The term biosolids refers to the solid organic matter residuals generated by wastewater treatment processes. These residuals or biosolids contain essential nutrients that can be applied as fertilizer to farmland when properly treated and processed, improving soil health and fertility and enhancing plant growth. Returning biosolids to farmland completes a natural food cycle where the food farms produce is consumed by humans who then produce biosolids, which, when treated appropriately to kill pathogens and enhance the fertilizer value, can be returned back to the farms to offset input costs and replenish the soil. Biosolids are also used for sod farming, soil remediation, horticulture, golf courses, mine reclamation and more.
LysteGro® includes predictable nitrogen, phosphorous and potassium values as well as a variety of micro-nutrients such as iron, zinc, magnesium and copper – all essential for healthy agriculture soil and plant growth. Biosolids also contain valuable organic matter which helps improve the overall health, structure and tilth of soil – something that cannot be replicated by synthetic chemical fertilizers.
The video below produced by the Water Environment Association of Ontario (WEAO) provides an excellent overview of biosolids and their sustainable benefits:
Biosolids and sludge are often confused. Sludge includes the untreated solids separated out from the liquids during wastewater treatment, while biosolids are the result of the sludge undergoing additional treatment at wastewater plants, meeting certain quality criteria for pathogens and metals.
Wastewater treatment facilities clean and reclaim water from community sewage systems through physical, chemical and biological processes. The treated, purified water is discharged into waterways and the solids that remain undergo further treatment to eliminate pathogens.
These solids are treated using a combination of processes including: heat systems, digestion, lime stabilization, composting or hydrolysis to prepare the material for safe, beneficial use.
Depending on the treatment process and method, biosolids fertilizers may contain a distinctive odor. This odor comes from sulphur and ammonia compounds – both plant nutrients found in the biosolids material. The type of treatment affects the type and intensity of the odor.
In addition, the handling and management of the biosolids has a significant impact on odor emissions at the wastewater plant and at the field application site. The liquid properties of LysteGro allow it to be completely contained from processing at wastewater plant to application in the field, with contained vessels, pumps, tanker trucks and subsurface application equipment. This is a significant advantage when managing odor concerns throughout the lifecycle of the product.
Due to significant advancements in sewer infrastructure and regulatory compliance for wastewater treatment plants, metal concentrations in treated biosolids are typically low and pose no risk to human health, agriculture or animals. In order to be used beneficially biosolids must comply with strict regulatory standards for metal concentrations.
Biosolids are carefully researched, studied and monitored on an ongoing basis to ensure they are safe. Metal concentrations found in biosolids are similar to those found naturally in healthy soil.
Biological nutrient removal systems remove nitrogen (N) and phosphorus (P) from the liquid stream at wastewater treatment plants using biological processes. Wastewater plants must meet certain N and P limits in the effluent water they discharge into the environment, and if these limits cannot be met through the basic wastewater treatment processes, additional nutrient removal must be implemented.
Biological N removal involves the use of bacteria, facilitated by sequential aerobic and anoxic conditions, to convert ammonium to nitrogen gas which is then volatilized into the atmosphere.
Biological P removal involves the modification of the activated sludge system in order to promote the growth of phosphorus accumulating organisms (PAOs) and splits the aeration basin into the (1) anaerobic section and (2) the aerobic section.
There Are Different Classes Of Biosolids
The U.S. Environmental Protection Agency (EPA) issued a 40 CFR Rule categorizing biosolids as Class A or Class B. The difference has to do with the level of pathogens and metals.
What Are Class A Biosolids?
In Class A biosolids, pathogens must be reduced to virtually non-detectable levels and the material must also comply with strict standards regarding metals, odors and vector attraction reduction (VAR) as specified in the US EPA, Part 503 Rule. VAR refers to processing which makes the biosolids less attractive to vectors, which have the potential for transmitting diseases directly to humans or can play a role in the life cycle of a pathogen as a host.
Various processes can be utilized to achieve Class A designation such as anaerobic digestion, lime stabilization, composting and thermal hydrolysis. This designation means the material meets U.S. EPA guidelines for land application with minimal restrictions.
What Are Class B Biosolids?
Class B biosolids are treated but contain higher levels of detectable pathogens than Class A biosolids. The use of Class B biosolids may require a permit from the EPA with conditions on land application, crop harvesting, and public access. However, in terms of nutrient value, Class B and Class A biosolids are similar as they both contain important nutrients and organic matter.
There is a distinct shift away from Class B use and toward Class A treatment solutions as a result of increasing regulatory pressures in many regions.
In the United States, the application of biosolids are regulated at the local, state, and/or federal level to ensure safe beneficial use. To a certain extent, each jurisdiction has its own policies and regulations regarding application procedures that can vary depending on the processes utilized and characteristics of the end product.
At the federal level, guidelines are set out by the United States Environmental Protection Agency (US EPA). Details of the regulations can be found under rule 40 CFR Part 503 (see Plain-English Guide to the Rule). To meet the regulatory requirements, biosolids must undergo initial treatment to reduce pathogens and attractiveness to vectors. This rule also sets strict quality standards such as specified limits for metals in biosolids, site restriction, crop harvesting restrictions, and monitoring.
Generally speaking, on a state-by-state basis, the Department of Environmental Quality (DEQ), or a similar agency, is responsible for overseeing programs that encourage the beneficial use of biosolids in a manner that protects public health and maintains or improves environmental quality.
In Canada, the regulations and guidelines for the use of biosolids is generally administered at the Provincial level. For example, in Ontario the Ontario Ministry of Agriculture Food & Rural Affairs works closely with the Ministry of the Environment to administer Ontario’s successful biosolids land application program. The practice is governed by provisions and regulations set out under the Ontario Water Resources Act, the Environmental Protection Act, and the Nutrient Management Act.
Once biosolids are converted into a pathogen free fertilizer that meets or exceeds the acceptable criteria for NPK and metals concentrations , the product is regulated under the federal Fertilizers Act by the Canadian Food Inspection Agency as a fertilizer product. It can then be utilized in the same manner as any commercial fertilizer.
Water supply and sanitation has been a primary logistical challenge throughout human history. Wastewater treatment plants have been around since the late 1800s. Basic sewer systems have been in use almost since the beginning of civilization, but it was the rise of industrialization and increased human density in the 19th century that prompted the creation of modern wastewater treatment plants and sewer systems.
In addition to the odor, outbreaks of deadly cholera killed thousands in large European cities by 1850. Recognizing that untreated wastewater was the source of the problem, many cities built underground sewer systems to pipe the sewage away from human populations. Often, the waste was sent directly to farmlands for use as fertilizer.
Within a few decades, it also became possible to treat sewage by removing pollutants through chemical processes. Sir Edward Frankland is widely credited with having been the first to discover that filtration of sewage through gravel had a purifying effect, separating and neutralizing the solids. By the 1890s, rudimentary wastewater treatment plants popped up across Europe, resulting in cleaner and safer cities.
These early concepts for wastewater processing and treatment represent the foundation on which Lystek’s scientifically advanced solutions for Wastewater Resource Recovery were built.