Case Study: Hydrocarbon removal from industrial wastewater.

Challenge

This was for an industrial site that was releasing process water that after an oil-water separator the water contained polyacrylic hydrocarbons (PAHS) as well as phenolics ( the “target” contaminants) including, but not limited to pentachlorophenol at concentrations exceeding the local discharge by-laws.

The waste water is currently being treated using activated carbon filters housed in three vessels, each removing portions or all of the certain contaminants and lowering the concentrations to below the recommended sanitary sewer discharge limits.

The performance of GRAFTA™ was evaluated at a screening level to remove target contaminants from a sample of water with the overall objective of the potential use of GRAFTA™ for the treatment of the subject water streams solely or as part of the treatment train.

Key Project Requirements

Meet strict hydrocarbon and phenolics discharge requirements;
Provide enhanced removal of contaminants over activated carbon;
Short retention times and longevity of materials;
Cost-effectiveness of the treatment solution;
Long-term sustainability.

Solution

GRAFTA™ 1.0 is an engineered graphene-based nanotechnology developed to target a broad range of industrial contaminants including organics such as PAHS, phenolics and many other industrial compounds.

Removal was achieved through adsorption on graphene nanosheets. The graphene provides a very efficient platform for the removal of organics. The end result being water quality with lowered concentrations of target contaminants not only below discharge standards, but in most cases to non-detectable concentrations.

Results

Raw water was permeated through three GRAFTA™ packed columns.

As shown below, tetrachlorophenol compounds and fluorene were removed in the first column, leading to non-detectable concentrations in the effluent. These compounds remained consistently at non-detectable concentration all through the second and third columns.

Pentachlorophenol was removed by over 94% in the first column followed by about 82% and over 92% removal in the second and third columns respectively. The overall removal efficiency of pentachlorophenol in three columns was over 99.5%.

The results indicated that GRAFTA™ is highly capable of removing tetrachlorophenol compounds and fluorene, whereas removal of pentachlorophenol required in essence a longer retention time or sequential permeation.

The screening and sequential use of GRAFTA™ packed columns resulted in remarkably high removal efficiency of tetrachlorophenol compounds, fluorene and pentachlorophenol achieving nondetectable concentrations (<0.1 ppb).

Outcomes

A GRAFTA™ pilot was implemented at the site in Spring 2023 in order to refine the design parameters for a full-scale implementation and replacement of the existing activated carbon system train.