Granular biofilms in wastewater plants
(2016) 3rd Meeting of the Belgian Interdisciplinary Biofilm Research (BIBR) — Location: Liège, Belgium (8.September.2016)
Files
BIBR2016_OlivierHenriet.pdf
Restricted Access - Adobe PDF
- 2.29 MB
Details
- Authors
- Abstract
- The discharge of untreated wastewaters in the environment is responsible of the rapid degradation of aquatic ecosystems. The current leading technology of treatment is the activated sludge process, where the dissolved pollution is degraded by free-floating consortia (flocs). The major drawback of these loose aggregates is their low settling velocity. An emerging technology aims to improve this process by selecting consortia that form granular biofilms in aerobic conditions. These biofilms, usually named aerobic granular sludge (AGS), have a spherical architecture and a higher density than flocs. They settle down ten times faster and the process accommodates a biomass concentration five times higher than that of activated sludge. So far, AGS has been mostly developed in sequencing batch reactors. Among the main strategies to select the appropriate microbial consortia, the application of a feast and famine regime has proven the most efficient. The principle relies upon the feeding of the biomass under anaerobic conditions (feast) and the subsequent selection under a long aerated phase (famine). An additional selection pressure is usually applied to the biomass by reducing the settling time. As a consequence, the flocs are washed away and the granules are kept inside the reactor. Aerobic granular biofilms are efficient to treat common nutrients in wastewaters (nitrogen and phosphorus) but also a large panel of organic pollutants including dyes, pesticides or pharmaceuticals. The spherical architecture of the granules is a key parameter to biologically remove nutrients that require both aerobic and anoxic conditions. The extracellular matrix of the granule provides an efficient barrier to the diffusion of the oxygen. Hence, aerobic conditions are present at the edge of the granule, while the core is depleted in oxygen. Specific microbial populations are susceptible to colonize differentially these microenvironments. During the last decade, most researches were conducted in lab-scale reactors using synthetic influents. However, recent works have focused on real wastewaters from both urban and industrial origins and have reported the successful application of the process in full-scale reactors. The industrial development of the AGS process is already ongoing with plants being built and operated in Belgium, The Nederland, Portugal, Ireland, South Africa and Brazil.
- Affiliations
Citations
Henriet, O., Meunier, C., Henry, P., & Mahillon, J. (2016). Granular biofilms in wastewater plants. 3rd Meeting of the Belgian Interdisciplinary Biofilm Research (BIBR), Liège, Belgium. https://hdl.handle.net/2078.5/70540