• Wastewater odours spiralling into control


Wastewater odours spiralling into control

Mar 13 2009

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. One major odour source pinpointed was the wastewater treatment lagoons. These large, rectangular, shallow ponds collect and treat wastewater and surface run-off containing hydrocarbons, before controlled discharge into a large watercourse.

Years ago, surface aerators had been used to aerate the lagoons in order to reduce COD from the hydrocarbons present on such a site. However, these aerators broke down and were removed, leaving the lagoons to ‘aspirate’ naturally. The resulting hydrocarbon odours emanating from the lagoons led to the refinery installing a system of atomised spray nozzles to apply an odour control agent. This was ineffective due to the sheer surface area of the problem (nearly 6 acres of surface area giving off odours) and after a further lapse of time, it was decided to re-aerate the main lagoon.

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 (Germany) equipment, were able to provide a complete start-up package, comprising installation of 12 x 11kW floating Spiral Aerators, advising 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 again Spiral Aerators have vindicated their reputation, continuing to run reliably without maintenance or fault and bringing the situation under control to the extent that there have been no further odour complaints attributed to the lagoons over the 2 years since installation. This is no mean feat considering that some 80 complaints had been received in the season prior to installation.

Spiral Aerators are used in a wide variety of situations where good mixing and aeration combine in one machine to give high efficiency and reliability, often with short paybacks from energy and maintenance cost savings. Other typical applications where Spiral Aerators come into their own include oxidation ditches, shallow aeration tanks and balance tanks.

Spiral Aerators are a maintenance dream - they have no submerged bearings or wearing parts, only stainless steel and GRP components below water level, and the spiral-shaped propeller is designed to prevent any clogging with rags or debris.

Corgin also hold distribution rights for high- and low-speed surface aerators, and the innovative Foam Skimmer which removes filamentous foam and selects against filamentous bacteria, improving settlement and final effluent clarity as additional benefits. Corgin also supply both mobile and fixed atomised odour control spray systems as part of their range of solutions for environmental compliance issues.



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