Oliver Grievson, Flow Compliance & Regulatory Efficiency Manager, Anglian Water explores what it means for a wastewater network to be “Smart” and how it can help the water industry to make better, more informed decisions about how to operate the wastewater network.

Oliver Grievson: What does it mean for a wastewater network to be “Smart”? What is the wastewater industry hoping to achieve by going on a “Smart” Journey?

It is a subject that has rattled around the water and wastewater industries for many years and yet most of the focus has been on the potable water network side of the business where the obvious gain is reducing non-revenue water. However in the past few years the value of acting more “intelligently” in the wastewater network…nay the wastewater system has come more to the forefront as the value of taking a similar journey to our potable water colleagues comes to bear.

The question is though, where do we start? The wastewater network is a complex system as it has multiple inlets and multiple outputs (if you take storm overflows) into context. The answer from some of the water and sewerage companies (WASCs) and consultants working with them has been to take a number of different approaches as we have recently heard at a number of conferences and workshops in the area of Smart Wastewater Networks.

Starting small and from the ground up

The major problem is understanding what exactly the problem is and from where it comes from - and in doing so, devising a strategy for its resolution. Is the problem related to:

• Flooding of both internal & external properties
• Pollution incident detection and management
• Alarm handling and response
• Blockages & sewer misuse
• Asset reliability & the cost of running the network
• Sewer capacity and storm overflows
• All of the above
• Weather radar and modern rain gauges
• Sewer Level Monitors
• Centralised sewer network model capable of fast simulation
• Communication and telemetry systems to tie it all together

It is in fact a combination of all of the above, and there are various teams in all of the WASCs handling different aspects of what has to be done to protect the customer and the environment.

One of the major issues is that of sewer misuse - from fats, oils & greases (FOG) to the wonderful aspects of what people throw down the supposed “wet bin,” Any network technician in the industry will talk about FOG and unflushables as a major problem that has been attributed to 50% of all pollution incidents and 66% of all flooding incidents for one of the UKs WASCs.

The solution is of course education and working with customers to understand the consequences of putting the wrong thing down the drain. However, there are technological solutions to the problem as well. A recent SWIG workshop on Smart Wastewater Networks heard from one engineer his vision of building the technological solution up from the bottom by using a combination of pump reversal modules that reverse the pump to clear blockages on an automatic basis, to restarting pumps to providing flow meters to detect whether a pump is actually working or not.

The effect is to increase the technicians' visibility of what is going on in the network and enable them to be more effective in their diagnosis of issues. The customer can therefore be protected in a more efficient manner but the technicians' Health & Safety can also be improved by ensuring they are not called out to a false incident in remote areas in the middle of the night.

And getting bigger….

Working on the small scale has its value but of course it won’t resolve all situations.There is a place for increased monitoring in the wastewater network, the major benefit being the protection of the environment. This is where the Event Duration Monitoring programme comes in - one of the focuses of the water and sewerage companies during this Asset Management Period (AMP). It stems from a Ministerial Direction that promised the monitoring of the “majority” of storm overflows by 2020. The knowledge about these assets and their performance has been questioned.

The subsequent impact on the environment is a big question that the Minister and the Environment Agency want answered to find out the inherent problems that lie in the wastewater collection network. Over the next few years teams of people will install thousands of monitors, prioritised so that the highest impact areas are completed first to monitor when, where and for how long spills from the wastewater network are happening.

The first storm overflow monitors have already been installed. From the first year’s worth of data approximately 12% of combined storm overflows warrant further investigation based upon their current performance. Depending upon the results further investment within the network infrastructure may be driven. A key consideration for the future will be to evaluate the impact that schemes have on the water environment as a whole to see what improvements can be made, and the quality of future discharges from our wastewater treatment works.

…..and bigger

Taking a step on from the monitoring of the network the next question that has to be asked is what we can do to provide a more strategic management of the wastewater network. It is an approach that has been taken in Europe for many years. The multiple reports by UKWIR & Mouchel on Active System Control describe in detail what work needs to be done and what has been done in other countries. A great example of this is the work in Denmark that has been done to provide an overall management of the wastewater network using high speed modelling techniques that allows the wastewater network to be managed more effectively.

An example of this is the work that was done in the Southern Water region of the UK in the Eastney project that has used a combination of modelling techniques and rainfall radar as part of the solution to mitigate the risk of flooding within the area. This was part of a much wider solution that included green infrastructure.The Smart Wastewater Network gives the company advanced warning of what is going to happen moving forward and allows the company to make decisions on methods of operation of the pumping station - a critical part of the overall wastewater treatment system.

The individual parts of this project form building blocks to what the Smart Wastewater Network is made up of including (in a simplified way):

• Weather radar and modern rain gauges
• Sewer Level Monitors
• Centralised sewer network model capable of fast simulation
• Communication and telemetry systems to tie it all together

The weakness- if anything - is the quality of the weather radar systems but this data as service is a solution that others within the water industry are looking at – a couple of years ago high quality XRF weather radars were investigated by the University of Delft and weather data and prediction has become a data service within the water industry. It is the impact of the weather radar and using the data from the rain gauges that will allow for predicative models to look at the impact onto the “Smart Network” to help the industry to manage the flows that we receive.

The future of Smart Wastewater Networks – a holistic approach

The ultimate aim of a “Smart Wastewater Network” is to help the water industry to make a better, more informed decision about how to operate the wastewater system by facilitating the flow of wastewater through the entire system all the way from the customer’s toilet, through collection, into treatment and out to reuse or recycle in such a way that we optimise not just the cost of the whole process but the impact that it has on both people and the environment.

Operationally, this is by limiting events such as pollution incidents and flooding to either zero, the brave aim of the future, or to as near to zero as we can possibly get. This can be achieved and we are seeing water companies take this approach now with a number of different technologies. For example a simple “Customer Flood Alarm” that warns of rising levels in areas of known problems so that priority issues can be dealt with. Other useful technology includes systems that can stop pump blockages and warn of problems such as using pump reversing, monitoring of pump currents and using flow meters to give a true picture of what is happening.

The strategic direction is looking at the much wider more encompassing systems and the advantage here is to limit the capital build of detention tanks in the network and storm tanks within the treatment works. The best case of this was in Barcelona where a Smart Wastewater Network was constructed for the Olympics in 1992. The alternative was a vast detention tank under the centre of the city and the Smart Wastewater Network approach was the considerably cheaper option.

From a holistic point of view the treatment works must be brought into the equation too and it is at this point, bringing together two aspects of the industry – network and treatment, where the real savings can be made. By controlling the flow of water through the whole system and limiting the environmental impact of the wastewater systems we can truly get more for less.

So, what does this wastewater system of the future look like?

In normal day to day conditions the smart wastewater network of the future controls flows by flattening out the flows that are received at the wastewater treatment works and monitoring how much time sewage spends in the network. It is also aiming for a completely flat flow profile at the treatment works, with regular automated flushing cycles to ensure that the sewer keeps as debris free as possible, controlled by sewer level monitors to pick up unusual levels that might highlight blockages starting to develop.

Various tools are used to keep the problems at bay such as pump-reversing and flow monitoring to ensure that the flows keep moving and pumps don’t block. Where problems are starting to appear and hot spots start to develop this drives an alert to look into potential sewer misuse. Combined Storm Overflows from the system are dry.

Flows pass forward to the treatment system where the relatively uniform flows enable an efficiency in the treatment and the virtual elimination of the need for treating peak flows. This enables a uniform production through the process which further improves the treatment efficiency.

The system predicts a rainfall event and this is where the intelligence of the system kicks in. The prediction is that the sewer in its current state can’t manage all of the flows within a 6 hour period and the system re-calculates and ramps up flows minimised so that the required capacity of the sewer is available with an appropriate safety margin. The flows are managed and held within the sewers. The CSOs are still dry. The rain-storm continues longer than predicted and this causes a potential problem at a customer’s premises. This causes an alert in the control centre and allocates a team to resolve the issue for the customer so that an incident doesn’t happen.

The wastewater system of the future - in reality not that far away

Now this is a fictional potential system of the future but what we have heard at various workshops and conferences is that this is a future that in reality isn’t that far away. The technology exists from the sewer alarms, pump-reversing systems and the potential for network flow monitoring as well as event duration monitoring on the network as well as the customer flood protection alarms. Taking a step up in complexity the weather radar systems, network model and active system controls systems also exist and finally the analytics and visualisation systems also exist  so that the vast amount of data that is inevitably produced is shown in a way that can be understood and actioned upon.

It’s a system that is starting to be developed by some of the water companies and more recently we have seen the development of the factory approach that was famously mentioned in the STOWA report of the wastewater treatment works of 2030. Arguably things have gone in a slightly different direction, and the energy, water and nutrient factories have their “production efficiency monitoring system,” which any other industry would consider its absence, at best, unwise. The approach is of course working fantastically well and the extension of this approach to the wastewater network is just another step to a “Smart Industry” future. ‘Industrie 2.0’?

The next SWIG workshop will be ‘Specification & Installation of Sensors on 3 May, Principality Stadium, Cardiff. For further information see www.swig.org.uk The Sensors for Water Interest Group (SWIG) is a not for profit, knowledge-exchange and networking group with a diverse UK-wide membership which holds cost effective events covering all aspects of water sensing.