Factors Affecting Plant Growth
Biosolids are nutrient-rich organic material that are processed from our own human waste. The treatment plants which make the material use a polymer to precipitate the suspended solids in the wastewater. The water is then drained and the rest of the product is used as fertilizer. While incredibly gross, biosolids may prove to be a stepping stone towards a better environment.
Prevents pollution. Before biosolids were used, raw waste used to be dumped into rivers, lakes, and streams.
Method of recycling. It saves landfill space.
Excellent source of nutrients.
Improves crop production.
Reduces the need for chemical and commercial fertilizers.
Can be used for mine reclamation.
Potential health hazards. Many regulations have to be set in place in order to apply biosolids to land.
Contains nitrogen. A pollutant found in any fertilizer.
Pathogens (disease causing organisms).
Nutrient flows through urban environment.
Biosolids Microbes Pose Manageable Risk To Workers
ScienceDaily (Oct. 27, 2008) — Class B biosolids are sewage sludges that have been treated to contain fewer than 2.0 x 106 fecal coliforms/dry gram. The USEPA estimates that 6.3 million tonnes of Class B biosolids are generated in the United States each year, and that by 2010, the amount generated per year will increase to 7.4 million tonnes.
Biosolids produced during municipal sewage treatment are most commonly applied to land as a fertilizer at agricultural sites throughout the United States. Class B biosolids, which are the principal type of biosolids applied to land, contain a variety of enteric pathogens.
Land application of biosolids has received national attention due to the potential for off-site transport of disease-causing microorganisms through soil, water, and air. Workers face greater exposure to bioaerosols from biosolids than those not associated with the operation. A new study investigated levels of microorganisms in air immediately downwind of land application operations and estimated occupational risks from aerosolized microorganisms.
The authors report that risks of aerosol-borne infection for biosolids workers are generally low, at less than 1 or 2% per year. Overall, occupational exposure to bioaerosols from biosolids appears to be less risky than similar exposures among wastewater treatment workers.
In all, more than 300 air samples were collected downwind of biosolids application sites at various locations within the United States. Coliform bacteria, coliphages, and heterotrophic plate count (HPC) bacteria were enumerated from air and biosolids at each site. Concentrations of coliforms relative to Salmonella and concentrations of coliphage relative to enteroviruses in biosolids were used, in conjunction with levels of coliforms and coliphages measured in air during this study, to estimate exposure to Salmonella and enteroviruses in air.
The HPC bacteria were ubiquitous in air near land application sites whether or not biosolids were being applied, and concentrations were positively correlated to windspeed. Coliform bacteria were detected only when biosolids were being applied to land or loaded into land applicators. Risks from aerosolized microorganisms at biosolids land application sites appear to be lower than those at wastewater treatment plants, based on previously reported literature.
At a first glance, this article appears to be against the use of biosolids. The title "Biosolids Microbes Pose Manageable Risk to Workers" seems very negative, which is surprising because most sources on the internet are plenty in favour of this method. But as you read on it becomes clear that the article sides with the majority of researchers.
It delves into the studies done to review the health concerns that come with biosolids, which are mostly the involved risks of pathogens such as Coliform bacteria, coliphages, and HPC bacteria. The article reports that the chances of infection for those working closely with biosolids are generally very low; low being one to two per cent. It also states that these bacteria were found everywhere, whether or not biosolids were used in the area, and that the severity of the concentration depended more on windspeeds than the actual presence of our natural fertilizers.
The source of this article appears credible. It was found on ScienceDaily but was reposted from the SSSA (Soil Science Society of America). The SSSA is an international group of more than 6 000 scientists across the United States. The current president of the society, Dr. Gary Pierzynski, is the Interim-Dean College of Agriculture at Kansas State University and the rest of the officers are also university professors or have obtained their PhDs.
http://www.biosolids.com.au/what-are-biosolids.php
Australian & New Zealand Biosolids Partnership. "What are biosolids?" 2009. Web. 5 Jun 2012.
http://www.cwwa.ca/faqbiosolids_e.asp
Canadian Water and Wastewater Association. "Frequently Asked Questions." 2012. Web. 5 Jun. 2012.
http://www.sciencedaily.com/releases/2008/10/081027140821.htm
Soil Science Society of America. "Biosolids Microbes Pose Manageable Risk To Workers." ScienceDaily, 27 Oct. 2008. Web. 5 Jun. 2012.
http://lancaster.unl.edu/enviro/biosolids/whatare1.shtml
Ogg, Barb. University of Nebraska-Lincoln. "Biosolids?? What are Biosolids?" 2012. Web. 5 Jun. 2012
http://www.sciencedaily.com/releases/2008/10/081027140821.htm
Soil Science Society of America. "Biosolids Microbes Pose Manageable Risk To Workers." ScienceDaily, 27 Oct. 2008. Web. 5 Jun. 2012.