What is in Heart & Soil® Biosolids?
RMI’s Heart & Soil® product line includes biosolids fertilizers and our customers have been enjoying the benefits of high quality yet cost-effective fertilizers for several years. Heart & Soil Biosolids are available to customers throughout New Hampshire and Vermont.
What are biosolids?
Biosolids are the mostly organic solids resulting from the treatment of wastewater. They are rich in nutrients such as nitrogen and phosphorus and contain other supplementary nutrients such as potassium, sulfur, magnesium, calcium, copper, and zinc. When used as a fertilizer, biosolids provide extended benefits due to the slow-release nature of their performance.
What is wastewater?
Wastewater comes from home kitchens, bathrooms, and laundries, as well as from process and wash water from industries and businesses.
What is in wastewater?
Wastewater is mostly water (about 99.5%). Less than 1/2% is suspended and dissolved solids which must be removed so the water can be returned safely to the environment. The solids are either inorganic (sand, grit, nutrients such as nitrogen and phosphorus, salts, and metals) or organic (primarily waste products of animal or vegetable origin, but also a variety of synthetic chemicals). Wastewater also contains living organisms such as bacteria.
Why do we have wastewater treatment?
Wastewater treatment is necessary to protect public health and the environment. Discharging raw sewage into lakes and streams harms those environments and can spread disease. In lakes and streams, native bacteria, algae, and other microscopic organisms (microbes) use the waste as food. These microbes eat and reproduce, using the available oxygen dissolved in the water. If too much waste enters a waterbody, the microbes will use too much of the available oxygen needed by fish and other aquatic life.
How does wastewater treatment work?
Wastewater treatment plants mostly use the same biological and physical processes by which water is cleaned in nature. The steps to clean water include industrial pre-treatment, preliminary treatment, primary treatment, and secondary treatment.
Advance removal of unacceptable levels of chemicals or metals prior to delivery to a community wastewater treatment facility.
Initial physical screening to remove debris (rags, wood, plastic)
Storage of wastewater in a sedimentation tank motionless for several hours to allow solids to settle to the bottom. Grease and oils float to the top and are removed for disposal.
Secondary treatment is a biological process which relies on the same microbes that clean natural waterways. After primary treatment, wastewater is held in another large tank in which microbes feed on the suspended and dissolved solids in the wastewater. Treatment plant operators carefully monitor and control the temperature, pH (acidity), and amount of oxygen in the wastewater to ensure the health of the working microbes. Gradually, older microbes, which have eaten their fill, die and settle to the bottom. They take with them the suspended and dissolved solids that they consumed. The nearly pure water flows out of the top of the secondary treatment tank and is disinfected prior to being released into a river, ocean, or groundwater. The collected “secondary solids” are mixed with the “primary solids” and, if they are going to be recycled, treated and tested. Secondary treatment removes about 85% of the remaining suspended solids and nutrients.
Where do the biosolids come from?
The solids or “sludge” collected from the primary and secondary treatments are mixed together and undergo further treatment. Most often, these combined solids are “dewatered” to make a more manageable, semi-solid material. Dewatering usually involves centrifuges, vacuum filters, drying beds, or presses that remove excess water. The solids are also “stabilized” by some form of digestion (aerobic or anaerobic), and/or composting, or some other treatment. There are stringent U. S. federal guidelines (the federal “Part 503” regulations of the U. S. Clean Water Act) which identify approved treatment processes. In Canada, provincial regulations or guidelines do the same. These stabilization processes reduce pathogens (microscopic organisms that can cause disease in humans) and odors. They also make the solids less attractive to “vectors” (animals that can carry pathogens, such as flies). Only once they have been through these treatment and testing procedures can “sludges” be called “biosolids” and used as Heart & Soil® Complete and Complete+ as fertilizers and soil amendments.
Is using Heart & Soil Biosolids safe? How do we know?
Yes. When properly managed in accordance with federal, state, and/or provincial regulations and best management practices, the risk to public health and the environment from recycling biosolids are negligible. Federal and state standards and management practices for biosolids recycling were developed from a detailed scientific risk assessment completed by the U.S. Environmental Protection Agency (EPA). Input included research and expertise from the U.S. Department of Agriculture and premier universities including the Universities of Arizona, California, Colorado, Florida, Maine, Michigan, Massachusetts, Minnesota, New Hampshire, Oregon, Vermont, Washington, Colorado State, Ohio State, Penn State, and Cornell Universities.
What about heavy metals?
Biosolids contain trace amounts of “heavy metals,” as do natural soils, manures, and commercial fertilizers. The U.S. EPA and university researchers around the continent have studied the potential risks from these trace metals and U. S. EPA, state, and provincial regulations set maximum levels in biosolids to ensure protection of public health and the environment. Because of required industrial pretreatment and the risk-based standards for biosolids recycling, the risks posed by trace metals in biosolids are minimal.
Will the use of biosolids adversely impact nearby surface waters and/or groundwater?
No. Properly treated and properly managed biosolids products do not have a negative impact on surface water or groundwater quality. As with any fertilizer or soil amendment, best management practices must be followed to prevent impacts via surface water runoff or via leaching to groundwater. By law, biosolids recycling programs in the Northeast must follow such best management practices; the same is generally not true for the use of manures and chemical fertilizers.
Is biosolids recycling the right thing to do?
- Biosolids recycling returns nutrients and organic matter to soils.
- Biosolids recycling avoids the need for more costly landfill space or incinerators.
- Biosolids products are efficient fertilizers and soil amendments that build healthy soils, restore barren lands, and help keep New England and eastern Canadian landscapes open and growing.
- Biosolids recycling in accordance with regulations and best management practices has been proven safe and beneficial by decades of scientific study and peer review.