Efecto de los metales pesados cadmio y níquel sobre la producción de metano de un lodo anaerobio a escala de laboratorio

Abstract

On this research project toxicity assays were performed in serum bottles to measure the biogas production for every added metal concentration. Preliminary assays were performed to evaluate a wide cadmium and nickel concentration having the following factor into account: time of contact, methane production and redox potential. The time of contact employed in the test was 96 hours which was found by means of a substrate degradation test. The range of concentration of every metal that caused inhibition of the methane production in a 50% was determined and the final assay was performed with concentration within that range, as much for cadmium as for nickel; this inhibition was calculated based on a control and by applying the Probit method with some modifications. The preliminary and the final assays were performed without any temperature controlled. The effective concentration that inhibited the methane production to 50% (EC50) with a confidence limit of 95% was 526.8 mg Ni2+/L for nickel and the interval 403.8 mg Ni2+/L to 690.6 mg Ni2+/L and 54.2 mg Cd2+/L for cadmium with an interval of 47.7 mgCd2+/L to 60.9 mg Cd2+/L. Finally the soluble fraction of some tested concentrations of cadmium and nickel to prove the accumulation of these metals in the anaerobic biomass