EFFECT OF COPPER AND LEAD ON THE PERFORMANCE OF A 2-PHASE ANAEROBIC DIGESTER

The effect of metals on the performance of anaerobic digesters has been examined extensively. However, most of this work has been done with single-tank reactors where the various phases which constitute the digestion process were fully integrated. The use of two-phase digestion enables the impact of toxins on specific phases to be examined. In this study, a two-phase reactor fed with a starch-based substrate was used to evaluate the effect of copper and lead (0.5 mM) on the individual phases. The metals were added both individually and in combination. The reactors were operated in their normal sequential mode and separately. In the latter case, the methanogenic reactor was fed with an acetate substrate to which copper and lead had been added. The results showed that the most significant impact was on the performance of the acidogenic reactor and that copper had a greater effect than lead.