Mejoramiento de la Calidad de Lodos Anaerobios. Influencia de la Adición de Cloruro Férrico

Abstract

The start-up period of anaerobic reactors is a critical and relatively slow step since it has to develop a sufficient and well-balanced microbial population that frequently determines the operation\'s efficiency of the reactor. The biomass activity depends on many factors; with relation to the micro-nutrients, the lack of one can limit the biological process; and methanogenic bacteria have also shown a critical dependence on iron. The influence of the continuous addition of ferric chloride on the improvement of a sludge used as inoculum at the start-up of an anaerobic reactor has been evaluated. The sludge came from an anaerobic UASB reactor used for treating domestic sewage and presenting the characteristics of a flocculent sludge, with low methanogenic activity and settleability. The ferric chloride dosage of 4.83 mg/l was equivalent to a soluble iron concentration of 0.5 mg/l. Two reactors were used, the first one was utilized as control (R1) and on the second (R2 reactor) ferric chloride was continuously added. Both reactors achieved an organic rate load - ORL up to 3 6.40 kg COD/m .d and an up-flow velocity of 8.55 cm/h. Compared with the control reactor (R1), the R2 reactor was less susceptible, with better COD removal efficiencies, in shorter times. Additionally, the sludge quality at the end of the start-up was better in terms of methanogenic activity and settleability. The strategy used to improve the sludge quality, showed its viability and favorable effects on the sludge quality of poor characteristics used as inocula to start- up anaerobic reactors.