New composting campaign turns sanitation into fertilization


The Coal Authority uses a zero waste method to dispose of its reed bed cuttings by composting the material to divert it from landfills.

Reed beds are used as a final step in the mine water treatment process where they filter out the remaining finer iron particles (ocher). Over time, the resulting ocher buildup affects their ability to filter particles and they need to be maintained. This involves removing the reed and ocher and replanting the reed bed with new or transplanted reeds.

This is an expensive operation and historically the materials were sent to the landfill. Materials derived from the water treatment system at the Bates mine near Blyth, Northumberland, were sent for the first time to a nearby farm. Consisting mainly of reed cuttings and ocher residues, on one project, 1594 t of material were distributed over 50 ha. of agricultural land to provide cover and enrich the soil. The process, known as land application, beneficially adds organic matter to the soil and reduces our dependence on manufactured fertilizers and other conditioners and additives.

Stephen Smithson, Head of Contractual Services at the Coal Authority, said: “We have adopted highly effective planning and scheduling practices and worked with external partners, including the Environment Agency and Farmers, to see whether our by-product streams could become inputs for other processes to achieve better sustainability results.

“The application of these materials offers significant environmental benefits, as well as operating cost savings of up to £ 1million. As the raw material was transported in bulk, this minimized the need for transport and helped reduce our carbon footprint. The product itself provides an environmentally friendly solution in agriculture and this decision reinforces our commitment to sustainability. Ultimately, we want to achieve full circularity and this is the first step in that direction. “

Prior to launching the retrofit program, several models were developed to identify maintenance needs at individual sites. In addition, a costing template was prepared which estimated the maintenance required for each site. These models worked together to provide the Optimal Overall Cost (WLC) for the duration of the project. This has allowed programs to offer a flexible, business-as-usual approach to accommodate annual budgets.

At the Bates mine water treatment system, the Coal Authority refurbished an 8,000 m2 area of ​​reed beds between 2019 and 2020. To date, a total of 6,700 t of ocher and reed cuttings have been removed and replaced by more than 17,800 new individual reed plants at the end of March 2021.

The Coal Authority uses passive stand lagoons and reed beds when it comes to the most environmentally friendly way to treat mine water. In addition to their role in treating mine water, these man-made wetlands serve as valuable habitats for a variety of birds and insects. Preserving these habitats is a key consideration when we need to remove cuttings from reed beds. This is to ensure that the wildlife for which we have created spaces are not disturbed by the renovations.

Bird surveys by students at the University of Hull have shown that the habitats in our man-made wetlands are used by 12 bird species listed on the British Trust for Ornithology’s Conservation Bird List. This allowed the Coal Authority’s environmental team to work with the RSPB to understand their reed bed management techniques. The team draws on the expertise of conservationists to explore new habitat management options, approaches and techniques that can provide greater effectiveness without compromising the long-term viability of these important sites.

Read the article online at: https://www.worldcoal.com/coal/08062021/new-composting-drive-turns-remediation-into-fertilization/


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