Advances in high-rate anaerobic treatment: staging of reactor systems

Anaerobic wastewater treatment (AnWT) is considered as the most cost-effect ive solution for organically polluted industrial waste streams. Particularl y the development of high-rate systems, in which hydraulic retention times are uncoupled from solids retention times, has led to a world-wide acceptan ce of AnWT. In the last decade up to the present, the application potential s of AnWT are further explored. Research shows the feasibility of anaerobic reactors under extreme conditions, such as low and high temperatures. Also toxic and/or recalcitrant wastewaters, that were previously believed not t o be suitable for anaerobic processes, are now effectively treated. The rec ent advances are made possible by adapting the conventional anaerobic high- rate concept to the more extreme conditions. Staged anaerobic reactor conce pts show advantages under non-optimal temperature conditions as well as dur ing the treatment of chemical wastewater. In other situations, a staged ana erobic - aerobic approach is required for biodegradation of specific pollut ants, e.g. the removal of dyes from textile processing wastewaters. The cur rent paper illustrates the benefits of reactor staging and the yet un-explo ited potentials of high-rate AnWT.