TOXICIDADE DE ESPÉCIES DE ENXOFRE EM REATOR ANAERÓBIO TRATANDO ESGOTOS DOMÉSTICOS

This study aimed to monitor the operation and inhibitory effect of sulfur (sulfate and sulfide) in UASB reactor treating domestic sewage. To achieve the objectives of this research were collected weekly samples in the influent and effluent of the UASB. To determine the effect of toxicity of sulfur during monitoring, four sampling points were marked on the inside of the UASB reactor at different depths (P1, P2, P3, P4), and the point P1 was 1m of the bottom of the reactor and the other points located 2, 3 and 4 m from the bottom of the reactor. The pH values ranged from 6.4 to 7.5 in the reactor effluent. Average concentrations of volatile fatty acids in the influent and effluent were 75.9 and 34.8, respectively. The removals of BOD and COD were 61 and 58%. The reactor showed low removal of ammonia nitrogen, indicating that anaerobic reactors have a poor capacity to remove nutrients during treatment. The highest sulfide was found to be 1.3 mg / L in the reactor at the point P1. It was possible to check a decay of the concentration of sulfide from the entry of raw sewage into the reactor. The experimental data and the literature surveyed show that the values of sulfide inside the reactor are well below those required to inhibit the methanogenic activity. Key Words: wastewater, sulphur, toxicity, UASB reactor.