Sludge Treatment & Minimisation



Disposing of the oil sludge in the state it is in when removed has its problems; the client is disposing of hydro-carbons which can be recovered and reused; the additional weight of the oil is billed; plus the disposal cost is more expensive because of its presence, then of course the additional mass of this valuable oil also increases the cost of transporting the waste.

KHIDMAH Industrial Services can offer an on-site solution treating the waste before any transport or disposal costs are incurred. As this is our own in house equipment the cost for this along with our experienced and skilled operators makes an attractive commercial proposition, saving on sludge disposal and recovering the oil.

The system comprises of;

  • Pumps and pipe lines
  • Any heating required to keep the sludge mobile;
  • A dosing system, where a flocculent/polymer will be added to aid separation, this chemical will be specially selected after analysis of the sludge;
  • An certified centrifuge/decanter for dewatering the solids and liquids, our range of centrifuges are all designed for coping with highly abrasive contents;
  • And a baffle tank to effectively separate the liquid phases giving the clients back the oil ready to reuse.

Sludge Extraction


Sludge Extraction

The waste generated from tank or lagoon cleaning is often a dense sludge with a high percentage of solids suspended in a water and oil mix. This can make removing the sludge problematic and if the correct method is not selected or the equipment is not suitable a failure of some kind will be inevitable.

KHIDMAH Industrial Services can offer a range of extraction methods and these are covered in this website under Innovative Tank Cleaning and Lagoon Remediation. As well as these methods detailed other options are heating the tank bottoms to increase mobility or adding a diluent, such as LCO or diesel, and recirculating the contents, this will mix the sludge banks in the tank and will make the sludge more manageable.

KHIDMAH Industrial Services have the pumps and pipes specially designed for these conditions and with the expertise to deal with any unforeseen challenges which may arise giving peace of mind to our clients. Amongst the vast range of pumps sizes and construction which KHIDMAH Industrial Services can employ there are a fleet of Molex pumps, which are positive displacement pumps with a screw assembly. These pumps have been designed for use transferring high solid fluids and are hydraulically driven meaning they are safe for use in any environment and the diesel power pack which supplies the hydraulics for the pumps, and if required the dozer, are fitted with spark arrestors and chalwyn valves to ensure safety on all our clients sites.

This combination will transfer even the thickest sludges ensuring delivery from tank or lagoon to either undergo sludge treatment or a designated collection point.

Sludge Pre - Treatment


Sludge Pre – Treatment

The Sludge when it is extracted from the tank or lagoon is usually highly viscous due to the high percent of solids suspended in the oil and water mix. This is not an ideal state for the centrifuge to dewater the solids and liquids and so prior to this the sludge needs to go through a number of stages, the amount of treatment and type of treatment depends on the sludge and its composition.

If heat has been used in extraction this will assist the pre-treatment unit in warming, mixing and homogenising the sludge. The unit uses steam coils on the bottom of the storage tank fed by a fully certified boiler to increase the mobility of the sludge as it warms. Mounted on the roof of the pre-treatment unit is an intrinsically safe, and EEx-d certified stirrer with stainless steel paddles which will agitate the sludge, creating a uniform pumpable composition.

At this point many sludges will also benefit from the addition of a coagulant/flocculent in line from here to the centrifuge. This chemical addition is to aid the solids separating from the liquids in the centrifuge giving a dryer centrifuge cake. This addition is not always required however if it is found to be beneficial to the process the choice on which of the many available formulas will be made based on the unique composition of each sites sludge through analysis.

Centrifuge Technology


Centrifuge Technology

The disposal of waste sludges can be a worry for our clients as the costs can be difficult to ascertain before the work commences. With no treatment in place very little hydro-carbons can be returned to the client and the disposal of moisture heavy solids can be expensive. For many years KHIDMAH Industrial Services have been offering the sensible option to dewater the sludge on site before any costly transport or disposal and have an excellent system for reducing waste and returning hydrocarbons to the customer.

The range of decanter/ centrifuges KHIDMAH Industrial Services can offer are all ideal for heavy lagoon/basin sludge as well as tank bottom sludges. All our equipment is designed and built for a high solid throughput and functions reliably in harsh circumstances ensuring a dependable process and is certified for use on any site/environment.

The centrifuge is designed to eject the solids (cake) at a G force speed into containers, either by a screen carrier or direct by gravity, for disposal. The liquid phase (centrate) is available to be pumped for skimming or separated via a baffle tank after which the recovered oil is returned to the client and the water is available for re-use in the clients system.

The KHIDMAH Industrial Services framework holding the centrifuge and other associated equipment can be matched to suit the available foot print at each site.