In this module, you will hear about how particle removal is a very important step in water reuse and is present in almost all water reuse applications. We will show how this can be done in a smart way using ultrafiltration and by adding intelligence to the water reuse system.

At the heart of a water reuse process is an ultrafiltration unit for particle removal.

The ultrafiltration membrane technology is defined with a pore size between 0.01 and 0.1 micrometers. This ensures that all suspended particles and bacteria are removed. Depending on the level or mix of organic and inorganic content in the wastewater, other treatment steps can be added as required on the feed-side and the filtrate side. The water is then ready to enter the next stage of the reuse treatment process.

Let’s look at the feed-side and the backwash side of the ultrafiltration unit in more detail.

The filtration cycle starts by pumping the pre-treated water through the ultrafiltration membranes. Ultrafiltration systems work most of the time in filtration mode while in operation. Optimal filtration membrane performance requires a constant flow. This can be achieved via a speed-controlled pump. At some point, it will be necessary to carry out a backwash to clean the membrane, because impurities and fouling material will block its porosity, and the transmembrane pressure (TMP) will increase.

The backwash cycle is used to clean the membrane, usually by pumping the ultrafiltered water product in the opposite direction to the filtration flow, to flush all foulants in the membrane.

Often done on the basis of time-in-production or per batch (for example, after a fixed amount of filtered liquid), this process can be inefficient, as cleaning happens at fixed times, also when there is no need, using valuable already-filtered water.

Chemical-enhanced backwash increases cleaning effectiveness by adding chemicals such as chlorine or an acid or base solution to the backwash flow, depending on the foulant. This requires precision dosing not only for the effectiveness of the process but also to reduce chemical use.

With intelligent control you get high efficiency in the backwash process.

The air-scouring cycle is used to loosen particulates deposited on the outside of the membrane surface.

Whatever the reasons behind a decision for adding a water reuse system to your industrial processes, you must consider the total cost of ownership of the system. In addition to the ultrafiltration, the processes on the feed-side and backwash side and the energy costs, the total cost calculation also includes the cost of chemicals, consumables, work hours, amortisation and downtime.

These are all areas that can be optimised through a smarter and more intelligent approach to the ultrafiltration-based water reuse system.

For example, on the feed side in an ultrafiltration system, an intelligent solution includes sensors for pressure, flow and chemical parameters.

On the backwash-side, there are also sensors for pressure, flow and chemical parameters.

Intelligent pumps have built-in monitoring and fault prediction, a flow meter and pressure monitoring.

Remote connectivity to PLC, Cloud and Internet of Things (IoT) solutions provides access to data visualisations and predictive maintenance services.

Furthermore, Grundfos is working on an operational ‘digital twin’ of critical process which will run via an IoT platform. This means you get auto-adaptive control of flocculation, scaling, fouling, filtration, backwash and cleaning.

Let’s summarise the potential benefits of our intelligent approach, which we call Grundfos iSOLUTIONS, by presenting the following scenarios:

Reducing chemical use:

-Digital dosing pumps ensure precision dosing, saving on chemical use and ensuring optimal usage of chemicals

-The intelligent use of flocculant reduces the amount of sludge produced while optimising the performance of your filtration system

-Whenever there is a risk of scaling and fouling, an intelligent backwash can be implemented.

This optimises the amount of chemicals and water used during the cleaning process.

Cost savings on resources:

- You get savings on water, energy and chemical use

-Your chemically-extended backwash is according to system demands

- The optimised system gives you better control of your chemical storage, the ordering can be done on demand by the system towards your ERP systems

Process optimisation:

-The optimised control of the interval between filtration and backwash saves water and energy and extends the lifetime of your ultrafiltration membrane, increasing the overall efficiency of your system.

-No matter the changes or variability in the raw water quality, the intelligence built into your system will adapt to keep conditions and performance optimised

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

- An ultrafiltration unit sits at the heart of a water reuse system

- Optimising the system on the feed-side and filtrate side of the ultrafiltration unit means you save on the total cost of ownership

- An intelligent system approach gives you efficiency gains and cost savings for flocculation, scaling, fouling, filtration, backwash and cleaning.