Materials Handling and Biosolids Technologies

Field Storage of Biosolids

Now that you’ve implemented your process (perhaps the Bioset Process?) for turning sludge into Class A biosolids, you’re probably faced with a new concern: what to do with all this high-quality fertilizer? If you’re providing it to farmers or citizens for land application, it might go out fast enough during some seasons of the year, but municipalities are generating wastewater year-round, even if the ground is frozen or fallow. The EPA provides guidelines for biosolid storage. Some of the primary concerns are:

• Site Selection Considerations
• Field Storage: Stockpiles
• Field Storage: Constructed Facilities
• Odor Prevention and Mitigation
• Spill Prevention and Response

For site selection, you’ll want to consider some key factors:

• Climate: How will weather affect the location? Do the prevailing winds blow odor toward a community? In many areas of the United States, land application of biosolids is severely limited from November through March.
• Topography: Is the location regularly inundated by water or in a wetlands? Is it fairly level? Stockpiles should be near the top of slopes to minimize exposure to up-slope runoff. Storm water controls may be necessary. Storage locations should be in areas with adequate buffers.
• Soil/Geology: Sites should not be located on excessively moist or wetland soils that regularly have standing water or excessive runoff after storms, or areas with loose soils (gravel or sand) that permit excessive infiltration.
• Buffer Zones: Sites must comply with any federal (10 meters by the 503 rule), state, or local regulations regarding minimum buffer distances to waterways, homes, wells, property lines, roads, etc.
• Odor Prevention/Aesthetics: Try to minimize visual and odor impact on residential areas. Storage during the summer poses a greater potential for development of unacceptable odors and requires a higher level of management.
• Accessibility and Hauling Distance: How far do you have to haul sludge and/or biosolids? What’s the accessibility of the site during bad weather, or heavy traffic? Take note of weight restriction and other roadway limits along the haul route. Consider the traffic impact as well.
• Property Issues: Ensure local zoning requirements and ordinances are met, and consider the relative security and liability associated with leasing versus ownership of the land. Any leases should extend for several years and preferably over the expected life of the facility.

Schwing Bioset’s advanced processing technology can help you understand and meet these requirements. To learn more, contact Schwing Bioset.

Feeling Green: Biosolids 101

Can you imagine living in a world where all of our raw sewage is dumped directly into rivers, lakes, or bays? What would that mean for your next fishing trip, your next family vacation to the ocean, or your next hot summer day spent splashing around in the local lake or creek?

Many of us don’t need to use much imagination to picture this scenario, because it wasn’t so very long ago that this careless sewage dumping happened in thousands of cities across America. According to the EPA, it was just thirty years ago that sewage made a one-way, non-stop trip to the water surrounding us.

My, how far we’ve come.

Today, thanks to vast improvements in wastewater treatment processes, American waterways are no longer the dumping grounds that they once were. Advanced wastewater treatment makes our waterways more hospitable to swimmers (both human and aquatic), and it also produces one very green side effect: biosolids.

As defined by the EPA, biosolids are “the nutrient-rich organic materials resulting from the treatment of sewage sludge.”

Sewage sludge isn’t very useful on its own, but once it is turned into biosolids, its potential is nothing short of extraordinary. Biosolids can be recycled and turned into super-powered fertilizer, which can be applied to land used for growing food. Today, roughly half of biosolids produced in the United States are being applied to land to beneficially improve soils. That’s a lot of recycled waste!

The EPA uses strict criteria and guidelines to ensure that biosolids are used safely. Thanks to these regulations and reliable, efficient biosolid processing systems like the Schwing Bioset process, raw sewage can be part of the ever-increasing green movement. Who knew poo could be as trendy as a canvas grocery bag?

The Biosolid Journey

Somewhere, perhaps not far from where you are, biosolids are enriching soil and improving the land. Much of the biosolids produced in the United States are used to beneficially improve farmland, and biosolid application isn’t necessarily limited to agricultural use. Biosolids meeting the EPA’s criteria can be beneficially applied to forest land, reclamation sites, golf courses, public parks, roadsides, plant nurseries, and, in some cases, lawns and home gardens.

So biosolids can end up just about anywhere—but how do they get there? Biosolids result from the treatment and processing of sewage sludge. Biosolid processing can be a relatively simple process, especially when the right treatment system is put to work. Schwing Bioset has the treatment process down to a science, and many wastewater treatment plants prefer the Bioset process for its ease of operation, lack of dust and odor, minimal maintenance requirements, and low cost.

Systems like the Bioset process are able to turn sewage sludge into biosolids that meet the EPA’s criteria for ‘Class A’ biosolids. Class A biosolids are safe for land application—even land that is used to grow food. Once the biosolids have been treated and processed, they are ready to be put to use, enriching soil with necessary nutrients.

Sometimes biosolids are sprayed onto soil surfaces, and they can be tilled or injected into the land. In a liquid state, biosolids can be applied using tractors, tank wagons, irrigation systems, or special application vehicles. As a matter of fact, biosolid land application doesn’t differ too much from the application of limestone, animal manure or commercial fertilizers (but thanks to the treatment from systems like the Bioset process, biosolids don’t smell like animal manure!).

All across America, soil is being conditioned and fertilized by biosolids that began as sewage sludge.

What does your town do with its sewage?

Land Application Requirements

EPA Part 503 rule lists four options for meeting pollutant, pathogen, and vector limits in biosolids that are applied to land:

• Exceptional Quality (EQ)
• Pollutant Concentration (PC)
• Cumulative Pollutant Loading rate (CPLR)
• Annual Pollutant Loading Rate (APLR)

Each option is equally protective of the public health and the environment, so EQ, PC, CPLR, and APLR biosolids used in accordance with the Part 503 rule are all equally safe. For a detailed discussion on these four options, the best bet is to refer to the EPA, but the table below gives a brief primer on each.

Option*	Pollutant Limits	Pathogen Requirements	Vector Attraction Reduction Requirements
Exceptional Quality (EQ) Biosolids	Bulk or bagged biosolids meet pollutant concentration limits	Any one of the Class A requirements listed here	Any one of options 1–8 listed here.
Pollutant Concentration (PC) Biosolids	Bulk biosolids meet pollutant concentration limits	Any one of the Class B requirements listed here	Any one of the ten options listed here.
		Any one of the Class A requirements listed here	Option 9 or 10 listed here.
Cumulative Pollutant Loading rate (CPLR) Biosolids	Bulk biosolids applied subject to cumulative pollutant loading rate limits listed here	Any one of the Class A or Class B requirements listed here	Any one of the ten options listed here.
Annual Pollutant Loading Rate (APLR) Biosolids	Bagged biosolids applied subject to annual pollutant loading rate limits	Any one of the Class A requirements listed here	Any one of options 1–8 listed here.

* Each of these options requires that the biosolids meet ceiling concentrations for pollutants, monitoring requirements, and recordkeeping and reporting requirements. See the EPA’s Part 503 Rule, Chapter 2 [PDF] for more information.

Schwing Bioset’s advanced processing technology can help you understand and meet these requirements. To learn more, contact Schwing Bioset.

What's your vector?

Biosolids can attract “vectors,” which are basically any living carrier that transmits an infectious agent (think ticks, mosquitoes, fleas, some kinds of flies, etc.). Meeting EPA Part 503 standards for Class A or B biosolids of various types requires that the biosolid meets at least one (sometimes more) of the ten vector attraction reduction options listed below:

Option 1. Reduce the mass of volatile solids by a minimum of 38%.

Option 2. Demonstrate vector attraction reduction with additional anaerobic digestion in a bench-scale unit.

Option 3. Demonstrate vector attraction reduction with additional aerobic digestion in a bench-scale unit.

Option 4. Meet a specific oxygen uptake rate for aerobically treated biosolids.

Option 5. Use aerobic processes at greater than 104°F (average temperatures 113°F) for 14 days or longer (e.g., during biosolids composting).

Option 6. Add alkaline materials to raise the pH under specified conditions.

Option 7. Reduce moisture content of biosolids that do not contain unstabilized solids from other than primary treatment to at least 75% solids.

Option 8. Reduce moisture content of biosolids with unstabilized solids to at least 90%.

Option 9. Inject biosolids beneath the soil surface within a specified time, depending on the level of pathogen treatment.

Option 10. Incorporate biosolids applied to or placed on the land surface within specified time periods after application to or placement on the land surface.

The Bioset process can help you achieve these options for your wastewater treatment. Contact Schwing Bioset for more information. For a more detailed explanation of these vector attraction reduction options, refer to the EPA’s Part 503 Rule, Chapter 5 [PDF].

Case Study: Stewartstown, PA

The Stewartstown Sewage Treatment Plant (STP) is owned by the Stewartstown Borough Authority of Stewartstown, PA. The plant experiences flow at an average rate of 0.625 MGD (millions of gallons per day) plant with MBR (membrane bioreactor) treatment. Sludge is dewatered with a 1.5m belt filter press that produces 16-17% solids. Before working with the Bioset process, the Stewartstown Sewage Treatment Plant's disposal strategy typically consisted of processing liquid sludge at a neighboring facility. Alternatively, dewatered sludge was hauled to a landfill.

Upon recommendation of their consulting engineer, the Borough investigated Class A technology to take advantage of more disposal options. A thermophilic digestion process was considered. However, given the relatively small size of the plant, this option was rejected for requiring the investment of too much capital and manpower. The Bioset process offered a low-cost Class A option that could be integrated into the plant operation. Alkaline stabilization was designed into an overall plant upgrade and put out for tender in 2007.

The layout flexibility of the process was again crucial as the mixer, pump, power unit, and reactor were engineered to fit into a single garage bay, with reactor discharge pumping to an adjacent garage bay to load the truck. The process was operational by the end of 2007.

Today, using the Bioset process, the Class A biosolids are disposed of at two agricultural sites. The farmers are responsible for spreading the product. The farmers have reported positive results with their crop yields and have not had any odor-related complaints. Pennsylvania regulations permit spreading Class A biosolids year-round, so there is no need for material storage through the winter.

Everyone likes a nice waterbed...

If you were to visit a plant using fluid bed technology, you might be expecting a warehouse full of waterbeds. You'd be wrong, of course. But what you would find is nothing short of engineering wizardry.

Schwing Bioset engineers, manufactures and installs advanced technology that can be used to process sewage and biosolids into valuable Class A material. Fluid bed technology, a hallmark of Bioset's process, works with biosolids in a way that is multifunctional, ultra-efficient and even environmentally friendly.

Fluid bed technology can be applied to biosolids in a number of ways: drying, cooling, conditioning, classifying, and solvent removal and recovery are just a few of the possible applications.

Fluid beds have numerous advantages over comparable technologies. The fluid bed drying system uses high thermal energy efficiency, which allows maximum performance at minimum temperatures. Because the temperatures are so low, drying biosolids using a fluid bed is extremely safe-not only for operators, but also for the environment. Furthermore, fluid beds self-cleaning, and everything in a fluid bed system is contained, so dust is limited as well.

Fluid bed processing allows for reduced consumption of energy and utilities, but doesn't sacrifice an ounce of performance. With a fluid bed, drying, cooling and/or conditioning steps can be combined in one unit. If space is still a concern, a fluid bed is worth considering: this entire system requires minimal space for installation compared with other processing technologies, and it contains minimal internal parts-and very few moving parts-as well. Finally, the process can be completely automated and even operated unattended.

Ultimately, fluid bed technology carries numerous benefits while still resulting in improved quality and consistency for the end product. If you're interested in learning more about fluid bed technology, contact Schwing Bioset today.

Generating "Revinu"

Lime stabilization is a proven, EPA-approved method for treating sewage sludge. In the capable hands of Schwing Bioset, the technique of lime addition has gone from effective to exceptional.

Bioset's process optimizes the chemical requirements and system efficiencies of lime stabilization. The end product, called Revinu, is safe and has many uses including fertilizer and as a soil stabilizer. Revinu is inexpensive and reliable, and produces a readily usable and valuable Class AA product.

Compared to other methods of producing Class AA material, the Bioset process is affordable from both initial capital expenditures and ongoing operation and maintenance costs. The equipment is fully automated and requires very little operator time. As a Class AA biosolid, the end product can be widely used and handled without many of the restrictions imposed on a Class B product.

Revinu's nutrient composition is a strong selling point. First, Revinu's low phosphorus content means it can be applied in phosphorus-sensitive areas. Second, Revinu provides a slow-release alternative to commercial nitrogen, which gives consumers three times the amount of nitrogen breakdown for prolonged plant nutrition. Third, Revinu provides sufficient potassium-a nutrient that is often prohibitively expensive-to support root growth and proper seed germination for a fraction of the market price of potassium.

Finally, Revinu is made up of 35% to 55% organic humus. The humus in the material acts as a topsoil, replenishing the natural bacteria that are essential for optimal plant growth and root strength. Until Revinu arrived on the market, landowners were often unable to replace eroded topsoil due to the astronomical cost associated with the process. Revinu makes topsoil replenishment accessible and affordable.

In short, the Bioset process is the most versatile and attractive method for biosolids treatment on the market today.

Case Study: London, Ontario

The London Greenway Pollution Control Centre ("Greenway" for short) is the main wastewater treatment facility for the city of London, Ontario. Greenway is an activated sludge plant that also receives liquid sludge trucked in from the city's other five wastewater plants. 

Greenway dewaters the sludge and relies on a fluid bed incinerator. In 2008, the incinerator required shutdown for major overhaul that would last over three months. The city's Wastewater and Solid Waste departments are separate entities and are required to charge each other for services rendered. After determining that a prolonged incinerator shutdown would have a prohibitive cost, the Wastewater Department sought alternatives.

Schwing Bioset piston pumps were previously installed at the Greenway plant to feed the dewatered sludge to the incinerator, so plant personnel were knowledgeable about Schwing Bioset capabilities. The Bioset process was proposed to treat the dewatered sludge to beneficially reuse the biosolids as landfill cover. Representatives from the Wastewater and Solid Waste departments visited Bioset installations in Florida to observe the process and it was determined the end product would be acceptable as landfill cover at a preferable cost.

A change order was issued to the incinerator rehabilitation contractor to install the Bioset process equipment as a back-up sludge treatment train to the incinerator. The component equipment permits flexibility in the layout design that allowed the plant to use distinct idle spaces so that no new structures were needed to accommodate the installation.

The plant processed 25,000 metric tons of Bioset product between August and December 2008 while incinerator rehabilitation work was completed. The city has since returned to incinerating the biosolids, but maintains the Bioset equipment as a back-up for annual shut-down/rehabilitation work.

Biosolids Yield Happy Farmers & Happy Crops

In order to maintain your health, your doctor might recommend that you take a multivitamin. Biosolids act like a multivitamin for agricultural crops-and the result would make any nutritionist smile.

                               

Biosolids, like the ones processed using Schwing Bioset's advanced technology, can be applied as fertilizer to fields used for raising crops. According to the EPA, agricultural use of biosolids that meet strict quality criteria and application rates has been shown to produce significant improvements in crop growth and yield.

Why do biosolids make a difference for crops?

• Biosolids are chock full of essential nutrients. Nutrients found in biosolids, such as nitrogen, phosphorus and potassium and trace elements such as calcium, copper, iron, magnesium, manganese, sulfur and zinc, are all necessary elements for crop production and growth.
• Rejuvenation. The use of biosolids replenishes the organic matter that exists naturally in soil, but gets depleted over time with repetitive planting and harvesting cycles.
• Moisture management. The organic matter improves soil structure by increasing the soil's ability to absorb and store moisture.
• Defense. The organic nitrogen and phosphorous found in biosolids are used very efficiently by crops because these plant nutrients are released slowly throughout the growing season. This enables the crop to absorb these nutrients as the crop grows. This efficiency lessens the likelihood of groundwater pollution of nitrogen and phosphorous.
• Environmental Friendliness. The application of biosolids reduces the need for chemical fertilizers.
• The Bottom Line. Biosolids benefit farmers by reducing production costs.

Happy farmers, happy crops, happy-and-healthy-consumers. To learn more about how the Schwing Bioset process makes these valuable biosolids possible, contact Schwing Bioset.