A newly published report from a University of Arizona research group says biosolids, properly treated, pose little if any health risk to the public. The study, "Pathogens in Biosolids: Are They Safe?," is online in the Journal of Environmental Quality.
Ian L. Pepper, director of the NSF Water and Environmental Technology Center and a professor of soil, water and environmental science, or SWES, at the UA, led the study, a 19-year analysis tracking pathogens in biosolids from the wastewater stream in Tucson, Ariz. The study also included current data from 18 other wastewater treatment plants across the country.
The study's co-authors include another SWES professor, Charles P. Gerba, as well as researchers from the U.S. Department of Agriculture, Loma Linda University and Drexel University. The study is the first of its kind since current federal regulations, specifically the Environmental Protection Agency's Part 503 Rule, for wastewater treatment began in 1993.
The Part 503 Rule governs how wastewater is treated in order to maintain public and environmental safety.
Most people in the U.S. live in communities where raw sewage is treated at wastewater facilities. Biosolids, the end product of the treatment process, have a broad range of uses in agriculture, from fertilizing agricultural fields and woodlands to lawns and gardens. Biosolids fall into two categories, Class A and Class B. Both use a combination of processes to kill pathogens including heating, composting, anaerobic digestion or changing pH levels.
Class A biosolids are those that have been treated to the point where pathogens are undetectable and there are no restrictions on their use as fertilizer. Standards for Class B biosolids are less stringent and have small but measurable levels of bacteria and come with restrictions on how they can be used on crop plants, grazing livestock and human exposure.
Pepper said one big question has been what kind and how many human pathogens are found in Class B biosolids. He said the study analyzed data prior to and after 1993, when the Part 503 rule took effect in order to determine the impact of regulations.
The study, Pepper said, showed that concentrations of fecal coliform bacteria and viruses are actually lower than 1993 levels. It also showed that between 94 and 99 percent of pathogens are eliminated by wastewater treatment, crediting treatment in reducing pathogen loads.
"Further, the fact that pathogen levels are lower now than in the 1980s shows that the Part 503 Rule has been effective in reducing public exposure to pathogens relative to 25 years ago," he said.
The study suggests that levels of some enteric viruses, the bacteria Salmonella and Ascaris ova, or roundworm eggs, in the U.S. are low in Class B biosolids that are treated by anaerobic digestion. Pepper and his colleagues also found no Campylobacter or E. coli bacteria in their tests.
Other studies suggest that Class B biosolids also are treated further simply by exposure to sunlight, wind, heat and soil microbes as they are distributed as fertilizer. Using biosolids as fertilizer also is a more ecologically sound approach to their disposal than either taking up space in landfills or polluting air and water through incineration.
The UA Water and Environmental Technology Center has gained a nationwide reputation for research on biosolids by providing data on human exposure to microbial pathogens, allowing for risk assessments on potential adverse effects of pathogens on human health and welfare.
Contact:Ian L. Pepper
| University of Arizona
How much drought can a forest take?
20.01.2017 | University of California - Davis
Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences