Although it is widely believed that biosolids composting is beneficial to the community, to farmlands, and especially to the environment, there are still limitations to this process that may cause some to turn their backs on the advantages of treating wastewater sludge (to be called biosolids post-treatment).
Yes, the benefits have limitations. Treating biosolids and applying it on land are not without its drawbacks. As early as now, let us clarify that the benefits of biosolids far outweigh the limitations imposed on it because of physical and scientific incapacities.
Biosolids smells bad. Really, really bad. Even Class A and organic soil smell bad because the various processes and treatments it underwent were not enough to devoid it of its natural odors. Can you then imagine how bad the smell is emanating from biosolids plants and facilities? The operations of a treatment plant are not only a nuisance to the community, but it can also be a pollutant. Offensive odors are the primary reason why the public perception about biosolids has never been good. Many well-operated plants have also closed down because of public opposition.
Experts, scientists, and federal authorities believe that the odor of biosolids composting does not pose health hazards. However, they are also in unison in the belief that processing facilities have the ethical responsibility to control odors and protect nearby areas from exposure.
Presence of primary pathogens
Aside from odors, the presence of pathogens, endotoxins, and various other volatile compounds must also be controlled. Primary pathogens such as bacteria, viruses, helminth, and protozoa can be found present in wastewater residuals. When consumed, it can invade a normal and healthy human being, and produce an illness or debilitation.
If done correctly, composting can reduce the chances of viral pathogens from appearing. The temperature of composting to reduce pathogens to non-detectable levels must be greater than 55 degrees Celsius for 15 days or more.
Dispersion of secondary pathogens
When primary pathogens are treated and kept to a minimum, there is still the possibility of the compost being infected by secondary pathogens such as Aspergillus fumigatus, particulate matter, and other airborne allergens. The regrowth of Salmonella in composted biosolids is also possible because composting is not a sterilization process, and it is only through sterilization that Salmonella sp. can be fought off.
Even properly composted products maintain an active population of beneficial microorganism that compete against pathogenic members. Under certain conditions, the regrowth of pathogenic microorganisms is still possible.