The key element of Biobed Advanced is the design of the settler placed in the reactor top to separate the treated water from the produced biogas and keep the anaerobic biomass in the system, Veolia says. The sludge retaining efficiency of a settler is determined by the available settling area for particles and the reactor turbulence, which is mainly caused by the biogas produced.

In high-rate systems the biogas production is so violent that multi-level gas separation is often used to control the turbulence. But multi-level gas separation reduces the effective reactor volume and thus the performance of the reactor. Veolia says the new Biobed Advanced settler achieves at higher reactor loading rates not only the sludge retention of a UASB system, but also similar COD removal efficiencies.

The company says the compact and standardized settler design reduces the reactor height and investment costs. Compared to other anaerobic systems, Biobed Advanced reactors have a smaller footprint and their performance results in lower operating and post-treatment costs, according to Veolia.