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The Benefits of On-site Sludge Treatment

20 Jan 2021

The Benefits of On-site Sludge Treatment

On-site sludge treatment is a process which saves time and money, reduces waste and makes it much easier to recycle vital resources.

Anyone working in an industry such as petrochemicals, oil refining or steel manufacturing will know all about the problems associated with waste sludge and the legal responsibilities they have when it comes to dealing with hazardous waste, but on-site separation facilities work across a range of other industries as well, such as shipping, food and beverages and wastewater treatment.

In simple terms, sludge is the halfway house between solid and liquid waste, taking the form of semi-solid slurry which the business in question has to store and dispose of safely. In many cases, this sludge will contain, in addition to hazardous waste, valuable resources which are wasted if the sludge is simply incinerated. Here at Separo, we provide bespoke on-site sludge separation systems which can be designed and engineered to exactly meet the requirements of each client, so we know the advantages this approach offers.

Perhaps the best way of outlining the benefits of onsite sludge treatment is to detail the way it works and in particular, how it delivers value in sectors such as oil refining and storage and steel manufacturing.

Oil Refining and Storage

When crude oil is initially sourced and shipped to a refinery it arrives in an unrefined state which means it contains contaminants. Once the oil is on-site and stored in large storage tanks – and is therefore no longer in motion - the heavier and denser contaminants will sink to the bottom of the tank where they form the kind of complex sludge that needs expert management. We have the capacity to deal with sludge of this kind in quantities as large as tens of thousands of cubic metres, both before the refining process has taken place and after, when a much smaller level of contaminants might still be present.  

Steel Manufacturing

When crude iron ore first arrives at a steelworks it is commonly graded, washed and separated with the largest pieces being processed first. In some circumstances, the ore will contain fine, lightweight material which would normally go to waste, but which we can extract, separate and then feed back into the production process. In this way, the in-situ separation facility works in conjunction with the on-site management of the crude iron ore to maximise the resources which can be drawn from cheaper, lower quality ore which would otherwise lead to higher levels of waste.   


As with oil refineries and steelworks, our service for international shipping clients focuses on dealing with waste material in a manner which is efficient and safe while maximising the resources which can be recycled and re-used. When a ship reaches a port the ballast water which has been taken on board has to be discharged, usually into a port reception facility. By this time the water has become contaminated with oil and other solid waste products, and our facilities can take that contaminated material and separate the oil and other contaminants from the water, resulting in clean water and oil which can be re-used. The same processes are applied to any waste oil from the large engine rooms of the ships, which is treated so that contaminants are removed and as much of the oil as possible can be returned to be used again. At each stage, our processes guarantee that the shipping companies in question adhere to the many complex environmental controls which govern anyone operating in this industry, at the same time as recycling valuable resources in a way which saves them money and cuts their carbon footprint.   

Wastewater Treatment

What all of the industries described so far have in common is a requirement for large scale wastewater treatment. This applies to virtually every industry we work with, since managing and controlling water in one way or another forms a part of the vast majority of industrial operations. An oil refinery, for example, will have a wastewater plant or facility on-site, dealing with everything from surface water which falls as rain to the water used within cooling processes and that which is naturally contained within the unrefined crude oil. A steel plant can cover an area as large as ten square miles and utilise water for purposes such as cooling, lubricating and washing as well as dealing with rainfall. Any industry which relies on a steady supply of water will have to treat that water, and this treatment creates the kind of semi-solid slurry which our systems are designed to cope with. Our processes remove the solid matter from this sludge for easy processing and recycle the water present for re-use within the wider facility.   

The Advantages of On-site Separation

No matter what industrial sector you work in within the UK you have a legal obligation to deal with the waste which your processes produce. Non-hazardous waste, for example, needs to be treated at source before being sent away for disposal, with the intention of reducing the quantity of that waste and changing its’ nature.

Where hazardous waste is concerned – of the type produce within an oil refinery, for example – the duty of care is just as strict and the legal obligation is to reduce the amount of waste and minimise the hazard it presents. There is an option to simply gather all the waste and send it to an external facility to be dealt with, but the infrastructure within the UK renders that option both expensive and practically difficult. In France, for example, most manufacturing sites will have a facility that deals with hazardous waste located within just a few miles, whereas in the UK there are only two high-temperature incinerators capable of providing this service nationally.

The good news is that the on-site separation facilities we can provide treat the sludge in such a way that the solid, hazardous part of the waste is separated out and the other 80%-90% of it that doesn’t need to go anywhere can stay on-site for repurposing and re-use. At a stroke, the costs related to the off-site transport, treatment and disposal of semi-solid slurry are cut by 80% or more.  

Because the wider infrastructure for disposing of hazardous sludge isn’t present in the UK for example, on-site solutions bring the equipment and expertise needed to the business which is producing the waste. Let’s look at the benefits more fully:

1. Waste is easier to categorise and assess

Semi-solid slurry, by its very nature, will fall somewhere between the categories of liquid and solid waste. Any process for dealing with waste has to begin with categorising the different substances within that waste in order for it to be coded correctly in line with legislation and doing this with a semi-solid slurry which could contain contaminants such as hydrocarbons is extremely difficult. The separation process simplifies everything by splitting the slurry into liquid components such as oil and water and solids which, once they’ve been separated out, are much easier to manage.

2. Separated waste is much easier to handle  

In many cases, a facility will be dealing with thousands of cubic metres of sludge which might flow easily or might not and could even have different properties depending upon factors such as the presence of thick, viscous or waxy hydrocarbons and external influences such as the weather and temperature. Once this sludge has been separated, however, the solid component can be containerised or even stored in bags and is easy to simply stack or stand without the worry that it could be leaking and contaminating the rest of the facility. What’s more, unlike vast quantities of semi-solid slurry, solid waste can quickly and easily be packed into a truck and taken away to be dealt with. 

3. The overall quantity of waste is reduced

In simple terms, thousands of cubic metres of sludge is a large problem to deal with. If it has to be sent off-site for treatment, then the business in question is facing the enormous cost of moving and treating a vast quantity of hazardous semi-solid waste. The fact that there are only two high-temperature incinerators in the whole of the UK equipped to deal with waste of this kind has the effect of distorting the market, with the lack of supply acting to drive the price of treatment higher. Separating the sludge on-site and then only having to deal with the 10% which comprises solid, hazardous waste cuts the cost to the business and the size of its carbon footprint at a stroke. 

4. The possible hazardous effect of waste is reduced

By its very nature, a semi-solid slurry is a difficult substance – difficult to store, difficult to transport and difficult to control. Once it’s been separated, however, it takes the form of liquids, such as oil and water, which the systems within a facility are set up to handle. As long as the sludge remains sludge there is a risk that it could reduce the capacity and or contaminate the water treatment system of a facility, or that oil could contaminate the water supply.

5. Valuable resources can be recovered for reuse or sale

Using the separation of sludge to recover resources such as oil, water and iron pays dividends in many ways. In the first instance, it means that a valuable resource such as oil, rather than being burned as waste, is being recovered so that it can be reused within the facility. The same applies to water, which is itself becoming a hugely valuable resource. Many businesses are working toward operating a ‘closed-loop’ system for water, which means that the same water is constantly re-used rather than having to be taken from an external source. Our processes make this possible, constantly extracting, cleaning and replacing the existing water within a system.  On-site separation of waste sludge will play a huge role in recycling efforts of this kind, not only cutting costs but also playing a part in reducing the environmental impact of the business in question. 

6. Reduces (or negates) the necessity to store waste on-site

Once the solid waste component of slurry has been separated out it can be packaged, assessed and easily sent away for final disposal. This means that it either doesn’t need to be stored on-site at all or, if it does, that the storage is much simpler, safer and on a smaller scale than that which is needed for thousands of cubic metres of hazardous sludge.

7. The need to transport large quantities of waste is removed or reduced

Many of the projects we work on are location sensitive. This means that they are facilities such as gas holders, which were once built on the outskirts of towns and cities but which, over the years, have seen residential areas spring up around them. Although they may have been off-line for a couple of decades or more, these facilities are still often packed with hazardous waste which needs to be dealt with. By separating this waste on-site and reducing the hazardous component by up to 90% we can massively reduce the number of trucks and the time required to transport the waste from the site. When the fact that these trucks will be travelling past people’s homes and businesses is taken into account, traffic management of this kind becomes a huge part of a project, and the on-site separation facilities we provide make that management much simpler.

A Tailored Approach to On-site Sludge Treatment

We can provide a bespoke on-site separation service which has been tailored to suit the business in question. In some cases, this means helping to deliver a project over a set period of time, with a purpose-built facility for treating semi-solid slurry removing the need for on-site storage to be built and maintained. For other clients we work on a longer-term basis, contracting for periods of as much as 20 years to provide the separation services which help to keep their systems running efficiently. In all cases, we help clients deal with the waste their processes create in a manner which is cost-effective, efficient and environmentally friendly.

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