What are Biosolids?
Biosolids are a nutrient rich material created from the municipal wastewater treatment process. Scientific studies have shown biosolids contain nitrogen, phosphorus, stabilized organics and other important constituents. This makes biosolids a valuable resource that can be recycled by farmers and ranchers as a nutrient rich soil amendment.
Q. What is the difference between Biosolids and sludge?
The term “sludge” refers to the untreated or partially treated solids associated with municipal wastewater. The City of Fort Worth’s (CFW’s) Biosolids are a highly treated and processed material that is routinely tested to ensure compliance with environmental standards.
Q. How is sludge treated to become Biosolids?
Three core operations complete this process:
- Aerobic wastewater treatment - beneficial bacteria use oxygen to destroy organic matter.
- Anaerobic treatment - other types of bacteria break down the biodegradable solids in the absence of oxygen. This process typically takes three weeks to “digest” the solids.
- Solids are further treated with materials such as lime to eliminate pathogens. Solids settling and dewatering also play key roles in producing the final product (Class AB Biosolids).
Q. What are Biosolids tested for?An independent, certified lab tests samples of biosolids for the following:
- 10 Heavy Metals
- PCBs (polychlorinated biphenyls)
- Fecal Coliform and other pathogens
- Percent solids
- Additional Sampling (if needed)
- Toxicity Characteristic Leaching Procedure
Regular periodic testing helps determine if the biosolids are in compliance with federal and state regulations found in 40 Code of Federal Regulations (CFR) Part 503 and 30 Texas Administrative Code (TAC) Chapter 312.
The CFW produces EPA Class “A” Exceptional Quality Biosolids, also known as TCEQ Class AB Biosolids. Any biosolids that do not meet the EPA Class A or TCEQ Class AB standards are landfilled and are not applied to ranches or farmland.
Q. Do Biosolids generate an odor?Ideally, biosolids will have an “earthy” odor. Sometimes the material may produce ammonia or hydrogen sulfide type odors, but biosolids typically produce less odors than animal fertilizers such as dairy manure. Once applied to fields, odors usually dissipate within a few days.
Q. Are Biosolids safe?Yes! Numerous studies have shown that biosolids are safe for application on food crops. (For a list of references, please email us at email@example.com.)
Q. Should I be concerned about other contaminants that are not addressed under state and federal biosolids rules such as personal care products, pharmaceuticals, and household cleaners/chemicals?Research indicates that the risk to human health and the environment from these compounds is negligible when biosolids are managed according to state and federal rules for several reasons:
- Any synthetic organic compounds that may survive wastewater treatment are degraded or strongly bound to organic matter in soil.
- Plant roots take up negligible amounts of these compounds.
- Site management practices for biosolids (such as buffer zones and restrictions on application timing) significantly reduce the opportunity for these compounds to move to water bodies.
(For a list of references, please email us at firstname.lastname@example.org.)
Q. Who oversees biosolids generation and management?The dewatering (biosolids) facility is operated by Renda Environmental, Inc., in a public/private partnership. The following agencies provide regulatory oversight:
- Region 4 Texas Commission on Environmental Quality (TCEQ)
- CFW Environmental
- CFW Water Department
- Region 6 Environmental Protection Agency (EPA)
Q. What are the benefits of biosolids land application?When conducted in compliance with state and federal regulations and by utilizing best management practices, biosolids land application provides the following benefits:
- Improved soil quality.
- Higher crop yields and lower costs for farmers.
- Improved water content of the soil (an important feature in drought-prone Texas).
- The nutrients in biosolids are released slowly compared to commercial fertilizers, preventing the release of nutrients into groundwater.
- Landfilling biosolids is expensive and wasteful.
- Commercial fertilizers are essentially salts and are much more susceptible to leaching and run-off than biosolids.
Public Policy Issues
There is no waste in nature! Wastewater treatment facilities and biosolids land application activities mimic the processes and nutrient (food) cycles found in nature; organic material generated by one organism provides resources for another organism. The entire wastewater treatment process is designed to produce clean water, renewable energy (biogas) and allow for the beneficial use of biosolids.
Beneficial land application returns nutrients to the earth and closes the loop in the food cycle, rather than permanently discarding a reusable material.
While some individuals refer to the practice as urban “dumping”, the general public should understand that the beneficial reuse of biosolids through land application is one of the most successful recycling programs in the nation. As such, it is important for citizens to continue to support the use of this renewable and cost effective resource.
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