Agenda 01/09/2018 Item #16C 401/09/2018
EXECUTIVE SUMMARY
Recommendation to authorize an increase of $250,000 to the purchase order for Bioxide Plus 71,
Aktivox and VX456 from Evoqua Water Technologies LLC for use by the Public Utilities
Department Wastewater Division.
OBJECTIVE: To ensure the Wastewater Division remains in regulatory compliance (62-604 F.A.C.),
minimizes odors consistent with the good neighbor policy, and meets demand with sustained reliability by
utilizing Evoqua Water Technologies LLC’s (Evoqua) advanced products in the wastewater collection
system and the water reclamation facilities.
CONSIDERATIONS: The Collier County Wastewater Division operates more than 60 odor control
systems. The technologies that Evoqua provides enable the Wastewater Division to reduce dissolved
sulfides to minimize the impact on the odor control systems located in the more than 850 lift stations and
two water reclamation facilities. On May 23, 2017, the Board of County Commissioners (Board)
approved agenda item 16C3 for the sole source purchases of Evoqua’s Bioxide Plus 71, Aktivox and
VX456 for a period of one year in the estimated amount of $500,000. This contract expires on May 31,
2018 and an increase in the purchase order will retain the contract pricing currently in effect.
The Public Utilities Department requests authorization for an increase of $250,000 to maintain
uninterrupted and continued use of Evoqua’s odor control products. In July 2017, staff conducted an
internal study of Collier County’s wastewater treatment and chemical usage and surveyed local sister
utilities of Manatee County, Loxahatchee, City of Tampa, Fort Pierce, Boca Raton and Lee County to
obtain an understanding of the technologies and chemicals used in the collection and treatment of
wastewater. Collier County, Lee County and Manatee County are similar in size, demographics and
topography. This review and analysis did not provide a conclusive determination of "the best" odor
control technology. Rather, it supported the contention that the existing conditions, treatment objectives
and economic restraints must be considered in selection and design of any odor control strategy. The
results and recommendations of this study are attached for Board review.
Collier County has a prohibition on using any hazardous rated materials in the collections system,
limiting the technology choices available to control odorous and corrosion issues. The County ensures
that technologies used will not affect natural resources, public health and or personal safety. Some odor
control chemicals such as bleach and chlorine can be volatile and create containment concerns. Use of
these chemicals in the collections system can create biological and delivery issues.
Bioxide Plus 71 is a non-toxic and safe product that is fed into the piping system between pump stations
to minimize dissolved sulfides created in the collections system. Reduction of dissolved sulfide assists
with minimizing higher levels of hydrogen sulfides to a manageable level for the odor control systems.
Aktivox and VX456 are utilized at the water reclamation facilities to provide an immediate impact to
reduce dissolved sulfides. The use of these technologies also assists with other odors associated with
sewage processing.
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These products provide the following additional benefits and advantages:
Reduces fats, oils and grease in the piping and pump station wet wells. This results in labor
and equipment cost savings by reducing the frequency of cleaning.
Allows the continued use of the existing, smaller odor control systems.
Reduces the potential of higher strength gasses that may affect the health and safety of plant
employees and residents who reside near the plants.
Modifications have been made at the North County Water Reclamation Facility odor control units and it
is anticipated that the amount of Bioxide Plus 71 used will be reduced substantially over the next year. It
will take time to for these system changes to become acclimated and adjustments will be made as
necessary.
Staff is requesting to the continual purchase of Bioxide Plus 71, Aktivox and VX456 from Evoqua
pursuant to the Procurement Ordinance, Section V.C1, Section 9, as the sole-source provider for these
patented products that have proven effective for the intended purpose. The Bioxide Plus 71, Aktivox and
VX456 from Evoqua constitute an implied license to practice the processes described in the United States
Patent numbers 7,779,224B2,7,799,215B2 and US8,968,646B2. Bioxide Plus 71, Aktivox and VX456 are
registered trademarks of Evoqua Water Technologies LLC.
FISCAL IMPACT: Funds are available in the Collier County Water-Sewer District Operating Fund
(408) and the Wastewater User Fee Fund (414). The actual amount to be expended will depend on the
demands on the wastewater system. The estimated cost is $250,000.
GROWTH MANAGEMENT IMPACT: This project meets current Growth Management Plan
standards to insure the viability of public facilities.
LEGAL CONSIDERATIONS: This item is approved as to form and legality, and requires majority
vote for Board approval. -SRT
RECOMMENDATION: Recommendation to authorize an increase of $250,000 to the purchase order
for Bioxide Plus 71, Aktivox and VX456 from Evoqua Water Technologies LLC for use by the Public
Utilities Department Wastewater Division.
Prepared by: Beth Johnssen, Wastewater Division Director
Steve Messner, Water Division Director
ATTACHMENT(S)
1. Business Case - Evoqua (PDF)
2. 17-7156 Evoqua_Contract_FullExec (PDF)
3. Waiver Request 261 - Evoqua_Waiver (Update) (PDF)
4. Odor Control Chemical Study (PDF)
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COLLIER COUNTY
Board of County Commissioners
Item Number: 16.C.4
Doc ID: 4307
Item Summary: Recommendation to authorize an increase of $250,000 to the purchase order for
Bioxide Plus 71, Aktivox and VX456 from Evoqua Water Technologies LLC for use by the Public
Utilities Department Wastewater Division.
Meeting Date: 01/09/2018
Prepared by:
Title: Operations Analyst – Public Utilities Department
Name: Susan Jacobs
11/29/2017 11:24 AM
Submitted by:
Title: Department Head - Public Utilities – Public Utilities Department
Name: George Yilmaz
11/29/2017 11:24 AM
Approved By:
Review:
Procurement Services Opal Vann Level 1 Purchasing Gatekeeper Completed 11/29/2017 11:37 AM
Procurement Services Sandra Herrera Additional Reviewer Completed 11/29/2017 4:53 PM
Public Utilities Operations Support Joseph Bellone Additional Reviewer Completed 12/01/2017 8:29 AM
Water Beth Johnssen Additional Reviewer Completed 12/01/2017 11:56 AM
Wastewater Beth Johnssen Additional Reviewer Completed 12/01/2017 12:01 PM
Procurement Services Ted Coyman Additional Reviewer Completed 12/06/2017 9:03 AM
Procurement Services Adam Northrup Additional Reviewer Completed 12/14/2017 5:02 PM
Public Utilities Department Heather Bustos Level 1 Division Reviewer Completed 12/14/2017 5:14 PM
Public Utilities Department George Yilmaz Level 2 Division Administrator Review Completed 12/20/2017 2:37 PM
County Attorney's Office Scott Teach Level 2 Attorney Review Completed 12/20/2017 4:32 PM
County Attorney's Office Jeffrey A. Klatzkow Level 3 County Attorney's Office Review Completed 12/21/2017 8:40 AM
Office of Management and Budget Valerie Fleming Level 3 OMB Gatekeeper Review Completed 12/26/2017 8:41 AM
Office of Management and Budget Susan Usher Additional Reviewer Completed 01/02/2018 4:36 PM
County Manager's Office Leo E. Ochs Level 4 County Manager Review Completed 01/03/2018 8:55 AM
Board of County Commissioners MaryJo Brock Meeting Pending 01/09/2018 9:00 AM
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Business Case
Evoqua Water Technologies LLC
1. What would the impact be to change to a different product (include: training,
inventory parts, maintenance, project (or staff time) to replace the item?
Increased maintenance and labor costs associated with frequency of cleaning piping and
pumps. Resident and visitor complaints of odors and pump stations in proximity to
residences. Utilizing other products or services could result in modifications to existing
infrastructure. Fines and violations imposed by local, state and federal regulations for non-
compliance under permit numbers FL0141356-013 and FL0141399-027, Florida
Administrative Code 62-600 (Domestic Wastewater Facilities), 62-610 (Reuse of
Reclaimed Water and Land Application) and 62-555 (Permitting, Construction, Operation
and Maintenance of Public Water Systems).
2. If the product requested is one-of-a-kind item, provide background information on
how this was determined and backup resources utilized.
Pursuant to the Procurement Ordinance, Section V.C1, Section 9, Evoqua is the sole-source
provider for these patented products that have been proven to be effective for the intended
purpose. The purchase of Bioxide Plus 71, Aktivox and VX456 from Evoqua constitutes
an implied license to practice the processes described in the United States Patent numbers
7,779,224B2,7,799,215B2 and US8,968,646B2.
The Public Utilities Department has more than 60 Siemens odor control units in the Collier
County Water-Sewer District. Almost 20 years ago, Collier County test piloted an odor
control program with Siemens equipment, products and services. This program was highly
successful and its proven technologies have only improved. In 2011, Siemens demonstrated
an advanced product, Bioxide 71, which was also very successful. Collier County has a
strict "good neighbor" policy and reliable odor control systems, products and services are
essential. Siemens was acquired by Evoqua Water Technologies LLC in 2014. If Collier
County switched products, it would have to change out all current odor control systems
since Evoqua products and services are proprietary. The products requested do not interfere
with further processing of waste, contain selective oxidants with specificity to sulfides and
related organic odor causing compounds, do not form chlorinated organics and fast -
reacting with long duration control. These characteristics meet the current equipment
requirements.
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Packet Pg. 618 Attachment: Business Case - Evoqua (4307 : Evoqua PO Increase)
3. Provide information on why a particular product and/or vendor was chosen.
The technologies that Evoqua Water Technologies LLC provides enable the Wastewater
Division to reduce dissolved sulfides to minimize the impact on the odor control systems
located in the lifts stations and wastewater reclamation facilities throughout Collier
County. This is proven technology compatible with proprietary equipment. Evoqua
products and services are warrantied, reliable and consistent.
4. If unique features are required to successfully perform the required function, identify
what those features are any why they are required. (Be specific)
This is a proven technology only provided by Evoqua Water Technologies LLC. Bioxide
Plus 71 is a non-toxic and safe product used to minimize dissolved sulfides created in the
collections system. Reduction of dissolved sulfide assists with minimizing higher levels
of hydrogen sulfides to a manageable level for the odor control systems located at pump
stations and wastewater reclamation facilities. Aktivox and VX456 are utilized at the
water reclamation facilities to provide an immediate impact to reduce dissolved sulfide.
The use of these technologies also assists with other odors associated with sewage
processing.
5. Provide information on other models available and why they were rejected. Provide
brand name, model, vendor name, date and name of each resource contacted. To
“exactly match existing equipment” or to “inter-member (connect) with existing
equipment” is not normally an acceptable justification for sole brand. When you
determine this is a justified factor that should be considered; the quantity,
manufacturer, brand, model, property number of the existing equipment, and
necessity for “interfacing” must be provided.
The requested products are sold exclusively through Evoqua Water Technologies LLC.
Purchasing from another vendor or contractor would add a markup to Evoqua's direct
pricing and not guarantee the current proven technology to remain in compliance.
6. Provide product listing of sole/single sourced items you are purchasing.
Bioxide Plus 71, Aktivox, VX456 to reduce odors associated with sewage processing.
16.C.4.a
Packet Pg. 619 Attachment: Business Case - Evoqua (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 620Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 621Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 622Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 623Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 624Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 625Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 626Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 627Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 628Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 629Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 630Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.4.bPacket Pg. 631Attachment: 17-7156 Evoqua_Contract_FullExec (4307 : Evoqua PO Increase)
16.C.3.bPacket Pg. 607Attachment: Waiver - Evoqua - 5-16-2017 (3124 : Evoqua Water Technologies Purchase of Bioxide Plus$750,000.00
Edward F. Coyman Jr.
Approval of increase
cn=adamnorthrup@collier
gov.net
07:28:22 2017.11.16
'00'05-
tedcoyman@colliergov
.net
Digitally signed by tedcoyman@colliergov.net
DN: cn=tedcoyman@colliergov.net
Date: 2017.11.22 08:19:51 -05'00'
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Packet Pg. 632 Attachment: Waiver Request 261 - Evoqua_Waiver (Update) (4307 : Evoqua PO Increase)
16.C.3.bPacket Pg. 608Attachment: Waiver - Evoqua - 5-16-2017 (3124 : Evoqua Water Technologies Purchase of Bioxide Plus16.C.4.c
Packet Pg. 633 Attachment: Waiver Request 261 - Evoqua_Waiver (Update) (4307 : Evoqua PO Increase)
WASTEWATER ODOR CONTROL CHEMICAL REVIEW
1
Table of Contents
Section Page
I. Introduction……………………………………………………………2
II. Section II: Background and Historical Data…………………………..3
III. Odor Control Facts…………………………………………………3 - 4
IV. Odor Control Technologies Evaluation …………………………..4 - 10
V. Odor Control Municipalities Comparison………………………..10 - 12
VI. Odor Control Categorized Chemicals……………………………13 - 17
VII. Current Conditions Overview…………………………………………18
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WASTEWATER ODOR CONTROL CHEMICAL REVIEW
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Section I: Introduction
Today, Collier County uses a coordinated approach to odor control, balancing the use of
monitoring, operational controls, chemical additives, biofilters and chemical scrubbers to achieve
its goals. This review will summarize reasons why technologies are used in strategic and
geographical areas within Collier County.
Odor complaints, corrosion concerns and worker safety are the three main drivers for the odor
control program. All complaints received are logged and then investigated using a variety of
monitoring tools that include an Interscan, JEROME 631-X H2S analyzer, OdaLog gas data
compilation units and third-party investigation. These monitor odor levels inside and outside the
well over several days and evaluate the effectiveness of the programs that are instituted. Once the
timing and concentration of the odors are quantified, odors may be reduced by cleaning the wet
well, cleaning the gravity system feeding the well or raising the well level and adding drop pipes
to reduce turbulence. In some cases, chemicals and mechanical means are used to address higher
concentrations of hydrogen sulfide (H2S).
Although operational procedures usually reduce H2S levels by as much as 50 percent, odors may
persist. In such cases, a vapor-phase technology and or chemical additives upstream are
considered. The testing and sampling in the field will determine what technology or combination
of technologies can be used to reach the County’s goals.
In addition to biofilters for odor control in the collections system, the County uses chemical
scrubbers for odor control at the treatment plants. Liquid-phase treatment (chemical addition to
the wastewater stream) at strategic locations in the collections system helps stabilize odor levels
at the biofilters and scrubbers and provides a means of controlling chemical cost. The optimal
balance of chemical usage (liquid-phase additives versus scrubber chemicals) is achieved by
maintaining the H2S levels at the headworks scrubbers near an average of 100 parts per million
(ppm).
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Section II: Background and Historical Data
1997: Collier County’s Odor Control Program started with the installation of chemical scrubbing
units at both treatment facilities due to high concentrations of hydrogen sulfide and organic odors
resulting from excessive detention times in the collections system. Customer complaints were
reduced significantly near the treatment facilities but not at the lift stations feeding these
facilities.
1999: In response to odor complaints at master lift stations and treatment facilities, chemical
additives (Bioxide) were introduced to remove hydrogen sulfide from the solution to mitigate
odors until the chemical scrubber units could treat the problem.
2001: An evaluation of 68 lift stations was conducted by CDM. CDM provided
recommendations to update the odor control units. Based on CDM’s recommendations, the
County updated the odor control units and elected to replace Granular Activated Carbon Systems
(GAC) and Iron Sponge systems with Multi Stage Biological Odor Control Systems. The study
also evaluated liquid phase treatments for various sections of the County. The chemicals studied
were Hydrogen Peroxide, Bioxide and Magnesium Hydroxide.
2007: Complaint logs were initiated to ensure the collected data could identify hot spots
throughout Collier County. The log has been beneficial to determine seasonal occurrences,
duplicate odor complaints, indoor odor responses, time of events and the amount of complaints
per year. Based on this information, the County identified what changes should be added to the
utility standards. One significant change was to ensure that any new master/sub master lift
stations constructed had a multi-stage odor control system. Additionally, a new chemical
(VX456) was added to the bio-solids stream to control odors emanating from sludge trailers at
the North Collier Water Reclamation Facility (NCWRF).
2008: Dispersion modeling studies were conducted and weather station installations were
completed at South County Water Reclamation Facility (SCWRF) and NCWRF to assist with
location, duration and time of odorous events before offsite odors were noticed. The real-time
data provides the capability to detect which areas of the treatment plant were out of odor
compliance. In addition to the weather stations, six H2S monitors at the NCWRF and six H2S
monitors at the SCWRF were installed to signal alarms when levels of 5 ppm H2S was detected.
Additionally, a the chemical Aktivox was added to the MLE influent stream to control organic
odors emanating from aeration basins at the NCWRF.
Section III: Odor Control Facts
Odor Control: This program provides for the operation and maintenance of over 60 odor control
units. All odor complaint calls within the collections system are investigated and rectified by
this program. Also, all air quality testing for odor and corrosion control are conducted under this
program.
Odor Control Units and Odor Complaint Legislation: Requires compliance of F.A.C 62-604
(Level 2) addressing reasonable assurance that a facility will be designed and located to
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WASTEWATER ODOR CONTROL CHEMICAL REVIEW
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minimize adverse effects resulting from odors. Provides that all odor control units and odor
complaints be submitted and areas identified for remediation will proactively address customer
complaints.
The Collier County Water-Sewer District (CCWSD) operates and maintains approximately 1,100
miles of sanitary sewer, 829 wastewater pump stations and 2 regional water reclamation
facilities. The service area is divided into a north and south collections system, with wastewater
from the north service area treated at the 24.5-MGD NCWRF and wastewater from the south
collections system treated at the 16-MGD SCWRF.
Collier County developed a growing concern for odor and corrosion problems in its collections
system triggered by rising costs for sewer rehabilitation work and complaints from citizens living
nearby existing sewer lift stations. Similar to most wastewater collection systems in this area of
the country, the County sewer collections system is characterized by a number of factors known
to create a potential for the development of an odorous and corrosive environment:
• Gravity sewer lines are regularly installed at a minimum slope of 0.33 percent to 0.40
percent, resulting in long detention times.
• The collected wastewater frequently needs to be re-pumped several times before it
reaches a water reclamation facility which further increases the detention time.
• Flow rates from areas currently under development are only a fraction of the design flow
rates at built-out conditions.
• Average wastewater temperatures during the summer months range between 80 degrees
and 90 degrees Fahrenheit.
• Inspection program of lift stations and manhole locations to effectively prevent odor and
corrosion problems.
Section IV: Odor Control Technologies Evaluation
This paper consists of an evaluation of the qualitative characteristics and the economic properties
of the various technologies available for wastewater odor control. The goal of this paper is
simply to compile and summarize this information. There are a virtually limitless number of
unique odor control problems and challenges and it would be impossible to identify one
technology as the most applicable for all situations. It is hoped that this paper could be used as a
guide to select the most appropriate technology or technologies based on the unique
characteristics of a given application.
Background
Any place or process in which wastewater is collected, conveyed or treated has the potential to
generate and release nuisance odors to the surrounding area. However, most odor problems occur
in the collections system, in primary treatment facilities and in solids handling facilities. In most
instances, the odors associated with collections systems and primary treatment facilities are
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generated as a result of an anaerobic or "septic" condition. This condition occurs when oxygen
transfer to the wastewater is limited such as in a force main. In the anaerobic state, the microbes
present in the wastewater have no dissolved oxygen available for respiration. This allows
microbes known as "sulfate-reducing bacteria" to thrive. These bacteria utilize the sulfate ion
(SO4-) that is naturally abundant in most waters as an oxygen source for respiration. The
byproduct of this activity is hydrogen sulfide (H2S). This byproduct has a low solubility in the
wastewater and a strong, offensive, rotten-egg odor. In addition to its odor, H2S can cause severe
corrosion problems as well. Due to its low solubility in the wastewater, it is released to the
atmosphere in areas such as wet wells, headworks, grit chambers and primary clarifiers. There
are typically other "organic" odorous compounds, such as mercaptans and amines, present in
these areas, but H2S is the most prevalent compound.
Solids handling facilities are another significant odor problem area. In biosolids dewatering and
treatment processes, the biosolids commonly undergo extreme turbulence, pH adjustment and/or
thermal treatment. Depending on the nature of the biosolids stream and the treatment used, the
odor compounds released can consist of any combination of the following compounds in a wide
range of concentrations: ammonia, amines, hydrogen sulfide, organic sulfides and mercaptans.
Additionally, anaerobic digestion of sludge creates the anaerobic conditions in which sulfate-
reducing bacteria thrive, causing the formation of hydrogen sulfide that is vented with the
digester "biogas" formed from the digestion of sludge.
There are many different technologies that can be applied to control odors from wastewater
collection and treatment systems. These technologies can be split into two main groups: vapor-
phase technologies, used to control odorous compounds in the air or gas; and liquid-phase
technologies, used to control odorous compounds in the liquid wastewater itself. Vapor-phase
technologies typically are used in point-source applications such as wastewater treatment plants
and pump stations or for the treatment of biogas. Liquid-phase technologies typically are used in
collection systems where control of both odors and corrosion are concerns and/or where multiple
point odor control is an objective.
Discussion
This article breaks the technologies into vapor-phase and liquid-phase groups for comparison.
The technologies are compared easily within the same group, but generalized comparisons across
groups are not possible. Vapor-phase designs are driven by the ventilation rate for headspace to
be treated and the mass loading of the contaminant volatilized from the wastewater to the vapor
phase. Liquid-phase designs are driven by the wastewater flow rate and/or the total mass loading
of the contaminants within the liquid phase. The ventilation and volatilization rates
corresponding to liquid flow and mass loading vary widely for individual applications, making
generalized comparisons of vapor- vs. liquid-phase treatment impossible. Often the general
objectives and the logistics of an application will dictate one approach being desired over the
other. If that is not the case, it is suggested that the designer evaluate vapor phase and liquid
phase technologies independently to determine the most appropriate technology for each group,
then make an application-specific analysis to choose the ultimate technology or combination of
technologies.
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Vapor-Phase Technologies
Vapor-phase technologies ventilate the point sources of odor problems (wet wells, headworks,
etc.). For air treatment, the ventilation system is designed to maintain a negative pressure on the
area at all times. This prevents the "leakage" of odorous air from vents, manways, access hatches
or other areas. The discharge from the ventilation system is the only route for the odorous air to
escape, therefore it must be treated. Vapor-phase systems are very effective at preventing
fugitive emissions from the ventilated sources and preventing odor problems associated with
those sources.
If large amounts of air are ventilated, vapor-phase systems also can be effective at providing
adequate ventilation for occupancy and/or reducing the contaminant concentration to levels that
do not pose safety or corrosion hazards. Biogas treatment systems are concerned primarily with
the removal of hydrogen sulfide to prevent the formation of sulfur dioxide (SO2), a product of
the combustion of gas containing hydrogen sulfide. Most plants that have anaerobic treatment
burn the methane-rich biogas produced from the anaerobic sludge digestion (either as waste gas
in a flare or in engines, turbines or boilers for the production of power or steam). Because of this
practice, the removal of hydrogen sulfide many times is required to meet emissions standards or
to prevent corrosion in the combustion equipment. The technologies evaluated in this paper for
use in treating the ventilation air or biogas are wet air scrubbing, liquid redox technology,
biofiltration, solid scavengers and carbon adsorption.
Wet Air Scrubbing
Wet air scrubbing is the most flexible and reliable technology for vapor-phase wastewater odor
control. This technology can be used to treat virtually any water-soluble contaminant. In addition
to hydrogen sulfide and "organic" odors, wet scrubbing is very effective for ammonia removal.
In a wet air scrubber the odor contaminants are solubilized from the vapor phase into an aqueous
chemical solution. The removal mechanism is purely chemical and is not subject to upsets as are
biological processes. The chemical balance in the system is automatically and continuously
maintained, even under changing loading conditions, minimizing the chance for odor break-
through. The application of a multi-stage scrubber allows the utilization of a different chemical
solution in each of the stages to efficiently use chemicals and target a wide range of
contaminants for treatment.
One major advantage of wet scrubbing systems is the reliability and flexibility provided by the
use of chemicals and chemical reactions. A major challenge in the design and operation of wet
air scrubbers is the minimization of chemical use and cost while maintaining complete, flexible
and reliable treatment. One design used to reduce chemical use is the multi-stage scrubbing
system. As mentioned above, in raw wastewater odor control applications the most prevalent
contaminant is hydrogen sulfide, but other organic odorous compounds typically are present as
well. Hydrogen sulfide can be solubilized with a solution of sodium hydroxide. However, the
other odor-causing compounds are best treated by sodium hypochlorite. In a single-stage
scrubber system, sodium hydroxide and sodium hypochlorite are used in a recirculating chemical
solution. Since sodium hypochlorite is a strong oxidizer, it readily reacts with the sulfide that is
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WASTEWATER ODOR CONTROL CHEMICAL REVIEW
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solubilized by the sodium hydroxide. Therefore, in a single-stage system sodium hypochlorite
must be added in sufficient quantities to oxidize the hydrogen sulfide and maintain a residual to
treat the other odor compounds. In a multi-stage system, sodium hydroxide is used alone in the
first stage to solubilize hydrogen sulfide. Sodium hypochlorite is added to the last stage only. By
eliminating the sodium hypochlorite from the sulfide removal process, the consumption rate for
this chemical is greatly reduced.
Biofiltration
Biofiltration technology can be used to treat a variety of biodegradable, water-soluble
contaminants. In a biofilter, the odor contaminants are solubilized from the vapor phase into an
aqueous phase on the surface of an organic medium such as compost, mulch or peat. The
compounds are then degraded by the bacteriological population on this media. Biofilters are very
effective at removing sulfur-based odor compounds such as hydrogen sulfide, organic sulfides
and mercaptans. Biofilters generally are not effective at removing nitrogen-based compounds
such as ammonia and amines.
Two major challenges in biofiltration systems are stability of the media and control of the
biofiltration process. The media used in biofilters can be prone to breakdown. When this occurs,
the bed settles and compacts, increasing the headloss through the filter. This causes a decrease in
airflow and fugitive odor emissions typically result from the air source. Control of the
biofiltration process also is an important concern. The biological population within the filter is
subject to upsets, as are any organisms. If the media are exposed to wide swings in
environmental conditions, upset of the bacteria population may result and break-through odors
will occur.
These challenges can be addressed by applying an engineered or "manufactured" biofilter.
Engineered biofilters typically address media stability and control issues and are provided with
process guarantees. The media stability is addressed through the use of an "engineered media,"
as contrasted with a "simple media." Simple media typically consist of materials locally available
near a specific application (e.g., compost, mulch, wood chips, etc.). Engineered media typically
are designed to meet a particular composition and performance specification with a performance
guarantee. Engineered media have a specific combination of organic materials that is followed to
ensure consistent and repeatable performance. Process control is addressed through the design of
the filter. Most engineered systems utilize an enclosed design to protect the media from
temperature and humidity swings. In many cases, the enclosed design also is modular. The media
are contained in modules that are arranged in an array to provide a complete biofiltration system.
This modular design provides quick and easy construction of the system and extremely easy
media replacement.
Solid Scavengers
Scavengers are solid or liquid materials that remove sulfur compounds from gas or liquid
streams, reacting with them and converting them to stable compounds. Since the media are
actually consumed, scavengers typically are limited to low levels of contaminants. For the
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purposes of this paper, only solid scavengers will be considered as they have the widest
application to wastewater facilities odor control and digester gas treatment.
Solid scavengers differ from carbon adsorbers in that the sulfur compounds (hydrogen sulfide
and light mercaptans) actually react to form stable compounds. As a result, spent media from
scavengers are easier to handle than spent carbon media. A downside is that scavengers normally
cannot be regenerated. An exception is aerobic applications where the scavenger medium
actually acts as a catalyst, and is not consumed in the removal of hydrogen sulfide. Aerobic
scavengers are regenerated in situ until the production of sulfur causes plugging of the media
bed.
Solid scavengers are of two major types; those that use an organic substrate (generally called an
iron sponge) or those that use an inorganic or ceramic substrate. The iron sponge has a long
history of treating digester gas with low levels of hydrogen sulfide but suffers from safety
concerns associated with the removal and disposal of the spent media. Because of its organic
substrate (usually wood), and the fact that the reaction of the product (iron sulfide) and air
releases heat, care must be exercised when removing and disposing the media, as a fire can result
from the improper handling. A recent alternative to iron sponge is media using the same iron
oxide active ingredient as iron sponge, but utilizing an inorganic substrate that has none of the
safety concerns associated with media combustion. These media have seen widespread use in the
natural gas market and have spread into the treatment of anaerobic biogas and even, in some
cases, odor control ventilation air due to their simplicity and low capital costs. Operating costs
for scavenger systems are comparable to single-stage wet scrubbers, but have the added benefit
of not absorbing carbon dioxide (a large constituent of biogas), making them ideal for treating
biogas with low to moderate levels of hydrogen sulfide.
Carbon Adsorption
In a carbon adsorption system, the air stream is passed over a bed of adsorbent (carbon) and the
odor-causing compounds are attracted to and adhere to the surface of the adsorbent. This is the
simplest of the three wastewater odor control technologies. There is no on-going chemical supply
to the system, and there are no biological processes to be upset. Adsorption is applicable to a
wide range of compounds. Hydrogen sulfide and related sulfur-based compounds are removed
effectively by carbon adsorption systems, but ammonia and other nitrogen-based compounds are
not effectively treated. Various carbon type systems including activated and impregnated can be
used independently or in combinations to remove many different contaminants.
Liquid-Phase Technologies
Liquid-phase technologies involve the treatment of a wastewater stream to control the release of
odor and corrosion-causing compounds from the stream. Most liquid-phase technologies involve
the addition of a chemical to the wastewater to either control the formation of odorous
compounds or react with those compounds once they are formed. Liquid-phase treatment is most
commonly applied in wastewater collection systems, not treatment plants. It often is applied in a
collection system for downstream control at the headworks of a treatment plant. Since liquid-
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phase treatment controls the odor compounds in the wastewater itself, it provides corrosion
control in addition to odor control.
With liquid-phase treatment, hydrogen sulfide is prevented from escaping the liquid into the
vapor, therefore it is not present to cause corrosion on process structures, pipe crowns, etc.
Liquid-phase treatment can provide multiple point odor control. Through proper application of a
liquid-phase treatment in a collection system, multiple odor release points such as manholes, air
relief valves and re-pump stations can be controlled through one chemical application point. The
liquid-phase technologies evaluated in this paper are iron salts, bioxide process, oxidizers and
anthraquinone.
Iron Salts
Iron salts are applied to wastewater to oxidize and/or precipitate dissolved sulfide. Ferrous salts
such as ferrous sulfate precipitate sulfide as ferrous sulfide. Ferric salts such as ferric chloride
oxidize some of the sulfide to sulfur while reducing the ferric iron to ferrous iron. The remaining
ferrous iron then reacts with dissolved sulfide to form the ferrous sulfide precipitate. Ferrous
sulfide is a light precipitate, black in color, that is carried downstream to the treatment plant.
Within the aeration process of the treatment plant the ferrous sulfide is dissociated. The sulfide is
oxidized to sulfate and the ferrous iron is oxidized to ferric iron. The ferric iron then can be used
for chemical precipitation of phosphorous. Iron salts are specific to dissolved sulfide. Other
odorous compounds are not treated by iron salts. Iron salt solutions are classified as hazardous
compounds and often require double-wall tankage and piping systems.
Bioxide Process
The bioxide process involves the application of a nitrate solution (Bioxide, Bioxide71 or other
blends) to wastewater. It is a patented process, proprietary to USFilter. The process uses
naturally occurring bacteria to biochemically oxidize dissolved sulfide in the presence of nitrate.
This mechanism takes place when the solution is applied in wastewater that contains dissolved
sulfide. The sulfide typically is either generated upstream of the injection point where no nitrate
exists in the wastewater or is contributed downstream via a septic lateral flow. Nitrate is injected
in sufficient quantities to biochemically oxidize the sulfide via the following reaction.
8NO3- + 5H2S –> 5SO4- + 4N2 + 4H2O + 2H+
This reaction takes place in the bulk flow and in the upper zones of the slime layer. Nitrate is not
added in sufficient quantities to fully saturate the slime layer; therefore sulfide production
continues to occur in the lower zones of the slime and is removed in the upper zones or in the
bulk flow. The Bioxide solution is not classified as a hazardous compound. It is relatively easy
and safe to store, handle and apply.
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Oxidizing Agents
Oxidation for wastewater odor control involves the application of a strong chemical oxidizing
agent to the wastewater. The oxidizing agent is used to chemically react with dissolved sulfide,
converting it to sulfate or sulfur. In addition to dissolved sulfide, many other odorous compounds
are treated by the oxidizing agent. Many non-odorous compounds also are oxidized, causing
application rates to be higher than those predicted by the stoichiometry of the sulfide reaction.
All of the oxidizers commonly used for wastewater odor control are classified as hazardous.
Hydrogen peroxide is the most commonly used oxidizer.
Conclusion
As expected, this review and analysis does not provide a conclusive determination of "the best"
odor control technology. Rather, it supports the contention that the existing conditions, treatment
objectives and economic restraints must be considered in selection and design of any odor
control strategy.
References:
Vaughan Harshman, P.E., and Tony Barnette; Wastewater Odor Control: An Evaluation
of Technology
Section V: Odor Control Municipalities Comparison
Collier County Benchmarking Study of Technologies Utilized and Cost Comparison - Collection
System Odor Control Comparison to Manatee County, Loxahatchee, City of Tampa, Fort Pierce,
Boca Raton and Lee County.
Collier County, Lee County and Manatee County are similar in size, demographics, and
topography.
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Figure 3
Collier County has more pump stations due to lower elevations, resulting in more local gravity
stations that require odor control technologies. The detention time and biological breakdown in
return causing higher concentration of dissolved sulfides. The increase dissolved sulfides will
convert into H2S resulting in higher usage in odor control technologies in the field or treatment
facilities. The County has a prohibition on using any hazardous rated materials in the collection
system, limiting the technology choices available to control odorous and corrosion issues. Collier
County ensures that technologies used will not affect natural resources, public health and
personal safety.
Technologies Employed* (Figure 3)
Collier Bioxide71, Biofiltration, Biotrickling Filters and Carbon Adsorption
Manatee Bioxide, Biofiltration, Carbon Adsorption, Wet scrubbers, Iron, salts, PRISC, Alk-
AQUIT and
Bioxide71
Loxahatchee Bioxide, Biofiltration, Carbon Adsorption, Wet scrubbers, PRISC, Alk-AQUIT
and
Bioxide Plus 71
City of Tampa Bioxide, Biofiltration, Carbon Adsorption, Wet scrubbers and
Mag Hydroxide
Fort Pierce Bioxide, Biofiltration and Hydrogen Peroxide
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Boca Raton Bioxide and Biofiltration
Lee County Bioxide, Alk-AQUIT Iron Salts and
Hydrogen Peroxide
Figure 5
Collier County Benchmarking Study - Collections Odor Control comparison to Manatee County,
Manatee County, Loxahatchee, City of Tampa, Fort Pierce, Boca Raton and Lee County. Collier
County’s expenditure on odor control are closely related to flow in odor technologies used in the
collections system shown in figures 3 and 5. Increase in flow will result in higher usage of odor
control technologies.
Collier,
$1,000,000
Manatee,
$2,500,000
Loxahatchee,
$700,000
City Of Tampa ,
$2,300,000
Fort Pierce,
$250,000
Boca Raton,
$390,000
Lee County ,
$1,000,000
Total Odor Control Chemical Annual Expense FY16
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This chemical evaluation and cost comparison show that the technologies used for odor control
are charged fairly throughout the state as shown in figures 6, 7 and 8.
Section VI: Odor Control Categorized Chemicals
Solubility Enhancers:
The solubility of a substance fundamentally depends on the physical and chemical properties of
the solute and solvent as well as on temperature, pressure and the pH of the solution. In the waste
stream these variables are inconsistent and will change hourly, daily and seasonally. For odor
and corrosion control, solubility enhancers are generally used to increase the pH of the waste
stream, which increases the solubility of sulfide. Solubility Enhancers must be monitored
frequently and adjustments must be made to accommodate according to the pH fluctuations in
the sewage and flow. Some of these enhancers will need longer detention time to work
effectively.
• Lime
• Caustic
• Magnesium Hydroxide
• Alk Aquit 25
Oxidizers:
Oxidizers are chemical compounds that release oxygen when they react with another substance.
Different classes of oxidizers have different levels of reactions, and several types can be utilized
in the waste stream with little to no detention time. Oxidizers can work effectively and are easily
manageable to achieve the end goal. Although highly effective oxidizers, will require additional
means of safety gear and handled with precaution when applying to the waste stream. In some
cases, containment and enhanced training is needed to ensure the safety of those working near
these types of chemicals.
• 50% Hydrogen Peroxide
• VX456
• Aktivox
• Chlorine
Biochemical Oxidizers:
Biochemcial oxidizers provide oxygen to the waste stream in a form that is used by naturally
occurring bacteria rather than in direct chemical reactions. These types of chemicals are very
effective and are generally considered non-hazardous. They have a much lesser impact to the
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environment and can be managed without continuous monitoring. These types of chemicals are
less destructive and harmful when handling in a work environment.
• Bioxide • Bioxide71
Precipitation Agents:
Precipitation agents are chemicals which bind sulfide as an insoluble precipitant in the waste
stream, preventing release as hydrogen sulfide gas. Precipitants are limited to treatment of
sulfide. They are not effective on other wastewater odors and can achieve sulfide levels of
less than 0.5 mg/L, but cannot produce non-detectible sulfide levels.
• Iron Salts
• Odaphos
• Pri-sc Odaphos plus
• Pri-sc Ferric
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Figure 6
Figure 7
$2.27 $2.27 $2.21 $2.14 $2.27 $2.27 $2.27
$3.38 $3.34 $3.25 $3.34 $3.34 $3.34
$0.00
$0.50
$1.00
$1.50
$2.00
$2.50
$3.00
$3.50
$4.00
Collier Manatee Loxahatchee*City of Tampa Fort Pierce**Boca Raton**Lee County **
Bioxide & Bioxide71 Cost
Bioxide Gallon Bioxide Plus 71 Gallon Log. (Bioxide Plus 71 Gallon)
$0.94
$1.29 $1.19 $1.15 $1.19 $1.19 $1.19
$1.48 $1.44 $1.48 $1.48 $1.48
$0.00
$0.20
$0.40
$0.60
$0.80
$1.00
$1.20
$1.40
$1.60
Collier Manatee Loxahatchee*City of Tampa Fort Pierce**Boca Raton**Lee County **
VX-456
VX 456 Full Truck Pound VX 456 Partial Load Pound
VX 456 (Bulk Tanker) Pound VX 456 Partial (Tote) Pound
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Figure 8
Figure 9
The City of Tampa is the only evaluated organization that is currently using Magnesium
Hydroxide (Tioguard) and has been reported that the City of Tampa will no longer utilize
Magnesium Hydroxide and will replace it with Bioxide.
$0.83
$1.18
$0.88 $0.85 $0.88 $0.88 $0.88
$1.19
$1.44
$1.19 $1.19 $1.19
$0.00
$0.20
$0.40
$0.60
$0.80
$1.00
$1.20
$1.40
$1.60
Collier Manatee Loxahatchee*City of Tampa Fort Pierce**Boca Raton**Lee County **
Aktivox
Aktivox Full Truck Pound Aktivox Partial Load Pound Aktivox (Bulk Tanker) Pound Aktivox (Tote) Pound
$0 $0 $0
$700,000
$0 $0 $0
$0
$100,000
$200,000
$300,000
$400,000
$500,000
$600,000
$700,000
$800,000
Non-Evoqua Chem $/yr
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Figure 10
The combined cost that each evaluated municipality is using in their collection systems. The
chemical choice by far is Bioxide second to 50% Hydrogen Peroxide.
Figure 11
The Bioxide and Flow from FY06 to FY12 have followed the flow trend and adjustment to
chemical feed systems are made when H2S levels higher during the months of November – June
or in rainy season May - October.
$2,610,818
$1,004,728
$908,220
$442,730
$342,825
$240,252
$59,409
$28,289
$0 $500,000 $1,000,000 $1,500,000 $2,000,000 $2,500,000 $3,000,000
Bioxide
50% Hydrogen Peroxide *
Bioxide71
Alk Aquit 25
PRI-SC 50% Hydrogen Peroxide *
PRI-SC Odaphos
PRI-SC Odaphos Plus
PRI-SC Ferric *
Combined Cost by Chemical Usage
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
FY6 FY7 FY8 FY9 FY10 FY11 FY12 FY13 FY14 FY15 FY16
Bioxide & Flow Comparison
Bioxide GPY FLOW
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Section VII : Current Conditions Overview
In 2017 Collier County has 56 multi-stage systems, 12 chemical scrubbers and 13 chemical feed
sites. All systems are strategically placed in locations that odorous issues occur. Each odor
control system is evaluated biweekly for performance level in order to determine the operational
standards are met.
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