Innovative ways with waste

In the first programme, Stanlow has developed a partnership with a local third party chemicals processor to recover solvent from waste streams. This reaction solvent is a key material used in the conversion process in one of the chemical plants.

To control the catalyst chemistry, a portion of the reaction solvent needs to be constantly bled to remove impurities and degraded catalyst.
As far as practicable, this solvent is distilled and recovered within the plant process, but a pumpable waste slurry stream of 250 tonnes per annum still remains. Prior to the local partnership being established, this entire stream was sent overseas for metal recovery and waste disposal, at a significant cost.

"We were able to identify a local processor with the infrastructure to process the waste stream in a responsible way, and enter into a mutually beneficial commercial contract," says David Topliffe, a Production Unit Manager at the plant. "They recover more pure reaction solvent from the slurry which Stanlow can then re-use, as well as extracting other useful components for selling on. This leaves a far smaller quantity of concentrated waste for routing to metal recovery. "Through this partnership, Stanlow recovers and recycles 70% of the original waste stream (185 tonnes per annum). And because the processor is local, there is the added benefit that transport requirements have been reduced, further cutting Stanlow’s CO2 footprint.

The second programme, which has involved taking a fresh look at mixed waste, has significantly reduced Stanlow’s waste disposal volume.

Waste is segregated at source wherever possible, both to facilitate recycling and to achieve compliant, cost-effective waste disposal. However, for some industrial cleaning activities, segregation at source has not been feasible because of workplace congestion and ergonomics, resulting in skips of mixed waste as a regular site stream.

"Mixed waste skips were a problem for us," says Ian Wellings, Stanlow’s Head of Waste Management. "We used to send these off-site for segregation and disposal, but then we introduced an in-house waste sorting step which has resulted in a 70% reduction in the quantity of waste sent off-site. This equates to a net 80% cost saving per year compared with the previous cost of disposal."

Now, material that can be recycled (wood, metal) is recycled through existing site facilities. Compatible waste is processed through an in-house energy recovery chemical waste incinerator, which generates steam for the site as well as reducing the necessity for off-site disposal. This leaves a much smaller residual waste stream to be routed off-site for further processing and disposal.

"With these two schemes, we have demonstrated that innovative and mutually attractive solutions can be found, both by working with business partners and by ‘thinking out of the box’," says Wellings. "This is consistent with Shell’s goal of reducing our impact on society by requiring a sustainable performance that demonstrates respect for our neighbours and for our environment."

- Stanlow Manufacturing Complex employs around 1,000 people.

- Key products manufactured include fuels, lubricants, olefins, detergent intermediates, toluene and other aromatics.

- The Energy Recovery Plant incinerates both liquid and solid waste and is capable of generating 350 tonnes of steam every day for refinery use.

This feature was added to the Innovations section in November 2008.