Tuesday, January 05, 2010

What are you reading?

Today, I'm reading the following: Induction of purple sulfur bacterial growth in dairy wastewater lagoons by circulation (PDF, 7 pages).

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.


soil mama said...

cool, thanks.

so did the increase in PSB result in reduced H2S, VOC's and alcohol emissions? or is that in their next paper ;)

Thomas Joseph said...


Here is an excerpt from their last paragraph: Because PSB utilize both H2S and volatile fatty acids as a source of electrons for photosynthesis and volatile fatty acids as a carbon source for growth, the presence of these bacteria within wastewater lagoons has been shown to reduce the rates of volatile organic compounds emissions and thus should be a benefit to both the dairy industry and the residents of dairy farming areas. Although we did not perform quantitative measurements of odour release from the wastewaters, we have consistently noted that circulated wastewater lagoons are less malodorous than stagnant lagoons, which is also a benefit to the residents of agricultural areas.

So they did the sniff test, and said they're reduced. ;)

soil mama said...

hehe, that's pretty funny to me. I'm trying to think of applications for the sniff test in my work- sounds pretty easy :)