reliability: will it operate reliably, and ensure quality demands?

* Legal and regulatory: does it have the necessary approval from relevant authorities?

* And economy: does it have a good business case?

There are various ways of establishing water reuse in industrial facilities, depending upon where and how water will be reused. Some industries will have ‘in situ decentralised water reuse’ at specific industrial processes. This decentralised approach may be preferred as it allows better process control and low investment cost. Alternatively, ‘end-of-pipe wastewater treatment & reuse’ allows for larger volumes of water to be reused, which for example can have a greater impact on reducing water footprint. However, this approach comes with heavy investment and executional complexity.

It’s equally important to consider where the recycled water should be used.

This impacts the selection of treatment technology, economy, as well as the legal aspects of water use. Often, water is reused as technical water within utility areas such as boilers, cooling towers, CIP and so on.

As there is no or minimal product contact, this provides a low risk application as well as least reuse resistance. Water reuse in the industrial core process does have product contact, and therefore has to go through a number of quality control and reliability checks and is subject to regulatory concern. In some cases, if the industry is unable to reuse water, they can simply choose to deliver recycled water to other nearby industries or for other purposes.

When designing a suitable water reuse process, it is essential to understand your water source, the given water quality, the contaminants present in the water, and whether the load type is organic, inorganic or mixed. You can then identify whether the water matrix is complex or simple.

Furthermore, the intended use following the reuse process defines how deep we need to go in the treatment process and what constitutes an adequate treatment method. At this point, the industry sector can be matched to the water matrix to show which treatment strategy is required.

Industries with primarily organic content loads include:

The food and beverage industry generally has high loads of organic content which is relatively easy to treat.

More difficult but less heavily-loaded is pharmaceuticals, where removing specific substances may require special treatment.

Pulp and paper industrial processes on the other hand normally have high solids content and are more likely to require filtration. "

For industry segments contending with inorganic wastewater, salt content is in general the most usual contaminant:

This is true for the steel, automotive mining, marine and semi-conductor industries, as well as power plants.

Chlorides, Sulphates and such like create a high salinity, leading to high pressure demands in the treatment required, for example with Reverse Osmosis and Nanofiltration.

 Heavy metals, poisonous substances and radioactivity from mining provide special challenges not only for water treatment but also for solids handling afterwards.

Mixed organic and inorganic loads include the chemical, plastics, print industries, recycling and petroleum industries, as well as industrial parks.

The textile industry is an example of a segment with mixed loads, however this is because the water has organic and inorganic contaminants depending on the production step.

"Let’s recap what we have presented in this module:

-The importance of understanding the water source, given water quality, the contaminants present in the water, and whether the load type is organic, inorganic or mixed

-The various aspects to consider when designing a water reuse process

-How industrial water treatment must always be matched to the desired end use

-Matching the industry segment to the water matrix and seeing which treatment strategy is required