ABSTRACT
The advantages of anaerobic treatment of wastewater are as follows: (1) no need in oxygen supply; (2) production of lower amounts of biomass in the form of well-stabilized sludge; it is three to 20 times less than production of biomass in aerobic process; (3) it produces , methane, a fuel. Five groups of prokaryotes are involved in the anaerobic digestion of organic wastes: (1) hydrolytic bacteria; (2) fermentative acidogenic bacteria; (3) acetogenic bacteria; (4) hydrogenotrophic methanogens; (5) acetotrophic methanogens. Sulfate reducers and methanogens are competitive microorganisms at COD/SO4 2- ratios less than 1.7–2.7. An increase of this ratio is favorable to methanogens, while a decrease of this ratio is favorable to sulfate reducers. The upflow anaerobic sludge blanket (UASB) reactor uses immobilized biomass to retain sludge in the treatment system. Anoxic methods of wastewater treatment use nitrate bioreduction, ferric bioreduction, sulfate bioreduction, manganese, selenium and arsenic bioreductions, anoxic oxidation of ammonia, and bioreduction of perchlorate. A tutorial with solutions and a quiz bank are added to this chapter.
