Project Background and Challenges
Mine sites are required to have a washdown area for all LV and HV mobile plant prior to entering maintenance workshops and other facilities. To ensure that any build-up of dirt is removed from the equipment prior to entry.
It is the duty of mine sites to capture and treat the contaminated wash down water generated from heavy vehicle wash bays to mitigate the wastewaters impact on the surrounding environment. The wastewater is often collected in sumps and will consist of a combination of greases, oils, diesels and dirt which need to be removed prior to the water being reused or disposed of. Oil water separators (OWS) are the minimum pre-treatment system required by regulators to treat the oily water. However, as raised by our client, issues arise when dirt and sediment generated from the washdown gets trapped within the OWS system. This often occurs as it is common that the only form of filtration for silts and clays in these systems are usually a settlement sump or filter/screen. Due to this, breakdowns are likely to occur within the OWS systems that do not have a silt removal process in place.
Our Solution
PR Water has developed a water treatment system which successfully separates silts and clays prior to removing the hydrocarbons from the wash water. The wash water is recycled so it can be reused in later washdowns. The system removes the fine silts and clays from the water before the hydrocarbon separation process begins. It can treat water at a range of flow rates, remove total suspended solids to below 20mg/L and reduce the Total Petroleum Hydrocarbons (TPH) to below 15mg/L.
Stages of the System
These results are possible with a fully automated treatment system which can be broken down into the following stages:
Wash water that is collected in the wash bay sumps is pumped through a Chemical Dosing Container via a feed pump. The Chemical Dosing Container consists of the following pieces of equipment:
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- Flow Meter – This device registers the incoming instantaneous flow rate and provides a signal to allow for proportional dosing of the dosing pumps.
- Various Dosing Pumps – To introduce coagulants, flocculants, acids/alkalis and sterilisation chemicals into the wash water.
- Various Probes – To measure pH, ORP and turbidity levels.
- Pipe Flocculator – To assist with the mixing and blending of the chemicals within the wash bay wash water.
The HB60 Lamella Clarifier – The lamella clarifier utilises the surface area of lamella plates to create small settlement chambers that allow for rapid settlement of the suspended solids which are collected in the hopper of the unit as a sludge. An optional automated de-sludge system is available upon request.
The CM400 Oil Water Separator – Once silts and clays have been removed from the water. The CM400 uses coalescer media to agglomerate the free-phase hydrocarbon droplets so they can be skimmed from the surface of the unit. An optional automated oil transfer system is available upon request.
Summary
PR Water offers a comprehensive, sustainable treatment system that continuously recycles washwater for reuse in future washdowns. In this case study, the multistage treatment system effectively settles suspended solids and reduces Total Petroleum Hydrocarbons (TPH) to below 15mg/L. By preventing silts from entering the oil-water separator, the system significantly enhances the overall effectiveness and longevity of the treatment process. The prevention of dirt build up within the oil-water separator eliminates unnecessary complications, ensuring a more efficient and reliable operation.
For more information enquire below or speak to our team on 1300 320 420.
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