The Client:
Scania is a global leading manufacturer in commercial and heavy vehicles. The client’s active
Södertälje recycling facility outside Stockholm city faced problems with disposal of some
specific materials left from their engine production business.
The facility was having difficulty in disposing non-recyclable substances including grinding
dust, cutting fluid, and wastewater. Containers were temporarily storing a mixture of steel
shavings from grinding dust and used cutting fluids. There were also mixtures of the used
fluid and abrasive wool which had bound to it as waste from production. Cutting fluid is a
hazardous waste requiring specialist disposal, however, the presence of other waste materials
in the fluid was making this disposal process more difficult and expensive as the materials
first needed to be separated. The wastewater from Scania’s recycling facility contained a
layer of oil emulsion alongside hydrocarbon contaminated liquid containing chlorine from the
facility’s cleaning agents.
Attempts to clean the oil contaminated wastewater at the facility was producing large
amounts of clogged filter paper material. This made it difficult to clean to stormwater
hydrocarbon limit values as filter paper had to be continually replaced – making the cleaning
process time-consuming and expensive.
Approach:
MycoMine took samples from across the production site from both the containers of cutting
fluid mixtures and the waste-water cleaning tanks (the waste-water recipient tanks, along the
production line to the final cleaning tank). With these liquid and partial solid samples, tests
were carried out in our lab to isolate strains of fungi suitable for bioremediation use which
were able to break down the hydrocarbons and organic compounds in the samples. We
carried out two separate lines of testing on the cutting fluid samples and waste-water due to
their differing contents and characteristics.
Outcomes:
Waste-Water:
In wastewater samples containing large amounts of oil, the hydrocarbons were degraded by
76-88% by our fungal mixture in 7 days. The levels of hydrocarbon present still exceeded the
limit levels for storm water – but we are confident a longer period of remediation would
achieve safe values. When we started to remove the chlorine from the water, we saw a
reduction of hydrocarbons by 96.3% over 10 days by our fungal mixture. It seems entirely
feasible to achieve the 99.5% reductions needed for stormwater quality when the water is
fully dechlorinated before adding the fungi.
Cutting Fluid:
Following testing, there was an evident decrease oil compounds. Over a 5-day period, we
were able to reduce the total organic carbon content by almost 60% and the oil content alone
by over 75%. For the testing on abrasive wool with bonded cutting fluid, there was a 66.3%
reduction in total organic compounds in the liquid mixture over 20 days which we believe
could be increased through more efficient aeration of the sample.
Grinding Dust:
We further experimented with bioremediation rates using our chosen fungal strains on
grinding dust and cutting fluid mixtures when present together – with extremely promising
results. Over a 5-day period, the hydrocarbon content of the samples containing mostly
grinding dust decreased by over 95%. With a longer duration for testing, we believe we can
further optimise this rate. Again, better air supply, and neutralising the chlorine
contamination before adding our fungal mixture are likely to further speed up and maximise
our rates of remediation.
Overall, this was a challenging project covering range of different materials from our client’s
recycling plant. Our bioremediation systems for wastewater are suitable for seamless
incorporation into existing production lines, which was perfect for the wastewater cleaning
house at Scania. With further testing and removal of chlorine from samples we can refine our
approach to effective remediation of a host of challenging materials which were otherwise
difficult and expensive to recycle or dispose of previously.
