Hydrodemolition Concrete Removal Produces High-Alkaline Wastewater — Here's How You Can Treat It.
- Kelly Bryant
- 2 days ago
- 3 min read
Hydrodemolition is the most eco-friendly, hugely efficient method of concrete removal, however the large volumes of slurry and high alkaline waste water generated pose a problem for contractors and site operators. This is because the high pH run-off (as a result of the combination of water and concrete) is classed as hazardous waste and needs treatment before being discharged to keep in compliance with environmental regulations.
In this article, we dive into the process of hydrodemolition, the problems that come with it, and the Kelly Tanks solution.
What makes Hydrodemolition such an effective method of concrete removal?
Hydrodemolition is defined as a technique that uses high pressure water jets to remove concrete in a controlled and non-vibrating manner. The high pressure water penetrates cracks in the deteriorated concrete and the hydraulic force bursts the concrete into small pieces, allowing for controlled, selective removal of concrete.
Hydrodemolition contractors can adjust the pressure of the water depending on the applications of hydrodemolition required, meaning that whether its precise removal around a bearing or large-scale demolition projects, the technique can be adapted to deliver safe, consistent, and targeted concrete removal.
For example, hydrodemolition methods are often used for the removal of concrete from bridge decks
This is because the precise and controlled removal of concrete allows for the protection of the structural steel to maintain the integrity of the bridge. Furthermore, the lack of vibrations help to prevent microcracking which could also compromise the integrity of the bridge.
More recently robotic hydrodemolition has been introduced and is becoming more and more used onsite.
Benefits of Hydrodemolition:
Preserving of structural integrity
Improved surface preparation
More environmentally friendly
Versatile application
Improved safety
Reduced noise and dust pollution
So what is the problem with Hydrodemolition?
We have looked at the advantages of hydrodemolition, but what is the problem? The main challenge is not with the concrete removal, but instead the by-product of this method- cementitious waste water. Due to the high alkalinity of concrete, the pH of water greatly increases when the two are combined and can reach as high as pH 14.
A pH this high is considered hazardous waste and legally must be treated before discharge due to the damage that can be caused by run-off, such as soil and groundwater pollution, water contamination and the destruction of ecosystems.
How can Kelly Tanks help?
At Kelly tanks, we have developed an innovative solution to the treatment of the waste water produced by hydrodemolition. Our HpC pH control system separates solids and contaminants and automatically treats the pH of the cementitious waste water making it safe and legal to discharge.
How does the HpC work?
Waste water is washed into an Adsorption Sack, specifically designed for retaining solids (like concrete) whilst allowing waste water to percolate through the sack.
This water is then tested by a pH electrode (pH probe) and if the pH level is outside the pre-set parameters, dosing and agitation is initiated using either C02 or KT liquid reducer until the pH reaches the desired level.
After the pH is corrected, the water flows up through the coalescing/lamella media forcing any remaining solids to clump together and settle out.
Resulting effluent can then be discharged safely.
Key features of the HpC
Adsorption sack
Adsorption Sacks enable retention of solids and oil residue, whilst allowing effluent to filter and drain. Frames available to suspend sacks in or out of water. Specially designed to allow the fast flow of water whilst retaining solids and adsorbing contaminants.
Coalescing/lamella media
Coalescing/lamella media are separation technologies, usually plates or packs, designed to extract various substances from liquids, like removing oil from water or separating suspended solids from waste water.
pH electrode and dosing unit
A robust electrode designed for harsh conditions measures the pH level and initiates dosing and agitation to neutralise the pH. The HpC doses in line with the logarithmic scale meaning no excess CO2 or pH Reducing liquid is wasted.
Other options for hydrodemolition waste water treatment?
Other options include our GWS hybrid which works in exactly the same way but is low enough for concrete wagons to empty into.
Limited space? The GWS compact is a small but mighty build with automatic pH monitoring and correction making it an ideal solution for hydrodemolition waste water treatment.
What separates us from the competition?
Kelly Tanks beats competitors in the management of waste water created by the removal of concrete using hydrodemolition by offering innovative, fully compliant, and user-friendly systems that efficiently separate solids, automatically control pH, and are available as both standard and bespoke solutions tailored to site needs. Our systems are recognised for their reliability, ease of use, and ability to reduce both environmental impact and operating costs.
Get in touch today to see how we can help.
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