Bioremediation of soil at the Avenue This presentation can be used to introduce the activities on testing soil samples, removal of soil contaminants and the bioremediation of soil. It sets the scene by describing how soil is decontaminated at the Avenue.

The Avenue Coke Works Processed coal to produce coke Coke used as a smokeless fuel and in the steel-making industry Wastes from the process left behind when the works closed in 1992 The Avenue Coking works was built in the 1950's. Its main purpose was to treat coal to produce coke. This is a form of solid coal. Coke can be used as a smokeless fuel to heat houses or in the steel-making industry. The site also produced tar, benzole and sulphuric acid as by products of the process. This was a heavy, industrial process and it produced a lot of waste materials. Some were dumped on the site and others just contaminated the ground that the buildings stood on. The works closed in the 1992 and the clean-up process started in 1999.

Demolition and dumps A range of solid materials need to be treated at the Avenue The old works have been demolished Areas where waste was dumped need digging out The remediation process has seen buildings being demolished and also the digging out of former solid waste dumps. These materials need to be sorted so that they can be processed appropriately.

Sorting solid waste Solid wastes are sorted The remediation process has seen buildings being demolished and also the digging out of former solid waste dumps. These materials need to be sorted so that they can be processed appropriately. Sorting grades materials according to their size or content. Large rubble can be re-used on site whilst other materials may be sent off site to be recycled or disposed of safely. Soil that is lightly contaminated is suitable for bioremediation on site. Solid wastes are sorted Soil is sent for bioremediation Rubble and other materials are re-used or sent off site for recycling or safe disposal

Soil bioremediation Soil that is not highly contaminated is treated using a process called bioremediation. Over the years, microbes have grown in the soil that are able to use contaminants such as benzene, phenols and poly-aromatic hydrocarbons as their energy source. These, in effect, eat the contaminants. These are likely to include a species of bacteria called Nocardia. When areas are excavated, large debris such as rubble, pipes, concrete, stones and other solid materials are removed. The soil is then taken to the bioremediation area. Areas are excavated and non-soil materials are removed (concrete, rubble, pipes, steel etc) Lightly contaminated soil is treated by bioremediation Microbes in the soil break down (‘eat’) contaminants such as benzene and phenol

Soil bioremediation area Soil is piled in the bioremediation area. It is checked for contaminant levels and monitored as the bioremediation process progresses. Microbes are already living in the soil as they are adapted to live in these conditions and utilise the contaminants present; an example of natural selection in action. So there is no need to add new microbes. Large piles of soil are left for bioremediation Microbes in the soil break down (‘eat’) contaminants such as benzene and phenol

Soil bioremediation Soil is regularly turned and aerated to encourage microbe growth and to speed up the bioremediation process. Samples are regularly monitored to track the progress of the process and monitor the soil temperature. The length of treatment varies depending on the level of contamination in the soil and the prevailing weather conditions. Typically a pile will undergo bioremediation for a couple of months. Samples tested for benzene and phenol. Soil is regularly turned and aerated to encourage microbe growth The temperature is monitored and samples are tested to find out when the contaminants have been removed Treatments usually last about 1-2 months