Air Pollution Control Innovations

IT3/HWC 2015 Conference October 20-22, 2015 – Wet Electrostatic Precipitator for Medical Waste Incinerators

Posted by Andy Bartocci on Tue, Sep 22, 2015 @ 01:47 PM

Envitech will attend the International Conference on Thermal Treatment Technologies (IT3/HWC), October 20-22, 2015 at the Crowne Plaza Hotel in downtown, Houston, Texas.  The preliminary technical program can be downloaded from the conference website.   The conference features key note speakers from Veolia, Clean Harbors, Essroc, TCEQ, and B3 Systems.

Envitech will have an exhibit booth and present a paper, “Meeting the New Hospital, Medical, and Infectious Waste Incinerator (HMIWI) MACT with a Wet Electrostatic Precipitator (WESP)”.  The paper will provide an overview of a new medical waste incinerator scrubber system with a wet electrostatic precipitator to treat the off gas from two existing medical waste incinerators. The new system was required to achieve a 20% reduction in particulate (PM) emissions, and a 93% reduction in lead (Pb) emissions from the previous gas cleaning system.  The new system has been operational since October 2014.  The table below compares the performance of the emission limits to the new compliance standards. The results demonstrate the system comfortably meets the new EPA MACT standards.







Test Result

% of limit

Particulates, EPA Method 5 gr/dscf 0.020 15%
Pb EPA Method 29 mg/dscm 0.018 6%
Cd, EPA Method 29 mg/dscm 0.013 10%
Hg mg/dscm 0.025 1.0%
Dioxins/furans, EPA Method 23 Total (ng/dscm) 0.85 5%
  TEQ (ng/dscm) 0.020 15%
HCl, EPA Method 26 ppmv 7.7 1.6%
SO2 ppmv 4.2 35%

Click on the icon below to download a copy of the paper.


Topics: particulate control, Venturi scrubbers, wet electrostatic precipitators, MACT Standards, Medical Waste Incinerator Scrubber, Incinerator Scrubber, HMIWI Scrubber

Arsenic Scrubber for Copper Mine Roaster

Posted by Andy Bartocci on Thu, Jan 09, 2014 @ 04:00 PM

With an expanding global population, demand for minerals continues to grow.   Development of non-traditional resources is expected to increase to meet this growing demand. This includesCopper Mine copper resources challenged by high levels of arsenic.  Mining operations may incur penalties for arsenic in concentrates that exceed a certain amount.  As ore with low levels of arsenic is depleted, these penalties will continue to rise.

One facility seeking to reduce the impact of penalties is the Aranzazu project in Zacatecas Mexico by Aura Minerals.  The facility will use a partial roasting technology by Technip to achieve arsenic reduction in the concentrate.  After treatment, the concentrate is expected to contain less than 0.3% arsenic.  This will decrease expected arsenic related penalties by up to $1.00 per payable pound of copper produced.

wet electrostatic precipitator


The roaster off-gas will be treated by an Envitech wet scrubber system to remove arsenic with a 99.9% performance guarantee. The inlet gas to the scrubber will be at an elevated temperature well above 1,000oF and will have a high concentration of particulate, sulfur, and arsenic. The scrubber system combines Envitech’s wet scrubber technology which has been used to remove hazardous air pollutants from medical and hazardous waste incinerators with Envitech’s wet electrostatic precipitator technology (WESP) for final collection and removal of arsenic.  Envitech’s WESP technology has demonstrated high performance for arsenic removal on other furnace applications at secondary lead smelting facilities.

 For more information on the removal of heavy metals using wet electrostatic precipatators, please download our white paper on the capture of emissions from a smelter.

Download Free White Paper


Topics: Venturi scrubbers, wet electrostatic precipitators

Wet Scrubber Technology for Reducing China’s Air Pollution

Posted by Andy Bartocci on Wed, Jun 26, 2013 @ 03:01 PM

Envitech recently got noticed in a local news story by Michael Chen of KGTV Channel 10 News, “San Diego Companies Could Help Clean China’s Air”.  The story is about how California’s Governor Jerry Brown’s diplomatic trip to China could lead to opportunities for local San Diego companies like Envitech.  During his visit, Gov. Brown signed a pact that will pave the way for California companies to help China measure and improve its air quality.   As a leader in industrial air pollution control equipment, Envitech has process technology that can be used in China for reducing hazardous air pollutants (HAPs) and pollutants that contribute to regional haze like sulfur dioxide (SO2). These technologies have been applied to many processes in North America including a coal gasification plant, hazardous waste incinerators, lead smelters, sulfite pulping mills, waste oil re-refiners, geothermal plants, and mining and mineral processing to name a few.  Envitech has pursued several opportunities in China through 3rd party customers and will have one installation starting up later this year.

For more information on Envitech's capabilities, please download our product brochure.

Download Brochure

Topics: particulate control, Venturi scrubbers, gasification, Scrubbers, SO2 Scrubber, wet electrostatic precipitators, cleaning systems

Medical Waste Incinerator Scrubbers for the new HMIWI MACT Standard

Posted by Andy Bartocci on Fri, May 24, 2013 @ 04:00 PM

In 2009 I wrote a blog piece about the new EPA rules promulgated for the hospital, medical, and infectious waste incinerator (HMIWI) maximum achievable control technology (MACT)describe the image standard.  The compliance dates for these rules are fast approaching.  Facilities with existing equipment must demonstrate compliance to the new standards by October 2014.  Envitech is already under contract with several facilities to retro-fit existing medical waste incinerator scrubbers with add-on control equipment to meet the new standards. 

The emissions reduction challenge with the new rules can be seen in the adjacent graph which compares the difference between the 2007 MACT standard to the new MACT standard.   Medical Waste ScrubbersStack emissions must meet substantially lower limits for Cd, Pb, and Hg. In many cases, this requires add-on controls capable of greater than 90% removal of sub-micron condensed metals.  Most facilities are putting on a re-heat and filter package to remove the condensed metals.  A few will use wet electrostatic precipitators (WESP) which are more expensive.   The ability to meet the new rules using a re-heat and filter package has been demonstrated for lead and cadmium on a commercial and industrial waste incinerator (CISWI).  The WESP capability has been demonstrated for reduction of lead emission achieved at a secondary lead smelter in California.

Another emissions reductions challenge is dioxins/furans (D/F).  Emission limits for D/F have been reduced from 125 ng/dscm Total and 2.3 ng/dscm TEQ (corrected to 7% O2) to 25 and 0.6 ng/dscm, respectively.  These emission limits are too low to be met with carbon injection.  An add-on control package of re-heat and carbon bed absorber is required to meet the new limits.

Solutions to these challenges exist and facilities are taking steps to meet them.  Click on the link below to download the HMIWI MACT Rule paper from the 2010 International Conference of Thermal Treatment Technologies and Hazardous Waste Combustors (IT3/HWC).

Download Free Paper 


Topics: particulate control, Venturi scrubbers, Scrubbers, wet electrostatic precipitators, cleaning systems, MACT Standards

Wet Electrostatic Precipitator Insulator Design

Posted by Liliana Chen on Mon, Mar 18, 2013 @ 09:00 AM

The purpose of a wet electrostatic precipitator (WESP) is to remove particulates that are smaller than one micron from a gas stream.  One of the common industrial applications is downstream of standard pollution control equipment on power plants or pulp mill facilities. Power plants typically use wet electrostatic precipitators after all other pollution control equipment for polishing.  Pellet mill facilities use wet electrostatic precipitators upstream of RTOs to prevent buildup on the RTO media. Particulate removal is achieved by sending process gas through an array of high voltage electrodes and grounded collectors.  Particles in the gas are charged and then attracted to the collector surface;  clean gas continues up the WESP.

The outlet section of a WESP houses the insulator compartments.  Insulator compartments support a high voltage grid which holds the discharge electrodes in place. This arrangement separates the high voltage grid from the grounded section. The introduction of purge air through the insulator compartment reduces dust and moisture buildup on the walls of the compartments. This not only keeps the insulator bushing clean but also maintains a positive air pressure to prevent process gases from entering the compartment. 


The diagram above shows how the WESP is connected to the insultator compartment with a shroud. Operating the system at minimum purge air flow helps reduce operating cost as less energy will be required to heat up the purge air. The caveat here is that inadequate flow will result in wet process gases swirling into the insulator compartment through the shroud from the WESP. In an attempt to optimize our operating conditions, flow simulation was performed to analyze the flow pattern of purge air through the shroud at varying inlet flow rates.

The close-up view of the shroud shown on the bottom was taken facing the insulator compartment with WESP at the back. The green/blue color indicates air flow towards the WESP (into the page), while the red/yellow represents flow towards the insulator (out of the page). This illustrates a positive air flow into the WESP achieved at minimal flow rate. Under this operating condition, energy savings will be maximized while ensuring no swirling of wet process gas into the insulator compartment. 



To see how this modeling is applied, download our case study on treating a lead fume using a wet electrostatic precipitator.

Download Paper

Topics: wet electrostatic precipitators

Wet Electrostatic Precipitators for Pellet Mills

Posted by Andy Bartocci on Thu, Mar 07, 2013 @ 06:42 PM

Envitech will be attending the International Biomass Conference & Expo in Minneapolis, MNWESP April 8-10, 2013.  We will exhibit at Booth 807.  During the conference I will be presenting in the Pellets & Densified Biomass track between 8:30 am and 10:00 on Wednesday, April 10th. The topic will be "High Performance Wet Electrostatic Precipitator (WESP) for Pellet Mills".   


A large portion of wood pellets produced in North America are exported to Europe to support aggressive low-carbon fuel incentives.  Growth of the export market has lead to large scale pellet mills with production capacities ranging from 500,000 to 750,000 tons of pellets per year.

Pellet MillThese mills use wood dryers to remove moisture from incoming feed material.  A wet electrostatic precipitator (WESP) collects particulate (PM) and condensed volatile organic compounds (VOC) from the dryer exhaust. This is required to protect a downstream regenerative thermal oxidizer (RTO) from fouling. The RTO destroys volatile organic compounds (VOCs) before exhausting to the atmosphere.  The process flow conditions are large and typically several hundred thousand cubic feet per minute.

This presentation will discuss a high performance WESP design to treat the pellet mill dryer exhaust.   The design leverages experience from several large flow rate applications including a coal dryer scrubber, secondary lead smelter WESP, and sulfite pulp mill recovery boiler WESP.  The presentation will focus on how the design achieves high performance.

A copy of the presentation is available by clicking the link below.

Download Free Presentation


Topics: wet electrostatic precipitators

Secondary Lead Smelter Wet Electrostatic Precipitator Case Study

Posted by Andy Bartocci on Mon, Dec 03, 2012 @ 12:30 PM

A secondary lead smelter in Southern California recovers leadlead scrubber, lead smelter scrubber from used automobile batteries. The process uses a combination of combustion processes including kilns and furnaces. Despite extensive control equipment including bag-houses, HEPA filters, and wet scrubbers, low concentrations of heavy metals were being emitted from various stack sources.  Cancer risk index standards were being exceeded due to the close proximity of residents to the plant.  To be compliant with state regulations a solution was needed to reduce these emissions. The special circumstances of nearby residents and a stringent cancer risk index required the facility to meet emission limits well below any other secondary lead smelter in the country.

A case study is now available to describe how an Envitech high performance Wet Electrostatic Precipitator was used to solve this problem.

Please click on the icon below to download the case study.

describe the image




Topics: particulate control, Scrubbers, SO2 Scrubber, wet electrostatic precipitators

Sulfite Pulp Mill Scrubber / WESP Case Study

Posted by Andy Bartocci on Mon, Nov 26, 2012 @ 11:43 AM

A specialty cellulose provider, Tembec,Sulfite Pulp Mill Scrubber is upgrading a sulfite pulping mill in Eastern Canada to incorporate a new red liquor recovery boiler for power generation.  The boiler system increases annual green energy production by up to 40-megawatts, reduces sulfur dioxide emissions by 70%, and increases annual production capacity of specialty cellulose by 5,000 metric tonnes.  The off-gas from the recovery boiler contains a high concentration of SO2 which needs to be recovered for re-use in the production process. 

A cost effective solution was needed to recover sulfur and clean the stack gases to meet stringent particulate and SO2 emission limits.  The plant is located in a high labor rate area, which makes a field erected system very expensive due to lengthy installation time.

A case study is now available to describe how an Envitech scrubber/wet electrostatic precipitator (WESP) system solves this problem.

Please click on the icon below to download the case study.

Download  Case Study

Topics: particulate control, Venturi scrubbers, Scrubbers, SO2 Scrubber, wet electrostatic precipitators

Wet Electrostatic Precipitator Case Study for Lead Removal

Posted by Andy Bartocci on Wed, Nov 21, 2012 @ 11:58 AM

lead removal, lead scrubber

I previously posted a blog post about a new project for lead removal using a wet electrostatic precipitator (WESP). A Midwestern manufacturer heat treats metal materials in a furnace that generates low concentrations of lead fumes.  The fumes are sub-micron in size, making them difficult to remove.  The facility is compliant with their existing permit, but wants to be pro-active to control emissions further. They investigated several technologies including HEPA and cartridge filters, Venturi scrubbers, and wet electrostatic precipitators (WESPs). Because of the small particle size, low concentration, and high removal efficiency, they had difficulty finding technologies or vendors willing to guarantee the requested performance limit.

A case study is now available to describe how an Envitech high performance Wet Electrostatic Precipitator solves this problem.

Please click on the icon below to download the case study.

Download Case Study

Topics: particulate control, wet electrostatic precipitators

Sulfite Pulping Mill Recovery Boiler Scrubber System

Posted by Andy Bartocci on Tue, Oct 30, 2012 @ 11:55 AM

Envitech has received an order from Tembec to supply an ammonia based red liquor recovery boiler scrubber for the Temiscaming sulfite pulping mill in Québec, Canada.   The scrubber system will treat the off-gas from an upstream sulfite power boiler supplied by Andritz and will meet stringent emission standards for particulate and SO2.sulfit pulp mill scrubber, recovery boiler scrubber, red liquor boilerr

This system is part of a $190-million power generation project that will upgrade Tembec’s existing specialty cellulose manufacturing facility.  The upgrade will increase annual green energy production by up to 40-megawatts, reduce sulfur dioxide emissions by 70%, and increase annual production capacity of specialty cellulose by 5,000 metric tonnes.  The upgrade will make Temiscaming one of the lowest-cost specialty cellulose manufacturing facilities in the world.

The scrubber system is engineered to Tembec’s requirements and is the result of close collaboration with the customer over several months and their engineering firm Pöyry.   The design leverages experience from several other large volumetric flow rate applications including a coal dryer scrubber, secondary lead smelter wet electrostatic precipitator (WESP) system, and a hazardous waste incinerator scrubber.  The scope of supply includes an inlet duct from the boiler exhaust fan, quencher, ammonia scrubber, condenser, WESP, caustic scrubber, heat exchangers, structural steel, access platforms, and stack.  Primary vessels will be shop fabricated and shipped to the site for assembly and installation.  This provides a lower total installed cost, greater quality control over manufacturing, and shorter delivery and installation time.  System start-up will occur in the fall of 2013.

To read more about this system, download the case study below.

Download  Case Study

Topics: particulate control, Scrubbers, SO2 Scrubber, wet electrostatic precipitators, quenchers