The reason why biosolids are being considered safer than other kinds of fertilizer is because of the low presence or the absolute absence of pathogens in it. Pathogens, by definition, are bacteria, virus, or other microorganisms that can cause disease. In the oldest and broadest sense, it is anything that can produce a disease. This is the reason why it is highly essential for biosolids land applicators to make sure that they are using well-treated and high-quality biosolids. Anything lower in quality than a Class A or Class B biosolids could ultimately lead to diseases and illnesses.
Part 503 of the guidelines and regulations of the US Environmental Protection Agency refers to the treatment of pathogens and the classification of biosolids into Class A or Class B. Class A biosolids refer there is almost no trace of pathogens in the material, and it is the safest form of biosolids there is. Class B biosolids, on the other hand, means the treatment process followed the guidelines set by the EPA, but failed to remove all traces of pathogens. However, it should be noted that Class B biosolids are still safe to use because there’s only a small detectable level of pathogens. This is allowed by the EPA guidelines.
Low risk of transmission
The concern that the use of Class B biosolids, which have low traces of pathogens, in land application could affect the communities where the sites are in is unfounded. The continuous research on the subject matter found out that there is low risk of transmitting pathogens from land application sites to surrounding residents. This is the reason why treatment facilities are allowed and permitted in commercial and even residential areas.
In fact, scientific studies have shown no correlation in the existence of human pathogens in biosolids and illnesses found in nearby residents. Studies have concluded that as long as best management practices are utilized, the application of biosolids poses negligible health risks from pathogens. Such studies are based on scientific understanding about pathogen survivability in the environment.
The treatment alone used in the collecting of household waste and the filtering of the liquids from the biosolids can kill pathogens in the materials. Many pathogens cannot survive the collection and treatment system, not to mention the additional treatment processes that sewage sludge has to go through to disinfect solids and effluent. Besides, pathogens are the kind of organisms that prefer and need the conditions of the human body to thrive. Once they are outside human bodies, they find it hard to survive in such a harsh environment.