Hydrocarbon Removal – Oil Company

Case Study

Removal / Treatment of hydrocarbons in groundwater

Background

A oil company operated a service station which subsequently closed down.  A water bottling company now accommodates the neighbouring land.

The Problem

The neighbour to the site drilled a borehole and determined that the water has a hydrocarbon odour and when he took the water in for analysis, it was confirmed that the water was contained with Gasoline Range Organic (GRO) compounds.  The oil company then drilled monitoring wells at their former site where laboratory results confirmed that the groundwater at the site was contaminated with GRO and BTEXN compounds.

The borehole drilled on the neighbouring property is for commercial water bottling purposes and the oil company was liable for remediation of groundwater in the area.  In this regard, they wanted to remove/treat the hydrocarbons in the groundwater to allow the neighbouring site to bottle the water and also to clean the underlying aquifer. 

The Solution

Procon Environmental Technologies where contracted in June 2008 to install a Mycelx filtration solution in conjunction with a GAC (Granular activated carbon) removal process.

In July 2008 Procon completed installation of filtration system and regular sample testing was undertaken for six months.
- System setup up to remove any possible Gasoline Range & Diesel Range organics from pumped water. 
- Composed of a bag filter to remove solids and sediments, from there the water moves through two sets of filters loaded with Mycelx media, absorbent filter media designed to remove hydrocarbons.  From the Mycelx, water is treated in a 350kg granular activated carbon (GAC) filter
- The filter assembly as described has been duplicated to accommodate the volume and flow rate of water to be treated, and to prolong filter change out intervals.
- Sampling was done twice-weekly basis for a month and then weekly for 6 month period
- Two samples where taken during each sampling event. Quality of water flowing into system (IN) and quality of water flowing out of system (OUT).

The Results
Initially water samples from IN port had distinctive odour associated with weathered hydrocarbon compounds. No solids or discoloration was observed visually.

The OUT samples did not have any odour or discolouration.

No GRO or DRO volatile organic substance could be detected in any of the samples.

Initially it is estimated in the region of 20 million litres of water has already been pumped through the system in two weeks of fulltime operations (7000 litres per hour pumping rate was measured)

The GAC filters were backwashed and rinsed every two weeks thereafter for 6 months.

Sediment in bag filter due to borehole pump inlet not positioned correctly.  The 25/5 micron bag filter was replaced on a weekly basis to prevent solids passing to Mycelx