Emergency Aeration Case Study

Emergency aeration is a simple and straight forward treatment solution for surface waters affected by organic pollution. The aim is to provides a rapid improvement of the water quality. Generally, this is more cost effective compared to other solutions (filtration, disposal as waste etc.).

The water aeration process is designed to increase or maintain the oxygen saturation of the water. In addition to the dissolved oxygen increase, aeration can also reduce volatile organics and volatile gases through air stripping, reduce carbon dioxide concentrations, oxidise iron and manganese and control bacteria.

The most frequent types of pollution incidents where emergency aeration is used include sewage, slurry and silage spills. Such pollution incidents can lead to ecological impact (dead fish, invertebrates,

impact to the aquatic food chain etc.), present a microbial risk to human health (spread of viruses, bacteria and parasites), nuisance odours, loss of business etc. A high remediation cost and reputational damage are also consequences that are best avoided.

Aeration can also be deployed proactively during the hot summer months in ponds with depleted dissolved oxygen before the situation becomes critical. The aeration of surface waters can be achieved via two key mechanisms:

Mechanical

Water is mixed, agitated, sprayed using discs, blades, paddles, rotors, pumps etc. In this case, the water is broken up into small droplets or a thin film and then dispersed for contact with air.

Diffusive

An alternative method is to pump the air into the water through perforated pipes, tubes, membranes, strainers, porous plates etc. with the aim to create small air bubbles with a high surface area for contact with the water.

Case Study: Silage Leak, Staffordshire

A silage leak occurred at a farm in Staffordshire, impacting a series of five ponds at an exclusive retreat, located downstream.

The silage impact resulted in significant mortality of the fish population, affected the ecosystem of the ponds and affected the business of the retreat. Elevated ammonia and low dissolved oxygen were recorded in the affected ponds.

Ecologia deployed emergency aeration within all five ponds. The aeration equipment included a variety of submerged and floating venturi aerators powered by two generators. A filtration system with zeolite and sprayers for volatilisation were installed for the most heavily impacted ponds. In addition, peroxide dosing was carried out for the larger ponds.

Onsite and laboratory testing was carried out throughout the operation period, to ensure optimum operation and efficiency.

Due the limited accessibility, the deployment operations were challenging. Competent operatives and technicians completed the installation and decommissioning works safely using a telehandler and a dingy.

The system was operational for approximately 5 weeks. A rapid increase of dissolved oxygen was recorded along with a

decrease of the ammonia. The fish mortality stopped almost immediately.