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Wastewater Lagoons (wastewater + lagoon)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

Induction of purple sulfur bacterial growth in dairy wastewater lagoons by circulation

LETTERS IN APPLIED MICROBIOLOGY, Issue 4 2009
J.A. McGarvey
Abstract Aims:, To determine whether circulation of dairy wastewater induces the growth of phototrophic purple sulfur bacteria (PSB). Methods and Results:, Two dairy wastewater lagoons that were similar in size, geographic location, number and type of cattle loading the lagoons were chosen. The only obvious visual difference between them was that one was stagnant and the water was brown in colour (Farm 1), and the other was circulated and the water was red in colour because of the presence of PSB that contained carotenoid pigments (Farm 2). Both wastewaters were sampled monthly for 3 months and assayed for PSB and extractable carotenoid pigments (ECP). After this point, circulators were placed in the wastewater lagoon on Farm 1, and samples were taken monthly for 9 months and assayed for PSB and ECP. Before the installation of circulators, no PSB-like 16S rRNA sequences or ECP were observed in the wastewater from Farm 1; however, both were observed in the wastewater from Farm 2. After the installation of circulators, statistically greater levels of PSB and extractable carotenoid pigments were observed in the wastewater from Farm 1. Conclusions:, Circulation enhances the growth of PSB in dairy wastewater. Significance and Impact of this Study:, Because PSB utilize H2S and volatile organic acids (VOA) as an electron source for photosynthesis, and VOA and alcohols as a carbon source for growth, the increase in these bacteria should reduce H2S, volatile organic compounds and alcohol emissions from the lagoons, enhancing the air quality in dairy farming areas. [source]

Abundance of six tetracycline resistance genes in wastewater lagoons at cattle feedlots with different antibiotic use strategies

ENVIRONMENTAL MICROBIOLOGY, Issue 1 2007
Nicholas Peak
Summary The abundance of six tetracycline resistance genes tet(O), tet(Q), tet(W), tet(M), tet(B) and tet(L), were quantified over time in wastewater lagoons at concentrated animal feeding operations (CAFO) to assess how feedlot operation affects resistance genes in downstream surface waters. Eight lagoons at five cattle feedlots in the Midwestern United States were monitored for 6 months. Resistance and 16S-rRNA gene abundances were quantified using real-time PCR, and physicochemical lagoon conditions, tetracycline levels, and other factors (e.g. feedlot size and weather conditions) were monitored over time. Lagoons were sorted according to antibiotic use practice at each site, and designated as ,no-use', ,mixed-use' or ,high-use' for comparison. High-use lagoons had significantly higher detected resistance gene levels (tetR; 2.8 × 106 copies ml,1) relative to no-use lagoons (5.1 × 103 copies ml,1; P < 0.01) and mixed-use lagoons (7.3 × 105 copies ml,1; P = 0.076). Bivariate correlation analysis on pooled data (n = 54) confirmed that tetR level strongly correlated with feedlot area (r = 0.67, P < 0.01) and ,total' bacterial 16S-rRNA gene level in each lagoon (r = 0.51, P < 0.01), which are both characteristic of large CAFOs. tet(M) was the most commonly detected gene, both in absolute number and normalized to 16S-rRNA gene level, although tet(O), tet(Q) and tet(W) levels were also high in the mixed and high-use lagoons. Finally, resistance gene levels were highly seasonal with abundances being 10,100 times greater in the autumn versus the summer. Results show that antibiotic use strategy strongly affects both the abundance and seasonal distribution of resistance genes in associated lagoons, which has implications on water quality and feedlot management practices. [source]