Identification of degradation products of erythromycin A arising from ozone and advanced oxidation process treatment.

The degradation products of the macrolide antibiotic erythromycin A (ERY) arising from direct ozone attack and hydroxyl radical attack are presented for the first time. Ozone treatment was carried out by spiking ozone stock solutions to solutions containing ERY-ERY:O3 = 1:5 and 1:10 (M:M), while, in parallel, t-BuOH was used as a hydroxyl radical (*OH) scavenger. The advanced oxidation processes (AOPs) O3/UV, O3/H2O2, and UV/H2O2 were carried out to recognize and verify possible differences between their primary degradation products; the initial concentrations were ERY:O3 = 1:5 (M:M), ERY:O3:H202 = 1:5:5 (M:M:M), or ERY:H202 = 1:5 (M:M), respectively. Six degradation products were identified from ozonation-one originates from direct ozone attack on the tertiary amine group, while the others arise from radical ion attack, which might be formed during degradation of O3 in water. Fewer primary degradation products were observed arising from *OH-based treatments (AOP) than from ozonation, possibly because the reaction of *OH radicals is non-selective and typically is diffusion-controlled. Four degradation products were detected by *OH radical attacks; two of them already were observed during ozonation, with one as an oxidized ERY molecule and the other as a non-oxidized fragment of the ERY molecule.

Determination of inorganic and organic priority pollutants in biosolids from meat processing industry.

The biosolids (BS) generated in the wastewater treatment process of a meat processing plant were monitored and the priority pollutant content was characterized. The trace metal and organic pollutant content--polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF)--were determined quantitatively and compared to guideline limits established by the US EPA and EU. PCBs were not detected in the solid samples, while trace metals, PAHs and PCDD/PCDF were detected in concentrations below the limits established by international standards. Toxic equivalent factors were evaluated for the biosolids, and the results proved that these wastes can be safely deposited on land or used in combustion/incineration plants. Since no previous data were found for meat processing waste, comparisons were made using municipal sewage sludge data reported in the literature. Since, this report monitored part of the priority pollutants established by the US EPA for meat and poultry processing wastewater and sludge, the results verified that low pollution loads are generated by the meat processing plant located in the southern part of Brazil. However, the BS generated in the treatment processes are in accordance with the limits established for waste disposal and even for soil fertilizer.