No abstract

This study was conducted to determine the effect of iron and aluminum on odor generation from anaerobically digested and dewatered sludge cakes. Blended primary and waste activated sludge samples obtained from 12 different wastewater utilities was batch digested in the laboratory for 30 days at 37 o C, conditioned, dewatered and the organic sulfur odor generation potential measured. In addition to sulfur gas analysis, all sludge samples were analyzed for total and volatile solids, Fe and Al concentrations in the solids, mono and divalent cations in solution and soluble biopolymer (proteins and polysaccharides). A correlation between iron and peak organic sulfur gas concentrations in the headspace of incubation vials was found. Following anaerobic digestion, a significant increase in solution protein occurred and correlations between solution protein, ammonium production, percentile volatile solids reduction and iron content in sludge were observed. These data suggested that iron plays an important role in anaerobic digestion and in odor generation from dewatered sludge cake. Aluminum reduced the odor potential for sludges that were high in iron, suggesting that proteins associated with aluminum are resistant to degradation following shear.

The beta-blocker pharmaceuticals propranolol and metoprolol are administered as racemates. In municipal wastewater treatment plants, propranolol underwent apparent enantioelective degradation during biological treatment. As a result, EF values for propranolol greater than 0.48 in surface water samples are indicative of raw sewage sources (e.g., leaking sewers, combined sewer overflows) while values below 0.45 are indicative of wastewater effluent sources and could be used for source identification. Metoprolol EF values did not change appreciably during wastewater treatment, with EF values in effluent ranging from 0.47 to 0.53 in wastewater effluent. However, in effluent-receiving waters, the EF values decreased as the compounds undergo biotransformation. In the Trinity River, an effluent-dominated river with a travel time of approximately two weeks, the concentrations of metoprolol decreased by over 90% and the EF values decreased to less than 0.35 as the water moved downstream.