News from Schwing Bioset

Capital Idea for Biosolids Processing at Springfield Wastewater Treatment Plant

 

Written by Larry Trojak, Trojak Communications

Version also published in WE&T Magazine, December 2019

 

Springfield, Ill., wastewater treatment plant supplements its sludge disposal effort with a pair of screw presses and alkaline stabilization.

Effective wastewater treatment is predicated on equal parts science and planning. The science element of that premise includes keeping abreast of the latest technology to best manage both the treatment and disposal of biosolids. For the Sangamon County (Illinois) Water Reclamation District, that has meant rethinking its approach to biosolids, particularly in the area of dewatering prior to land application. Once solely dependent upon liquid applying its Class B byproduct, the District’s Sugar Creek Wastewater Treatment Facility recently upgraded its process to include a pair of fully-automated screw presses and a Class B alkaline stabilization system from Schwing Bioset, Inc. (Somerset, Wis.). Today, with a viable option to that liquid process in place, the plant is generating more than 17,000 lbs. of Class B cake monthly, and has peace of mind that its biosolids effort is poised for future growth.

 

Schwing Bioset Screw Presses   Schwing Bioset Screw Presses

 

A Pair of Plants

In addition to being the state capital, the city of Springfield (and immediate surrounding areas) hosts scores of facilities related to a booming agribusiness industry. These include one of the nation's largest stockyards and feeder cattle facilities, as well as various creameries, meatpacking plants, flour mills, etc. To meet the demands these and other industries place on the area’s wastewater system, a pair of treatment plants were built: Spring Creek in 1928 and, to accommodate area growth, a sister plant, Sugar Creek, in 1972.

“Since that time, both plants have been retrofitted to better handle increased volumes,” said Steve Sanderfield, Sugar Creek’s plant supervisor. “Spring Creek is by far the larger of the two with an average flow of 32 mgd and a peak of 80 mgd. Here, we average 15 mgd and top out at 37.5 mgd, so our max is really only 5 million gallons more than their average. Spring Creek has been updated every couple of decades, but this plant had remained fairly constant until a 2017 upgrade which resulted in a 50% increase in both the average and peak flows. That upgrade also paved the way for the current change to the dewatering effort.”

The most recent changes were improvements for flow control and diversion to wet weather treatment facilities that included mechanically cleaned perforated plate fine screens, grit removal tanks, and activated sludge tanks designed to meet both current and future effluent phosphorus limits.

 

A Better Alternative

In addition to the changes mentioned above, the biosolids area also underwent a significant upgrade, including those areas for thickening, stabilization, dewatering, and storage. Until those changes were made, Sanderfield said they had only one option for disposing of the sludge created in their treatment process.

“Since the mid 1990s, to meet 40CFR Part 503 requirements for Class B Biosolids, we post-stabilized liquid sludge (1.5% TS) by adding standard hydrated lime in a slurry,” he said. “Batches of the biosolids/lime mix were held in batch mixing tanks for 24 hours, after which (if they met 503 pH requirements) they were land-applied on a 30-acre farm owned by the District. If the batch pH dropped overnight below the acceptable standard, it would have to be “re-limed” and given another 24 hours to achieve the requirements within the standards. The stabilized liquid sludge was then pumped and spray-applied through a series of fixed irrigation nozzles installed throughout the farm. Because it is a liquid-sprayed application, large sludge storage tanks are required for times when field limitations (wet seasons, frozen ground, etc.) prevent application.”

While it was less expensive to apply the stabilized sludge in liquid form, those shortcomings prompted a re-thinking. Taking a page from their sister plant’s playbook, they began looking into options for dewatering prior to land application.

“Spring Creek was already dewatering with screw presses and sending the dewatered product to a pad for drying and eventual land application,” said Sanderfield.” However, because our process differs from theirs — aerobic versus anaerobic — and we saw some shortcomings in the presses they use, we decided to look at what else was out there. Vendors were invited to show us their products and, after an impressive two-week pilot test and subsequent bid process, we chose a pair of FSP 1102 screw presses from Schwing Bioset.”

 

Schwing Bioset Municipal Pump   Schwing Bioset Storage Silo

 

Two Are Better Than One

The model of presses in place at Sugar Creek represent one of the largest designs Schwing Bioset offers. Low speed by design, they offer dewatering results comparable to high speed centrifuges and — by nature of that slow speed and robust construction — provide a much longer lifetime of service. Sanderfield was particularly interested in one feature of the screw press: a split-screen cage that both simplifies screw removal and minimizes footprint requirements. The split cage allows the sealing lip and screen to be replaced with the screw in place — much simpler than removing the screw from one end of the machine.

“Once we knew the press would give us the product we needed, we tended to focus on the upkeep side of things,”
he said. “For example: how easy would the units be to repair if one of them went down? How self-cleaning is it? What kind of wear items does it contain? That last point was important to us. The presses at Spring Creek utilize brushes that wear down and, once they do, we have to pull the entire screw out to change them. That’s a huge undertaking we wanted to avoid over here.”

Immediately after the pilot test, Sanderfield was impressed with the self-cleaning process for the Schwing Bioset
presses. Unlike the units at Spring Creek which simply spray as the disc rotates and must be done when the unit is
not de-watering, these utilize a low-volume, high-pressure spray ring that tracks down the length of the screw — during operation.

“This approach is so much better than others we’ve seen,” he said. “Our dewatering operation does not need to be
interrupted for cleaning, and the cleaning cycle is typically only three to five minutes long, once per day. We’ve also
found that after a thorough cleaning the presses can sit for a while and, when they are needed, will be in operation
immediately — nothing hardens up in the lines. Because we don’t run the presses continuously here at Sugar Creek, that was important to us.”

 

Strength in Numbers

Although Sugar Creek never intended to run both presses at once, they nevertheless opted to go with two units rather than just one, based on equal parts the desire for redundancy and an eye toward future growth.

“For us, the purchase of the second press was definitely driven by the need for a backup,” said Sanderfield. “We
are in a situation here where a press failure or, more likely, one of the pumps we have feeding each press, would be
catastrophic to the process. That’s no longer a concern for us. In addition, as this area continues to grow, we are better poised to meet that growth without the need for any major overhaul.”

At Sugar Creek, sludge enters the press at roughly 1.3% solids, mixes with a polymer, and exits at 25 to 30%
dry solids. While they are extremely pleased with those numbers, Sanderfield is quick to point out that, as with any
press system, they have to take additional steps to deal with the filtrate. “The filtrate tends to be high in ammonia
and phosphorus, so it’s considered a side stream,” he said. “When we bring that back to the plant we have to be certain to do so slowly. So when the presses run, the filtrate that is getting squeezed out is pumped back at a slow rate and is controlled by the tank level. So, if we program it to start pumping when it’s at five feet and stop when it is at three feet, that’s what it will do.”

 

Push of a Button

Sanderfield’s allusion to equipment autonomy is telling. Automation of the presses was also a huge consideration
for Sugar Creek when making their purchase decision, and Sanderfield said they are very pleased with the level
of self-operation the 1102’s can maintain. 

“We start and stop it, monitor it, and run tests on the solids as it comes out,” he said. “But, for the most part, we are
able to hit ‘start’ and the sludge pump will control the feed rate that we set, the presses will do their thing, the
polymer will activate — it essentially runs itself and fits perfectly with the rest of the process which is also heavily
self-operating.”

From the screw press the biosolids still needed to be treated per the EPA 503 to Class B levels. The project
had already started down the path to utilize another technology, but after piloting the Schwing Bioset alkaline
stabilization technology with the screw press, the project switched gears. The biosolids are now routed from the
screw presses to the Class B lime system (also supplied by Schwing Bioset) where quicklime is introduced to
stabilize the dewatered biosolids by elevating the pH. 

“As with the liquid application, according to EPA 503 we cannot field apply the material until we’ve met the 24-hour
pH criteria,” said Sanderfield. “Doing so eliminates the risk of rodents, birds, animals, etc., coming in contact with
the sludge and possibly transferring diseases to other animals or people. Once we’ve stabilized it in the lime
system that’s no longer an issue.”

And, with an eye toward the future, Sugar Creek’s Class B lime system is also designed to facilitate expansion into a Class A Bioset alkaline stabilization process, should they choose. After treatment in the lime system, sludge — now with the consistency of a slightly wet modeling clay — is conveyed to a drying pad where it gets regularly turned using a skid-steer loader with a Brown Bear windrow turning attachment; once fully dried, it is ready for land
application.

 

Just Gets Better

If things seem to be going great for the team at Sugar Creek, it’s because they are. They just wrapped up a
well-attended open house for area residents and local officials, they are meeting all the necessary biological and
phosphorus thresholds without the use of chemicals, and they were just recently nominated for Plant of the Year in
Illinois.

“That last fact — a nomination for Plant of the Year — is mind-blowing, given that we’ve only been online for over a
year,” said Sanderfield. “Things were crazy here for quite a while, but we are now settling in to a nice routine and the Schwing Bioset presses and alkaline system have helped provide a lot of that peace of mind. We will still do both solid and liquid land applications of the sludge — that’s always been the plan. But, since we can press in five days what would probably take us three weeks to do otherwise, the process is far more efficient than it’s ever been.”

 

Click here to read more about our Products, then contact us to learn more about this project or find out how we can help your plant too.

 

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Tags: Alkaline Stabilization, Wastewater Treatment Plant, screw presses

Sugar Creek WWTP Screw Press Records Impressive Data

 

Written by Tom Welch, November 2018

The Sugar Creek WWTP, owned by the Sangamon County Water Reclamation District located in Springfield, IL, has two Schwing Bioset model FSP 1102 screw presses and our Class B alkaline stabilization process. The screw presses dewater the plant’s aerobically treated biosolids and the downstream equipment produces the alkaline stabilized Class B biosolids. These biosolids are then windrowed in the District’s storage shed and eventually land applied for beneficial use. Data recorded from a recent site visit on a single screw press in operation was impressive and can be seen below.

Incoming Flow: 280 gpm
Incoming % DS: 1.5%
Throughput: 2,100 lbsdry/hr
Polymer Dose: 12 lbs/ton
Output % DS: 22%
Capture: >95%

 

Check out the included photos and operational videos, which show an overview of the installation and the equipment in action. 

Contact your Schwing Bioset Regional Sales Manager to learn more about how our biosolids management systems may be able to improve your current processes.

 

  IMG_0453_small  IMG_0452_small

 

 

 

 

 

 

 

 IMG_0461_small  IMG_0459_small  

 

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Tags: Alkaline Stabilization, Biosolids, Screw Press, Dewatering

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

SBI Installs New Beneficial Reuse Bioset System in Northern Minn.


FOR IMMEDIATE RELEASE

Schwing Bioset Announces New Beneficial Reuse Bioset System Installation in Northern Minnesota

The Bioset System will enable the Coleraine/Bovey/Taconite Joint Wastewater Commission to produce a soil amendment that meets the USEPA Class 'A' standards year round

Itasca County, MN- In Q3 of 2009 Schwing Bioset was awarded the contract to provide a Bioset System to the Coleraine/Bovey/Taconite Joint Wastewater Commission. This system was the lowest cost when compared to other technologies, and it produces a USEPA Class ‘A’ end product, unlike the other technologies that produced a USEPA Class ‘B’ material. The installation was completed in Q2 of 2011 and is fully operational.

The existing digesters could not meet the USEPA Class B standards in the winter months so the Commission needed to find a solution. After a reasonable amount of due diligence, the Commission secured the services of a local consulting engineering firm to explore alternatives for meeting the USEPA standards year round.

The engineer was faced with several challenges as they began their investigation. The plant was small, processing 0.5 MGD, and most available technologies would not scale down well or work well with intermittent biosolids processing. Another challenge was related to protracted winters and the need to find a place to store Class ‘B’ materials until the ground thawed and the biosolids could be land applied on the Commissions’ hay fields.

After considering options of a new digester, retrofitting the existing digester with heat exchangers, and reed beds, ultimately the Bioset process, Schwing Bioset’s alkaline stabilization process, was selected as the best available technology to meet these challenges.

About Schwing Bioset

For more than 25 years, Schwing Bioset has been helping wastewater treatment plants, mines and power generation customers by engineering material handling solutions. Schwing Bioset’s custom engineered solutions can be found in hundreds of wastewater treatment plants in North America as well as mines and tunnels around the world.

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Tags: Biosolids Processing, Bioset Process, Alkaline Stabilization, Class 'A' Materials, Biosolids, Wastewater Treatment

Managing Cost, Air Quality and Odor Control with Schwing

Case Study: Ellsworth, WI

The West Central Wisconsin Biosolids Facility (WCWBF) is a regional biosolids processing facility in Ellsworth, Wisconsin, serving Ellsworth and over 20 neighboring communities. The biosolids are dewatered by centrifuges to 20-24% total solids. The dewatered sludge enters an alkaline stabilization system that mixes the sludge with lime and fly ash to yield a Class A product. The treated biosolids are stockpiled in a 37,000-square-foot covered storage building, and beneficially reused semi-annually by local farmers.

In 2008, WCWBF decided to upgrade the lime stabilization process, with the main goals being to contain cost and maintain air quality and odor control. The existing mixer used open hoppers; between that and the fly ash, the system generated a lot of dust. Furthermore, the facility received periodic complaints from neighbors about the odor.

WCWBF chose a Schwing-Bioset system employing a closed hopper, screw conveyors, and pressurized piping system to contain dust and odors. To avoid costly contract hauling charges, WCWBF had to achieve demolition of the old system and installation of the new Schwing-Bioset system within 10 days of shutting down the old system. Demolition and preparation took three days; Schwing Bioset's team installed the new equipment, including the electrical, within the remaining seven days.

With a few minor modifications to adapt it to the winter weather, the Schwing-Bioset system has performed within expectations since commissioning, achieving its goals of managing cost, dust, and odors.

Tags: Class 'A' Biosolids, Bioset Process, Alkaline Stabilization, Biosolids, Dewatering