The Latest Innovations In Wastewater Treatment
Typically, urban wastewater (or what we commonly refer to as sewage) is a mixture of domestic wastewater from baths, toilets, sinks and washing machines, as well as wastewater from industry and rainwater runoff from impermeable surfaces like paving and tarmac.
More than 11 billion litres of wastewater is collected from sewers all over the UK each and every day, which is treated at around 9,000 different sewage treatment works before the treated effluent is then discharged into inland waterways, estuaries and the sea.
If this treatment process didn’t take place, the wastewater produced each day would damage the water environment and cause all sorts of public health problems.
Untreated sewage has a lot of organic matter in it, such as proteins, fats and carbohydrates, as well as chemicals and bacteria. These are broken down by bacteria naturally present in watercourses, but the bacteria uses the oxygen dissolved in the water to achieve this.
As such, if there is too much or continuous untreated discharges of wastewater into natural water sources, the end result would be too little oxygen for aquatic life to survive. Wastewater treatment is carried out in order to remove these organic substances and afford the natural environment greater levels of protection.
However, with climate change now taking serious hold, the UK is expected to see more frequent extreme weather events such as heavy and intense rainfall and more flooding, all of which puts extra pressure on our already-struggling sewer network.
This means that when pipes are hit with a sudden influx of water, they can easily become overwhelmed by it, so water companies release permitted amounts of untreated wastewater into the natural environment to ease this pressure on infrastructure.
With the WWT Wastewater 2022 Conference having just been held online on January 25th, there’s no time like the present to take a look at what work is being done to help the water industry make improvements where wastewater treatment is concerned… so here are just some of the latest innovations and developments taking place around the country.
Cold anaerobic wastewater treatments
A collaboration between Thames Water, United Utilities, Welsh Water, South West Water, Yorkshire Water, Scottish Water, Northumbrian Water and the University of South Wales has seen two cold anaerobic wastewater treatment processes tested out to try and decarbonise the practice and boost resource recovery.
Anaerobic digestion is a low-cost treatment method but it’s typically carried out at temperatures of between 20 to 45 degrees C, which requires energy. Cold processes, however, could reduce the amount of energy required, delivering cost and environmental benefits as a result.
Carbon capture from sewage treatment
Utility company Severn Trent has focused on carbon capture technology to aid its sewage treatment processes, using waste to create sustainable fertiliser.
The firm teamed up with CCm Technologies to use captured carbon dioxide to stabilise organic chemicals, phosphates and nitrogen in waste so it could be turned into plant nutrients.
Rich Walwyn, head of asset intelligence and innovation with the water company, said: “Using carbon capture technology, we’re able to treat waste in a much greener and more efficient way than ever before, as well as getting a fantastic product at the end, which has carbon locked into it.
“This new approach has taken us a step closer to making sure absolutely nothing is wasted in the sewage treatment process.”
United Utilities has been making excellent use of artificial intelligence (AI) and machine learning, meanwhile, to be more proactive in its approach to monitoring and maintaining its wastewater network.
The company’s dynamic network management programme involves using real-time data and AI to identify issues like blockages and rising water before they become too problematic, as well as assessing levels of the system such as hydraulic performance, pump performance and operational performance.
Severn Trent, the Organics Group and researchers from the University of Coventry have been collaborating on turning sewage waste into a valuable green fuel for tankers and other vehicles.
The project involves capturing waste ammonia from a sewage treatment facility and converting it into hydrogen. The benefits of doing this are twofold – firstly, gaining a more efficient processing method for ammonia and secondly, producing hydrogen as a clean fuel.
If the ongoing trials prove to be successful, Severn Trent will be able to recover up to 10,000 tonnes of green ammonia per year from its treatment plants. This could then be converted into 450 tonnes of hydrogen.
What’s going on abroad?
It’s always interesting to see what other countries are up to when it comes to sustainable water management practises, especially when considering the pressures that climate change is expected to bring.
In Malmo in Sweden, for example, an open storm water system has been designed to help wastewater treatment plants during extreme weather events.
The system itself is capable of accommodating a 15-year rainfall event, including ten retention ponds, six kilometres of canals and water channels, a botanical roof garden and 30 green roofs. Natural ditches and reservoirs also collect rainfall, which is then directed into a conventional sewer system
It has been integrated within green spaces that are capable of being temporarily flooded, which helps with water management by slowing flow rates down as water enters the conventional sewer network, as well as avoiding energy use by diverting storm water away from collection systems.
And over in Malta, the Ta’Bakrat urban wastewater treatment plant treats approximately 80 per cent of the country’s wastewater, but it is hit with additional pressures during the tourist season each year.
To ease the situation, investment in treatment technology has been made, with the installation providing up to seven billion litres of reclaimed water annually for agricultural irrigation and aquifer recharge, helping to tackle the problem of water stress and scarcity.