Water 4.0 and the wastewater cycle
To make a success of Water 4.0, the industry needs to work from the bottom up, installing the right monitoring equipment to capture the data required to make the right decisions, writes Oliver Grievson
by Oliver Grievson, Director, Sensors for Water Interest Group (SWIG)
The water industry is in a phase where it wants to get smarter. There have been recent steps towards a “digital water industry” being driven by political will. However, the concept of the smart water industry - or Water 4.0 - has to be driven from the bottom. The right infrastructure and the right sensors need to be in place so that the right data is being collected to drive informed decision making.
The recent Sensors for Water Interest Group workshop, hosted by ABB, discussed where we are as to the state of wastewater monitoring and how this can be used to drive the industry to something approaching Water 4.0.
Firstly, monitoring needs must be identified to help the industry deliver a holistic approach to its wastewater operations. From the customer’s home to the treatment works, there are existing monitoring solutions that can be used.
The journey of water and its points of entry into the collection network are largely unmonitored at present, but one of the fundamental challenges is to attempt to measure what passes through our collection networks each and every day. Apart from customers, one of the almost unmonitorable inputs is from rainfall. Technology is certainly moving on in this area though, with rainfall radars, advanced rain stations and advanced analytics platforms able to measure the type of precipitation. Add in artificial intelligence and machine learning and there is the ability to measure the impact on the sewer environment and adapt network operations to suit.
Once water is in the sewers it has two routes: the first through the gravity system (which most people think of when they think of sewers), and the second through the pumped wastewater network. Monitoring of the gravity system has been virtually impossible in the past, but through work led by the University of Sheffield we are seeing developments in this area. Work on free surface dynamics, acoustic holography and microwave sensing show the potential for measuring free-surface flow within the gravity system allowing us to picture what is going on in the sewer network. The work is ongoing but the results so far are promising.
The pumped network
Developments are a little further ahead within the pumped wastewater network and flow meters are actively being installed at the current time. There is also experimental work happening in collaboration within the water companies. Lorenzo Pompa of Anglian Water and Mark Hendy of Syrinix are specifically looking at what can be done with pressure monitoring. It’s a technique that has been used for many years in the water distribution network but is not yet used in the wastewater collection network. Centred around Anglian Water’s Shop Window the work is ongoing to see if high frequency pressure monitoring on the rising mains to the wastewater treatment works can be used to predict mains failure. If this can be predicted in advance, damage to the infrastructure can be limited and pollution events avoided. In the case study presented, a slow failure of the rising main was shown, which caused a large crack to develop in the 600mm rising main that caused a failure of the pipe. Luckily the monitoring in place was used to avert a pollution event, aptly demonstrating the usefulness of the technique.
Characterisation of the collection network is the first step towards Water 4.0 and control of the network leads to overall improvements in the water environment but with sensors at the heart of Water 4.0. We have to ensure that the data that is received is correct or the analytics engines that will take the data will produce information based upon false assumptions. It is only with good quality data that there are the possibilities of optimising the processes that are within the wastewater system as a whole (Figure 2).
Clogging, poor installation, fouling, lack of calibration and the challenge of managing the up-time of instrumentation are challenges to the industry in Water 4.0. These are issues being actively worked upon by instrument manufacturers trying to limit maintenance requirements, install cleaning systems and provide instrumentation installation advice to enable companies to eliminate the major sources of error. The next step is helping the companies with their Calibration & Maintenance Management Systems (CMMS) and ensuring that what is in place is recording accurately.
The online and laboratory instrumentation manufacturer Hach has gone one step further with their Claros system, which in part has the ability to tie laboratory and site data together making sure that the reading at time of sampling is correct. The Claros system as a whole is there to support the instrumentation life cycle from mobile sensor management to predictive diagnostics and onwards to onsite visualisation and display helping operators to understand the operation of the wastewater treatment works on a holistic basis rather than element by element. Looking at the holistic approach allows the improved management of the works and potential for the installation of real time control systems.
It is the control system element on the treatment works that is vital. Whether you look at instrument-based process control or holistic management via multi-variate process control, some of the challenges have always been sensor based and how they cope in a harsh environment. Some of the challenging aspects of measurement have always been organic load/Biochemical Oxygen Demand and the actual performance of secondary treatment where Activated Sludge Plants are the secondary treatment process.
To a certain extent, it has been a case of designing the concrete box correctly and letting the biology look after itself. Technology has moved on, and where fifty years ago the use of respirometry was experimental at best, it is now actively being used as part of a multi-parameter activated sludge plant control system. This allows the more efficient operation of this part of the wastewater cycle. Couple this with final effluent BOD monitoring and it is possible for the treatment part of the wastewater cycle to be finely tuned to maximise the treatment whilst also maximising the efficiency.
The instrumentation level is one of the key fundamentals of Water 4.0 and there is a need to ensure that this level is producing good quality data for the more advanced techniques that are starting to appear in the water industry. If we, as an industry, want to make a success of Water 4.0 then this starts at the instrumentation level; by ensuring the quality of the data is correct. This can then lead to a future in the water industry with a huge potential to maximise the efficiency of our operations.
The flip side of course is that the data is wrong and so the assumptions based on the data are also wrong. Then the industry faces a future where we have a “resistance to the effective use of instrumentation” and are stuck in a cycle where technology “doesn’t work” and the future becomes a lot more bleak as the pressure of demands for greater and great efficiency start to bite.
-This article appeared in the September 2018 issue of WWT magazine
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