ClariPhos™: A less acidic coagulant that improves phosphorus removal and operator safety

DATE POSTED: May 25, 2021


Aluminum and iron-based coagulants are acidic, which means the more you add for phosphorus reduction, the more likely you are to lower the pH of the wastewater system. Consequently, wastewater plants must have pH adjustment measures in place to protect microbial populations from unfavourable conditions and to ensure the pH of treated effluent complies with discharge regulations. For operators, it means handling dangerous chemicals, more rigorous testing and monitoring, and unfortunately, increased exposure to safety risks when completing those tasks. 

ClariPhos™ Rare Earth Coagulant can dramatically reduce or even eliminate pH swings caused by chemical phosphorus precipitation and help improve operator safety at the same time. This unique, non-hazardous coagulant is up to 100x less acidic than Al- or Fe-based alternatives and can achieve better phosphorus removal with a far lower dose—anywhere from 30 to 70% lower dose, depending on the P removal requirement.  

By simply switching coagulants, operators can gain several health and safety benefits:

  • Lower ClariPhos dose rate enables operators to dramatically lower the volume of coagulant that is stored and handled in the plant.
  • Reduced impact on pH allows operators to decrease or eliminate the use, handling and storage of dangerous pH adjustment chemicals.
  • Non-hazardous, non-toxic rating reduces PPE requirements and the potential for operator injury. 
  • Low ClariPhos freeze temperature (-40°C) permits outdoor storage in totes or bulk tanks
  • Inhibits struvite buildup on pumps and staining of equipment, decreasing maintenance requirements and the associated risks of injury or exposure to pathogens 

ClariPhos also provides significant improvements in phosphorus removal and sludge management. Treatment plants using ClariPhos can: 

  • Achieve P level as low as 0.07 mg/L or better without the need for tertiary filtration 
  • Reduce sludge production by 30 to 50%
  • Improve sludge dewaterability by 40% 

Switching to ClariPhos is easy. In most cases, the existing dosing equipment can be used for ClariPhos. So far, we’ve only encountered one issue—occasionally a smaller pump must be installed to ensure precise control of the low ClariPhos dose rate! 

Learn more about the operational advantages of ClariPhos Rare Earth Coagulant 

Contact us and we’ll show you how much less coagulant and pH adjustment chemical you’ll use by switching to ClariPhos.

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Case study: Lagoon sludge removal provides affordable solution for algae and H2S issues

DATE POSTED:


  • Lagoon sludge removal and dewatering
  • Bishop Solids Management Solution 
  • O’Leary Wastewater Treatment Facility, O’Leary, PEI, Canada

The challenge: Algae blooms and corrosive gases caused by sludge accumulation

Sludge accumulation was thought to be causing significant operational challenges for the O’Leary Wastewater Treatment Facility (WWTF), a two-cell lagoon system on the west side of Prince Edward
Island, commissioned in the 1990s. 

O’Leary’s treatment lagoon serves about 800 residents, several businesses and, for a period of time, was also receiving wastewater from a potato processing plant. 

Sludge maps are an important step in planning and executing lagoon cleanouts. WSP’s map of the O’Leary lagoon revealed significant accumulation.

The lagoons were experiencing serious blooms of blue-green algae during the summer months and exceedances of TSS, BOD and coliform bacteria in treated effluent. Hydrogen sulfide (H2S) gas, which was also attributed to the algae and sludge, was building up in a below-grade chamber that housed the plant’s UV disinfection system.   

Not only was the gas accumulation a hazard for operators, but it caused corrosion that damaged ductile iron pipes, an electrical panel and the plant’s UV system. 

Operators also saw “islands of sludge” periodically rise out of the water before bursting and releasing clouds of methane and H2S gases.

The solution: Dredging and passive dewatering meets regulatory and budget requirements 

In 2019, the Town of O’Leary began working with engineering consultants WSP to repair the damage to the UV system, alleviate the algae blooms and end the release of corrosive gases from the lagoon. 

WSP began with a comprehensive sludge survey, obtaining sludge depth measurements from several locations in each of the lagoons. 

The results revealed that despite their large area, the lagoons are relatively shallow, with a maximum depth of only 5 ft (1.5 m). Each cell had accumulated about 1.5 to 2 ft (0.45 to 0.6 m) of sludge, which significantly reduced their ability to remove nutrients and settle out solids. 

The team evaluated several options and awarded the project to AJL Contracting and Bishop Water Technologies to desludge the lagoon and dewater removed solids with the Bishop Solids Management Solution. This simple, low-energy system uses Geotube® containers, optimal polymers and gravity to collect, dewater and consolidate dredged sludge. 

Dredging the lagoon enabled it to remain in operation while sludge removal occurred and also complied with a provincial regulation that prohibits tracked heavy equipment from operating in lagoons with clay liners. 

The project began in the summer of 2020, with the construction of a lined laydown area designed to accommodate a layer of three Geotube containers 85 ft in circumference and 114 ft in length (26 x 34.7m) and a second layer of two 95 x 100 ft (29 x 30.5m) containers that would be laid on top. This stacking arrangement minimizes the footprint and cost of the dewatering cell. 

The results: No algae, no gases, no rush to haul away solids

Dredged sludge was first pumped through a 0.6 inch (15 mm) screen to remove debris, trash and improve the quality of the final dewatered biosolids for land application. 

From the screening plant, the sludge was pumped to the Geotube containers. Bishop Water’s VEPAS™ (Venturi Emulsion Polymer Activation System) added and mixed polymer directly in the feed line, eliminating the need for polymer aging and mix tanks. 

The Bishop Solids Management Solution accepts and dewaters solids as quickly as the dredge can pump, dramatically outperforming centrifuges or belt presses for speed and energy efficiency. Low-TSS filtrate released from the microscopic pores of the Geotube container was directed by gravity to cell two. 

Technicians continually monitored polymer performance and dose rates to ensure optimal dewatering and retention of contaminants. Daily sampling showed that the system was achieving about 20% solids
concentration after just a few hours of dewatering.  

The Bishop Solids Management Solution used a two-layer,  stacked arrangement of Geotube dewatering containers to  minimize the footprint and cost of the dewatering cell.

Desludging of cell one was completed in about four weeks. Two more weeks of sludge removal filled the first layer of Geotube containers to capacity and technicians stacked a new container on top of the others. 

One more week of dredging and pumping completed the project.  The total volume of wet sludge removed was 26,480 m3, which corresponds to 872 bone dry tonnes. 

A major advantage of Geotube containment is that the solids can remain at the site for months or even years, allowing ample time for the town to find a suitable location for land application and arrange funding for hauling. Throughout that time, passive dewatering will continue further consolidating the material. 

A seasonal freeze-thaw cycle also significantly improves dewatering, potentially elevating the solids concentration of the dredged material to 40% or more in this case. 

Since completing the project, operators report that there have been no issues with gas accumulation in the below-grade chamber or blue-green algae growth in the lagoons. 

Learn more about the Bishop Solids Management Solution for lagoon sludge cleanouts. 

Download the case study.

Contact us to discuss your sludge removal and solids management challenges. 

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Partial lagoon cleanouts help balance performance and budgets

DATE POSTED: August 28, 2020


If you’re going to clean out a cell or two at your wastewater lagoon, there are circumstances when a partial cleanout might be the best, fastest way to quickly fix an urgent capacity or performance issue until the lagoon is ready for a full desludging.

Partial cleanouts, using the Bishop Solids Management Solution, can most often be completed while the lagoon remains in operation, so there’s no need to decommission the cell or disrupt the process flow. Bishop Water can quickly diagnose lagoon performance issues caused by excess sludge and determine the volume and locations of sludge that should be removed from the cell. 

Once a plan is ready, the team can mobilise a dredge, its mobile polymer conditioning system and prepare a laydown area for Geotube® containers, are used to collect, dewater and consolidate the solids. Or, if the volume of sludge is small, they can be filled and removed inside 30-yard roll off boxes, making transportation and disposal fast and simple.

Partial sludge cleanouts can also become part of an ongoing lagoon maintenance program to ensure optimum performance. Rather than waiting until sludge accumulation reaches a critical level, lagoon operators or Bishop Water technicians can monitor sludge accumulation in the lagoon and when needed, proactively perform a partial cleanout to maintain an optimized level of performance.

Partial lagoon cleanouts have been used by many lagoon operators to achieve operational and economic benefits including: 

  • Quickly restore lost storage and treatment capacity in the lagoon; 
  • Correct flow issues caused by sludge accumulation that create short-circuiting of lagoon flow and reduced retention time; 
  • Defer the cost of a full lagoon cleanout over an extended period of time; 
  • Maximize the capacity and dewatering of each Geotube® container. Partially filled containers can remain onsite for continued filling at the next cleanout interval. They will experience significant volume reduction between fill intervals, which will reduce the number of containers needed as well as hauling and disposal costs.

Learn more about Bishop Solids Management Solutions for partial lagoon cleanouts. 

Contact us to discuss your lagoon clean out needs. 

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Is your treatment plant suffering from washout?

DATE POSTED:


Every wastewater plant can experience washout—a condition where high hydraulic loading causes microorganisms to be flushed out of a treatment cell at a faster rate than they can be replenished. It most often happens during periods of peak sanitary flow or during wet weather and its occurrence may be on the rise as we experience more frequent and severe storms due to climate change. Inflow and infiltration can compound the problem adding more water to the sanitary system and further diluting the treatment process.

Diagnosing washout at your plant

Reducing retention times in primary, secondary and tertiary processes is the most common approach to enable the plant to accommodate the higher hydraulic loading and avoid the need to bypass one or all of the treatment steps. But due to the faster flow, operators may see a decline in the treated effluent quality.

The telling sign of washout is that even after the influent flow returns to normal levels, the quality of treated effluent may continue to suffer for many hours or even days after the event. This lag in performance indicates that a significant portion of the microbiological population has been lost to washout and the remainder is unable to provide adequate nutrient removal. The condition will continue until the microbiological population is re-established to the optimum level. 

Fall washout = winter performance problems

In the warmer months, the microbiological population can rebound fairly quickly. But since temperature plays a major role in the rate of microbiological growth, a washout in the fall or winter can have serious long-term consequences to plant performance, particularly for wastewater lagoons or other plants where secondary treatment occurs outdoors. In these plants, the microbial population may not fully recover until the spring, which means the plant could have to operate at reduced capacity or face compliance issues through the cold-weather period. 

Build a better home for bacteria

Bishop BioCord™ Reactors are a fixed-film technology that can help alleviate the washout problem. BioCord is like a condominium for bacteria, enabling the formation of a robust biofilm with preferred microorganisms that are strongly attached to the growth media and resistant to washout. Even though suspended microorganisms may be lost to washout, microorganisms in the BioCord reactors remain in the system and continue to provide treatment while also helping re-establish suspended bacteria to optimum levels.  

BioCord Reactors can be installed directly into a treatment lagoon. They quickly establish a robust, stable biofilm that is resistant to washout and enhances plant performance in cold-weather conditions. 

The BioCord Reactor system is also designed to provide robust cold-weather performance. BioCord biofilm develops in layers enabling both BOD- and ammonia-reducing bacteria to coexist and thrive. Layering also helps insulate inner microorganisms from cold water to remain active during the winter and continuing to provide nutrient removal. 

Learn more about BioCord Reactors.

Contact us to discuss your concerns about washout and other wastewater treatment needs.

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