An aerobic digestion project was commissioned on a closed landfill site in Hubei Province. Aerobic digestion in this particular application is from a biological waste water treatment process; once sediments are removed from waste water, oxygen is used to break down the organic matter. The site had been covered with an overlay of clean soil to enable the land to be used again safely, removing any references to it once being a landfill site. Typically a closed landfill site is capped by several layers of varying thicknesses, including topsoil, drainage and low permeability layers. With this project, the land was built on and turned into an international show garden as part of the annual Chinese International Garden Exposition.
The customer’s challenge
Due to the nature of the show garden being built on top of contaminated land, and the Exposition attracting visitors, it was mandatory for the Institute to monitor the gases that were still being produced under the capped layer of soil.
The Geotech product
The site spans a huge area and required substantial monitoring; as such the Institute had seven Geotech GA3000 PLUS fixed gas monitors commissioned from Geotech’s Chinese distributors, Onuee Electronics, to measure the biogas at various locations around the site.
The fixed system is ATEX certified, UKAS calibrated and used by plant operators for process control and protection of their CHP engine. The Institute’s project leader chose the GA3000 PLUS because they had previously used Geotech products and had a positive experience with the company and the technical and customer support received from the company and Onuee in Shenzhen. They were also impressed with the unit’s reliability and general easy maintenance.