Search

The aim of this research was to improve the removal of organic matter and nutrients from wastewater from pig farms in a combined batch reactor performed as anaerobic-aerobic sequential. For this purpose, it was suggested to include recirculation cycles of wastewater in a sequentially pulsed manner in the anaerobic treatment followed by intermittent aeration in the aerobic-anoxic treatment. This novelty implemented in both sequential reactors was studied under pilot scale conditions. The process of pulsed intermittent recirculation allowed better contact between the microorganisms and organic matter, and intermittent aeration improved the removal of nutrients, primarily nitrogen (nitrification and denitrification), total phosphorous and organic matter. The best configuration tested for the combined system was the one consisting of pulsed intermittent recirculation with 1 hour of recirculation and 3 hours rest in the anaerobic step and 2 hours of aeration and 1 hour without aeration cycle in the aerobic step. The removals achieved were 98 ± 1% of total organic matter, 86 ± 5% of soluble organic matter, 96 ± 1% of total phosphorus and 55 ± 18% of total nitrogen. Hence, it was demonstrated that a combined system with pulsed intermittent recirculation in the anaerobic stage and intermittent aeration in the aerobic stage could enhance the overall treatment of swine wastewater. [ABSTRACT FROM AUTHOR]

Abstract: Pollution caused by pesticides is becoming relevant because of their harmful environmental effects. The persistence, bioaccumulation and toxicity of some organochloride pesticides have resulted in their restricted use since 1970 and a requirement to monitor them in many countries. Pesticides have endocrine, immunological, reproductive and carcinogenic effects in both humans and animals. The facilitated infiltration of substances results in the pollution of hydric underground resources in karstic limestone such as that found in the state of Yucatan. Observing the north occidental region of the state of Yucatan is particularly important as it is characterized by agricultural activities (wide use of pesticides), significant human settlements and underground water flows oriented towards the north coast. In this study, the underground water quality of a karstic aquifer was evaluated by quantifying the presence of organochlorine pesticides in 29 wells located throughout the Mérida‐Progreso transect, Yucatan, Mexico. The presence of DDT, lindane and their metabolites was detected at concentrations above the permissible limits stated by Mexican regulatory standards (NOM‐127‐SSA1‐1994 2010) in the majority of wells studied. Continuous monitoring of the underground hydric resources in this region is therefore essential to raising awareness of pollution risks and the vulnerability of the coastal north to the contamination of the underground water flows. [ABSTRACT FROM AUTHOR]

Copyright of Mexican Journal of Biotechnology is the property of Sociedad Cientifica Internacional de Biotecnologos and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)