The petrochemical industry is not often credited with being “environmentally friendly,” and consequently a lot of effort and resources are spent on controlling pollution and environmental impact.
Offensive odours were one area of concern at a major refinery, where various abatement measures had been tried unsuccessfully. The wastewater treatment lagoons were pinpointed as one of the major odour sources. The large, rectangular, shallow ponds collect and treat wastewater and surface run-off containing hydrocarbons, before controlled discharge into a large watercourse.
Originally, the lagoons were aerated by surface aerators to reduce COD from the hydrocarbons present on the site, however, after breaking down, the aerators were removed and the lagoons were left to to "aspirate" naturally. The refinery installed a system of atomised spray nozzles to apply an odour control agent but due to the sheer surface area of the problem it proved to be ineffective.
After a further lapse of time, it was decided to re-aerate the main lagoon to reduce odours and prevent re-occurrences of the problem.
Following extensive research, Fuchs-manufactured spiral aerators were selected as the most appropriate form of aeration, giving excellent mixing and aeration in the shallow (1.8m deep) lagoon.
Corgin, the UK distributors of Fuchs equipment, were able to provide a complete start-up package that comprised the installation of 12 x 11kW floating spiral aerators, advice on regular sampling of liquors for COD, SS, NH3, DO analysis and the test results, microscopic assessments of the lagoon biomass and bio-augmentation to recover desirable biology in the lagoon.
Once installed, the spiral aerators proved their worth, running reliably without maintenance or fault and bringing the situation under control.
In the two years following the installation there were no odour complaints attributed to the lagoons, a stark difference to the some 80 complaints received in the season prior to the installation.