Volatile solids content – substances that can easily transform from a solid to vapour without going through a liquid phase – in UK sludge is already over 50% higher than it was in the late 1800s, with a resultant increase in contaminates in the ground and fresh water. In the future, we can only expect both the volatility and volume of sludge to increase further, and costs and complexity to grow in parallel. Fergal Campbell, CustomCare Manager at waste specialists CDEnviro, looks at what can be done to tackle the sludge problem.
The characteristics of the sludge that the wastewater industry has to treat is determined by a wide range of factors. These include regulations, water use and environmental factors, changes in type and quantity of industries within catchment areas and the recycling habits and wealth of the general public, along with population increases and new developments being added to the wastewater network. In practice all these mean volumes increase rather than decrease, so the treatment and disposal challenges also intensify.
Sludge management – a key driver
With continued population growth expected in the next 50 years, along with an increased demand on infrastructure, sludge management will become, where it hasn’t already, a key driver within the planning of all new build treatment works or refurbishment plans within the wastewater industry.
The increase in population will place enormous strain on the current methods of sludge management. Water UK reports that 80.3% of sludge is recycled to land, 18% disposed of through thermal destruction and 0.7% went to landfill.
If we continue to see the trend for urbanisation and increasing city sizes, the cost of transporting sludge to suitable land will increase to unsustainable levels. The result will be that there will be such a demand for suitable land, that the owners will begin to charge disposal fees.
Based on what land agents and other parties with experience of disposal costs gauge as a fair price we, could see these costs shift significantly which will also be true of landfill methods, as the costs per tonne will become prohibitive.
This could well lead to large scale privatisation, along with an increase in cost to the tax payer, as private operators invest in sludge management facilities and take on the process of sludge management and remove the onus from the main water companies.
This change is likely to be long and protracted, similar to the nuclear energy debate that has been occurring over the past few years, as the reality is that no-one wants this type of facility near their property due to negative perceptions, possible noise and/or odour issues, increased vehicle movements and negative effects on property prices.
Making the most of sludge
Whoever is responsible for dealing with sludge in the future, will need – as they do now, the most effective processing solutions. The latest machines are able to eliminate blockages, so any downtime processing sludge is minimised. They also have high processing rates, which means that high-frequency vibrations break the surface tension on the sludge and allow it to be processed very quickly.
The wastewater industry has limited control over the volume of sewage it receives and the amount of sludge produced, but it is clear that the sludge issue isn’t going anywhere. However, by using the latest innovations in screening and processing, companies can reduce costs and maximise efficiencies while we see what the future of sludge brings.
www.cdenviro.com
