Clean Seas Please had a tour of the Southern water Treatment Works in Hastings, which cleans the water for Hastings as well as Bexhill.
have a look at our video and read about our visit and the different stages the water goes through here:
The Bexhill and Hastings Wastewater Treatment Works and sludge recycling plant.
Southern Water’s Bexhill and Hastings Wastewater Treatment works serves approximately 150,000 people across Hastings and Bexhill.
The treatment works receives flows of around 922 litres every second during dry weather but this can rise to more than 1,500 litres a second during wet weather.
The wastewater passes through four stages of treatment before being released out to sea.
It takes 8-12 hours to go through the treatment process – around two hours at each of the four treatment stages.
These stages are:
– Screening and grit removal facilities
– Primary settlement tanks – called lamellas
– Aeration tanks
– Final settlement tanks
For the sludge treatment:
– Sludge thickening plant
– Sludge digestion plant
– Sludge drying and recycling plant
– Odour control plant
The treatment works runs 24/7, 365 days a year.
The main treatment building houses the inlet works, preliminary treatment and sludge handling facilities.
At the inlet works the water arrives and undergoes treatment through screens which remove fat, oils and grease from the wastewater as well as items such as wet wipes which have been flushed away.
Grit, mainly from roads, is then removed in the aerated grit lanes and taken away for disposal at landfill.
The five primary settlement tanks, called lamellas, are 13 metres long, seven metres wide and seven metres deep. They settle the majority of the remaining solids out of the wastewater – called sludge. This primary settlement process separates the sludge and wastewater into two separate sets of secondary treatment.
Wastewater secondary treatment
The secondary treatment process begins in five aeration tanks, which pump air into the wastewater to encourage bacteria which digests the waste to thrive. The tanks are 13 metres long, seven metres wide and eight metres deep. After the biological process, the water is passed through a final stage of settlement to filter out finer particles of solids before the cleaned wastewater is released to sea through the 1.5 mile long sea outfall.
The site’s sludge treatment centre treats about 45 tons of solid waste every day – turning it into an organic soil conditioner.
The first stage in the sludge treatment process is the thickening plant which removes water from the sludge before From here it passes through large treatment tanks called digesters where bacteria literally eats the waste. Large centrifuges separates the dried sludge, liquid lime is injected to the digested sludge to create a cake that is used as an organic soil conditioner.
Combined Heat and Power Plant
Methane gas produced during the sludge treatment process is converted into electricity by a Combined Heat and Power Plant. It produces enough electricity to power 1,500 homes but the power is actually used to run many of the processes on site. This gas, which would otherwise have been burnt off in a flare, is now being used to produce renewable energy – providing power and heat to the works, with any surplus exported to the National Grid. As well as generating electricity, the CHP plant also recovers heat from the engine and exhaust systems via water from heat exchangers. This water is then used to warm the treatment tanks, helping speed up the bacterial digestion of the waste. The plant reduces the works’ carbon emissions by 3,000 tonnes a year.