Wastewater Smart Networks How to Achieve Zero Pollution, Zero Flooding and Net Zero GB Patent 1718576.0

Introduction

This month will see the publication of a new British Patent that could aid the world move one step closer to creating retrofit Smart Wastewater Networks to achieve zero pollution, flooding, and net zero, without breaking the bank.

Every year in the UK, there are over 400,000 pollution incidents recorded from overloaded sewers, where millions of cubic meters of sewage, laden with plastics and microplastics spill into our streams, rivers, and oceans via thousands of Combined Sewer Overflows [CSOs] and sewage treatment works storm bypasses. Furthermore, hydraulic overload within the network causes sewer flooding that affects tens of thousands of properties per annum.

After many decades of lobbying, delays, and deliberation the UK Government has recently passed into law a new Environment Bill which mandates the eventual eradication of pollution and flooding from our sewage networks and treatment plants. The primary cause for this delay we believe has been cost, with estimates varying wildly from ￡40bn to ￡400bn and the fear of the knock-on effect on water bills.

Without doubt, this will be a massive undertaking that could ultimately dwarf civil projects such as HS2 and call upon a multiplicity of traditional engineering disciplines from hydrologists, modellers, planners to civil engineers. However, need it all be implemented using concrete, pipes, storage tanks and decades of disruption to highways, plus with the emission of millions of tons of CO2 in the process?

This month sees the official publication by the IPO of patent GB1718576.0 that covers the design of a key element to creating retrofit smart wastewater networks, without having to rip-up and replace thousands of km of sewers and hence offers the potential to slice billions off the cost of network upgrades.

Smart Networks in Sewer Flow Management

Conventional sewer networks are open loop systems where rainwater and sewage enter and one end and under gravity make their way to the sewage treatment works. However, as seen by the statistics this is not always the case, as too often hydraulic overload during rainfall leads to pollutive spills from CSO overflows, flooding into properties and overloads at sewage treatment works.

A smart network in its simplest form is where we add an up-stream flow control device, a down-stream level sensor and a feedback path between the two, to create a closed loop control system, that harness up-stream storage to implement peak flow control / flow modulation to reduce overloads.

?Smart Networks & Carbon Reduction

The viability of any sewer flooding or CSO overflow reduction scheme will ultimately be determined by the benefit delivered vs its cost, the latter of which now has to factor in imbedded carbon.

The most significant costs, disruption, and carbon emissions are generally attributable to civil works. Hence reducing the amount of civil works must and one of the key motivators behind the creation of smart networks.

However, low carbon, cost and minimal disruption can only be delivered if the smart network design is created around the exiting sewer network, rather than the existing network having to be modified to accommodate the smart network upgrade.

Practical Smart Networks

The sensors required to create smart networks have been around for over a decade, these include fully integrated devices with wireless communications such as the Radio Data Networks BDT transmitter, which has been used extensively in the creation of numerous smart networks using pumps and motorised penstock valves.

However, after observing first-hand the disruption and cost of installing a motorised penstock into an existing sewer network it was clear that there was plenty of scope for improvement. This led to the formulation of the “must have” list below which became the key ingredients behind the design of the sewer flow regulator [SFR].

The key design constraints for a retrofit flow controller for a smart network:

Dimensional?????????????Installable via an existing access chamber cover

Weight ??????????????????????Lightweight easy to install by hand without cranes

Hydraulic ??????????????????Offer a simple on-off flow control, with sealing of typically better than 95%

Retrofittable ????????????Mount over the existing invert and not require it to be modified in any way

Flow ????????????????????????????Be installable while the sewer is still in service

Maintenance ???????????Once installed be serviceable from the surface without the need for confined space entry

FOG & Rags ?????????????Include a facility to wipe and self-clean the mechanism of rags and FOG

Fail safe ????????????????????In the event of failure in the closed position include a safety bypass

Override ????????????????????Include the facility to manually override operation from the surface

Electrical Safety ?????Not require any electrical supply within the chamber

Speed of Install ????????Target installation time to hours rather than days to keep road closures to a minimum

Low Carbon ?????????????Minimal imbodied carbon and low energy solar operable

Controllability ?????????Be agnostic to any smart sensor that offers a simple open/close binary type of control

Fault Reporting ??????Be able to detect and report defects

The sewer flow regulator, has since been deployed at several location and has been scaled for installation in 4in (10cm), 6in (15cm) and 8in(225mm) inverts. Operating from compressed air the SFR has also permitted the control air lines to be run between the chamber and a small roadside control kiosk in shallow saw cut slits, backfilled with resin.

Communicating (feedback) around a Smart Network ?

We previously touched on the need for feedback in a smart network. The distance between the various parts of a smart network can vary vastly. Our experience to date has shown it can be from just a few hundred meters to several km, with paths passing along streets and though buildings making cabling impractical.

Wireless communications provide the ideal medium for the control and feedback. However, from a closed-loop control and cyber security perspective, it is essential that the smart network created should have the ability to operate autonomously with direct feedback and in real-time.

Independence from the 3rd party networks and especially the internet is highly recommended.

In addition to carrying the various control signals the feedback network should include a regular “heartbeat” or “health message” so that operational status of all elements can be monitored and reported 24/7/365.

Finally, if IoT or telemetry is required, we strongly recommend this is only limited to this condition monitoring and reporting and is kelp out of the control loop.

In the case of our smart network deployments, we have obtained radio licences from Ofcom over which the networks operate on legally protected and exclusive radio spectrum, unlike IoT such as Sigfox or LoRa which has no protection whatsoever from jamming, by other users of overload from its own traffic.

Smart Sensors for Smart Networks

The actual control function provided by a smart network sensor need not be anything more than three states: Level Normal, Level High and most importantly Fault.

In sewers, what you can be certain about is a lack of power and if you want power, it will be costly and come with many safety implications due to the presence of potentially explosive and highly corrosive atmospheres. Hence the need for smart sensors and wireless combinations that are ultra-low power and battery operated.

Conclusion

The sewer flow regulator [SFR] is an invaluable tool for the Wastewater Industry in the creation of smart networks, without having to rip-up and replace thousands of km of sewers or drains.

The many virtues of the SFR have already successfully been demonstrated by several deployments from which the feedback to date over ease of installation, which in all cases included the ability to use the existing networks, has reinforced our claim that many billions could be sliced off the cost of achieving zero pollution, zero flooding and net zero, by retrofitting smart networks using the SFR as the control point.

Smart Sensors are mature too, with sensor like the Radio Data Networks BDT and Wireless Float Switch demonstrated reliable in providing the necessary autonomous feedback for the closed loop control required in the smart network.

Smart networks can also act as automatic flushers to reduce septicity, dislodge FOG and regulate flows into sewage treatment plants to improve efficiency too.