Hybrid IMBBR

After a mechanical pre-treatment by a grid and aerated sand trap, raw sewage arrives into the buffer with variable water levels, where additionally to hydraulic equalisation a hydrolysis of fine dispersed pollutants and first biochemical conversion of organic pollutants into volatile fatty acids takes place. From here a constant quantity of acidified sewage is pumped into the anaerobic reactor, containing active methanogenic bacterial biofilms, fixed on adsorbing porous LEVAPOR-carrier , enabling a fast and quantitative microbial colonisation and retention of active cells in the reactor. In this reactor bioconversion of generated acetic acid into biogas, takes place at ambient temperatures. The sludge growth in anaerobic process is only 3 to 5% of removed COD, instead of 35% in the aerobic treatment, resulting in a remarkably better process economy. Final treatment of residual pollutants occurs in a subsequent aerobic fluidised bed biofilm reactor, where additionally to COD removal, quantitative nitrification of ammoniacal nitrogen into nitrate (NO3-) takes place. Aerobically treated effluent, containing suspended biomass leaves the reactor to the clarifier, where sludge flocs will settle, while retention of LEVAPOR cubes with fixed biofilm occurs by a screen, installed inside of the reactor.