A Commitment To Quality Control
Biosolids, n. A nutrient-rich organic material resulting from the treatment of wastewater.
Ensuring the high quality of biosolids is an important and never-ending commitment for those involved in biosolids recycling. An age-old process, biosolids recycling benefits from the long-term, in-depth research and study conducted by health, environmental and regulatory officials.
In February 1993, the U.S. Environmental Protection Agency concluded more than 20 years of study and research on wastewater solids by issuing its most comprehensive set of regulations ever. The regulations implementing Part 503 of the Clean Water Act are aimed at ensuring both the quality of recycled biosolids and their safe application.
In promulgating this rule, the EPA examined every aspect of wastewater solids in the environment, including their impact on groundwater, air and soil quality and surface runoff. Far-reaching analysis of potential exposure pathways--eating, breathing, drinking water--contributed to the development of the final rule.
The new rule sets quality criteria for biosolids by establishing strict limits for trace metals and mandating processing that destroys pathogens and minimizes odor. In addition, the rule details requirements to monitor biosolids for the presence of contaminants, restrict access to sites with certain quality biosolids, ensure that biosolids are applied only at the rate that can be used by the crop being grown (called the agronomic rate), and prevent runoff.
Pretreatment Is Essential
Regulations prohibit pollutants generated by industry from entering the municipal wastewater collection system by requiring that they be treated or removed at the industrial plant from which they originate. Pre-treating industrial discharges in this manner ensures that wastewater solids can be processed and recycled safely with no threat to the environment.
Land Application Is Strictly Monitored
Biosolids recycling is also monitored at the state or province level to enforce quality, application and access requirements. Each state sets criteria for the land application of biosolids; the health department or environmental agency issues permits and approves all sites prior to the application of biosolids. This process ensures that factors such as soil type, topography, water table level and environmental suitability are known and evaluated before biosolids are applied.
In addition to field inspections, permits for applying biosolids to land are based on information about the biosolids' nutrient composition and the farmer's plans for growing crops to make sure that biosolids are applied at rates appropriate to these crops. Professionals oversee the actual application of biosolids to the land, maintain records of where and what quantities are applied, and test periodically as needed.
Biosolids products used by the public, such as compost or pellets, must also meet the highest quality standards as enumerated by the Part 503 regulations.
Copyright @1996 Water Environment Federation
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Adapted by: Philadelphia Water Department, Biosolids Management Unit, 215-685-6248