News from Schwing Bioset

Pima County, AZ, Tres Rios WRF Biosolids System Upgrades - Part Two: Live Bottom Cake Bins

 

Written by Josh DiValentino

 

Background: The district of Pima County, AZ, operates a total of eight wastewater treatment plants. The Tres Rios Water Reclamation Facility (WRF) is the centralized biosolids processing facility for all Pima County plants. Tres Rios WRF currently operates 24/7/365 at a 30 MGD capacity, with a projected flow of 50 MGD in 2030. The facility process is; BNR, Anaerobic Digestion, Dewatering, Pumping, Truck Loading, and Land Application of biosolids (cotton is common use). For nearly 20 years, Schwing Bioset, Inc. has provided solids handling solutions at Tres Rios with projects ranging from biosolids cake pumping and cake storage bins, to most recently, nutrient recovery and temporary Screw Press dewatering equipment.

 

Live Bottom Cake Storage: In 2012, the facility completed a Regional Optimization Master Plan expansion, which included upgrades to the centrifuge building and a new truck loading building. Prior to this expansion, dewatered cake was pumped (using the original Schwing Bioset Piston Pump) directly through a pipeline to the truck loading area. There was no intermediate storage capacity in the system on the dewatered cake side. Further, trucks could only be filled as fast as the cake pump could deliver cake, significantly reducing truck fill times.

 

Tres Rios Storage w-caption 2During the 2012 expansion, Schwing Bioset, Inc., supplied the new truck loading cake bins. Three (3) live bottom bins were provided, each with a capacity of 3,000 cubic feet of cake storage.

  • Bin Silo Sizing Details (each): Circular Design, 12’ diameter and 33’ tall storage area. Total height of 51’ including truck loading area.

Each bin utilizes a live bottom to deliver biosolids cake to the trucks below. The live bottoms are center discharging.

  • Bin Live Bottom Details (each): 18” diameter shafted, Twin Screws. Complete with 36” x 36” pneumatically actuated slide gates to control cake fill.

 

The top of the bins extend through the roof of the truck loading building. The bins provide storage capacity for dewatered cake and can fill trucks in less than 15 minutes when needed. The systems came complete with access ladders, safety railing, and ventilation connections for odor control. The bins have been in operation for nearly a decade, requiring only regular upkeep and maintenance to bearings and drive systems.

 

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.

 

Read Part One: Cake Pumping

Stay Tuned for More on Pima County Projects:

Part Three: Temporary Screw Press Dewatering

Part Four: NuReSys Struvite Management Project

 

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Tags: Biosolids, Wastewater Treatment, Water Reclamation Facility, Live Bottom Bins

New Replacement Membrane Bioreactors Benefit Small Community

 

The Manor Water Reclamation Facility owned by Forsythe County located in Milton, GA, consisted of four trains utilizing Zeeweed 500D membrane bioreactors sized for a total of 500,000 gpd of flow. As the system aged, the County decided to replace the old membranes. Half of the existing membranes were replaced with Schwing Bioset’s Econity CF54D membrane bioreactors (MBRs) to process 250,000 gpd of flow. Due to the modular nature of Schwing Bioset’s Econity membranes, an easy, direct “in-kind” replacement of the old membranes was possible.

In the operator’s words regarding the retrofit, “the replacement was a breeze,” simply making pipe flange and hose connections. During replacement activities it was found that the existing membranes were fouled with debris, which revealed another advantage of the Schwing Bioset Econity membrane design.

Schwing Bioset’s Econity membranes are manufactured with an “end free” fiber (potted on bottom only) that eliminates fouling issues associated with membrane designs using top and bottom potting of the membrane fibers.

The Schwing Bioset Econity design is such that the fibers are contained in modular “cartridges” that are assembled into “cassettes” of more than one cartridge within a frame support. Unlike the existing MBR frames, the Schwing Bioset Econity frame is designed as a self-supporting structure. 

This modular design greatly simplifies installation and removal when necessary as the cassettes can be removed by a single operator in a couple hours, unlike the original equipment which required multiple staff members and a full day.

 

New MBR at Manor WRF   New Membrane Bioreactor at Manor Water Reclamation Facility

 

Based on the foregoing comparison, the following conclusions can be drawn about the Schwing Bioset Econity Membranes:

1. The modular design allows customization to fit virtually any basin shape or size.

2. The end free design solves the recurring problems of solids build up at the ends of the membrane fiber. The  membranes are not prone to fiber breakage and deterioration of effluent quality.

3. The construction is easier to maintain.

4. The end-free membrane design allows for more vigorous movement of the fibers requiring up to 40% lower air scour compared to the competitor.

5. The new MBR's have helped the community update its tertiary treatment system that treats sewage to re-use quality.

The advantages of Schwing Bioset Econity membranes are easily recognized by customers. It is for this reason that there well over 2000 installations world-wide.

 

Check out these photos of the old clogged membranes that were replaced!

Old MBR at Manor Water Reclamation Facility  Old Membrane Bioreactor at Manor WRF

 

To learn more about Schwing Bioset’s MBR systems, visit our website here or contact our Regional Manager closest to you.

 

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Tags: Wastewater Treatment, Membrane Bioreactor

Big Changes at Pine Creek Wastewater Treatment Facility

 

Written by Larry Trojak, Trojak Communications

Version also published in TPO Magazine, February 2020

 

Alabama facility sets lofty goals for its upgrade; meets or exceeds them all.

When the City of Prattville, Alabama, recently chose to upgrade its Pine Creek wastewater treatment facility, it spared no effort in doing so. While they had made smaller, incremental modifications in the past, this time around they took the plant from simply adequate to boldly forward-thinking, designing it to be viable and effective for at least the next quarter century. Included in the wholesale changes was a rethinking of its solids handling capability which, up to that point, was both basic and costly. Today, the Pine Creek Clean Water Facility uses a new approach to aeration, dewaters through a pair of new screw presses, is generating a Class A biosolids for area land application, and is now accepting sludge from a nearby sister facility. In this case, being up a creek is definitely a good thing.

 

Dealing with Growth

Located 20 minutes northwest of Montgomery, Prattville is a city of 34,000 which has seen some impressive development of late. According to the local Chamber of Commerce, between 2014 and 2018 alone, more than 130 new businesses have opened in Prattville and immediate surrounding areas — a total of $760 million in capital investment. All that growth prompted city officials to look at existing infrastructure demands and determine that upgrades to their wastewater treatment effort were in order.

“This was a wholesale overhaul of the entire treatment process to help deal with the growth in the area,” said Greg
Thompson, project engineer with Engineers of the South. “We are a consulting engineering company and have been working with the City for more than 15 years now. So, we were actively involved in the research and planning leading to the upgrade. The original plant, built in 1979 as part of the Clean Water Act, had a 3 mgd capacity. In addition to options for dealing with the anticipated increases in volume, we talked with city officials about re-thinking the entire biosolids treatment and disposal process.”

 

Alabama Dream Sheet

Though a plant-wide change was in the cards, the evaluation criteria for that change were very ordered and specific. According to Dale Gandy, Prattville’s Director of Public Works, the desire to use state of the art technology headed up the list of desirables. 

“Obviously, we wanted to tap into the strengths of today’s newer technology,” he said. “However, we also wanted to try to utilize ‘green’ infrastructure within the plant; had our sights set on looking into a Class A biosolid; wanted to create an effluent that was cleaner than the environment into which it was headed; wanted the whole effort to be energy efficient; and needed the plant to gain an additional 25-30 years of viability. In addition, because we didn’t have unlimited funds to throw at the project, we had to be relatively cost conscious in our efforts. It was a long list to try to meet but we set out confident that it could get done.”

The new plant design that Thompson and his engineering team — working hand in hand with Gandy and Prattville’s
plant management — envisioned, would take the facility from 3.0 to 5.7 mgd — almost doubling in volume. That
increase in capacity, they felt, would give them the 25-30 year life expectancy they needed.

 

Schwing Bioset Screw Presses  Schwing Bioset - Bioset Process Reactor

 

Outdated Concepts

To get to that point, there was not one area of the Pine Creek facility that would be left untouched by the overhaul. Designed in the late 1970s as a conventional activated sludge facility, the plant utilized a coarse screen in a deep sump, prior to the raw sewage pump station, followed by aerated grit removal.

“Aeration in the original design consisted of three parallel basins with two fixed-mounted, low speed surface aerators per basin,” said Thompson. “Control of the aeration system consisted only of locally-mounted low/high-speed selector switches. Not only was the process energy-inefficient, the inability to aerate sufficiently or deal with varying flow rates and oxygen demands led to plant upsets and periodic effluent violations. The warm summer months, when effluent limits are lowest, made it particularly hard for operators to maintain compliance.”

At that time, once biosolids met Class B requirements, they were hauled off to a local field — with 100% of the liquid
— for land application. The facility averaged 10-15 tanker loads of the wet material per day. “But if it had rained and the field was wet, they couldn’t land-apply, so the plant had to be prepared to store material in the digesters,” added Thompson. “It’s not surprising they knew a change was needed.” Finally, the previous clarifiers utilized a mix of organ pipe and scraper blade solids-removal systems. Disinfection, which originally used gaseous chlorine, was updated to UV in a 1999 plant modification.

 

In With the New

Thompson and his group worked hard, not only to address all the issues with the existing design, but also to ensure
the plant’s viability for decades to come. In aeration, to deal with the high ammonia numbers caused by an inability to nitrify, they opted for a VertiCel solution (Evoqua Water Technologies, Pittsburgh, Pa.).

“VertiCel uses a combination of disk aeration followed by fine bubble diffused air,” said Thompson. “In that way, we
felt we could tap the efficiencies of both types of aeration to meet our need for an energy-efficient design and to get full biological nutrient removal.”

Conversely, changes to the plant’s digestion phase included taking them from using surface mechanical aeration to
diffused aeration. “Prattville always had issues getting enough oxygen transfer with the old system,” said Thompson. “This combination of disc aerators and fine bubble diffusers powered by Howden blowers (PD Blowers, Inc, Gainesville, Ga.) is both energy efficient and has great oxygen transfer.” Also covered in the expansion’s design were an all-new headworks, two new fine screens (Duperon, Saginaw, Mich.), and grit removal which incorporated Eutek HeadCell technology and WEMCO Hydrogritters.

 

Road Trip

With preliminary design considerations in place, representatives from both the City and Engineers of the
South, visited a number of wastewater treatment plants throughout the southeast U.S. to review various approaches
to dealing with biosolids. One of the things driving the city’s decision to create a Class A biosolid product was, again, growth in the area.

“We were seeing new industries coming in regularly and knew that we could soon be running out of industrial fields
like the one on which we’d been applying,” said Sam Russell, Pine Creek’s former plant manager who was brought on as a consultant during the upgrade. “So, we knew solids handling had to change and that dewatering would be a huge part of that discussion."

Evaluations of available dewatering options included visits to a half dozen facilities to view belt presses, screw presses and centrifuges, and conversations with operators about their experiences with each. With that growing volume of information at hand, the group started seeing the screw press as the best fit for Prattville, and a visit to a plant in Immokalee, Fla. confirmed that for them.

“Immokalee was an eye-opener for us,” said Thompson. “That installation utilizes a Schwing Bioset screw press
(Schwing Bioset, Somerset, Wisc.) for dewatering and creates a Class A product using the Bioset solution. We saw
so many similarities between what Immokalee had dealt with and our own situation at Prattville that we all felt we’d found our answer. ”

 

Pressing Issue

Coming online in August 2019, the biosolids treatment at Pine Creek now begins by taking material from WAS storage basins — where sludge is held, mixed and aerated — and fed to a pair of new Model FSP-1002 screw presses for dewatering. Each of Pine Creek’s screw presses is rated for 1,122 lbs. of dry solids per hour, with a minimum cake dryness of 17% and a 95% minimum system solids capture. With “tweaks” still being made to the process as operations stabilize, the facility is currently getting cake discharged up to 18%. While the performance stats proved key in making their decision, Prattville was also drawn by the self-cleaning function the Schwing Bioset screw press offered, where the units continue to dewater whenever a cleaning cycle is performed. This continuous operation ensures no equalization storage is necessary between dewatering and the Class A operations.

“We have each unit scheduled to clean itself every hour, but that function is flexible and easily changed,” said Napoleon Wilks, Pine Creek’s current plant manager. “We also like the fact that these presses are almost self-operating,” he said. “We have them programmed to run for only seven hours a day, five days a week, which allows us to keep staffing costs down.”

 

A Stabilizing Presence

In addition to being a sound decision for the City, the fact that both Sam Russell and Dale Gandy own and operate
farms helped solidify Prattville’s decision to go with a Class A product. Their understanding of the benefits a soil
amendment product can bring, the ways it can be used and how positive it could be to the community, led to that
decision.

“We like what can be done with a good Class A product — whether it’s a resident needing it for flower beds, for grass in front of City Hall, or a farmer using it on crops. And, after seeing the success Immokalee was having, it made sense to go with the Bioset solution,” said Russell. “We also felt that there was a real up-side in accountability
to sourcing both the dewatering and the Class A process from the same company.”

The Bioset process uses a screw conveyor to take Pine Creek’s untreated biosolids from the screw presses to
a twin-screw mixer where quicklime and sulfamic acid are added and mixed. From the mixer, a Schwing Bioset
KSP-25VKL pumps material through a 22 ft. long reactor. There, the chemical reactions raise the temperature and
the pH level, stabilizing the mixture and creating a product that meets EPA Class A requirements.

According to Wilks, they are maintaining a minimum temperature of 131°F (55°C) in the reactor with a retention time of 40 minutes in accordance with the operating conditions approved by the Unites States Environmental Protection  Agency (USEPA) through the Process to Further Reduce Pathogens (PFRP) in the 503 regulations. “The way we process our biosolids today — pushing a lower quantity through there than our future design conditions — material is actually in the reactor far longer than that,” he said. “The results have been a consistently good Class A biosolid that we take to a field owned by the department, dump it, spread it a bit, and turn it for a few days until it dries to a point that we are able to pass it along to a local farmer — and right now he will take all that we can provide.”

 

Schwing Bioset Municipal Piston Pump  Schwing Bioset Truck Loading

 

No Mistake About It

In the past, a continual stream of trucks, each carrying roughly 6,800 gallons of liquid headed to the field to
land-apply as much as 81,600 gallons of liquid waste per day. Today’s disposal effort involves just two tri-axle
trucks loaded ¾ full per week. And that energy efficiency criteria? It’s been met to a degree they never imagined,
according to Gandy.

“This is amazing to even comprehend but, despite almost doubling the size of the plant in terms of capacity, when we ran the numbers we found that our energy consumption had only increased by 8%,” he said. “Thinking I must have missed something I checked the data several times and even had a representative from Alabama Power verify
it for me. There was no mistake — that’s how energy efficient this plant is.”

The new biosolids effort is working so well that Pine Creek CWF has already begun processing material from
its sister plant, the 4 mgd Autauga Creek CWF. To do that, the City hauls approximately 200,000 gallons of wet
sludge (at 1.75% concentration ) per month from Autauga Creek to Pine Creek for processing.

Said Gandy: “We set out with a pretty challenging to-do list. But tapping the innovative technology available to us,
we feel we accomplished it all — and then some.”

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: Class 'A' Biosolids, Bioset Process, Wastewater Treatment, Municipal Pumps, Screw Press

Schwing Bioset Trailer Mounted FSP 1103 Screw Presses Now Available for Contract Operations

 

Written by Kelly Kramer

 

Schwing Bioset is pleased to announce that we can now help solve your dewatering challenges with our fully automated trailer mounted FSP 1103 screw press dewatering systems. Available for onsite demonstrations and/or contract operations, the 1103 screw press is one of our largest models and is engineered for durability, reliability, ease of operation, and low power consumption, making the units an efficient method to dewater.

As with all of our screw presses, our mobile units are designed for quick set up, ease of use, and high-performance for dewatering all types of wastewater. 

One of the screw press features our customers are most excited about is the self-cleaning wash cycles. With low wash water requirements and automation, dewatering operations do not need to be suspended during cleaning and a cleaning cycle typically lasts less than five minutes.

Once dewatered, the solids can be treated, loaded, hauled away, and/or beneficially reused, depending upon the method of the end user.

For more information on our mobile screw press units, please contact our Regional Manager nearest to your plant. The screw press and Schwing Bioset’s full product offering can be viewed here.

 

Schwing Bioset Mobile Screw Press   Schwing Bioset Mobile Screw Press

 

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Tags: Wastewater Treatment, Screw Press, Dewatering, Mobile Screw Press

Membrane Bioreactors Increase Effluent Quality at Hotel and Casino

 

Written by Surya Pidaparti

 

The Santa Ynez Band of Chumash Indians operates a hotel and casino in Chumash, California. The sewage from the facilities used to be treated by a conventional sequencing batch reactor (SBR) and sand filtration. As the hotel and its vicinity expanded, the existing SBR was not able to treat the increased flow, which was the major driving force for upgrading the facility. As the area is a high drought zone, a requirement of any permit for expanding the hotel would require water reuse.

Two options were selected to evaluate for the wastewater treatment expansion project – an expansion of the existing SBR alongside the existing and abandoning the SBR in favor of a Membrane Bioreactor (MBR) system. An extensive engineering evaluation showed that the MBR system had a total construction cost of $3.3 million versus a cost of $5.3 million for the SBR.

Econity MBR’s were selected, as offered by Schwing Bioset, for not only their performance, but their flexibility in design. With a cartridge and cassette configuration, maintaining the membranes becomes a simple exercise. The MBR system was built using two containers to minimize disruptions to current plant operations and to fit in the limited site space available. The facility was commissioned in January of 2016.

With the improvements, there has been a significant increase in the facility’s capacity all while showing that that the effluent quality, measured in turbidity (0.05 – 0.2 NTU) vastly exceeds California Title 22 requirements for reuse water (< 1NTU).

To learn more about Schwing Bioset’s MBR systems, contact Surya at spidaparti@schwingbioset.com or visit our website here.

 

Schwing Bioset Membrane Bioreactors  Schwing Bioset Membrane Bioreactors

 

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Tags: Wastewater Treatment, Membrane Bioreactor

Recovering a Valuable Nutrient From the Wastewater Stream

 

Published in TPO Magazine, August 2019

 

Phosphate recovery technology offered by Schwing Bioset can be tailored to meet each facility’s specific operating challenges

 

Resource recovery is a major trend in wastewater treatment — to the task of cleaning water, facility teams are adding the capture of energy and nutrients.

One increasingly popular type of technology is the capture of phosphorus as struvite, which has market value as a fertilizer additive. One entry in that sector is Schwing Bioset, which offers a phosphate and nitrogen recovery technology under license from Belgium-based NuReSys.

The offering is unique in that it is not necessarily designed to extract revenue from nutrient capture, although that option is available. The process is designed to be tailored to each facility’s objectives in dealing with phosphate-related issues.

Besides nutrient recovery, the process has the benefits of preventing buildup of struvite scale in treatment equipment and improving dewaterability in biosolids. Wim Moerman, chief technology officer for NuReSys, and Chuck Wanstrom, director of new business development with Schwing Bioset, talked about the technology in an interview with Treatment Plant Operator.

 

Click here to read the full interview.

 

Nutrient Management Plant

 

To learn more about Schwing Bioset’s Nutrient Management solutions, visit our website here or contact your Region’s Representative.

 

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Tags: Wastewater Treatment, Struvite Recovery, Nutrient Recovery, Phosphorus Removal, Nutrient Harvesting

Screw Presses Help Plant Reduce Maintenance Costs

 

Written by Chuck Wanstrom

Version also Published in TPO Magazine, August 2018

 

The city of Bradenton, Florida, operates a wastewater treatment plant that processes roughly 8 million gallon per day. The plant had historically aerobically digested their biosolids and dewatered them to 15% dry solids content using two, 2.0-meter belt filter presses. Due to the age of the belt filter presses, the maintenance expenditures were continually increasing and were creating a burden not only with expenses, but also with personnel time to keep the equipment functioning.

Bradenton began a search to identify new dewatering techniques that could replace the aging belt filter presses.  Several pilot studies were completed, and Schwing Bioset was invited to run our screw press pilot. The pilot proved successful with results of up to 21% dry solids. The Schwing Bioset screw presses were also able to fit within the confines of the available space on the second floor of the existing dewatering building. 

The Schwing Bioset equipment was chosen as the best value and was procured under a sole source contract. The two new FSP902 screw presses were designed into the existing dewatering building and were commissioned early in 2018. The dewatered biosolids exceed the old belt presses cake performance and reduces the city’s hauling and disposal costs while at the same time reducing the amount of wash water required and significantly reducing the maintenance load to city staff. 

Learn more about our screw presses or contact our regional manager closest to you.

 

Bradenton Screw Presses

 

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Tags: Biosolids, Wastewater Treatment, Screw Press, Dewatering, screw presses

Push Floor Bin and Biosolids Pumps Help Plant Stabilize Operations

 

Written by Chuck Wanstrom

The City of High Point, NC, was previously pumping biosolids to an incinerator using hydraulically actuated piston pumps supplied by another manufacturer. These pumps were aging and the city couldn’t reliably obtain spare parts to support their operation. Additionally, the wastewater treatment plant occasionally struggled with operations as it didn’t have any buffering capacity for the dewatered biosolids ahead of the piston pumps. In an effort to solve the support issues with the existing equipment and stabilize operations, the city solicited bids from consulting engineering firms to update and improve their process.

The selected engineer began surveying biosolids handling systems available in the market and with input from their Client, settled on a push floor storage bin and piston pump arrangement as offered by Schwing Bioset. With over 30-years of experience in biosolids storage and conveyance, and numerous successful installations to its credit, Schwing Bioset was the logical choice to provide the design and equipment for this retrofit application.

A new push floor bunker with 60 yards of storage capacity was supplied to handle the centrifuge dewatered biosolids. Directly coupled to the bottom of the new push floor bunker are two Schwing Bioset model SD 350 screw feeders and KSP 17 piston pumps. The piston pumps have a dual-discharges that allows the biosolids flow to be split and fed into the incinerator at a total of four injection points for more efficient incinerator operations as well. If the incinerator goes down, biosolids can also discharge to a new truck loading facility.

To learn more about our pumps and push floor bins, visit our Products page, Contact Us, visit our Website, or find us on social media.

 

High Point Piston Pumps  High Point Truck Loading

 

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Tags: Piston Pumps, Biosolids, Wastewater Treatment, hydraulic push floor bin

City of Orlando WWTP Utilizes Schwing Bioset Piston Pumps in Class AA Process

 

City of Orlando, FL, Conserv II WWTP Utilizes Schwing Bioset KSP 25 Piston Pumps in Class AA Biosolids Process

Written by Tom Welch, December 14, 2016

The City of Orlando, FL, Conserv II WWTP became aware of the Schwing Bioset process and immediately saw the potential it had to meet all of their requirements for both short and long-term implementation.  In addition, Schwing Bioset could offer conversion of the stabilized Biosolids to a licensed commercial fertilizer product.  The City staff visited current Bioset operations in Florida and were impressed with what they saw and with the simplicity of the process.  The City conducted an in-house feasibility study that considered Bioset and other technologies and concluded that Bioset was the preferred treatment process.

The current dewatering facility has four belt filter presses that discharge onto two belt conveyors that converge onto one common belt conveyor that takes the dewatered Biosolids to truck loading.  The decision was made to move away from the common belt conveyor to make the process more robust.  A KSP 25 piston pump was added at the end of each belt conveyor.  The two pumps are utilized to transfer the dewatered cake to the Bioset (Class A alkaline process).  The Bioset process also utilizes a third KSP 25 pump as the heart and soul of the system to blend the chemicals needed for the Class A process and pumps the end product into a plug flow reactor and ultimately out to two truck loading areas.  These pumps are programmed to work together to make sure that a consistent flow of Biosolids can be treated to Class A status through the reactor.

To learn more about our pumps and Bioset process, or this project specifically, contact this blog’s author, Tom Welch, and/or visit our Products page. For other inquiries, call 715.247.3433, visit our website, or find us on social media.

Schwing Bioset Piston Pump

 

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Tags: Bioset Process, Piston Pumps, Class 'AA' Biosolids, Wastewater Treatment

Southerly Sets The Standard with Sludge Disposal Efforts

 

Schwing Bioset Application Report 14, Columbus, Ohio

Written by Larry Trojak, Trojak Communications

Version also published in WE&T Magazine (click to view)

 

Pumps and sliding frames allow options for effective disposal of cake from Columbus, Ohio, operation.

Wastewater treatment plants can distinguish themselves in any number of ways: by the volumes they can handle, by the number of industry awards they have earned, by the manner in which they handle an interruption in “business-as-usual”, and so on. They can also do so by demonstrating a creative, effective and successful effort to use or dispose of the biosolids they generate. Given those criteria alone, the Southerly Wastewater Treatment Plant could likely be seen as one of the premier WWTPs in operation today. Just coming off a five-year, $350 million expansion which nearly tripled its peak capacity from 114 mgd to about 330 mgd (built-in contingencies for further expansion can take the plant as high as 550 mgd), the plant services the majority of the greater Columbus area. State-of-the-art in every regard, Southerly is poised to build upon an already impressive reputation that has won them numerous National Association of Clean Water Agencies (NACWA) awards for plant and employee performance.

Columbus_Southerly_1.jpg

But it is also its innovative sludge disposal program that separates Southerly from super-plant wannabes. Using a quartet of heavy-duty pumps and a number of sliding frame components (all from Schwing Bioset, Inc. [SBI] Somerset, WI) cake can either be routed directly for incineration or sent to a pair of storage silos. Once in the silos, the material is readily available for truck-loading and transport, either to an already-successful composting operation run by the department or directly to the landfill.  Options, it seems, are the hallmark of this successful operation. 

Change They Can Use

Built in 1967, the Southerly WWTP is one of two plants serving the Columbus metropolitan area (the other being the nearby Jackson Pike WWTP). The current plant expansion which so dramatically increased overall capacity, also increased volumes in the solids handling area. New centrifuges, installed a number of years in advance of that expansion, handle that increase nicely, according to Jeff Hall, Assistant Plant Manager.

“That upgrade was implemented both to replace aging equipment, as in the case of the centrifuges, and to add functionality to other areas like the transportation of solids,” he says. In the past, primary solids were gravity thickened while older centrifuges thickened the waste activated sludge (WAS). The new units now thicken both the primary solids and the WAS. This new approach boosts the solids content of the resulting dewatered cake to about 20-25%, a nice improvement over the 17-21% solids content with the older system.”

Additional changes brought about in that initial upgrade included installation of new cake pumps, a pair of storage silos, and sliding frames at two points in the solids handling process. 

Columbus_Southerly_3.jpg

The Route To Disposal

Getting cake to the point where disposal options are available is a function of Southerly’s pumps and silos. As material exits the centrifuges, it is routed to any of four Schwing KSP 45V(HD)L-SFMS pumps which direct it to the appropriate area. Where that is, varies greatly according to need.

“Even though incineration is the most efficient method of disposal, we still try to keep the compost operation fed with as much as it needs, since that is the better use of the product,” says Carmon “Skip” Allen, Solids Supervisor 2. “Obviously that can vary from day to day. The balance of the material—we can do anywhere from 5.5 tons up to 9 tons an hour—is then sent for incineration. But we know at all times what is going to the silos for storage and what’s getting burned.”

The sludge pumps at Southerly are designed to generate a force sufficient to move cake the long distances needed for either incineration or storage. He says it is easily 300 feet to the multi-hearth incinerators (which have operating temps of 1400°F), and about 400 feet to the storage silos. Equipped with Schwing Bioset’s Sludge Flow Measuring System, the pumps are able to measure to within +/-5% the amount of sludge that is pumped to the incinerator. This simplifies their USEPA reporting requirements for their incinerator operations.

“Material headed to the silos, however, has an additional challenge to overcome,” says Allen. “Once there, the cake has to go straight up another 100 feet to enter the top of the structures, so the force needed to do that is really pretty impressive. I don’t think any regular equipment would be up to a task like that; these are definitely the right pumps for the job.”

Giving it the Slip

Despite maximum operating pressures of 1,100 psi for each pump, those extended distances at Southerly prompted Schwing Bioset to make accommodations to help move the sludge along. To do so, they added a “slip ring,” or pipeline lubrication system. Schwing Bioset’s unique design includes a 360 degree annular groove that evenly injects a thin film of water around the entire annulus of the pipe that separates viscous and sticky materials from the inner wall of the pipeline. The end result is a reduction in friction loss in the pipeline, and lower—in some cases better than 50% less—pipeline operating pressures.

Additional benefits include a savings in energy by reducing the demand on each pump and hydraulic unit, and, because of the reduction in pipeline friction, an increase in wear part life. While other systems try to address the friction issue through the use of as many as four drilled ports which inject more fluid, this offsets a percentage of the gains made by the centrifuges. Still other designs mix polymer with the water to help reduce pressure which, while effective, adds both up-front and perpetual costs to the operation.

Tom Thomas, Maintenance Supervisor 2 at Southerly, says the reduction in friction has also shown benefits in wear part life for the pumps—a fact that is borne out in similar results at Jackson Pike. “We run these pumps round the clock and, even with that 24/7 operation, parts such as the pumping rams, poppet valve discs and seats are getting six months of wear. That’s about 4,000 hours of wear part life, which is outstanding given what they’re being asked to pump.”

Silo Efficiency

As mentioned, the SBI sliding frame silos offer a storage option for cake headed either to the landfill for disposal or to the compost site. Prior to their installation, Southerly relied upon a smaller holding vessel known as “the pit,” a belt-fed, hopper-equipped component that used a series of screws to feed a truck sitting under the discharge chute. City officials say the new silos are larger (providing about 75% more capacity) as well as far more efficient, thereby reducing truck loading times from 45 minutes with “the pit,” down to only five minutes. This was an important criterion when selecting equipment.

Because the City pays a contractor to haul the biosolids, reducing loading times lowers overall hauling costs—the trucks now spend more time hauling and less time waiting to be loaded. The net result is more trucks loaded per day (and a lower cost to do so.) In addition, because of that added storage capability, the composting operation now has the option of drawing material solely from Jackson Pike, if necessary. "Anytime you can reuse something rather than just burying it or burning it, you are making a positive impact," says Assistant Plant Manager Jeff Hall.

“Today, we are reusing about one-third of the solids we handle through the composting operation,” says Hall. “That’s obviously good from an economic standpoint, since we are generating revenue from a product that was once simply discarded. However, it is also a plus from an environmental perspective."

The concept of the sliding frame silo is simple, yet very effective. Hydraulic cylinders move an elliptical frame across the silo floor. The frame’s action not only breaks any bridging that can occur over the extraction screw, it also pushes and pulls material towards the silo extraction screws for discharge into trucks.

Allen says the sliding frame silos were a nice addition to the operation. “Each silo holds better than 1,500 tons of cake, so even if one of the incinerators went down and there was an interruption in the trucking operation, we’d still have a nice short-term storage option while things get back up again. It’s really all about flexibility and these silos afford us that.”

Due to the sheer size of the silos, they are each equipped with three extraction screw conveyors at the bottom which allows the trailers to be evenly loaded without having to be jockeyed back and forth.

The silos also include an odor and splash control shroud that pulls fumes directly off the trailer, thereby minimizing the need for odor control in the truck loading building. In addition, it helps reduce the chance of material splatter during load-out, and confines any such instances to the area immediately adjacent to the trailer, which makes periodic cleanup of the area much easier.

Allen adds that they also use SBI sliding frames on hoppers in advance of the pumps which feed the incinerator. Doing so provides a wide spot in the process line enabling them to maintain steady incinerator operations for several hours in the event of any upset condition with the centrifuges.

Sibling Growth

Southerly WWTP’s growth is being mirrored in the expansion of its sister plant, Jackson Pike WWTP, located a mere seven miles from Southerly’s facility. That plant also installed SBI equipment for similar end uses, but because its capacities are less, scaled down the size of that equipment. So today, Jackson Pike uses a quartet of KSP 25 V(HD)L pumps, rather than the 45s in use at Southerly and powers them with a 100hp power pack compared to its 150hp counterpart. The silos, though smaller in height, are of the same design and offer the same performance benefits as Southerly’s. Once the expansion at Jackson Pike is complete, the two plants will effectively meet all of Columbus’s wastewater treatment needs for decades to come. For Skip Allen, seeing construction at Southerly come to an end after nearly six years is a welcome relief.

“We are all really happy about the changes that have taken place here; there’s no doubt about that. But it feels like we will now finally be able to get back into the treatment plant business. With construction done, we have a big headache behind us, we have a great operation in place, and we’re doing good things for the residents of Columbus. That’s not a bad place to be.”

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To download the entire #14 application report for Columbus, Ohio, 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.

 

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Tags: Biosolids, Wastewater Treatment, Municipal Pumps, Sliding Frame Silos, Truck Loading