Air Pollution Control Innovations

Wet Electrostatic Precipitator (WESP) for submicron lead particulate

Posted by Andy Bartocci on Mon, Sep 27, 2021 @ 11:02 AM

WESP Mag 2

In 2012 Envitech supplied a wet electrostatic precipitator (WESP) to remove submicron particulate and lead particles from a metal processing coating device. Envitech recently completed the start-up of a 2nd WESP for a different coating device at the same facility. Both systems are designed to remove greater than 95% of lead from low inlet concentrations. The inlet lead concentration is similar to that of a secondary lead smelter reverb furnace. Click on the link to read about the secondary lead smelter WESP.

The scope of supply for the new system includes a WESP, instruments, control system, pre-assembled pump skids, interconnect ductwork, dampers, stack, access platforms, and make-up water treatment system. The WESP is a hexagonal tube, upflow design. The gas enters the bottom of the WESP and passes through the conditioning section to ensure the gas is fully saturated and evenly distributed to maximize collection efficiency.

After the conditioning section, the gas enters the collection section. Electrostatic forces remove particles contained in the gas stream (see graphic below). The collector consists of grounded collector tubes and high voltage discharge electrodes. A voltage is applied to the discharge electrodes to both charge the particles and create a powerful electric field. The voltage on the discharge electrodes instigates a corona discharge of electrons from disks on the electrodes. The electrons move from the discharge disk to the collector tubes. Some of the electrons intercept particles in the gas stream which charges the particles. Once charged, particles migrate across the gas stream towards the grounded collector tubes. The particles are intermittently flushed with water from a spray header above the collector. Collected particulate containing lead fall by gravity from the tube walls into the WESP sump.

WESP Collection MechanismThe outlet section is the last section and contains an entrainment separator to collect water drops that were entrained in the gas stream during the collector wash cycle. It also houses a support structure for the high voltage electrodes and wash water spray header.

The system has a unique water and wastewater treatment system that mitigates the need for a hazardous liquid blowdown. An upstream water treatment system conditions the city water used to makeup losses associated with evaporation. The recirculation water to the system is filtered to remove hazardous particulate as a solid, greatly reducing the operating cost of disposal. The collection of the hazardous waste as a solid substantially reduced the facility hazardous disposal costs.

The facility reports high reliability and uptime with little intervention required to maintain operation and performance. The electrodes are rigid mast and firmly held in placed after alignment during start-up. Less than 2% of the electrodes have been replaced in seven years of operation. The WESP is designed to meet the below parameters:

  • Inlet flow rate - 35,000 acfm
  • Inlet temperature – 140°F
  • Lead particulate performance guarantee – greater than 95% removal

Click on the link below to download a case study on this application.

Download Case Study

Topics: particulate control, wet electrostatic precipitators

Wet Electrostatic Precipitators for Submicron Particulate Removal

Posted by Andy Bartocci on Mon, Apr 19, 2021 @ 08:30 AM

Industrial facilities are increasingly called upon to consider the use of wet electrostatic precipitators (WESPs) for emissions control as regulations for PM 2.5 and specific heavy metals become more stringent. Facility and Environmental, Health, and Safety (EHS) Managers may need to become familiar with WESP technology and how they can be applied to their facilities.

WESPs date back to the 1970’s and are a tried-and-true method for removing submicron particulates, aerosols, SO3, opacity, and condensed heavy metals. They are generally robust and suitable for 24/7 continuous operations. Their use is found in steel melting furnaces, secondary lead smelters, hazardous waste combustors (HWC), medical waste and sewage sludge incinerators, wood products and pellet manufacturing, mineral wool and glass manufacturing, silicon monomer manufacturing, semiconductor manufacturing, and even industrial fryers.

Particle Removal EfficiencyThe adjacent figure illustrates WESP’s primary use. The graph shows removal efficiency on the vertical axis and particle size on the horizontal axis. The red curve shows typical WESP performance.   The dotted blue curve shows typical Venturi scrubber performance. A comparison shows that a Venturi scrubber is highly effective at removing particles greater than 1 micron in size. However, performance drops off rapidly for particles below 1 micron. WESP performance is relatively immune to particle size and maintains high performance for particles below 1 micron. This capability is derived from the use of electrical forces for particle removal compared to a Venturi scrubber which uses mechanical forces. WESP’s are generally higher capital cost than Venturi scrubbers but lower operating cost. They are used in cases where performance cannot be achieved with a Venturi scrubber or other, lower cost control device.

Env wet scrubber arrangementWESPs are often integrated with other control technologies and used as a polishing device at the end of a process. This is shown in the adjacent illustration for a typical waste incinerator. Perhaps the most important aspect to understand about WESP technology is the relationship between performance, size, and cost. Higher performance requires more collection area, larger footprint, and more cost. This is different than other control technologies like a Venturi scrubber or packed bed scrubber. For these devices, size and cost is primarily determined by the gas flow rate while operating cost is determined by performance. Size and cost for a WESP on the other hand is determined not only by gas flow rate but also removal efficiency. It is therefore important to have a good understanding of the range of inlet particulate concentrations and outlet emission limits. Specifying performance of 90%, 95%, or 99% removal will make a substantial difference on size and cost.

WESP technologies can vary greatly between vendors which can have an impact on footprint, maintenance, and long-term performance. Some of these differences include:

  • Tube geometry (square, round, or hexagonal)WESP
  • Tube size
  • Tube length
  • Operating voltage
  • Electrode construction
  • Electrode alignment mechanism
  • Bottom support grid requirement
  • Gas distribution mechanism

It’s recommended that facilities evaluating WESP technologies dedicate time to understand differences in WESP designs and potential impacts on operations. Evaluation may also include how the WESP is integrated with other upstream equipment needed to meet multipollutant emissions criteria.

WESP technology is a substantial investment for any facility but may be the best available control technology for a submicron particulate application.

Click on the link below to download WESP scrubber literature.

Download Literature

Topics: particulate control, Scrubbers, wet electrostatic precipitators, SO3 Aerosol

Oxygen Strippers Using Natural Gas

Posted by Andy Bartocci on Tue, Jun 09, 2020 @ 08:30 AM

Oxy Petroleum Stripper TowersVintage Petroleum, LLC, a subsidiary of Occidental Petroleum Corporation operates oil and gas fields in Lost Hills, California, northwest of Bakersfield. The fields operate steam boilers that use nearby canal water. High concentrations of dissolved oxygen in the canal water caused excessive corrosion in the boilers.

Vintage was looking for an effective means to reduce oxygen content in the canal water to prolong boiler life and reduce maintenance costs.

The customer selected Envitech to design and build two stripper towers. The towers use high pressure natural gas to strip oxygen from the canal water. The water is pumped 1,000 feet from the canal to the tower locations. After stripping to remove oxygen, the water is pumped to an existing fresh water tank.

The vessels are constructed of carbon steel with a 3/16 inch corrosion allowance and painted internally and externally. The
vessels are fabricated in accordance with ASME Code Section VIII Division I requirements and stamped. The maximum vessel design working pressure is 100 psig at a maximum design temperature of 300 °F and also designed for half vacuum.

The lower vessels are 6 feet in diameter. The upper packed bed sections are 4 feet in diameter. The overall vessel height is 27 feet.

The first system was installed in 2013. The second system was installed in 2014. Both systems are operational and the facility reports success in prolonging boiler life. Designed to the parameters summarized in the adjacent table, the stripping towers resulted in an innovative process solution to solve a unique operational problem.

  • Gas flow rate, mscfd: 328
  • Water flow rate, gpm: 450
  • Operating temperature, oF: 60 to 120
  • Operating pressure, psig: 40
  • Oxygen content of in stripping gas, ppm: 70
  • Dissolved oxygen content in canal water, mg/L: 9
  • Dissolved oxygen removal: > 90%

Click on the link below to download literature about this application.

Download Literature



Topics: particulate control, Scrubbers, Incinerator Scrubber, quenchers, Packed Bed Absorbers, Packed Bed Scrubbers, Wet Scrubbers

Auto Shredder RTO and Acid Gas Scrubber

Posted by Andy Bartocci on Tue, Jun 02, 2020 @ 08:30 AM

The metal recycling industry provides tremendous societal benefit by preserving natural resources and reducing greenhouse gases. Metal recycling entails pulverizing and shredding vehicles and appliances into smaller pieces to facilitate melting processes. Large mega shredders are often eAuto Shredder RTO Scrubber_Browsenclosed to capture process emissions. Volatile organic compounds (VOCs) and other hazardous air pollutants (HAPs) are released during shredding, including small amounts of halogenated compounds.

In recent years, some state and regional regulatory agencies have begun requiring Best Available Control Technology (BACT) to treat shredder exhaust gases for VOCs and other HAPs. One facility had a need to treat a large volumetric flow rate from their shredder enclosure. The equipment must meet stringent performance limits, be reliable, and capable of 24/7 operation.

Envitech partnered with Process Combustion Corporation (PCC) to provide a comprehensive BACT solution. The partnership leverages PCC’s 50 years of experience engineering thermal systems for air pollution control with Envitech’s wet scrubber expertise. PCC provided a regenerative thermal oxidizer (RTO) for VOC control and interconnect ductwork and incorporated an Envitech packed bed acid gas scrubber system. The scrubber scope of supply includes two (2) equal trains consisting of a horizontal Hastelloy C276 quencher, 13 foot diameter fiberglass packed bed absorber, instruments, pre-assembled recirculation pump skid with redundant pumps, and stack.

The horizontal quenchers ensure the gas is fully saturated across all operating conditions and simplifies ductwork between the RTO and scrubber.

CFD modeling minimizes pressure drop and prevents re-entrainment.

The system will be installed and operational in 2021. Guarantees are provided to meet the below design conditions. The combined PCC/Envitech process provides a reliable, comprehensive solution to meet the demands of a more stringent regulatory environment.

  • Gas flow rate: 140,000 acfm
  • VOC destruction: > 98%
  • Acid gas removal (HF and HCl): > 99.5%
Click on the link below to download literature about this application.

Download Literature

Topics: particulate control, Scrubbers, Incinerator Scrubber, quenchers, Packed Bed Absorbers, Packed Bed Scrubbers, Wet Scrubbers

Thermal Oxidizer Quencher Treating Silicon Dioxide (SiO2) Particulate and HCl

Posted by Andy Bartocci on Wed, May 27, 2020 @ 07:26 AM

A pharmaceutical company, Roche Carolina, operates a thermal oxidizerThermal oxidizer SiO2 Quencher (TO) that treats a rich stream of chlorinated compounds and an organic silicon compound. HCl and silicon dioxide (SiO2) particulate are formed during combustion. The exhaust is treated by a Hastelloy evaporative quencher followed by a caustic scrubber.

The quencher utilizes spray pig tailed nozzles, some of which are orientated upward into the gas to prevent fouling from SiO2 accumulation on the spray headers. The pigtails gradually plug both inside and outside as SiO2 particulate collect outside the nozzles.

The stainless inlet duct flange connection frequently springs leaks, causing shutdowns for repairs. It was thought that the upward pointed nozzles wetted the welded flange surfaces resulting in acid gas corrosion from HCl and possible stress from thermal expansion differences between the two metals.

An improved design was sought to increase reliability and eliminate operational and maintenance problems. The design needed to address the potential for:

    • Spray nozzle plugging from SiO2 particulate.
    • SiO2 accumulation on the quencher walls.
    • Acid gas corrosion.
    • Weld leakage and failure.
The customer selected a custom engineered Envitech quencher.

Tangential pipes with large orifices at the top of the quencher keeps the walls fully wetted and prevents SiO2 particulate build-up.

A barrel at the inlet flange extends into the quencher with the same diameter as the inlet duct. The tangential nozzles are placed behind the barrel wall to protect injected water from traveling up into the duct.

Elimination of the pigtail nozzles prevents associated gradual nozzle plugging.

Because water is not put into the quencher-inlet duct interface, the possibility of leaking from this connection is eliminated. Risk of corrosion attack is also minimized.
Weld leakage and failure.

The bottom section is the same as the original design to facilitate integration.

The quencher has been operational since 2008 to the below design conditions. The facility reports good results and significantly improved reliability and lower maintenance costs.

  • Max flow rate, acfm: 6,700 acfm
  • Nominal flow rate: acfm 3,000 acfm
  • Max inlet temperature, oF: 850
  • SiO2 particulate, gr/dscf: up to 0.1
  • HCl, ppmv: 31
  • Saturation temperature, oF: 145

Click on the link below to download a case study and related quencher and wet scrubber literature.

Download Literature

Topics: particulate control, Scrubbers, Incinerator Scrubber, quenchers, Packed Bed Absorbers, Packed Bed Scrubbers, Wet Scrubbers

Peat Dryer Horizontal Venturi Scrubber

Posted by Andy Bartocci on Thu, Jan 09, 2020 @ 05:30 AM

An agricultural solutions company, American Peat Technology, transforms locally harvested unprocessed peatPeat Dryer Horizontal Venturi into a consistent granular media. The media is used as a natural microbial carrier to inoculate millions of acres of food crops each year. The transformation process relies on drying harvested material in industrial rotary dryers. A fraction of the material becomes entrained in the flue gas as particulate emissions. The facility is expanding operations to double the capacity. A scrubber solution is needed to reduce total plant particulate emissions.

The customer selected two identical Envitech horizontal Venturi scrubbPeat Dryer Horizontal Venturi_long viewers. The scrubbers are comprised of a variable throat Venturi scrubber and a chevron style entrainment separator mounted on an equipment skid. The scope of supply for each scrubber includes a control system, re-circulation pump with pre-assembled piping, valves and fittings. Instruments are pre-mounted in the piping where possible and pre-wired to a junction box on the skid. The horizontal configuration provides a compact design to fit inside the building with easy maintenance access to valves and instruments.

The skid arrangement allows the scrubbers to be shop assembled and tested prior to shipment.  The combination of a variable throat Venturi with a chevron style mist eliminator allows a wide turn-down ratio while maintaining high performance. The use of a wet scrubber instead of a bag-house eliminates the potential for bag fires that could be caused by occasional hot embers entrained in the gas.  The facility is also able to make use of the latent heat absorbed by the scrubber, making use of hot recirculated scrubber water to thaw out frozen peat in the winter before it is fed to the dryers. 

The scrubbers were commissioned in December 2019 and are now operational. Both scrubbers are used for two dryers providing a wide operating range. The scrubbers meet the design parameters listed below:


  • Inlet flow rate: 25,000 acfm
  • Inlet temperature: 185oF
  • Inlet Particulate: 15 lbs/hr 
  • Particulate Removal: > 99%

Click on the link below to download a case study and other Venturi scrubbing literature.

Download Literature

Topics: particulate control, Venturi scrubbers, Scrubbers, Wet Scrubbers

Mineral Processing Venturi Scrubber

Posted by Andy Bartocci on Wed, Dec 04, 2019 @ 08:04 AM

US Magnesium is implementing an electrolytic expansion project located in Rowley, UT. A scrubbing system isUS Mag Venturi Scrubber needed to remove particulate from a chlorine gas stream that originates in the anode compartments of electrolytic cells that produce magnesium metal. A significant portion of the particulate is less than 1 micron in size, making it difficult to remove.

Chlorine is an important by-product of the electrolytic process. Scrubbed chlorine flows to a chlorine plant for further processing and liquefaction. The scrubbing equipment must be designed and constructed in a manner to minimize air in-leakage and chlorine emissions. Materials of construction must be selected to withstand severe corrosive characteristics of > 90% chlorine (Cl2) gas.

Particulates in the gas leads to maintenance associated with downstream filters in the chlorine plant. It is therefore necessary to maximize removal efficiency to minimize filter maintenance costs.

The customer selected an Envitech high efficiency Venturi Scrubber. The equipment includes a fixed throat fiber reinforced plasUS Mag Venturi Scrubber Fanstic (FRP) Venturi scrubber and horizontal chevron style entrainment separator. Additional scope of supply includes instruments, pre-assembled pump skid with redundant titanium pumps (1 operating and 1 spare), pre-assembled CPVC piping, redundant fans with titanium wheel and housing, interconnect FRP ductwork, dampers, and equipment skid and platforms.

Because a large fraction of particulate is submicron in size and difficult to remove, the fans and vessels are designed to operate at -70” water column pressure drop.

An Envitech Venturi scrubber was installed on the original process in 1999. The new scrubber for the expansion project was installed in 2011. Both systems continue to operate with high reliability and uptime. The table below summarizes key design parameters for the new Venturi scrubber.


  • Inlet flow rate: 8,200 acfm
  • Inlet temperature: 130oF
  • Gas Composition:  > 90% Cl2 gas
  • Pressure drop: 60" W.C.
  • PM Removal: > 75%

Click on the link below to download a case study and other Venturi scrubbing literature.

Download Literature

Topics: particulate control, Venturi scrubbers, Scrubbers, Wet Scrubbers

Hot Mix Asphalt Dryer Emissions Control

Posted by Andy Olds on Wed, Dec 04, 2019 @ 06:30 AM

Hot mix asphalt (HMA) plants combine aggregate and petroleum byproducts to form paving material.  HMA plants can be permanent, transportable (skid-mounted), or portable.  For large asphalt projects, it is economical to use transportable or portable HMA plants so as to set up near the project and reduce the delivery time of asphalt to the site.  Large HMA manufacturers thus transport their manufacturing equipment from site to site.Env Horz VS scrub

The most common HMA plant is a batch mix plant.  A batch plant consists of an aggregate dryer to dewater the aggregate, a mixer to combine the aggregate with asphalt cement, and a load-out bay for transferring the final product to trucks for transport.  Auxiliary equipment includes a cyclone for aggregate collection after the dryer, a secondary collection device for particulate emissions, a blue haze control device to curb VOC emissions.  Reclaimed asphalt pavement (RAP) is typically used to reduce costs and promote sustainability within the industry.  The stage at which RAP is introduced depends on the qualities of the RAP and the desired properties of the final asphalt product.

According to the EPA, there are two primary techologies for the secondary collection devices: Venturi scrubbers and baghouses.  Venturi scrubbers are wet devices that capture particulate through inertial impaction.  Venturis are fractional efficiency devices capable of efficiently capturing particulate as small as 1 micron.  Venturis are inherently self cleaning: water sprays continuously from the Venturi throat and the accelerated gas shears any wall buildup.  Thus, Venturis are excellent in the removal of sticky particulate that would foul other forms of particulate control. Also, as a wet process, Venturis have the ability of capturing condensables and water soluble vapors.  The alternative technology for secondary particulate capture is a baghouse.  A baghouse achieves particle collection by filtering the gas through a physical barrier. Baghouses can efficiently remove submicron particulate, provided that the particulate is filterable.  Baghouses are not able to capture condensibles, but can capture some acid gases if an appropriate dry chemical is added to the dryer flue gas.

Recently, Envitech has developed an economical Venturi scrubber that can be either built on a skid for easy transport, or built on a truck bed for portability.  Envitech's Venturi scrubber is capable of meeting even the most stringent PM-10 requirements for particulate control, and works well with downstream blue haze control devices. Our Venturi scrubber is also anti-fouling and capable of consistently meeting control targets even with difficult RAP and exotic formulations with minimal maintenance.   

Topics: particulate control, Venturi scrubbers, Scrubbers

Wet Scrubber Basics

Posted by Andy Bartocci on Tue, Sep 10, 2019 @ 09:02 AM


As an equipment supplier of custom engineered wet scrubber equipment, Envitech frequently provides lunch and learns (L&L’s) to engineering companies to help educate engineers about the basics of available technology.

Figure 1 below is a summary chart of predominant wet scrubber technology options. The main product categories include packed bed absorbers, Venturi scrubbers, and wet electrostatic precipitators (WESPs). Each wet scrubber type serves a different purpose and is used in different circumstances. For instance, packed bed absorbers are primarily used to remove gaseous emissions like SO2, HCl, or HF. We often receive packed bed absorber inquiries for particulate removal, however, this would be a misuse of technology. Packed bed absorbers remove some particulate but they are not nearly as efficient as other options.

Figure 1: Wet scrubber technology summaryEnv wet scrubber technologies

Venturi scrubbers are used for particulate removal. Just like we sometimes receive packed bed absorber inquiries for particulate removal, we’ll occasionally get Venturi scrubber inquiries for acid gas removal. This would also be a misuse of technology. Venturi scrubbers achieve some acid gas removal, but they have poor mass transfer compared to a packed bed absorbers.  

Venturi scrubbers use mechanical forces to remove particulate. Particles are captured through a process of impaction between particles in the gas and water droplets in the Venturi throat. A high differential velocity is created between particles and droplets by accelerating the gas in the throat. A pressure drop in the throat provides energy to capture the particles. Smaller particles less than 1 micron in size avoid capture by behaving like gas molecules and finding slip streams around the water droplets. Venturi scrubber performance drops offs exponentially for submicron particulate. Overall removal efficiency may be limited for a gas stream with a high concentration of submicron particulate. Venturi scrubbers are a good choice for industrial dryers or other applications with large size particulate.

Wet electrostatic precipitator (WESP) are the third type of wet scrubber summarized in the table. Like Venturi scrubbers, they are also particulate removal devices. They differ from Venturi scrubbers in a couple of ways, 1.) electrical, not mechanical forces are used to capture particulate, and 2,) they are efficient at capturing submicron particulate. Figure 2 shows a performance comparison between a WESP and Venturi scrubber. It can be seen that performance drops off dramatically for Venturi scrubbers for particles less than 1 micron in size. WESP’s on the other hand remove particles regardless of particle size.

Figure 2: WESP, Venturi scrubber performance comparison versus particle size.

Envitech WESP Venturi Performance

The summary in Figure 1 also shows how each wet scrubber technology differs in regulatory control. A packed bed absorber is typically controlled for recirculation flow rate and liquid pH. A Venturi scrubber is controlled by recirculation rate and pressure drop. A WESP is controlled by voltage. Control limits are typically spelled out in the operating permit.

Finally, some examples of applications are given for each type of wet scrubber. It should be noted that there are many applications that have multiple types of pollutants. A hazardous waste incinerator, for instance, contains particulate, acid gases, and specific heavy metals like cadmium and lead. A fraction of particulate is submicron in size and difficult for a Venturi scrubber to remove. It is common for different types of wet scrubbers to be combined into a multi-pollutant device. Figure 3 shows a common arrangement for an incinerator scrubber. The gas is first cooled in a quencher. A packed bed absorber removes acid gases. A Venturi scrubber removes particulate and a WESP removes the submicron particulate and heavy metals.

Figure 3: Incinerator wet scrubber arrangement

Env wet scrubber arrangement

Wet scrubbers can also be combined with dry scrubbers in certain circumstances. An upstream bag-house can remove particulate followed by a packed bed absorber for acid gas removal. A cyclone can be used to knock out large particulate before using a Venturi scrubber for the remaining particulate. A cyclone helps to minimize blowdown and water consumption. In some cases, a dry filter or carbon bed absorber can be integrated downstream of a wet scrubber for mercury and/or dioxin/furan. Click here to read a blog piece about an example of a wet scrubber combined with a carbon bed.

This about covers wet scrubber basics. If you’re with an engineering company and want to discuss scheduling a lunch an learn, please give Envitech a call. You can click on the icon below for a set of Envitech brochures.

Click on the icon below to download an Envitech brochure.

Download Literature



Topics: particulate control, Venturi scrubbers, Scrubbers, SO2 Scrubber, wet electrostatic precipitators, Acid Gas, Packed Bed Absorbers, Packed Bed Scrubbers, Wet Scrubbers

International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors (IT3/HWC)

Posted by Andy Bartocci on Mon, Aug 26, 2019 @ 10:55 AM

IT3 Logo

Envitech will be attending and exhibiting at the 37th International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors (IT3/HWC) in League City, TX on October 2nd and 3rd, 2019. If you happen to be attending the conference, please stop by the Envitech booth or find me at the conference to say hello.

Three keynote panels will include high level experts and cover hot topics in the industry:

  • PFAS Overview, Regulatory Approach, Testing and Destruction
  • Emerging Air Quality Monitoring
  • Lessons Learned from the United Kingdom's 2018 Novichok Nerve Agent Incident

Papers presented in technical sessions cover:

  • Technologies and Trends in Incineration
  • Plastics Recycle and Reuse
  • Emission Monitoring
  • Waste-to-energy, Emission Monitoring, Pyrolysis 

Envitech will present papers on the following two topics.

Technology Solutions for Sulfuric Acid Formation and Removal in Liquid Waste and Waste Gas Thermal Oxidizers

Petrochemical plants, refineries, and waste-oil re-refiners operate liquid waste or waste gas thermal oxidizers.Candle filter The thermal oxidizers need a wet scrubber to neutralize and remove SO2. Flue gas entering the scrubber contain some sulfur trioxide (SO3) which is converted to sulfuric acid (H2SO4) in the quencher. Sulfuric acid is a submicron liquid aerosol that passes through the downstream packed bed absorber. Some facilities are now being regulated for H2SO4. This paper evaluates and compares candle filters versus wet electrostatic precipitators (WESP’s) for H2SO4 removal in these applications.

Sewage Sludge Incinerator (SSI) Mercury Control Technologies

Mercury Control ScrubberWaste water treatment facilities operating sewage sludge incinerators (SSI) can reduce sludge volume and disposal costs by combusting dewatered sewage sludge. Emissions are regulated by the US EPA Maximum Available Control Technology (MACT) standard 40 CFR Part 60 and 62 to control particulate, lead (Pb), cadmium (Cd), SO2, HCl, dioxins/furans, and mercury (Hg). Many SSI’s need a control device specifically for mercury. This paper evaluates two mercury control technologies: sulfur‐impregnated activated carbon and Gore sorbent polymer catalyst (SPC) modules. Several facilities have used sulfur-impregnated activated carbon but safety issues have arisen due to fires which have shut down some systems. The Gore SPC modules are a relatively new technology with at least seven installations. A comparison is made of capital cost, operating cost, mercury removal efficiency, fire and performance risks based on incineration of 3,000 lbs/hr of sewage sludge. Finally, an overview is provided for an Envitech SPC mercury control scrubber operating at one facility.

Click on the icon below to download an Envitech brochure.

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Topics: particulate control, Scrubbers, SO2 Scrubber, wet electrostatic precipitators, Acid Gas, Incinerator Scrubber, SO3 Aerosol