News from Schwing Bioset

Heat Integration – Opportunities and Concerns

 

Written by Joe Scholl, February 11, 2016

The word “heat” may be defined as the amount of energy that is transferred from one system to another, typically via a temperature differential or “gradient,” and the amount of heat something possesses may be stated in terms of British Thermal Units (BTU), Joules (J), calories (cal), etc. (as compared to reference temperature or datum state).  Measured over time, heat becomes energy that is used to accomplish tasks, and that energy may be measured in BTU/hr, J/sec, etc.  There is a definite cost to energy usage, as evidenced by any plant’s energy utility bill.  As such, there is a high emphasis nowadays in energy re-use (“heat integration”) via applying “waste” heat from one process to another process needing energy.  While many such heat/energy integration techniques may be easily accomplished, there may, under certain circumstances, be limitations to the extent such energy re-utilization efforts may be accomplished.

Many municipal wastewater treatment plants (WWTP’s) are utilizing anaerobic digestion systems and these processes may produce digester gas or “biogas” (chiefly methane and carbon dioxide with other trace chemical constituents and/or contaminants).  The biogas produced may be used by a variety of means, such as for maintaining heated conditions in the digester units and/or in gas engines that drive generators to produce electricity in a combined heat and power cycle (CHP).  These CHP processes generally produce two “waste” heat streams by which heat may be extracted and re-utilized (i.e. “integrated”) in another process.  These two streams are the exhaust (or “stack”) gas from the biogas combustion process itself and a hot water stream (typically a water/glycol mixture) or steam produced from using cooling water to maintain reasonable CHP engine temperatures. 

The extent to which these particular waste heat sources can be utilized depends on many factors, including the costs associated with purchasing, installing, and operating the heat recovery equipment.  With respect to utilizing a waste heat source in a sludge thermal drying operation, some of these factors may include:

  • How close to the drying system is the heat source? Specifically, what are the fluid movement costs from point A to point B, in terms of liquid pumping or gas handling requirements and how does this impact the overall heat integration strategy?  
  • What is the additional capital expenditure (“Capex”) requirement to install insulated piping or ducting from the source to the drying system and are these Capex requirements so high that the payback to incorporate the waste heat into the drying system result in an unreasonably long payback period? 
  • Are long-term corrosion issues a concern, such as materials of selection for digester gas piping, stack gas ducting, etc. (especially if “acid gases” condense-out of the gas stream upon cooling, leading to corrosive conditions within the piping, ducting, or heat transfer equipment) and, if so, what is their Capex impact, as well operating expense (“Opex”) impact (e.g. will long-term corrosion issues require long-term maintenance expenses)? 
  • How much heat will the waste heat stream lose from point A to B and will this heat loss drive the heat recovery economics toward an unfavorable overall result? This point is particularly important if the waste heat stream is steam, where the latent (or condensing/phase change) heat of the steam is the primary (or desirable) heat transfer mechanism.  For example, if the waste steam loses sufficient energy in transit from its source to the drying system, will the steam lose so much heat that it condenses to liquid form, thereby “robbing” the heat integration scheme of the steam’s latent/condensing heat prior to the drying system (noting that the latent/condensing heat of steam is significantly higher than the specific heat capacity of either the steam or liquid forms)?

In general, there are many possibilities for incorporating waste heat into a thermal drying process.  However, the costs (in terms of Capex and Opex considerations) to incorporate the heat integration step must also be considered to determine whether doing so is practical. 

To learn more about waste heat integration strategies and our Fluid Bed Drying Technology, please contact a Schwing Bioset Regional Sales Manager by calling 715-247-3433, email us, and/or visit our website here.

 

Below is just one example of numerous heat recovery possibilities.

Schwing Bioset Stack Gas Heat Integration Schematic

  

Tags: Fluid Bed Drying, Wastewater Treatment, Heat Integration, Energy Re-Use, Heat Recovery

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

Schwing Bioset Releases New Struvite Recovery Technology Brochure

 

Written by Chuck Wanstrom, January 22, 2016 granual_cup-transparent-SBI_logo.jpg

To support its marketing efforts of the NuReSys struvite recovery technology in North America, Schwing Bioset, Inc. is pleased to release its new brochure that discusses the benefits to plant operations utilizing its technology.  The brochure also includes specific operational features and shows several possible configurations of the process which are meant to solve various issues encountered by Municipalities.

At plants utilizing anaerobic digestion, Struvite commonly forms and creates issues with pipes clogging and equipment being damaged as a result of scaling.  Additionally, tanks can accumulate Struvite, which requires periodic removal and creates an additional expense to plant operations.

“By utilizing Schwing Bioset’s Struvite recovery technology, rather than the other “one-size-fit-most” solutions currently available, these specific plant operational issues are addressed, while at the same time reducing the load of phosphorous that is returning to the head of the plant, making it easier to meet ever strict discharge limits,” said Chuck Wanstrom, Director of New Business Development at Schwing Bioset.  Coupled with the capability of recovering one of nature’s most essential and limiting nutrients to sell in the fertilizer market makes the technology appealing to a wide range of Utilities. 

Solve operational issues, reduce phosphorous loads within the plant, and upcycle your waste stream to make your facility a true Resource Recovery Center - all from the name you can trust, Schwing Bioset.

Please download a copy of the new brochure now and contact us to answer any questions and see how struvite recovery may be the right solution for your plant.

Click here to visit the Struvite Recovery webpage and download the brochure.

 

About Schwing Bioset

For more than 30 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.

For questions or more information, please contact Schwing Bioset at 715-247-3433 or marketing@schwingbioset.com, or visit the website at http://www.schwingbioset.com.

 

Click this link to view the published PRWeb Press Release.

 

Tags: Wastewater Treatment, Struvite, Nutrient Recovery

Diversity, Equipment Longevity are Key for New York Wastewater Plant

 

Schwing Bioset Application Report 15, Glens Falls, NY

Written by Larry Trojak, Trojak Communications

Version also published in TPO Magazine, August 2013

Dewatering at WWTP

While most wastewater treatment plants focus their efforts solely on the material collected from within their own municipality, some choose-often for economic reasons-to supplement that volume with outside waste. After a major expansion in the late 1980s, and an upgrade in the mid-1990s, the city of Glens Falls (NY) Wastewater Treatment Plant found itself in just such a situation and opened up its facility to non-system waste. Today, drawing from a wide range of sources, the plant accepts an equally broad range of materials including: grease trap waste, sanitary holding tank waste, septage, sewer cleaning debris and wastewater sludge-both liquid and cake-from off-site facilities. That product diversity, coupled with impressive long-term equipment performance, has helped the plant remain viable in serving the upstate New York city and surrounding areas.

Legacy Lives On

Located on the Hudson River about 45 minutes north of Albany, Glens Falls is a picturesque small city, home to just under 15,000 residents, and a thriving base for the medical device and medical services industries. The city was also the site of a huge pigment manufacturing facility that was shut down in the 1980s, but left a legacy of contaminated soil in its wake. Today, nearly three decades after its closing, wastewater from the site’s groundwater treatment and collection system is still being processed at the Glens Falls WWTP, according to Jason Vilander, the plant’s maintenance manager.

“That pigment plant was actually a driving force in an expansion that took place here in the mid-‘80s,” he said. “A lot of water is used in chemical and dye work—water that couldn’t simply be discharged to the river—so the plant was designed to accommodate that additional wastewater volume. That expansion allowed us to move to activated sludge treatment and prompted installation of a fluid bed incinerator. Unfortunately for us, the pigment plant shut down during the latter part of our expansion, leaving us with a good deal of extra capacity.”

Since that time, Glens Falls WWTP has had an ongoing contract to accept and treat water from the groundwater collection system from the pigment plant site.

Filling the Void

Needing to fill the excess capacity left by the pigment plant’s untimely closing, Glens Falls WWTP began to actively seek companies or organizations looking to outsource their wastewater and waste product treatment needs. To say those efforts were a success would be an understatement. Today, the plant serves a fairly localized geographic area, taking in material from the town of Queensbury (six of its seven districts), as well as the Village of South Glens Falls, including the business centerpiece, Moreau Industrial Park.

But, because they were aggressive in reaching out to businesses throughout the region, they now also count many of them as customers. 

“We’ve had success in some unlikely places,” says, Vilander. “Most of our liquid sludge, for example, comes out of Vermont. That includes some of the larger ski resorts as well as many of the treatment plants from other towns and villages—plants that don’t have drying beds or digesters or any other means to take product through the final steps needed for it to be safe for disposal. So we provide that last step for them.”

Volumes are also supplemented by outside cake haulers, including regional correctional facilities such as Comstock Prison and the Washington County (VT) jail.

“These facilities all have their own wastewater treatment systems, complete with belt presses, which allows them to generate a cake. But that’s as far as they can go with it. So, twice or three times a week, they send us five tons of cake in a single-axle dump truck, and dump it onto a pad. We then use a pay loader to load that cake into a receiving station where it is stored until we have the time and manpower to incinerate it,” he adds.

Three Decades of Sludge

The benefits gained by reaching out for additional material would be a moot point were Glens Falls unable to effectively incinerate what it collects. Vilander says the equipment in place in many parts of the facility has amazed him in both its capability and its longevity.

“A good case in point would be our sludge pumps,” he says. “We had a pair of Schwing KSP-5 sludge pumps that were installed during that first plant upgrade in the 1980s. Those pumps—which were among the first made by Schwing for this market—have been outstanding for us, given what they’re asked to do. They were replaced just a couple years ago after nearly three decades of pumping. And mind you, they were replaced not because of wear issues, but because our volumes had grown so much over the years that we needed to upsize.”

He adds that the pumps’ impressive performance is made even more so given the fact that one of the critical steps in their routine maintenance was often overlooked for being “too inconvenient.”

“I’ve always felt that keeping the water in a pump’s water box clean is second only to keeping the hydraulic fluid clean,” he says. “Unfortunately for us, in the prior expansion, a grate, which allowed personnel to walk around the belt presses, was installed right over the top of the pumps’ water boxes, making access difficult. As a result, the water was changed far too infrequently. I’m still amazed at how well those pumps worked—and how long they performed for us—even with that lapse in an important operating procedure.”

With This Ring

Schwing Bioset Sludge Piston Pump at WWTP

With the upsizing to a larger pair of sludge pumps (Schwing KSP-10s), Glens Falls has increased their pumping capability to deal with the growth in biosolids handling at the plant. The new pumps take cake that has been dewatered to about 24%-26% solids and route it for incineration where a 32-ton load of cake (an 18-wheeler full) can be reduced to 100 pounds of ash. Moving that high solids content says Vilander, is helped by the addition of a “slip ring,” or pipeline lubrication system, a feature that injects a thin film of water to reduce friction loss in the pipeline and lower pipeline operating pressures—in some cases by more than 50%.

“We work so hard to get all the water out, so it seems a bit contradictory to be putting some back in," he says. "But, because we’re running these slip rings at about 20-30% of their capacity and they come on for only a matter of seconds, we are adding no more than three gallons per hour. So the amount of water added is minimal and pales by comparison to the improvement in throughput and the fuel savings we achieve with the drier sludge cake,” stated Vilander.

Additional benefits provided by the newer pumps include a much greater degree of versatility. Because the pumps are PLC-controlled, Vilander and his crew are able to have them run in several different modes including: “pressure,” tracking” or “manual.” That means they now have the capability to automatically control the speed of the hopper screws and the pump itself.

“With the old pumps, we could adjust our pressures a bit to get the speed we needed, but we couldn’t get independent control of both components—the screws and the pump, says Vilander. "Now we can and it’s made a huge difference. Because the pumps run nice and slow—and quiet— I’m not even seeing the level of maintenance that I had with the old ones. I can see these outlasting even those previous workhorses,” said Vilander.

Grease is the Word

The ultimate destination for all the cake processed through Glens Falls is a fluid bed incinerator which 18’ 3” in diameter with a height of 44’ 9”. The unit is designed to maintain an effective operating temperature of 1500°F and uses the cake itself as the primary fuel source. According to Vilander, if the cake is dry enough, it will reach an autogenous state and burn without an additional fuel source.

“However, if it’s too wet, or does not have enough VOC in it, we have to add BTUs through an alternative heat source which, in the past, was fuel oil. While the new belt presses gave us a much drier cake, we still found ourselves having to rely upon the fuel oil and the costs associated with it. As part of an overall cost savings move, we installed a two part grease system consisting of a concentrator and a storage tank,” said Vilander.

Doing so not only dramatically reduced the operational costs at Glens Falls; it also gave area businesses a way to efficiently dispose of grease from their operations. Now, the septage haulers simply bring the grease to the plant, pay a disposal fee and it gets concentrated, thickened and burned.

“Occasionally we will get a load of grease with wastewater added to it which has to be treated differently. So it goes into our storage tank where it is mixed and pumped up to our belt presses, combined with the cake and moved—once again using the Schwing pumps—out to incineration. The grease, which was once a waste product, is now both a fuel source and a small revenue stream,” said Vilander.

Better in the Long Run

If it sounds as though Vilander is a proponent of piston-style pumps versus their progressive cavity (PC) counterparts, it’s because he is, and that feeling is based on experience he’s gained at Glens Falls.

“We had an emergency situation arise a while back in which the incinerator was down and we had to take some steps to effectively store the cake until it was back online. We stockpiled it onsite but then had to find a way to re-introduce it into the system when we were up and running. So we teamed up a conveyor and a PC pump as sort of a makeshift solution. That experience taught me that, while PC pumps are certainly a lot less expensive; they do not handle grit at all and, given what we went through then, won’t last nearly as long,” said Vilander. He adds that they’ve never done a study to determine the total life cycle ownership/operation cost of their piston pumps versus that PC unit, but says he wouldn’t be surprised at all to find it costs more to run the PC pump.

“Our piston-style pumps were more expensive up front but we know they will provide decades of good service. I think we’ve already proven that,” said Vilander.

 

To download the entire #15 application report for Glens Falls, NY, 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 TPO Magazine, click here.

 

Tags: Sludge Pumps, Piston Pumps, Wastewater Treatment, Pumps, Dewatered Sludge Cake

Upgrading a Reliable Necessity - Piston Pumps at the Greeley WWTP

 

Written by Joshua DiValentino, December 2, 2015

The City of Greeley, Colorado, wastewater treatment facility recently implemented a series of strategic upgrades and major improvements were made to the Biosolids Facility. The Greeley facility repurposes its dewatered biosolids cake by trucking it for land application into remote Northern Colorado. The existing Schwing Bioset piston pump located in the sludge dewatering building had been in operation for 20 years and was a key component of this process.

The Greeley facility had relied on its sole Schwing Bioset KSP 25 cake pump for two decades prior to the upgrades. During that time, the existing pump was the only means of transportation for dewatered biosolids between the centrifuge dewatering equipment and the truck loading bin. The piston pump could have been a “bottle-neck” for a facility with limited storage capacity. However, the existing pump provided an exceptionally high level of uptime over its operational life at Greeley, with minimal wear part consumption.   

By 2014-15 the sole KSP 25 had been in operation since the mid 90’s. The City of Greeley facility, working on a larger plant upgrade, decided to implement a new pumping system for the coming decades. Greeley once again chose to invest in a Schwing Bioset KSP Piston pump.

In order to be as cost effective as possible, but also provide maximum redundancy for the foreseeable future, Greeley chose to purchase a new KSP 25, as well as upgrade the existing KSP unit to modern standards. The existing pump was upgraded to match the new KSP unit with control modifications, and upgraded safety features offer easier remote operation and even longer wear part life. The existing unit was also outfitted with a new Hydraulic Power Unit, offering modern hydraulic feed pumps and unlimited control variability.  The two pumps provide redundancy and additional capacity for growth, as well as a modern control network with the current plant SCADA.

Schwing Bioset KSP Municipal Piston Pump  Schwing Bioset Hydraulic Power Pack

The new pump system included a Hydraulic Power Pack, a Twin Screw Feeder, the Control Panel, and of course the Piston Pump. The Schwing Bioset services team worked with the installing contractor and Greeley personnel to integrate the updated control system features on both pumps with the plant MCC.  The new Schwing Bioset KSP cake pumping system (complete with two fully-operational pumps) was turned over to the City of Greeley in the fall of 2015.       

To learn more about this project specifically or learn more about our pumps, please contact this blog’s author, Josh DiValentino, call 715.247.3433, and/or visit our website here: SBI Municipal Pumps.

 

Tags: Piston Pumps, Biosolids, Wastewater Treatment, Pumps, Municipal Pumps

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

City of Stockton WWTP - Enduring Performance, Replacing a Legacy

 

Written by Joshua DiValentino, August 27, 2015

 

The City of Stockton wastewater treatment facility has seen its fair share of challenges in recent years. When financial resources were limited, the burden fell upon the operations/maintenance staff and the existing equipment to continue operations with aging infrastructure. At this point, the piston pumps supplied by Schwing Bioset, Inc. (SBI), located in the sludge dewatering building, had been in operation for over 20 years.

IMG_2796-1

The pair of KSP 25 pumps moved dewatered sludge cake from the dewatering building out to the truck loading building, several hundred feet away. The two systems were the only means of transporting dewatered sludge cake for the 30 MGD facility. Regardless of the operational circumstances, with a resourceful operations/maintenance staff and the help of SBI technical support, the pumps remained in service with over 129,900 hours on the meter.

By 2014-15 the pair of KSP 25’s had been in operation since early 90’s, and were now nearly 25 years old. The City of Stockton facility was now emerging from a turnaround and making critical investment upgrades. Stockton once again chose to invest in Schwing Bioset Piston Pumps and replace the aged pumps with brand new KSP 25’s in the dewatering building. The new pumps have the same durability to last another thirty years, and with upgraded safety and control features that offer easier remote operation and even longer wear part life.

The SBI field services team was also hired to remove the exiting units and re-install the new pumps. The pump system was replaced by SBI in full including; Hydraulic Power Packs, Twin Screw Feeders, Control Systems, and of course the Piston Pumps. The SBI crew was able to work seamlessly with Stockton personnel to not upset active onsite operations during installation. As such, the pumps were replaced in series to phase out the old system. A completely brand new turn-key cake pumping system will be turned over to the City of Stockton this year.          

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

  

Tags: Piston Pumps, Wastewater Treatment, Municipal Pumps, Dewatered Sludge Cake

Recent Changes Have WWTP Poised to Become a Regional Solution for Sludge Disposal

 

Recent changes have Buffalo-area’s Bird Island WWTP poised to become a regional solution for sludge disposal.

 

Written by Larry Trojak, Trojak Communications

Version also published in WE&T Magazine, July 2015

 

Sharing the Wealth

Wastewater treatment plants, like most of their business counterparts today, are being forced to cope with a barrage of challenges including rising costs, an often-demanding customer base and an ever-changing economic landscape. To effectively deal with these and other issues, a growing number of plants are thinking outside the box to improve their operations. For the Buffalo (N.Y.) Sewer Authority (BSA), that creative effort now includes supplementing their own volume of dewatered sludge with a similar (but richer) product from neighboring communities. Doing so is allowing them to dramatically reduce incineration-related fuel costs and, at the same time, assist those communities with their sludge disposal problems. Sharing biosolids? Seems only fitting from a utility serving the “City of Good Neighbors.”

 

Good Day at Black Rock

First chartered in 1937 as a primary-only treatment plant, the facility now known as the Bird Island WWTP near Buffalo’s Black Rock District was expanded to include secondary treatment in the late 1970s. According to Tom Caulfield, BSA’s administrator of capital improvements and development, the expansion was in direct response to Clean Water Act mandates.

“That massive expansion — essentially, construction of a totally new secondary treatment facility — added aeration and secondary clarification capabilities,” he says. “Even today, few people realize that Bird Island is the second largest wastewater treatment plant in all of New York state.  Only the Newtown Creek WWTP in Brooklyn’s Greenpoint community is larger. We are designed to handle a peak flow of up to 540 million gallons per day (MGD) but are currently averaging flows of about 130 mgd.”

In addition to the city of Buffalo, Bird Island WWTP serves a good number of other neighboring communities including the villages of Sloan and Depew, and the towns of West Seneca, Orchard Park, Alden, Lancaster, Cheektowaga, Elma and includes a limited amount of flow from the Town of Tonawanda. Despite that vast coverage, it was actually the nearby Town of Amherst which, by choosing to re-think its overall approach to sludge disposal, dramatically changed the complexion of Bird Island WWTP’s biosolids processing operation.

 

Plan B for Amherst

For more than a decade, the Town of Amherst had been dewatering its sludge, pelletizing it, and working hard to generate a market for it as a high-grade fertilizer product. In 2010, however, rising operational costs, coupled with aging equipment, prompted them to rethink that strategy, according to Michael Letina, BSA’s treatment plant superintendent.

“Amherst was hoping to have the same level of success with their fertilizer pellet that the Milwaukee Metropolitan Sewerage District has had with their Milorganite, but that just never happened,” he says. “Then they reached a point at which their digesters needed serious repair and, rather than incur the costs of upgrading the system, they started looking for alternatives. They determined that sending their [dewatered] waste activated sludge (WAS) here would make the most sense for them both logistically and financially.”

In early 2010 a 10-year agreement was signed, approving Amherst’s shipment of material from their facility to Bird Island. Today, about 70,000 pounds of WAS is trucked in on a daily basis from Amherst to the Black Rock location.

 

To Burn or Not to Burn

Getting Bird Island to a point where they could efficiently accept Amherst’s sludge was no small undertaking. Working through the Buffalo branch of the engineering firm Arcadis U.S., Inc., plans were drawn up and considered, with the final $2.38 million construction contract offering a couple of options for the material being delivered.

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“Essentially, the process began with construction crews cutting a hole in the15-inch thick floor of our truck weighing area, and installing a 60 cubic yard push floor bin supplied by Schwing Bioset (Somerset, WI). There, customers’ vehicles — at the beginning it was only the Town of Amherst’s trucks — could empty the dewatered WAS they were delivering,” says Letina. “The hopper contains a hydraulic push-floor that sends material through a gate where it drops into a screw feeder, then into a Schwing Bioset KSP 12V (HD) pump designed for 1,000 psi operating pressure which pushes it up to the third floor for incineration. Depending on our needs at the time, we also have the option to take that sludge out of the bin through an alternate extraction screw conveyor and drop it down to the sub basement where it can be re-wetted and sent to our digesters to produce methane.” 

Adding Amherst’s dewatered WAS to the operation was a win-win in a number of regards. Not only did it address the town’s needs to effectively dispose of its sludge, the material’s high volatile content — generally in the 76% range — proved an excellent fuel for Bird Island’s incineration effort.

“Our own biosolids are anaerobically digested and, as a result, are only about 46 percent volatile, so it takes a considerable amount of gas to burn,” says Letina. “However, putting material from Amherst on top of it is like throwing lighter fluid on an open flame. Now, we continually monitor to see whether methane production or incineration will serve us better. It’s a nice luxury to have.”

 

On the Up and Up

With the Amherst-generated cake added to the equation, steady, reliable equipment operation is key to ensuring that both plants realize the maximum benefit of the new effort.  The Schwing Bioset biosolids pump installed as part of the recent expansion has definitely risen to the challenge, says Alex Emmerson, BSA’s process coordinator.

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“The pump has its work cut out for it, taking material that is generally in the 26% to 28% solids range and sending it more than 65 feet straight up to the conveyor feeding the incinerator,” he says. “To handle issues of excessive in-line friction, Schwing Bioset also supplied an injection-ring system that lubricates the pipe wall with a small amount of fluid as it moves.”

On average, Bird Island maintains about 900,000 pounds of inventory on its secondary treatment system. They recently had a case, however, in which inventories ran low, prompting the need to curtail wasting. “That meant we had to rely solely on the ‘outside’ Biosolids and really push the pump — sometimes operating it at three times its normal speed,” says Emmerson. “Even with the added workload we were consistently pumping 8,000 pounds per hour and never had an issue. It’s definitely a key part of the operation.”

He adds that there is a certain peace of mind in knowing that the outside biosolids operation (which just recently was expanded to include a similar agreement with the Town of Tonawanda), affords them a nice contingency plan.

“Now we know we are covered if something unforeseen — like a centrifuge failure — occurs and we need to step up production using the imported biosolids to meet incinerator demand.” 

 

Money in the Bank

BSA has been prepping for growth for some time now, an effort that included a recent incinerator rehab. According to Letina, that updating, which included a new scrubber pack and burners, and carried a price tag of nearly $5 million, allows them to meet new environmental regulations that take effect in March, 2016.  However, their ability to become a regional biosolids processor — and keep costs steady in doing so — is a real source of pride.

“Much of the preliminary work for this part of the operation is the brainchild of Jim Keller our treatment plant superintendent and Roberta ‘Robbie’ Gaiek, BSA’s plant administrator,” says Caulfield.  “Because of their planning and foresight, we are already seeing the fruits of this effort.  Before the installation of the centrifuges and digesters, this plant used about 550,000 decatherms (Dth) of natural gas a year; now we are averaging about 175,000. So we’ve effectively cut our gas consumption by about 65%. With the rehabbed incinerator and addition of the higher volatile material from Amherst and Tonawanda, even with the added volumes we hope to be down around 150,000 to 160,000 Dth a year.”

The savings realized from Bird Island’s reduction in fuel costs is being reinvested in onsite projects, eliminating the need for bonding and the headaches that come with it. “More importantly,” says Caulfield, “it has also allowed us to go nine years now without a rate hike to our customers. In light of what the economy has been through, not a lot of utilities can say that.”

 

Looking Forward

Future plans under consideration —with additional anticipated savings — include a heat and power project designed to recover and re-use exhaust from the plant’s incinerators.

“The original plan was designed to incorporate the use of three waste/heat recovery boilers, says Letina.  “Once operational, the exhaust off the afterburners would create steam which would power a turbine and generate 1.5 - 2 megawatts of electricity — about 1/3 of our current load. Our electric bill right now is substantial — about $4.5 - $5 million a year. If we can save another $1.5 to $2 million annually, that money can be reinvested into the infrastructure, again avoiding bonding and rate hikes. The last few years have been challenging but definitely worth the effort. With these proposed changes and our growing role as a regional biosolids processor, this is an exciting time for Bird Island and BSA overall.”

 

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: Piston Pumps, Screw Feeders, Biosolids, Wastewater Treatment, Sewage Sludge, hydraulic push floor bin

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!

 

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