News from Schwing Bioset

How Transitioning to Class A Biosolids Saves Money

 

Published in TPO Magazine, February 2016. Written by Larry Trojak.

 

A southwest Florida treatment plant turns to lime stabilization to create Class A biosolids for land application and cuts handling costs significantly.

Cost-effective handling of biosolids is essential to clean-water plants’ economic and environmental performance.

The Immokalee Water and Sewer District in Florida faced a biosolids challenge in 2006. The district had been using drying beds to create Class B biosolids and spending about $500,000 a year to dewater and haul excess material from that process to a landfill.

Facing a change in regulations on land application of Class B material, and wanting to reach the biosolids’ full economic potential, the district looked at alternatives. The ultimate solution was a facility redesign centered on using the Bioset process (Schwing Bioset) to create Class A biosolids. As a result, the district has reduced handling costs by more than two-thirds and produces a Class A product for beneficial use.

Anticipating change

Located about 30 miles southeast of Fort Myers, the heavily agricultural Immokalee district is home to about 24,000 residents. Its wastewater treatment plant was expanded in 2013 from 2.5 mgd to 4.0 mgd design capacity. Until fairly recently, it generated 23,500 gallons of Class B biosolids per day at 1 to 1.5 percent solids.

Gary Ferrante, P.E., an engineer with the Greeley and Hansen engineering firm, says a number of factors in 2006 led the district to review its biosolids operation. “Immokalee’s plant was originally designed with a half-dozen drying beds in which a Class B biosolids was created and used on permitted area farms,” he says.

“While that was effective, the facility is next to a school, which repeatedly complained about students’ health risks and odor. The district later learned that the U.S. Department of Agriculture and the Florida Department of Environmental Protection were considering changes to biosolids land application regulations (passed in 2010 as Florida Biosolids Regulation Chapter 62-640 F.A.C.). All that prompted the district to hire a consultant to look at alternatives.”

Lots of options

Based on recommendations from the consultant’s report, in 2007 the district contracted with Synagro Technologies to dewater the Class B biosolids and haul it to a landfill more than 100 miles away. In time, rising prices and an increase in biosolids volume raised annual costs from $309,000 to more than $470,000, providing incentive for the district to pursue other options.

“Working with the district, we put together a couple of proposals and a couple of scenarios within each proposal,” says Ferrante. “The first one covered the design/build/finance of a biosolids facility at the existing location. Options under this plan included handling material from Immokalee only, as well as accepting material from Collier County and making Immokalee a regional processing facility. The second proposal had an outside entity leasing land from the district and constructing a Class A regional processing facility on it.”

An option under that proposal included a continuation of the contract dewatering program while the regional facility was taking shape. In the end, the district chose to establish a turnkey processing facility for its own biosolids sludge only and selected the Bioset process to deliver Class A material.

Schwing Bioset - Bioset Process  Schwing Bioset - Bioset Process

Class A operation

At the new facility, material exits the primary treatment facility’s sludge holding tanks at 1.5 percent solids and is fed directly to a high-performance screw press, selected for a number of reasons, including its relatively compact design.

“Because of the limited availability of usable land, a small footprint for the entire biosolids system was a major consideration, and the Bioset screw press fit in nicely,” Ferrante says. “We’ve found it to be an outstanding dewatering tool, yet extremely efficient in power usage.

“The belt press we looked at would have taken the material from 1.5 or 2 percent solids up to 8 to 10 percent. A centrifuge might get that up to 20 percent, but the electricity costs would be much higher. The screw press takes the material up to 16 percent solids. It uses twin augers and a changing pitch on the screws to advance the material and remove the water. Because it takes far less energy to turn those two screws than to power a centrifuge, the savings in power consumption can be significant.”

Another feature is that district personnel can wash the screw press down while it remains operational, says Michael Castilla, service technician 1: “The Bioset screw press has an automated self-cleaning function which in itself is nice. However, when we have a situation that calls for additional cleaning, we can simply push a button and a cleaning cycle will start. That’s a bonus. To shut a press down for maintenance or repair could cost us a half-day’s performance.”

Positive reaction

After dewatering, untreated biosolids are taken via screw conveyor to a twin-screw mixer in which quicklime and sulfamic acid are added. The mixing resolves issues such as unreacted lime in the final product and yields a highly homogeneous material. From the mixer, a Schwing Bioset KSP-10HKR pump feeds material into a 56 1/2-cubic-foot reactor in which heat from the acid and quicklime reaction raises the pH, stabilizing the mixture and creating a product that meets both Florida Chapter 503.33 and U.S. EPA Class A requirements.

“Retention time in the reactor is about 30 to 45 minutes at temperatures in the range of 122 degrees Fahrenheit,” says Ferrante. “The plant wastes sludge for 16 hours a day, consistently generating about­­­­­ 11 dry tons of the Class A material weekly and doing so at a markedly lower cost than for outright hauling and landfilling.”
Castilla adds that the system’s ease of operation was also key to getting up to speed quickly.

“It is very intuitive and simple to operate,” he says. “However, Schwing Bioset still went to great lengths to ensure that people involved in day-to-day operation are comfortable with it, have a handle on the maintenance routines, and so on. Ian Keyes from their Wisconsin office spent time here mentoring me to such a degree that there’s very little about the system I don’t understand.”

The Class A material exits the system, is loaded onto a manure spreader and taken to an area field where it is applied in place of fertilizer. Eliminating those fertilizer costs alone has saved about $50,000 per year.

In addition to lower costs, the district benefits from a much cleaner, less maintenance-intensive, more environmentally friendly operation. Dust from the lime-based process is controlled using hard-piped or totally enclosed components. Odorous air is contained by the pressurized reactor and then captured and scrubbed under a collection hood before release.

Schwing Bioset - Biosolids Hauling    Schwing Bioset - Biosolids Hauling

Room to grow

The district’s biosolids plant was designed with ample space to install a second identical processing line in case the regional concept becomes a reality. “One of the most important aspects of this system is its ability to accommodate the changes a regional operation would entail,” says Ferrante. “Things like fluctuations in the percentage of solids, increases and decreases in throughput, and compatibility with biosolids from aerobic or anaerobic digestion processes without modification, are all within its design capability.

“Simply put, the district is well positioned to have its wastewater treatment needs met for the foreseeable future. After the $2 million design/build/finance contract was awarded, the district, seeing itself in a good financial position, opted to pay that cost out of pocket, rather than financing it over 20 years.”

The annual operating cost for the new system is about $130,000 a year, including chemicals and electricity. With estimated savings of $370,000 per year over landfilling, the system will pay for itself by about mid-2019.

“This was a case in which Immokalee, a small independent special district with a serious financial headache, took real initiative in getting things done,” says Ferrante. “They will be the beneficiaries of those sound decisions for decades to come.”

 

To view this story on TPO Magazine's website, click here.

To learn more about Schwing Bioset and the Bioset Process, click here.

 

 

Tags: Class 'A' Biosolids, Bioset Process, Piston Pumps, Bioset System, Wastewater Treatment, Fertilizer, Screw Press

Screw Press and Bioset Demo Leads to Treatment Plant Expansion

 

Written by Tom Welch, September 10, 2015

The Springfield, IL, Metro Sanitary District (SMSD) Sugar Creek Plant is going to be expanding over the next two years.  They currently have no dewatering capability and they treat their liquid sludge with lime and liquid land-apply on their own fields onsite at the plant.  In June of 2013, Schwing Bioset was invited to run a dual demo of their screw press and Bioset systems.  The pilot study was conducted for two weeks where the Waste Activated Sludge (WAS) was dewatered with the screw presses and then converted to a Class A EQ product through the advanced alkaline stabilization Bioset process.  Crawford, Murphy, and Tilly Engineers coordinated the pilot study for the District.

Prior to the pilot study, the plant operations team was leaning toward using belt presses for their future dewatering needs.  They had familiarity with belt presses and they were concerned that screw press technology did not have the capability to meet their requirements of 2660 dry pounds per hour without having to install a large number of screw press machines.  They were basing their concerns on historical screw press throughput capability based on their market research.

Springfield_Demo_Image_1-1

(Pilot Study Setup at SMSD Sugar Creek Plant)

During the pilot study, the Schwing Bioset team brought their FSP 600 screw press machine to dewater the partially aerobically digested WAS.  The goal was to dewater the material to the highest percent solids, with an excellent capture rate, and also with the least amount of polymer consumption.  The dewatered product would then be passed along to the mobile Bioset operation, which is an advanced alkaline stabilization process that can produce a Class A EQ Biosolid end product that can be utilized as a fertilizer or a soil amendment. 

The first week of the demo was utilized to optimize the screw press performance, and the second week to monitor continued performance of the screw press while utilizing the Bioset operation to produce a Class A EQ product. The purpose of this was to monitor the product over a couple month period to determine the stability of the Class A EQ product at the Springfield plant.  Over the two weeks, the FSP 600 screw press unit produced a dewatered product of 30% solids on average, even while operating the machine at 130-150% of design throughput capability.  After polymer optimization, the end result was realized with 14 pounds of active polymer per ton and the capture rate was above 95% during the entire two week period.  During the second week of the pilot, the Bioset system was utilized the entire time and was successful in producing the Class A EQ product.

Based on the successful results of the pilot, SMSD gave Crawford, Murphy, and Tilly the direction to design the new biosolids handling facility to include two high-performance screw presses, each capable of dewatering 1330 dry pounds per hour.  Although they liked the simplicity of the Bioset Class A operation, they were uncertain if the need for Class A was justified for the new facility.  They settled on a Class B Bioset system that utilizes all of the components of the Class A design, except for the reactor.  Space was left in the building to install the reactor in the future should Class A become necessary.  The job bid in December of 2014 and Schwing Bioset received an order for the two high-performance screw presses and the Class B alkalization system in early 2015. 

These FSP 1102 screw presses showcase the capabilities of high-performance screw presses and offer larger plants an appealing alternative to traditional belt filter press or centrifuge dewatering.

To learn more about our screw presses, Bioset process, and/or this project specifically, contact a Schwing Bioset Regional Sales Manager, call 715.247.3433, email us, and/or visit our website here.

Springfield_Demo_Image_2-1

(Class A EQ product at 44% solids)

 

 

Tags: Class 'A' Biosolids, Bioset Process, Alkaline Stabilization, Class AA/EQ Biosolids, Biosolids, Wastewater Treatment, Screw Press, Dewatering

When WWTP Says "No Tanks," Innovative Bioset Process Fills the Gap

 

Schwing Bioset Application Report 17, St. Petersburg, Florida

Written by Larry Trojak, Trojak Communications

Version also published in WE&T Magazine, November 2013

 

Pumps_Snapshot

 

Wear is the unflagging enemy of every wastewater treatment plant. Plant operators can defend against it to the best of their ability; but in the end, time will win out, resulting in breakdowns and the occasional interruption in service. To cope with such occurrences, forward-thinking plants will always have a solid contingency plan in place. For the Southwest Water Reclamation Facility (WRF) serving the Water Resources Department’s southwest sector (including St. Petersburg, FL), their contingency - designed to deal with a pair of worn, aging digester tanks - involved bypassing the tanks entirely and processing biosolids through a Bioset sludge treatment process. Doing so is not only helping them avoid an operational nightmare and additional maintenance and expense, it is allowing them to improve the by-product of that biosolids operation - all at a time when costs to land-apply their “standard” product have skyrocketed. Timing, it seems, really is everything.

 

Decades of Wear

Originally built in 1955 as a four million gallon per day (mgd) facility, the Southwest Water Reclamation Facility (WRF) was literally replaced at the same location with a 20 mgd plant in 1978. It is one of four which serve the greater St. Petersburg area: Plant #1, for the southeast section of the area which includes downtown St. Petersburg; Plant #2, to serve the northeast section of town; Plant #3, for the northwest section of the area and the beach communities; and Plant #4, for the southwest section of St. Petersburg, as well as the incorporated towns of Tierra Verde and Gulf Port. According to Ken Wise, chief plant operator for the Southwest WRF, volumes at each plant are pretty much equal.

“Plant #1 is called the Albert Whitted WRF and it’s a little smaller since there are fewer residents downtown than in other parts of the city,” he says. “But each of the other three plants are 20 mgd facilities and treat roughly the same amount of sewage. Since the upgrade in 1978 we’ve all been running an anaerobic digestion process and creating a Class B product from the biosolids. For us, that approach worked well until time caught up with us in the form of badly-worn digester tanks which were causing odor issues for an adjacent college and residential developments in the area.”

Given that two of the tanks were built in 1955 with the original plant, and the third was added with the expansion more than 35 years ago, the wear factor is not surprising. Wise says other plants in the area were also seeing failures in both the covers and in their structures as a whole.

“We hadn’t had a failure yet, but the Water Resources Department was spending a good deal of money on
upkeep with us,” says Wise. “Under normal circumstances that would have probably sufficed and bought us a few more years. However, due to changing Florida regulations surrounding the land application practices of the Class B biosolids they were producing at the time, the department started seriously looking into alternative biosolids treatment technologies hoping to avoid repairing something that was not only at the end of its life, but also might not be a fit for that new effort.”

 

Repeat Success

Bioset_Snapshot

To find that solution, the department looked at all possible alternatives, an initiative that included conducting pilot projects with various technologies at other locations in the city. One of those, at the Whitted plant, involved installing the Bioset Process sludge treatment system which uses a combination of pH and heat to stabilize the biosolids, thereby eliminating the need for digesters. 

In addition to being extremely low maintenance and operator friendly, Wise says that it had proven quick to implement and very successful there. “Ultimately the decision was made to install another system from Schwing Bioset here at Southwest,” he says. “Installation took place in July of last year (2012) and we were online by August.”

The installation, he adds, went smoothly, despite the fact that the Bioset Process had to be made to fit within the confines of an existing section of the plant rather than in a totally new site.

“The Bioset crew really worked with us to maximize use of the space we had and minimize disruption,” he says. “As a result, we probably have one of the few Bioset systems in which the reactor is raised some ten feet off the floor to fit with an existing opening. Now, sludge comes off the belt presses, is mixed with quicklime and sulfamic acid, and is pumped up into the reactor, where it spends at least 40 minutes at 135°F and achieves a pH of 12.5, before being discharged to the trailers.”

The newly-stabilized sludge is kept in the trailers on-site for 24 hours, at which point a sample is taken to ensure the pH is still in excess of 11.5 as required by Federal regulations. Since going online with the Bioset Process, Wise says the pH has never been less than 12.5.

 

Added Benefits

In addition to the elimination of virtually any odor and the complaints associated with it, it is the end product of the Bioset process - now a Class AA biosolid (the Florida equivalent of Class A-EQ) - which is the real benefit for Wise and his operation.

“In the past, our Class B material was suitable for use on sod farms and pasture lands, but because of its designation would have to be set back from any kind of food crops. By contrast, the Class AA product we get off the Bioset Process can be applied on golf courses, pastures, food crops - pretty much anywhere. In addition, because of a recent change in regulations, the other three area plants still generating the Class B biosolid are now paying an extra $300 more per trailer, while our costs dropped $100 per load. Granted, by adding the lime, the volumes are up about 10%, so the number of trailers we are shipping has increased. But even with that added into the equation, we are still saving 40 percent when compared to the Class B and have a much more usable product,” says Wise.

All of the Class AA material generated at the plant is currently either land applied at a site within an hour of the plant or sold as fertilizer to the local agricultural market. The previous Class B, by comparison, was hauled to sites more than three-hours away where it often found limited use.

 

Tanks for the Memories

The St. Petersburg WWTP has proven to be something of a case study in how to best deal with a set of unfortunate, challenging circumstances. Faced with a pair of failing digesters that were going to require a significant investment to rebuild, and which were creating odor issues for nearby residents, businesses, and students - the plant was able to solve the problems by abandoning the existing tanks and by adopting new technology in their operation. That solution from Schwing Bioset was implemented for less money than the tank rebuild project would have cost, it eliminated the odor issue, and includes the added benefit of processing cake directly to a Class AA biosolid (and gain more flexibility in the beneficial reuse of the end product), resulting in substantial net savings across the board.

"Since bringing in the Bioset System things have definitely settled down around here,” said Wise. “It’s been a great solution for us.” And, it would seem, all the issues created by the failing tanks are just fading memories.

 

To download the entire #17 application report for St. Petersburg, Florida, click here.

To learn more about Schwing Bioset, our products and engineering, or this project specifically, please call 715-247-3433, email marketing@schwingbioset.com, view our website, or find us on social media.

To view a version of this story published in WE&T Magazine, click here.

 

Tags: Class 'A' Biosolids, Bioset Process, Bioset System, Beneficial Reuse, Class AA/EQ Biosolids, Wastewater Treatment, Fertilizer

Schwing Bioset Exhibiting at WEF Residuals and Biosolids Conference

 

June 4, 2015

Schwing Bioset, Inc. will be exhibiting at the 2015 WEF Residuals and Biosolids Conference in Washington, DC, on June 8th and 9th.

Please be sure to stop by our booth (#106) while you're on the exhibit floor.

 

Visit the conference website to view the event details and exhibition map: http://www.residualsbiosolids-wefiwa.org/

Here is the Schwing Bioset listing for the show: http://app.core-apps.com/15rbwe/exhibitors/d4d3b4f759e0e3a5025efd0a3d0e4fc4

Learn more about our Bioset Process and Class 'A' Biosolids, Dewatering Equipment, Pumps, and other products here: http://www.schwingbioset.com/products

 

If you'd like to meet with one of our team members, please contact marketing@schwingbioset.com for the names of the team members who are attending the show.

We hope to see you there!

 

Bioset_Video_Screenshot

 

Tags: Class 'A' Biosolids, Bioset Process, Events, Biosolids, Wastewater Treatment, Pumps, Dewatering

At Home on the Range

By Larry Trojak - October 2012

TPO

Though well past its boom times as a supplier of iron ore, the Iron Range area of northeast Minnesota enjoys a rich history and a fairly stable economy.

Three small Iron Range communities rely on the 0.5 mgd (design) wastewater treatment plant that bears their communities' names. The Coleraine-Bovey-Taconite Wastewater Treatment Facility nears its 25th anniversary having completed an expansion that includes a shift from Class B to Class A biosolids using a lime stabilization process.

The new process resolved a long-standing issue with meeting U.S. EPA standards for volatile solids reduction during the region's long, often frigid winters.

History of beneficial use

The CBT plant takes in wastewater at a main lift station with three Hydromatic pumps (Pentair) plus an overflow/bypass lift station with a Flygt pump (Xylem). From there, the flow enters an automatic bar screen (Parkson) and an aerated grit chamber that removes screenings and debris via a grit pump and classifier (Weir Specialty Pumps/WEMCO Pump).

Wastewater then passes through a Milltronics OCM III ultrasonic flowmeter (Siemens) to secondary treatment in two activated sludge tanks with Sanitaire fine-bubble diffusers (Xylem), and on to two secondary clarifiers (Walker Process). The waste activated sludge from the clarifiers is pumped to an aerobic digester with fine-bubble diffusers (also Sanitaire).

Secondary effluent is sent through a chlorine contact tank (Wallace & Tiernan), where chlorine and sulfur dioxide doses are fed automatically based on flow proportion. After dechlorination, the effluent travels to an effluent lift station (Hydromatic/Pentair) that pumps it 3.5 miles to the Swan River.

After a 40-day retention time, the solids are pumped to a belt filter press (Parkson) for dewatering and then to a reactor (Schwing Bioset) to produce Class A biosolids.

Before the recent expansion, dewatered biosolids were simply land-applied on area farms. "That was what we did from the time we opened in 1987 until about 1997, when the Minnesota Pollution Control Agency (MPCA) adopted the U.S. EPA regulations and changed the way we managed our biosolids," says Vernard Hawkinson, plant supervisor.

Part-time tundra

Iron Range winter temperatures can be challenging: In and around the town of Coleraine, average lows between November and February are near zero degrees F, and the thermometer once hit a record 51 below zero. For treatment plant operators like Hawkinson, that can be a logistical nightmare.

"The changes to federal EPA guidelines essentially made our whole biosolids process non-compliant during winter months," he says. "That process depends upon bacteria doing their job to reduce the volatile solids content in the biosolids to the level needed for producing a Class B biosolid.

"They do that just fine, except in extremely cold temperatures. When the rules were adopted, we had to meet the minimum 38 percent volatile solids reduction, or other options that were acceptable to meet the Vector Attraction Reduction rule. We were no longer in compliance during the winter, so we had to start taking steps to correct that."

One alternative approach CBT took was to stockpile the dewatered material during winter and then, when it thawed in spring, make it available to area farmers, who had to apply it to their land immediately and incorporate it into the soil. That too, had its problems, says Hawkinson.

"For one thing, because of the climate here, sometimes the biosolids piles would not thaw until the end of May, and most farmers wanted their planting to be done by then, not just starting," he says. "We did that for a few years before deciding it would be better to simply haul the liquid material to the Grand Rapids wastewater plant, or take the dewatered material to their landfill. Unfortunately, they were less-than-receptive to those plans on a long-term basis and we found ourselves back at square one."

Toward Class A

Hawkinson made other efforts to comply with the MPCA and EPA rules. Those included achieving the 38 percent volatile solids reduction using the approximate mass balance equation, and conducting a Bench Scale Analysis and Specific Oxygen Uptake Rate Analysis — all to no avail.

One solution that came to the forefront was to add a second digester. "That seemed like the only recourse we had at the time," says Hawkinson. "Adding a second tank would afford us the extra digestion time we would need to reduce the volatile solids. So we found an engineering firm to tackle the project.

"Their initial estimate came in at about $700,000 for the second digester, and the design process was started. Unfortunately, as the project progressed, additional site work was determined to be necessary which, through no fault of theirs, escalated the cost to roughly twice the original estimate."

bioset process

During that same time, Hawkinson attended a seminar put on by the Minnesota Rural Water Association at which representatives from Schwing Bioset presented their biosolids treatment process. Intrigued, Hawkinson spoke to a company representative at the show. After back-and-forth talks, Schwing Bioset estimated an installation at CBT would cost about $700,000 — the same as the original estimate for the digester — and the end product would be Class A biosolids.

"That made good sense to us on many levels, so we cancelled the digester design project and committed to Bioset," says Hawkinson.

 

Just add lime

The Bioset process mixes biosolids exiting the dewatering belt press (with a solids content of about 15 percent) with quicklime and sulfamic acid using a twin screw feeder. Then, using a Schwing KSP-5 pump, the mix is delivered under pressure through an insulated reactor. The enclosed process contains dust and odors while maintaining a constant temperature of 158 degrees F for at least 30 minutes to ensure that all pathogens are neutralized.

Working with the U.S. EPA Pathogen Equivalency Committee (PEC) through the Process to Further Reduce Pathogens (PFRP) treatment process in the 503 regulations, Schwing Bioset has obtained approval for the Bioset process to operate at 131 degrees F, provided the ammonium concentration within the reactor is above 0.5 mg/g dry weight. This offers a significant reduction in chemical usage from the standard 158 degrees F operating regime and translates into an approximate 30 percent reduction in operating costs.

The system at CBT also includes a recirculation feature in which biosolids that have not achieved the necessary temperature on startup are returned to the hopper for reprocessing. Upon exiting the Bioset process, now with a solids content in the 35 to 38 percent range, the Class A biosolids are discharged to a 48- by 75-foot storage building, constructed at the time of the biosolids upgrade. The plant produces about 35 dry tons of biosolids per year.

Popular with farmers

"We now have an excellent product with an effective acid neutralizing power of approximately 64 percent of pure lime," says Hawkinson. "Farmers in the area, who see the product as a great way to raise the pH levels of their soil, have agreed to take as much as we can produce.

"That's a far cry from having to actively seek a place where we could take it. Right now, we only need to rely upon the Bioset process for half the year — we get the volatile solids reduction we need in warmer weather. But it is an excellent alternative, and it has allowed us to create a Class A biosolid with the same outlay we would have incurred for the Class B product. It has really worked out well for us."

Tags: Class 'A' Biosolids, Bioset Process, Wastewater Treatment, Lime Stabilization

USEPA PEC Committee Grants PFRP Approval to the Bioset System

The USEPA PEC Committee Grants Nationwide PFRP Approval to Schwing Bioset and Its Class 'A' Biosolids Process known as the Bioset System

After extensive testing and research, Schwing Bioset is proud to announce that the USEPA has given nationwide approval to the Bioset Process to reduce its operating temperatures from 70°C (158°F) to 55°C (131°F) as a Process to Further Reduce Pathogens (PFRP). Operating at 55°C (131°F) results in a greater than 20% reduction in operating costs for owners of the Bioset process.

Somerset, WI 2011

After extensive testing and research, Schwing Bioset is proud to announce that the USEPA has given nationwide approval to the Bioset Process to reduce its operating temperatures from 70°C (158°F) to 55°C (131°F) as a Process to Further Reduce Pathogens (PFRP). Operating at 55°C (131°F) results in a greater than 20% reduction in operating costs for owners of the Bioset process. Prior to receiving nationwide approval, site-specific approval at one site in Texas had been granted.

The Schwing Bioset Process is a technology that continuously converts municipal biosolids into a Class A/EQ saleable product in full compliance with 40 CFR Part 503 Rule. The process mixes dewatered biosolids with calcium oxide (quicklime) and sulfamic acid (solid granular acid) and continuously pumps it into a plug flow reactor. The Schwing Bioset Process currently meets Class ‘A’ standards via pasteurization at 70°C for 30 minutes, and vector attraction reduction by maintaining an elevated pH.

At the elevated pH levels, ammonium contained within the biosolids evolves as ammonia, and the ammonia is maintained in solution with the biosolids in the pressurized plug flow reactor. Miscible contact of the ammonia with the biosolids enhances pathogen destruction to Class A/EQ standards at lower temperatures. Mixing is accomplished with Schwing Bioset’s twin-screw feeder and the blended material is pumped into the plug flow reactor with Schwing Bioset’s twin- cylinder positive displacement piston pump.

The combination of high temperature, high pH and the biocidal effects of ammonia ensure that the biosolids are pathogen free in accordance with Class A/EQ requirements. The end product is characterized as a lime enhanced soil amendment and is a valuable product for numerous land application markets. Because the Calcium in the Class A/EQ end product is readily available, soil pH adjustment occurs in less than half the time of what typical agricultural lime products require. An additional benefit of the end product is that the high percentage of organic content (35-55%) returns organic material to depleted soils.

###

Tags: Class 'A' Biosolids, Piston Pumps, Bioset System, Municipal Biosolids, Class 'A' Materials, Screw Feeders, Biosolids

Schwing Bioset Receives EPA Approval

Schwing Bioset's "Bioset" Process was approved by the Environmental Protection Agency (EPA) as a Process to Further Reduce Pathogens under certain conditions, which can be found in the attached document.

Tags: Class 'A' Biosolids, Bioset Process, Class 'A' Materials, EPA, Wastewater Treatment

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.

revinu fertilizer

Tags: Class 'A' Biosolids, Bioset Process, Biosolids, Wastewater Treatment, Fertilizer

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!).

biosolid fertilizer

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

What does your town do with its sewage?

Tags: Class 'A' Biosolids, Wastewater Treatment, Schwing Bioset Process, Fertilizer, Sewage Sludge

Case Study: Stewartstown, PA

piston pumpsThe 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.

Tags: Class 'A' Biosolids, Bioset Process, Sludge Pumps, Wastewater Treatment