News from Schwing Bioset

Water Reclamation Facility Steps Up its Approach to Biosolids

 

Written by Larry Trojak, June 2018

 

Central Florida is One “Class A” Place

Much like the State of Florida itself, the Water Conserv II facility, located in Orlando, is all about change. Almost since its inception in 1961, Water Reclamation Facility  (WRF) has been undergoing periodic upgrades, process changes and, at times, major overhauls to keep pace. So it should come as no surprise that, when confronted with the need to replace major anaerobic digestion components that were impacting capacity, all options were on the table. And when the Florida Department of Environmental Protection (FDEP) indicated that newer, tougher regulations would be impacting continued production of their Class B biosolids product, a range of alternatives was examined. The end result of those efforts is a new Class A Exceptional Quality (EQ) product created through use of the Bioset Process from Schwing Bioset, Inc. (SBI, Somerset, Wisc.) which effectively creates 120,000 lbs. of field-ready fertilizer product per day.  

Silo_Small

 

Use Then Reuse

Originally constructed in 1961 as the 4 mgd McLeod Road Treatment Plant, the Orlando facility was upgraded to 12 mgd in 1972 to deal with the area’s rapidly growing population and then further expanded to 25 mgd. Then, in the early 1980s, a number of factors, including the realization that the plant’s discharge was adversely affecting the health of nearby waterways, prompted the City of Orlando and Orange County to team up and create what is today called the Water Conserv II Distribution Center (DC) in west Orange County, about 20 miles from the Water Conserv II WRF. The DC reuses about 35 mgd of treated wastewater (reclaimed water) in west Orange County for agricultural, residential and commercial uses, as well as rapid infiltration basins (RIBs) to help with aquifer recharge. According to Paul Deuel, assistant division manager for the City of Orlando Water Reclamation Division, the scope of what was planned for the newly revised treatment plant was impressive.

“Much of this was driven by the growth we were seeing in the early 1980s and the projected impact on the aquifer that serves this area,” he said. “In addition, the EPA was mandating that discharge issues at nearby Shingle Creek be resolved. So, the Water Conserv II DC, which combined newly improved processes with the use of reclaimed water for area irrigation, was born. That last point is huge: up until then, very little agriculture involved the use of reclaimed water. The Water Conserv II DC went that route and for a long time was the largest citrus irrigation project in the world to do so.”

The move to make the resource available resulted in a contract which provided early participants access to free reclaimed water for a period of 20 years. For some, according to Deuel, the benefits proved invaluable.

“In the case of the citrus growers, this agreement provided a guaranteed water source, even in times of shortages or drought,” he said. “In addition, it could be used for frost and freeze protection when the lives of the trees themselves were at risk. Once we became established, additional users joined in over the years, including several area golf courses, Valencia Community College, Universal Studios’ theme park (which uses it both for site irrigation and in their cooling towers), the Mall at Millennia, even apartment complexes and single-family homes. It has really proven itself an invaluable resource.”

 

Time Takes a Toll

As mentioned, Conserv II WRF has been undergoing change of one sort or another since its inception. When major components in the anaerobic digestion area began to show signs of wear — and failing on an increasingly regular basis — the facility team started running the numbers to weigh the cost of shoring up the Class B biosolids operation or going in a new direction entirely.

“We started looking at the costs needed to rehab the anaerobic digesters to achieve [Class B] biosolids,” said Steve Shelnutt, Water Conserv II WRF plant manager. “At about the same time, FDEP advised us that new regulations, specific to the generation of a Class B product, were being implemented. It was obvious that continuing to do Class B was going to be more challenging and more costly. So, we began looking at alternatives available to us.”

Shelnutt said they contracted with engineering firm Black & Veatch and considered a combined heat and power process that still relied on anaerobic digestion but, because it went into the thermophilic range, it would give them the Class A EQ product they desired  “However, it also added a nutrient load back to the plant,” he said. “So, they sought to remedy that by recycling the gas it created, treating the side streams, and so on. Unfortunately, the project costs started growing into the $40-60 million capital range — far beyond what we had envisioned.”

 

Let the Games Begin

As is so often the case in any industry, word that Water Conserv II WRF was seeking alternative processing methods traveled quickly. One of the first to call upon them, according to City project manager Kristi Fries P.E., was Brian Schuette, vice president of Moss Kelly, Inc., SBI’s Florida sales representative.

“Brian came in and, based on equal parts: what the Bioset Process could do for us and its estimated costs, quickly got our attention,” said Fries. “He told us that he could take us into a Class A EQ fertilizer-grade product for about $1.8 million. Compared with the other proposal which seemed to be growing more expensive by the day, this seemed almost too good to be true. At the same time, we were hearing from other manufacturers who pitched their processes, each of which had some good points, but ultimately didn’t give us what we really needed.”

The alternatives examined included upgrading the anaerobic digesters, a process that employed a high-pressure steam pre-treatment, another which used a technique to accelerate the composting process, and others.

“We did an evaluation of capital costs for each, measured it against the proposed end-product, and decided that we would move forward with the Bioset Process,” said Shelnutt. We also took a ‘field trip’ to two different Florida locations where the process was already in operation and liked what we saw. In fact, our chief operator and I spent a good deal of time talking to the staff discussing the process and hearing how they felt about it. That really helped us make our decision.”

Bioset_Edited_Small

 

Feeling the Heat

The Bioset Process which Water Conserv II WRF has embraced takes biosolids that have been dewatered to about 15% dry solids and, using Schwing KSP-25 piston pump, routes it to a twin-screw mixer in which quicklime and sulfamic acid are added and blended. This type of mixing ensures a homogeneous product and alleviates issues such as unreacted lime in the final product — and the associated costs associated with it.

“At that point, the Schwing KSP-25 piston pump feeds material into the reactor in which heat from the acid and quicklime raises the pH level, thereby stabilizing the biosolids mixture and creating a product that meets EPA 503.33 requirements,” said Shelnutt.

Because the ammonia that is generated through addition of the lime is entrained with the biosolids inside the reactor, thereby killing the pathogens, the Bioset approach has been approved as a process to further reduce pathogens (PFRP). This approval allows the Bioset process to operate at 55°C (131°F) with a residence time of 40 minutes (versus 70°C (158°F) for 30 minutes) lowering operating costs by approximately 35%.

The stabilized Class A EQ product exits the reactor and is pumped directly to a pair of waiting trailers. Even though it is discharged from the process above 25% dry solids, the new product has very little surface tension until it cools, improving its flow characteristics and making it self-leveling in the trucks. According to Deuel, having SBI involved took care of an important step in the upgraded biosolids process: finding a customer for the end-product.

“We are fortunate in that Schwing Bioset has arrangements worked out with customers here in Florida who are anxious to take the Class A EQ material,” he said. “In this case, it is an organization called the Deseret Ranch which runs a cattle operation on about 295,000 acres (450 square miles) in Central Florida. And while they are happy to take the product in its raw form, Bioset will also accommodate customers who demand a pellet or finer product. Not having to deal with [the disposition of] the biosolids has been a nice bonus for us.”

 

Weathering the Storm

Schwing Bioset’s sister company, Biosolids Distribution Services (BDS) provided the first six months of hauling and marketing of the Class A EQ material .  Utilizing more than 15 years’ experience, BDS was able to add the production from the Water Conserv II WRF to their current operation. 

The benefit of having BDS haul Water Conserv II WRF’s Class A EQ product was felt soon after the equipment was installed, as Hurricane Irma struck in September of 2017. Due to the high-water table levels after the hurricane’s passage, virtually all sites available for Class B land application couldn’t be utilized and it wasn’t until three months later, when groundwater levels dropped, that those fields could be accessed again. The plant would likely have incurred substantial additional disposal costs taking Class B material to either landfills or longer-distance application sites that could still receive Class B biosolids. BDS and the city only missed one day of scheduled hauling — the actual day the hurricane struck. Otherwise it was business as usual leading up to and immediately after the storm.

 

The Need for Feed

Making the switch from a Class B biosolids product to a Class A EQ was not without its challenges. For example, at 371 cu. ft., the reactor installed at the Orlando site is quite large, yet the footprint in which the major components had to be installed was extremely tight. In addition, one of Water Conserv II WRF’s primary stipulations said that that their new process needed to be fully automatic.

David Bass P.E., Water Reclamation Division manager added. “We needed to automate everything. So the programming needed to achieve that was intricate and demanding. But Schwing Bioset, working with our own programmers, was able to make it happen.”

A good example of that automation at work can be found in the system’s lime feed process. At Water Conserv II WRF, should the temperature in the reactor drop, the lime feed will automatically increase; conversely, if the process is found to be running too hot, the lime feed will decrease. The program also monitors the output of the transfer pump and — whether they are running one or two dewatering presses — if the pump starts adding more sludge to the outside hopper it will also speed up the lime.

“This has taken our biosolids process to a whole new level,” says Shelnutt. ”We’ve gone from a situation in which the staff felt they needed to monitor things constantly, to one in which they are totally comfortable letting it operate as designed. Everything is now controlled by the HMI (human machine interface) on the control panel and, despite a few hiccups at the outset, it has proven an outstanding solution for us.”

Pump-1 

All About the Change

In its previous Class B biosolids scenario, four belt filter presses discharged the dewatered biosolids onto two belts that led to an incline conveyor, then to a traveling conveyor which deposited it into trucks below. True to Water Conserv II WRF’s spirit of continual improvement, those two belts are in the process of being converted to screw conveyors and rather than converging in the center, will go in opposite directions and dump into a pair of Schwing KSP-25 transfer pumps.

“Those pumps take the biosolids to the Bioset unit outside,” said Shelnutt. “While it would have been great to have the entire biosolids process under one roof, size constraints made that impossible. This plant is on an area that measures less than 40-acres — relatively small for a plant of this size — and any open space we have remaining has already been slated for other use such as new clarifiers, additional aeration, etc.  However, this does allow us to keep the Bioset process close to the trailer loading area, which was also important for us.”

Shelnutt added that the system design features a pair of Schwing Bioset bulk storage silos for redundancy in the lime storage area. They will also be keeping the traveling and incline conveyors as a backup, should there be anything that results in a service interruption to the Bioset system. In that case, they can simply send material through the belt presses and haul it to another facility for processing. “It’s an option, albeit an expensive one, but it is better than being completely out of business,” he added.

The biosolids process now in place at Water Conserv II WRF is capable of processing 20 dry tons/day and Deuel said that under normal conditions they would do about half that. “Right now, however, we are pulling material that has been stored from the shutdown of the anaerobic digesters,” he said. So we are doing between three and six trailers a day, depending on hauling and plant variables.”

 

Solid Relationship

According to Shelnutt, the relationship between the Water Conserv II WRF team and Schwing Bioset has been a good one, based equally on the product’s proven performance and the company’s quick, consistent response to their needs.

“It seems like such basic business sense, but while far too many companies don’t seem to get it, Schwing Bioset does,” he said. “By way of an example: we had a problem with an acid hopper, determined that we caused the problem, and went back to the manufacturer to order a new one. They wanted more details and were dragging their feet on the replacement. SBI found out about it and interacted with that manufacturer directly to make things right. We felt that was over and above what is expected of an equipment supplier — but it’s solidified our relationship.”

Obviously, given the savings cited and the market for the product, Water Conserv II WRF’s decision to go with the Bioset process was largely based on economic concerns. However, according to David Bass, they were also committed to the idea of having a usable, in-demand product leaving their facility.

“It seems like so many biosolids management facilities are coming and going; people are losing their permits, others are opting to leave the industry, and so on,” he said. “And to a certain extent, I can see that. If we were still generating a Class B product, the increasingly stricter regulations that the FDEP and EPA are now promulgating require a much larger application setback than previous regulations. We wanted to eliminate issues like that, create a viable product, and feel good about our operation. The Bioset Process was definitely the right solution for us at this facility.”

 

To learn more about this project or how we can help your plant, contact a regional manager or email us.

  

 Download Our Brochures    or Application Reports

Read More Schwing Bioset  News and Blog Articles

 

Tags: Bioset Process, Class AA/EQ Biosolids, Pumps, Biosolids Storage, Wastewater Treatment Plant

Dewatering with a Screw Press at Bradenton WWTP

 

Written by Chuck Wanstrom, May 2018

The city of Bradenton, Florida, operates a wastewater treatment plant that processes roughly eight million gallons 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 creating a burden not only in expenses, but also on 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 their 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. 

To learn more about this project or our screw presses, contact a regional manager or email us.

 

1  DSCN8025

 

 Download Our Brochures    or Application Reports

Read More Schwing Bioset  News and Blog Articles

 

Tags: Biosolids, Screw Press, Dewatering, Wastewater Treatment Plant

Metro WWTP Upgrades Piston Pump Sludge Flow Measurement System

 

Written by Chuck Wanstrom, March 2018

 

The Metro WWTP, operated by the Metropolitan Council of Environmental Services (MCES), located in St. Paul, MN, has an average daily flow of 215 million gallons per day (MGD) of incoming flow. Prior to 2004 the plant had been utilizing multi-hearth incinerators to burn their biosolids. A new incineration facility utilizing fluid bed technology was commissioned in 2004 and included a dewatered biosolids storage and feed system supplied by Schwing Bioset, Inc (SBI).

The feed system included four sliding frame silos providing intermediate storage of dewatered cake to provide a buffer in centrifuge and incinerator operations. Each of the four sliding frame silos were equipped with two KSP 45V(HD)L piston pumps to transport the dewatered cake to the incinerators. Each piston pump is equipped with a dual discharge to split the biosolids flow to multiple incinerator injection points, as well as a Sludge Flow Measuring System (SFMS) to measure within 5% the amount of biosolids being pumped into the incinerator. The SFMS is a critical piece of the operation as this is required to satisfy US EPA reporting requirements. This proven equipment configuration and flow measuring system has been utilized at numerous other facilities across North America for over 20 years.

Schwing Bioset has recently developed an improvement in its SFMS to reduce the possible sources of error that can be introduced with variations in pumping speed during operation. This next generation of SFMS results in an even more accurate means of recording and reporting biosolids flow and is further evidence of Schwing Bioset’s commitment to developing and improving its technology to better serve its family of customers. After nearly 15 years of reliable service, the Metro plant, and its continuing commitment to excellence, is currently in the process of performing upgrades throughout its Solids Management Building and is converting its piston pumps to this next generation of flow measurement. Schwing Bioset looks forward to many more years of supporting MCES and to the continued success of this impressive facility.

If you are currently using an SBI pump equipped with our SFMS and would like more information on upgrading your equipment to the latest generation of flow measurement, please contact us at (715) 247-3433 or schwingbioset.com/contact-us.

 

WWTP Schwing Bioset Piston Pump

 

 Download Our Brochures    or Application Reports

Read More Schwing Bioset  News and Blog Articles

 

Tags: Piston Pumps, Biosolids, Wastewater Treatment Plant

Heavy-Duty Pumps “Take the Cake” at Detroit’s Massive WWTP

 

Schwing Bioset Application Report 7, Detroit, MN

Written by Larry Trojak, Trojak Communications

Version also published in WaterWorld Magazine

 

Much like a chain, the wastewater treatment process is made up of individual segments, each linked to the next, each vital to its overall effectiveness. No single facet of the process, nor any single piece of major equipment, is more important than another; if one fails, it all suffers. Occasionally though, one piece of equipment has such challenging demands placed upon it that when it proves itself - and continues to do so for years - it bears mention.

At the Detroit Wastewater Treatment Plant (WWTP), a pair of heavy-duty pumps is used to take high solids-content cake from the dewatering operation to either incineration or a truck loading area.  That, in itself, is not noteworthy.  The fact that it accomplishes this both by pushing cake, dewatered to well over 20% dry solids content more than 500 linear feet, and taking it up five stories, is.  Today those pumps, a pair of Schwing Bioset KSP 110V(HD)L’s, move better than 100 wet tons of dewatered material per hour, have improved the efficiency of the incineration and haul-off operations, and have proven a key part of the system.

 Schwing Bioset Detroit WWTP Solids Pump

 

The Motor City Treatment

The first thing that strikes visitors upon arrival at Detroit’s WWTP is its sheer size. Covering several city blocks, the plant is the largest single-site wastewater treatment facility in the United States, with a capability for processing approximately 845 million gallons per day (MGD) through secondary treatment. The facility has undergone a number of major expansions since it was first built in 1940. At that time, it served Detroit and 11 neighboring communities; today it handles wastewater from 35 per cent of the state’s total population - a service area that covers 946 square miles.

The most recent of the major upgrades took place in 2004 when, according to Kenneth Paylor, Detroit WWTP’s Senior Maintenance Foreman (Solids), modifications to solids processing were included in the overall plan.

“One of the biggest changes that impacted this area of the plant was the addition of a Central Offload Facility (COF).  Up to that time, dewatered cake was taken by conveyor to a lime pad that was used to support land application for the biosolids.  When that land use was discontinued, however, an alternative was needed.  The COF, essentially a truck loading area to transfer biosolids to area landfills for disposal, is now that  alternative

 

Dewater is Different

To process its huge volumes of sludge, Detroit’s WWTP relies upon 14 incinerators located in two separate solids buildings, identified as Complex 1 and Complex 2 (C1 and C2). Solids content before dewatering ranges from 1.2 to 7% - generally in the 4.5% range. Paylor says the plant’s dewatering effort also underwent major changes in the ‘04 upgrade.

“To upgrade the dewatering operation, a number of belt presses were totally replaced and centrifuges were added in ’04,” he says. “We now dewater sludge with ten centrifuges and 22 belt presses: ten in C1, twelve in C2. Material exiting the presses has a solids content of about 23-27%; out of the centrifuges it can be in the 27-32% range.”

 

The Need to COF

In an ideal world, all of Detroit’s dewatered sludge would be sent directly to incineration, making the need for alternative disposal efforts a moot point. But this is not a perfect world and, to best deal with situations that are occasionally out of the ordinary, the COF was included in the design.

“There are times when we might have an incinerator or two that are down for maintenance and material needs to be re-routed,” says Paylor. “Another example is if our incoming volumes rise quickly - as they can after a heavy rain - and we are exceeding what we can normally handle. There was no way to avoid it; we needed a way to get material from C1 to a point where it could be hauled off site for disposal.”

Such occurrences are more commonplace than one would suspect. Even given the large number of incinerators in use and the obvious preference to keep those units fed with material to minimize fuel costs, Paylor says roughly 40% of their cake still heads to the COF. “That is when the Schwing Bioset pumps come into play: getting the cake from the belt presses in C1 to the COF where it can be treated with lime for odor control and loaded into trucks.”

 Schwing Bioset Detroit WWTP Truck Loading

 

The Long Haul

Using pumps to move cake in wastewater treatment plants is hardly a new concept. Scores of plants throughout the country—and internationally as well—have seen the benefits pumping can provide over moving material by conveyor. Improved production, better efficiency, improvements in site cleanliness and reductions in odor are just some of the gains that can be made by pumping.

“To get material to the Schwing Bioset pumps, which are located in the lowest level of the facility, a belt conveyor first collects the cake from all ten belt presses in C1,” says Paylor. “That belt feeds a Schwing push floor, which, in turn, feeds the two KSP 110V(HD)L pumps.”

With a maximum operating pressure of 1,500 psi, cake is pumped in high-pressure piping out to the COF. Mind you, it’s a fairly decent distance out to there.”

That assessment would appear to be something of an understatement. According to Keith McWilliams, Detroit’s Plant Supervisor, the distance from the C1 pumps to the COF is in excess of 500 feet. “Material first has to go up five stories—that’s 60-70 feet alone,” he says. “Then it has to make its way over to the facility, so 500 linear feet is probably a conservative guess.”

 

The Best Approach

McWilliams says there are alternatives to pumping the cake such a long distance. One of those, he says, is pumping it over to C2 where it could be dropped onto belts and taken to the COF.

“While that’s feasible, it is much better to do it this way,” he says. “Once we’ve put the cake into the pump, we may as well take it as far as we can. There is no advantage to dropping it on a belt—in fact, it’s a whole lot messier—and the pumps have shown that they can more than stand up to the challenge.”

Both Paylor and McWilliams say that since installation, the Schwing Bioset pumps, some of the largest the company makes, have been solid performers. XL model pumps were selected for Detroit WWTP based on the anticipated challenges to be placed on the units. Those particular models feature heavy duty poppets which reduce material velocity through the poppet housing. Doing so can result in a variety of benefits including: a reduction in pressure drop through the valve housing, an increased filling efficiency of the pumping cylinders, and a reduction in wear on the poppet discs, seats and pumping rams.

“In the five years the pumps have been in place, we’ve had very few issues with them, and those we’ve had, have all been minor” says Paylor. “That’s outstanding, given what they’re asked to do for roughly 30 hours every week, year round. Providing a continuous flow rate in the 150 to 200gpm range and taking it that distance is really impressive.”

 

Ongoing Changes

As mentioned, Detroit WWTP has seen its share of changes over the years, and new approaches to dealing with the biosolids are always under consideration. 

“We even have contingency plans already in place to handle things before any of those major changes occur,“ says McWilliams. “We put in different access points, for example, where the Schwing Bioset pumps could feed the conveyors in C2. 

Regardless of the direction Detroit’s WWTP takes, both McWilliams and Paylor say they are confident the pair of Schwing Bioset pumps will figure into those plans.  “Whatever happens will most likely involve further movement of the cake, says Paylor.  “And, given what we’ve seen from the pumps so far, I’m sure they can meet that challenge. They’ve been real workhorses for us.”

 

 Download Our Brochures    or Application Reports

Read More Schwing Bioset  News and Blog Articles

 

 

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

Sliding Frame Truck Loading Reliability at Puyallup, WA, WWTP

 

Written by Joshua DiValentino, November 14, 2016

The City of Puyallup, WA, wastewater treatment facility has implemented a series of strategic upgrades. Significant improvements were made to the Biosolids Facility. One major long term issue was not just biosolids cake storage capability, but also consistent truck loading. The 8 MGD facility does not have a large maintenance/operations staff, so they were searching for “set-it and forget it” type equipment.

The Puyallup facility considered several options to meet their needs, including traditional live bottom systems. The more traditional options did not offer ease of use for consistent repeated truck loading without additional operator support. The traditional route was also not found to be as layout-friendly and consisted of additional moving parts, which would also require more maintenance attention. These factors increased the strain not only on the design, but also on the long-term manpower required to run a future truck loading system.   

Puyallup WWTP Sliding Frame1.jpg    Puyallup WWTP Sliding Frame2.jpg

Selection of the Schwing Bioset sliding frame is attributed to its ability to overcome many of the concerns noted above. The system offers the desired storage capacity of 170 cubic yards, as well as the loading consistency needed. A truck driver is able pull into the loading bay initiating gates to open and fill the truck at multiple points. The system is also integrated to control the metering of Biosolids into each truck and uses load cells as part of the automated loading sequence, in order to avoid overfilling and putting overweight trucks on the highway.

The Sliding Frame offers this capacity from the lowest profile design and the system’s vertical side walls maximize usable space. This profile allowed the system to be built immediately next to the solids build and still accept the conveyor feed system, which originates from a floor below.

This is all accomplished from a system with the fewest wear parts of any comparable system on the market. Only bi-annual inspection and tightening of rope packings and changing of drive system filters are required for regular maintenance. Schwing Bioset has proudly installed nearly 100 of these systems in North America, and Puyallup is the first in Washington State.

For more information on Sliding Frame capabilities, watch the Sliding Frame video on our website, contact a Schwing Bioset Regional Sales Manager, call 715.247.3433, or email marketing@schwingbioset.com.

 

 Download Our Brochures    or Application Reports

Read More Schwing Bioset  News and Blog Articles

 

 

Tags: Sliding Frame Silos, Truck Loading, Wastewater Treatment Plant