Treating sludge has traditionally been an energy intensive process but Envorem has developed an innovative new process that efficiently treats higher volumes and uses 95 per cent less energy than traditional thermal treatment plants.

The technology, developed with assistance from the University of Brighton, uses a little-known property of water to disassemble oil production sludges, clean solids, and recover the entrained oil for recycling. It works using very little energy and without generating emissions.

It has taken 10 years to develop but the resulting process offers exceptional capabilities and solves a problem the oil industry has struggled with for decades.

After extensive lab testing, the core technology had its first major test in the UK and successfully processed oil waste at 50 tonnes of sludge per hour – some 10 times the capability of thermal treatment plants and using 95 per cent less energy, all in a system that is small enough to be mobile; contained in several trucks. Subsequently, Envorem was awarded a pilot project in Oman as a field trial.

A small production scale system was constructed in the UK and shipped to Oman to conduct a demonstration project for Petroleum Development Oman at their waste yard in Nimr. The scope of the demonstration project was to treat two separate types of feedstocks, highly hydrocarbon contaminated sandy soil and oily sludges with the emphasis on sludge treatment. The sludge was extracted from the surface layers, mid-layer and bottom from a pit and, directly from tankers.

The results of the project were that the technology overperformed in every measure. The system consistently operated at four times its specified throughput, the TPH of the solids was reduced to better than half the specified limit of 10,000 ppm and approximately 2.4 barrels of oil per tonne sludge were recovered.

The project proved that Envorem’s system recovers 99.5 per cent of the oil from the sludge. Its speed of processing was striking, in comparison to a thermal system with a five tons per hour capacity, Envorem’s system of a similar size would process 10 times as much.

In the case of fresh production sludges, the technology rapidly processed this hazardous waste, not only recovering the oil but also removing some of the impurities it contained. The recovered oil had a sediment content of around 1.4 per cent and would be suitable for return as wet crude.

This highly significant result means that for production sludges or residues, Envorem can not only offer its technology as a waste treatment system but potentially as an in-line technology that integrates with oil production equipment, increasing production efficiency, reducing the large volumes of waste that would otherwise be generated and the pollution and emissions from their disposal.

Utilising tried and tested technology

Crude and fuel oils contain contaminates comprising sediments and water that create an oily sludge. Every day, the equivalent of more than one million barrels of crude oil are discarded by the oil and maritime industries as hazardous waste at a huge environmental and financial cost. Many technologies and remediation techniques have been tried, including thermal desorption, chemical oxidation, bioremediation, and soil washing.

Envorem has combined established techniques with hydraulic shock and cavitation, where bubbles are created by the vaporisation of water, a phenomenon copied from the natural world. Cavitation can be generated ultrasonically, electrically, or physically and is widely known as a parasitic effect that destroys propellers on ships and the impellers of pumps. The collapse of cavitation bubbles is so powerful it liberates metal fragments from the surfaces.

Envorem harnesses these forces to create a water-based system that disassembles the sludge and strips oil contamination from particle surfaces. At the core of the system, millions of cavitation bubbles are artificially generated within the target material. T

hese bubbles collapse with incredibly high forces, forming microscopic water jets and shock waves that impact surfaces of solids and generate localized temperatures of up to 3,000oC.

The great news is that because all the cavitation occurs at a microscopic level and underwater, the energy is highly focused, making the process safe, highly energy-efficient and very fast. Furthermore, as water is only used for energy transfer, any type of water can be used including seawater or produced water.

In November 2022 Envorem MD, Mark Batt-Rawden announced that Envorem would build the world’s largest mobile greentech system for treating huge volumes of sand and sludge.

Financed by the UK Government Innovation Department (IUK) and private investors, the build is now well underway and is scheduled for completion in December 2023. The system will process an unparalleled volume of material, up to one hundred thousand (100,000) litres of liquid sludge every hour or 25 tonnes of soil per hour – all without generating any emissions.

It brings the seemingly impossible clean up challenges facing the oil Industry within reach, both technically and financially. It can also significantly reduce the environmental impact of oil production, whilst simultaneously saving costs – a true win-win.