Slash sludge disposal costs with ClariPhos™

DATE POSTED: September 22, 2021

ClariPhos™ rare earth coagulant reduces sludge by as much as 50%

Is sludge disposal hauling away too much of your operating budget?

A 2016 report* prepared for the Vermont legislature, relying on national level EPA cost analysis, “estimated that approximately 40% of a wastewater treatment plant’s total annual operating cost is spent on solids management.” That report also predicted a future increase in solids production due to the increased need to reduce the nitrogen and phosphorus contribution from sewage into the surface water basins. This is particularly true for phosphorus (P).

Why do lower phosphorus limits increase sludge?

Unlike nitrogen, which can be effectively removed biologically, phosphorus removal is typically achieved with chemical precipitation. Traditionally, this has been done using iron- or aluminum-based coagulants. But these coagulants can produce significant amounts of sludge especially when phosphorus limits in effluent are extremely low. In some cases, phosphorus precipitation with alum or ferric coagulants can produce 12 to 16 mg/L of sludge for every mg of P removed.

They operate on an adsorption mechanism, typically requiring between a 2.5-to-1 molar ratio and a 4-to-1 molar ratio of iron or aluminum to P. They also create a fluffy floc with high amounts of bound water that is difficult to separate through settling and dewatering processes. The phosphorus, a solids-dispersing agent, suspends these solids, making them more difficult to settle. The result is a sludge that remains high in water content and much more costly to transport and dispose of.

Rare earth elements (REEs) can reduce sludge by as much as 50% compared with iron or aluminum

Cerium, a rare earth element, reacts at a 1-to-1 molar ratio with P to form the mineral rhabdophane. This precipitate has a specific gravity of 4, compared with the specific gravity of iron or aluminum precipitates of between 2.4 to 3.4. Higher density solids settle better, binding less water in the process. To gain a thorough knowledge of how this works, see our white paper.

ClariPhos forms a strong, stable bond with phosphorus at a molar ration of 1:1. Fe or Al coagulants typically require at least a 5:2 molar ratio, but can go as high as 8:1 when greater P reduction is needed. 

Bottom line – ClariPhos helps achieve significant sludge reduction and cost savings

One 770,000 GPD facility discharging to a tributary to Lake Erie switched to REE precipitation primarily to meet a stringent aluminum limit by removing aluminum-based coagulants. The change provided immediate compliance with the aluminum limit, but the benefits didn’t stop there. Prior to switching to REE precipitation, the plant operated a belt filter press 8 hrs/day, 5 days/week, with an average solid content of 15%. That required hauling 75, 20-yard sludge containers to a landfill annually. 

After switching to REEs, the belt filter press run time was reduced to one 8-hr shift per week, at a solids content of 21%. The number of 20-yard sludge containers landfilled annually dropped from 75 to 31, resulting in a savings of $70,000 per year in sludge hauling costs alone.

Savings achieved after switching from alum to ClariPhos coagulant 

Belt filter press operation40 hrs/wk8 hrs/wk
% solids1521
20-yard sludge containers landfilled/yr7531
Sludge hauling cost savings/yr$70,000

Are you ready to slash your sludge disposal costs? 

Contact us to learn more about how ClariPhos reduces sludge and let the slashing begin.

Learn more about the advantages of ClariPhos rare earth coagulant for achieving ultra-low phosphorus limits and reducing sludge production at your treatment plant. 

* A Report to the Legislature on Wastewater Treatment Sludge and Septic Management in Vermont, July 16, 2016, Agency of Natural Resources, Department of Environmental Conservation.

Back to Top

Rare earth coagulant helps Hartford, WI achieve stringent phosphorus limit of 0.075mg/L

DATE POSTED: May 22, 2020

When the state of Wisconsin created stringent new water quality standards in 2013 to protect surface waters from eutrophication, about 400 treatment plants received tough new discharge limits for total phosphorus, ranging between 0.5 and 0.04 mg/L.

Though many of the treatment plants already had chemical phosphorus removal systems in place, the Wisconsin Department of Natural Resources (WDNR) estimated that most would not be able to comply with the new standard without additional equipment such as biological phosphorus removal, sand filtration, rapid mix and flocculation chemical removal or others. Chemical coagulation alone, it was assumed, would not be able to achieve the low phosphorus limit. 

One plant, the City of Hartford Water Pollution Control Facility (HWPCF), decided to try Neo rare earth coagulant to see if the chemical could enable it to achieve a new, ultra-low phosphorus discharge permit of 0.075 mg/L. If it worked, the plant would likely be able to avoid spending $2.8 million for new nutrient removal equipment, along with higher annual maintenance and operating costs that would accompany that approach.

HWPCF switched its ferrous chloride coagulant with Neo RE100, and within a three-week equilibration time was able to consistently maintain average total phosphorus in treated effluent from an average influent level of 7.3 mg/L to an average of 0.072 mg/L in final effluent. This was a remarkable achievement since attempts to reach 0.075 mg/L with ferrous chloride were unsuccessful. Even ferrous chloride doses as high as 120 ppm could only reduce phosphorus in final effluent to 0.3 mg/L.

Cold-weather testing with Neo RE100 was also very successful. A study from December to March showed that the rare earth coagulant could consistently reduce average total phosphorus to 0.036 mg/L in final effluent.

Neo RE100 and RE300 are able to achieve this high level of phosphorus removal because it incorporates rare earth elements Cerium and Lanthanum that bind tightly to phosphorus and form a dense precipitate that readily settles out of solution within minutes.

Since switching to Neo RE100, the plant has also experienced better sludge settling, a 35% reduction in solids production and reduced odour in the non-potable water system.

Read the full case study for the Hartford Water Pollution Control Plant and the successful use of Neo RE300 rare earth coagulant.

Learn more about RE300 rare earth coagulant.

Contact us to discuss how Neo RE300 can help you achieve ultra-low phosphorus limits without costly tertiary filtration systems.

Back to Top

The impact of rare earth biosolids as a soil amendment

DATE POSTED: February 27, 2020

The precipitate from chemical phosphorus removal systems typically becomes a component of the total biosolids produced by a wastewater facility. Biosolids containing ferric and alum sludge are often used as a soil amendment to add phosphorus as well as other nutrients. 

But if your plant is considering switching to rare earth coagulant to achieve an ultra-low phosphorus target or other operational benefits, how effective will the biosolids be as a soil amendment and how will the rare earth metals impact the plants that will grow in that soil? 

To find out, a study was conducted in Wisconsin to compare the availability of phosphorus to corn crops from rare earth biosolids, ferric biosolids and commercial fertilizer. Small plot studies were conducted at four different locations in the state and each one included plots with an untreated control and those that were treated with a commercial P fertilizer, ferric biosolids and rare earth biosolids.

The results showed that the commercial fertilizer increased phosphorus in the soil the most, followed by rare earth biosolids, then ferric biosolids, suggesting that rare earth biosolids provide more available phosphorus than ferric biosolids.

Measurements of corn whole-plant dry matter showed that the yield either increased or was unaffected by the rare earth biosolids. This indicates that soil amendment with rare earth biosolids is not expected to negatively impact the growth and yield of corn. 

Since rare earth metals were also found in plants from the untreated control plots, researchers concluded that the application of rare earth biosolids is not adding foreign metals to the soil. The study also suggests that since rare earth concentration in the plant material is not significantly higher than the control, the rare earths are not bioavailable. As a result, the application of rare earth biosolids is not expected to increase the concentration of rare earths in corn beyond what would be found naturally.

Read the full research study. 

Learn more about ClariPhos™ rare earth coagulant for phosphorus removal.  

Contact us to find out how easy it is to switch your chemical phosphorus removal to ClariPhos rare earth coagulant.

Back to Top

Here’s a New Year resolution you can stick to – achieving lower phosphorus limits

DATE POSTED: January 29, 2020

The New Year has come and gone, which means we all should be making good progress on achieving—or abandoning—our commitments for personal improvement in 2020. Maybe your treatment plant is also in need of improving some of its processes—such as phosphorus removal. This might be necessary to ensure consistent regulatory compliance, reduce chemical or sludge handling costs, or to hit a new, more stringent phosphorus limit.

Regardless of the reason, new, rare earth coagulant offers a fast, simple and cost-effective way to dramatically reduce phosphorus discharge that’s much easier to achieve than going to the gym four times per week or getting more sleep. 

With ClariPhos™ rare earth coagulant, treatment plants can reduce phosphorus levels as low as 0.07 mg/L, using far less chemical and without the need to spend millions for a tertiary filtration system. That’s because the rare earth elements in ClariPhos, cerium and lanthanum, bind tightly to phosphorus to form a dense precipitate that settles up to two times faster than alternatives. This helps clarifiers operate more efficiently, lower chemical consumption, reduce sludge production by 30-50% and improve solids dewatering by 30% or more.

ClariPhos forms a dense precipitate that settles up to two times faster than ferric- or alum-based coagulants

Easily switch to ClariPhos by simply replacing current coagulant

In most cases, plant operators can simply replace conventional alum or ferric coagulants with ClariPhos to easily and cost-effectively improve the chemical precipitation and settling of phosphorus. ClariPhos requires no special chemical feed equipment and will often work with existing feed pumps.

Dozens of treatment plants have already switched to ClariPhos to meet tough phosphorus limits and gain many other operational benefits. 

In one example, a 3.4 MGD municipal wastewater treatment plant tested Neo rare earth coagulant for its ability to meet a new final water quality effluent limit on phosphorus of 0.075 mg/L.

The trial showed that the coagulant alone could consistently reduce phosphorus in the treated effluent to 0.036 mg/L. This result was far superior to what the plant was able to achieve with its conventional coagulant, ferrous chloride, which could only reduce phosphorus to an average of 0.5 mg/L. After switching to Neo rare earth coagulant, the plant was also able to avoid installing new nutrient removal equipment, at an estimated cost of $2.8 million, and reduce solids production by about 35%. 

Learn more about ClariPhos rare-earth coagulant for phosphorus reduction and the operational benefits it can bring to your plant.

Contact us to discuss an ClariPhos test at your treatment plant.

Back to Top

Spring is coming. Get ready to remove your lagoon’s sludge blanket


It won’t be long before spring weather arrives and wastewater lagoons begin to thaw and return to more efficient operation. But as this happens, non-aerated lagoons can experience benthal feedback—a process where the turbulence of the warming water stirs up the sludge blanket and releases hydrogen sulfide gas along with nutrients that have accumulated in the settled sludge. 

The result is not only wafting odours, but also potentially high concentrations of TSS, BOD, phosphorus and ammonia in treated effluent. In some cases, the concentrations of some wastewater constituents can be higher in the treated effluent than the influent.

An excessively thick sludge blanket can often be the cause of these symptoms. Too much sludge also reduces lagoon capacity, retention time and can change the flow path of the wastewater. 

Removing some, or all, of the sludge blanket can quickly restore lagoon capacity and eliminate performance issues. In some cases, the installation of baffles, aeration and/or fixed-film biological treatment can also provide a significant, cost-effective improvement to lagoon performance.

Map the blanket to fully understand the problem

Creating a sludge map is an important first step to measure the thickness of the sludge blanket and how it’s distributed throughout the lagoon cell. Once the measurements are complete, Bishop Water can discuss important sludge management considerations and actions including: 

  • Current lagoon capacity vs. design capacity
  • Depth and distribution of sludge
  • Location and volume of recommended sludge removal
  • Budget and long-term planning for sludge removal

Bishop Water Technologies can provide comprehensive services to measure, plan, remove and dewater sludge from wastewater treatment lagoons of all sizes. Our advanced hydraulic dredge enables lagoon cleanout to occur while the facility remains in operation and the Bishop Solids Management Solution—using Geotube® dewatering containers—dramatically reduces the cost of sludge disposal and truck traffic.

Contact us to discuss your lagoon’s sludge blanket and a sludge management plan. 

Learn more about the Bishop Solids Management Solution