In this article the wastewater treatment experts at WTS take a look at the processes around sludge dewatering, focussing on the potential for cost savings and improvements in environmental performance if businesses take control with an on-site, DIY approach and the use of specialist equipment.
Does your business produce liquid sludge?
Does your business produce liquid sludge as a wastewater by-product of what you do? If so, you’ll be more than familiar with sorting out regular sludge dewatering services offsite. This is a common method chosen by many businesses producing sludge and needing to do something with it.
It might seem easier to pass the job onto someone else, choosing a reputable dewatering firm to come and collect the sludge in one or more tankers and take it away for processing elsewhere. It’s certainly practical – but does it make financial sense?
What is sludge dewatering?
While sludge can look far removed from water, it can contain as much as 75% water. Therefore, if it can be processed effectively, the solids can be removed from the water, allowing the water to be reused rather than sent off-site for disposal.
How do you remove water from sludge?
Sludge dewatering occurs in much the same way your washing machine works when on spin. The digested sludge is placed in a large industrial centrifuge and spun at speed, which separates the water from the solids. This means the water is potentially ready for use elsewhere, while the sludge is now a biosolid, free of most of its water and therefore lighter and easier to handle.
Other treatment methods commonly used for dewatering wastewater sludge include sump pumping. This technique uses gravity to help separate the liquids from the solids. This is common in construction though but may not be suitable in all scenarios.
Finally, other dewatering approaches using specialist equipment include filters and belt presses that can be adopted for helping to separate the water from the solids.
Why does sludge have to be dewatered?
The answer to this might begin to reveal itself when you start to review the situation for your business regarding tankers and the cost of hiring a company to handle the entire collection and disposal process for you.
The idea behind dewatering is to remove as much water from the waste sludge as possible, thereby concentrating the solids element into compact “cakes” of sorts. These compressed solids or “cakes” are much easier to handle, transport and dispose of owing to their smaller size.
Is it cheaper to tackle sludge dewatering in-house?
The decision to handle the dewatering of sludge yourself is not a simple yes or no question since all situations and businesses should be dealt with and considered separately. However, it is certainly worth assessing the situation for your business to understand if improvements and savings can be made.
A good place to start is with the current costs of hiring a specialist company to provide tankers to take away the sludge and deal with it offsite. Keep this base cost in mind but do make sure you also consider how much mileage this involves for those tankers. If your business is trying to improve its environmental performance, sludge dewatering is an area with huge potential to be much greener if you tackle the job onsite.
What are your options for sludge dewatering at your business?
If you’re considering introducing on-site dewatering, you’ll first need to consider the amount of sludge you produce each year – something you’ll already know from hiring another business to handle it for you. Can you potentially handle that yourself instead?
Earlier in this article, we mentioned various methods you can consider adopting as part of the dewatering process. You could use belt press equipment, a screw press, or opt for a centrifuge. A lot will depend on the amount of sludge produced.
It’s not just a question of how much sludge you’ll need to process though. You must also think about available space. Do you have the space onsite to accommodate one or more pieces of sludge dewatering machinery to cope with this task? The centrifuge tends to be the most compact option, and the most efficient too. However, they do tend to require more power, so that’s another element to think about. Would one method be suitable and create a lower power requirement than another?
You’ll also need to consider the possibility of training staff members to be able to operate and maintain the machinery. If you need to get external specialists in to handle that part of the process, it will push the costs back up in that area.
You also need to think about the disposal process because even when you do take on the dewatering of sludge yourself, you’ll still have the sludge cakes to get rid of. That said, they’re lighter and clearly won’t require multiple tankers to carry them away, so you’ll experience a potentially significant cost saving there, too.
Could a hybrid, onsite and offsite sludge dewatering approach work?
A hybrid approach to your sludge management issues is a possibility that could work in certain situations. For example, there are businesses that have adopted onsite sludge dewatering processes and vastly reduced the amount of waste that needs to be taken away via tanker.
If you’re looking for greener ways to do things, and more positive headlines, this in-house effort would certainly be something to look at. The cost savings can be significant, although of course researching and trialling certain methods would be advisable to get a more accurate answer to how promising it might be.
Dewatering your wastewater sludge can deliver long term benefits
We’ve previously mentioned greener solutions already, and it’s common to see reductions in CO2 emissions by some margin when you begin dewatering your own sludge on-site. Processed sludge that is removed via such methods can be used as an agricultural fertiliser in some cases. It also works well as a soil improver.
So, you can see that by considering all the options available to you, it might be prudent to consider the cost – and potential savings – involved with bringing sludge dewatering in-house, either fully or as a hybrid solution. You’ll also see CO2 savings to consider alongside the practical cash savings. Even if you cannot start dewatering your wastewater sludge immediately – and you shouldn’t until you have considered all the facts – it might be a plan to adopt in future.
You can see that the sludge cakes resulting from the dewatering process are often not considered to be waste. Once separated from the water, you’ve got something potentially useful that can be sold to other businesses looking for such materials. Going green could be good for your business in several different ways.
Hopefully, this article will give you plenty of food for thought about how you deal with your wastewater and sludge disposal issues. Right now it might be easier to continue paying for those tankers. However, when you consider the annual cost, both financially and in bigger terms, you might see there is an alternative. Yes, there are setup costs involved, but the long-term savings to be gained by installing the right sludge dewatering equipment might be visible sooner than you think.
Industrial wastewater solutions
Water Treatment Services offer a comprehensive range of innovative wastewater management solutions for business. Our specialists provide expert advice and support to help you identify the most appropriate strategies for the identification and implementation of cost efficient and environmentally sensitive wastewater treatment solutions for all industrial wastewaters and trade effluents.
With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specially trained environmental engineers and wastewater treatment specialists we offer cost effective environmental support solutions across the whole of the UK and internationally.
Contact us today to learn how our sludge processing and wider wastewater management solutions can help you optimise your treatment costs and improve environmental performance.