Best Design Practices for Odour Management of High Profile ...€¦ · 6th IWA Conference on Odours...

6th IWA Conference on Odours & Air Emissions, November 16-18, 2015, Paris - France

Best Design Practices for Odour Management of High Profile, Waste Water Applications in an Urban Environment

Written by Derek S. Webb and Caleb Olesen 1

Best Design Practices for Odour Management of High

Profile, Waste Water Applications in an Urban

Environment

Derek S. Webb1* and Caleb Olesen1

1 Biorem Technologies, Guelph, Ontario, Canada N1H 6H9

*Corresponding author e-mail, [email protected]

ABSTRACT Three case studies are presented that demonstrate best design practices for

biological odour control systems to be aesthetically pleasing, quiet and provide

high levels of performance for total odour control. These biofilters feature

custom, site specific, below grade installations and engineered permanent

biofilter medias that allow low EBRT’s; energy efficiency and higher total odour

removal.

KEYWORDS: biofiltration, biofilter, biotrickling filter, odour control,

odour, wastewater, WWTP, pumping station, urban, H2S.

INTRODUCTION

New Challenges Facing Odour Control

Decades ago wastewater treatment plants were designed and built on the outskirts of the cities

that they service. Wastewater treatment plants and sewer infrastructure are increasingly having

to deal with the reality of urban encroachment. As a result, quality of life issues such as noise

(De Heyder, Ockier, Jansen, & Huiberts, 2001), odour (Lasaridi, et al., 2010) and aesthetics are

becoming very important for nearby residents. This recent increase of concern for efficient

odour control in urban areas has not only been observed in developed countries but also in

developing countries (Lazarova, Abed, Markovska, & Dezenclos, 2013).

Historically odour control at wastewater treatment plants has focused primarily or solely on the

reduction of hydrogen sulphide (H2S) or ammonia (NH3). The problem with this approach is

there are always other compounds that contribute to the overall odour (Lebrero, Bouchy, Stuetz,

& Muñoz, 2011). While there are situations where H2S is expected to be the primary contributor

to overall odor, there are also many situations where the contribution of H2S to overall odour is

minor compared to other compounds (McGinley & McGinley, 2008).

A Brief Review of Odour

Odour is a psychophysical phenomenon in which the sensed odour intensity is related through

a power law to the concentration of the chemical following the equation:

𝐼 = 𝑘𝐶𝑛 Equation 1

Where I is the sensed odour intensity, C is the concentration of the odorant and k and n are

constants specific to each odorant (McGinley, McGinley, & McGinley, 2000). Odour

concentration is similar to odour intensity, but the two measurements should not be confused

to be the same. Odour concentration is number of dilutions necessary to reduce the odour in the

sample to threshold of detection, while odour intensity is the perceived strength of the undiluted




sample. The concentration of individual odorants can be measured using analytical methods

such as gas chromatography, however the resulting perception of odour is more than just the

concentration of the odorant. A measurement of odour intensity or concentration necessitates

the use of a human testing panel.

Odour concentration measurements are typically measured by laboratory dilution of air

samples. The diluted samples are presented to panelists in an ascending concentration series

along with either one or two blank samples (binary or triangular forced choice). The panelist

has to choose which of the samples they think is the odorous sample, and indicate whether they

are guessing, have actually detected the odorous sample or if they can recognize what type of

odour they are smelling. The dilution factor at which 50% of the panelists can detect an odour

is reported as the odour concentration, with units of OU.

In addition to the odour concentration, there are other parameters of odorous samples that can

be measured by human panel including intensity, character and hedonic tone. Intensity is

measured by presenting panelists with suprathreshold dilutions and requiring them to be

evaluated by panelists in a 7-item Likert scale from “no odour” to “extremely strong odour”.

Character is measured by having panelists assign a number from 0 to 5 to eight different odor

descriptors: vegetable, fruity, floral, medicinal, chemical, fishy, offensive and earthy. Hedonic

tone is measured by having panelists rank the overall odour on a Likert scale from unpleasant

to pleasant. (McGinley, McGinley, & McGinley, 2000)

Wastewater Treatment Plant Odours

As has been briefly discussed, there are many more compounds than just H2S and NH3 that

contribute to overall odour from wastewater treatment plants. Table 1 shows the compounds

that commonly contribute to wastewater treatment plant odours. The relative amounts of these

compounds are present at varying levels throughout the wastewater treatment plant process.

The odours generated by wastewater treatment processes can be generally divided up according

to where they are generated: collection systems, liquid treatment and biosolids treatment.

Collection systems and liquid treatment systems typically produce high levels of H2S, and low

levels of volatile organic compounds (VOCs), organic sulphide compounds (OSCs) and NH3

whereas biosolids treatment processes typically produce lower levels of H2S, but higher levels

of VOCs, OSCs and NH3 (Tchobanoglous, Burton, & Stensel, 2003). Since the odour character

is expected to be different depending on the process that is producing the odours, there isn’t a

one-size-fits all solution to wastewater treatment plant odours. Any solution should be custom

designed based on the expected levels of H2S, OSCs, VOCs, NH3 and the expected overall

odour concentration.

In addition to the relative amounts of compounds that can be present, there are several factors

that influences the resulting concentration of these compounds that is emitted from the

wastewater. Wastewater that is subjected to higher temperatures, excessive turbulence and that

has high wastewater/air interface areas allows dissolved odorous compounds to more easily

transfer from the water phase into the air phase (Lebrero, Bouchy, Stuetz, & Muñoz, 2011).

Additionally, while ventilation rates don’t change the mass of odorants treated (increasing the

ventilation rate usually results in proportionately decreasing the odorant concentration),

ventilation rates are important in order to prevent fugitive emissions, and in the case of occupied

spaces, to reduce the odorant concentrations to levels that are safe for operators to work in.




Table 1: Common wastewater treatment plant odours

Odor descriptor Sensorial experience Chemical compound Fecal/Sewer-like Faecal

Manure

Sewery

Skatole

Indole

Earthy/Musty/Moldy Earthy/Musty

Moldy

Geosmin

2-Methylisoborneol

2,4,6 Trichloroanisole

Oxidant/Chlorinous Chlorinous Chlorine

Monochloramine

Dichoramine

Grassy/Woody Woody

Green/Grass

Cardboard

Hay

Cis 3-Hexen 1-ol

Sulfide/Cabbage/Garlic Decaying vegetation

Rotten eggs

Garlicky

Canned corn

Marshy/Swampy

Skunk

Burnt rubber

Coffee grounds

Hydrogen sulfide

Methyl mercaptan (OSC)

Dimethylsulfide (OSC)

Dimethyl trisulfide (OSC)

Fragrant/Fruity Soapy/Detergenty

Fruity

Citrusy

Green

1 Dodecanal

D-Limonene

Rancid/Putrid Yeasty

Sour mil

Rancid

Fatty/Oily

Sweaty

Sour cheese

Putrid

Decayed

Heptanal

Pyridine

Ammonia/Fishy Ammonia

Cat urine

Fishy

Ammonia

Trimethylamine

2,4 Decadienal

2,4 Heptadienal

Medicinal/Alcohol Medicinal

Alcohol

Chlorophenol

1-Butanol

Solventy/Hydrocarbon Burnt/Smoky

Tarry

Rubbery

Solventy

Glue

Gasoline

Paint

Mothballs

Shoe polish

Chemical

Methyl methacrylate

Toluene

Xylene

Styrene

Methyl isobutyl ketone

Dichlorobenzene

Cumene

Nose feel Pungent

Irritating

Metallic

Sharp

Ammonia

Ferrous sulfate

Reproduced from (Lebrero, Bouchy, Stuetz, & Muñoz, 2011)




Recent Advances in Biological Treatment of Odours

Biological treatment of wastewater treatment plant odours has been performed commercially

for around 50 years. It was developed primarily in Europe using open top soil biofilter beds.

The concept for treatment of odours was to use a substrate to immobilize beneficial bacteria

on the surface and allow them to produce enzymes which would oxidize the compounds of

concern. This is an example of a fixed-film bioreactor.

Up until the 1990’s most biofilter media were compost, woodchips, peat or soil (Leson &

Winer, 1991). Unfortunately, these conventional materials had many limitations from an

engineering perspective. Given the fact that most of these materials were natural, variations

from batch to batch made it difficult to accurately predict performance, which had the

unintended consequence of vendors and consultants over designing the size of the systems to

ensure a minimum threshold of performance was achieved. In addition, the organic nature of

these materials behaved as a carbon source, gradually being consumed by the microorganisms

over time and resulting in declining performance.

One of the often overlooked deficiencies of conventional media was the energy consumption

that such systems exerted on their facilities. Organic media systems often operate with 2000

to 3000 Pascals of differential pressure. For small air flows, this may not add up to a financial

burden for the facility, however, with larger air flows, the cost of air movement can be a

significant proportion of the operating costs.

From the early 2000’s to present, there has been a significant amount of research to address

the multitude of deficiencies with conventional approaches. Various Universities as well as

commercial entities have examined ways to develop a microbial immobilization matrix that

would improve energy efficiency, increase predictability and longevity, increase performance

and decrease overall footprints.

Through a recognition that a large number of municipal odour applications were a result of

hydrogen sulphide emissions, many vendors started improving biotrickling or biotower media

to use a variety of structured plastic packing. This helped to reduce the footprint and energy

consumption challenges, but fell short of resolving issues with Total Odour Reduction,

especially on the more recalcitrant compounds such as DMS and DMDS, which are often

associated with biosolids applications.

Other research programs focused efforts on developing engineered biofilter media with very

specific surface properties to help address the challenge of increasing overall destruction

efficiencies of the recalcitrant organic sulphur compound family. As a part of this

development work, process optimization became a focus to ensure the reactor operation was

properly paired with the intended performance objectives. For example, one of the process

improvements was the realization that the removal of hydrogen sulphide and methyl

mercaptan was best achieved by autotrophs operating in an acidic environment; while the

removal of volatile fatty acids and the other organic sulphur compounds were best achieved

by heterotrophs in a neutral environment.

One vendor in particular, Biorem Technologies Inc., was successful in developing a suite of

engineered media that are tailored for the particular uses that may arise in the treatment of

wastewater odours from the various sources. These media offer extended operational lives (to




20 years and beyond), high rates of organic sulphur compound destruction; and reduced

footprints. When combined with pre-treatment stages for the removal of elevated hydrogen

sulphide or ammonia, an engineered media solution allows for unique construction of reactors

for dense urban applications.

The remainder of this paper will present three case studies of advanced biological treatment

systems which feature the advanced designs that are necessary to meet the stringent odour

requirements that are being encountered more and more often.

CASE STUDIES

Case Study #1: Ville de Repentigny WWTP, Quebec

The “station de traitement des eaux usées à l’île Lebel” is the wastewater treatment plant that

serves the city of Repentigny. The WWTP serves a population of 63,000, treating 24,000

m3/day wastewater and producing 10,000 kg/day dewatered sludge for land application. The

plant was built in the mid 1990’s, and up until 2013, operated without treating their air with any

odour control equipment. Instead, odours were controlled by adding caustic soda and potassium

permanganate to the raw wastewater.

Figure 1: Map of the Ville de Repentigny WWTP




As can be seen in Figure 1, the WWTP is located within a 20 hectare park that features multi-

use trails just 40 metres from the main wastewater treatment plant building. The park is a very

high traffic area and frequently holds events such as Oktoberfest, fundraising events and other

group activities. In 2009, land 200 metres from the WWTP was being developed for 3 high

density residential buildings totaling 150 condominium units. The city conducted an odour

study and determined that odour control was required at the WWTP.

The City required a system that could be kept out of sight and out of mind of the nearby residents

and the multitude of tourists that visit the park each summer. The system needed to be robust

in terms of performance and able to address potentially elevated levels of hydrogen sulphide

without acidification of the media while still having high rates of removal for the other odour

causing compounds.

Given the high visibility of the WWTP and the limited space available for odour control,

Biorem worked with the city to design a biofiltration system that is inconspicuous, low footprint

and high efficiency. Table 2 gives an overview of the design parameters for the odour control

system.

Table 2: Repentigny biofilter design parameters

Parameter Value

Airflow 34 000 m3/h

Design H2S 5 ppm average, 30 ppm peak

Design OSC 1 ppm average, 3 ppm peak

Design Odour 3 000 OU average, 20 000 OU peak

BTF Media Polyurethane Random Packing

BTF EBRT 4 seconds

BF Media XLD (Biorem proprietary engineered media)

BF EBRT 20 seconds

Performance Guarantee 99% H2S, 95% Odour

As is shown in Figure 2, the biofilter was designed by Biorem to be completely below grade,

with the mechanical equipment room and a future ozone generator room located on top of the

biofilter roof at grade. The stack of the biofilter was also designed to be pleasing to the eye.

Figure 3 through Figure 5 show some pictures of the biofilter.

Figure 2: 3D Rendering of the Repentigny biofilter

Figure 3: Outside view of the Repentigny biofilter




Figure 4: Repentigny mechanical room on roof of

BTF

Figure 5: Repentigny future ozone generation room

on roof of BF

The biofilter system was commissioned in May 2013 and performance tested by Biorem in

October 2013 and again by an independent third party in November 2013. As can be seen in

Table 3, with only 25 seconds of total EBRT the system is achieving greater than 95% odour

removal.

Of particular note are the very low absolute odour levels witnessed on the discharge of the

system. Industry standard guidelines for estimating odour concentration from a well-designed

carbon polishing unit is typically set at 100-150 OU. The odour concentration released from

the second stage of this system far exceeds the performance expected from even carbon

polishing.

Table 3: Repentigny biofilter performance

Date Description Inlet to BTF Outlet from BF Odour Removal

October, 2013 Sample 1 3 509 OU 64 OU 98.2%

October, 2013 Sample 2 5 470 OU 231 OU 95.7%

November, 2013 Sample 3 1 136 OU 23 OU 97.9%

November, 2013 Sample 4 2 145 OU 45 OU 97.9%

Case Study #2: Morton Avenue Forced Main Outlet, Ontario

Georgina is one of the many small towns in Ontario that is experiencing very high growth. The

population is expected to double from 2011 to 2036. As a result of this projection the current

water and wastewater infrastructure was expanded by 55% in 2011. Part of this expansion

involved building the Joe Dales pumping station and an associated odour control facility at the

force main outlet on Morton Avenue (Forcemains in Quick Time, 2013).

As can be seen from Figure 6, the force main outlet and its associated odour control facility are

located extremely close to residential properties (3 metres from the closest property line, 20

metres from the closest house) and, due to the relatively long distance of 5.6 km to the pumping

station, the H2S levels were expected to be relatively high for a northern application (peaks of

185 ppm).




Figure 6: Satellite view of Morton Ave biofilter

Biorem worked with the Region of York to design a robust biofilter at the remote odour control

facility. In order to achieve the highest removal possible, two proprietary engineered inorganic

biofilter medias were used, the first to remove the majority of the H2S, and the second to polish

the remaining H2S and to remove trace organic sulphides and other VOC’s.

Table 4: Morton Ave biofilter design parameters

Parameter Value

Airflow 1 700 m3/h


Design OSC <1 ppm average

Design Odour 150 000 OU peak

BF Stage 1 Media Biosorbens (Biorem proprietary engineered media)

BF Stage 1 EBRT 25 seconds

BF Stage 2 Media XLD (Biorem proprietary engineered media)

BF Stage 2 EBRT 20 seconds

Performance Guarantee 99.9% H2S, <350 OU or <500 OU with positive hedonic tone

Given the residential location of this odour control facility, the system was designed with a

control room housing the exhaust fans, humidification system, control panel, instrumentation

and control valves. The biofilter itself was designed as a below grade concrete vessel beside the

control room. Figure 7 through Figure 10 show some drawings and pictures of this odour control

facility.




Figure 7: Section view of the Morton Ave biofilter

Figure 8: Outside view of the Morton Ave biofilter

Figure 9: Morton Ave control room

Figure 10: Morton Ave biofilter with access hatches

open

The biofilter system was commissioned in December 2010 and performance tested by an

independent third party in June 2012. As can be seen in Table 5 and Table 6, with 45 seconds

of total EBRT the system is achieving greater than 99.9% odour removal and greater than 99.9%

H2S removal.

Table 5: Morton Ave biofilter odour performance

Description Inlet to BF1 Outlet from BF2 Odour Removal

Sample 1 615 000 OU 120 OU 99.98%

Sample 2 298 750 OU 50 OU 99.98%

Sample 3 430 500 OU 40 OU 99.99%

Sample 4 664 500 OU 120 OU 99.98%

Table 6: Morton Ave biofilter H2S performance

Description Inlet to BF1 Outlet from BF2 Odour Removal

Sample 1 50 ppm 0.03 ppm 99.94%

Sample 2 17 ppm 0.02 ppm 99.88%

Sample 3 34 ppm 0.01 ppm 99.97%

Sample 4 50 ppm 0.03 ppm 99.94%




Case Study #3: Ankeny Pumping Station, Oregon

The Ankeny Pumping Station was built in 1929, with major remodels completed in 1952 and

in 2012. The pumping station was originally designed to protect downtown Portland from

flooding, pumping sewage and storm water directly into the Willamette River. In 1952 the city

connected the pumping station forced mains that sent sewage to the then newly built Columbia

Wastewater Treatment Plant. From 2011 to 2015 additional upgrades were completed to

upgrade the pumps and controls and to add odour control while maintaining the pumping

station’s historic exterior (The City of Portland Oregon, 2015).

Figure 11: Satellite view of Ankeny biofilter

As can be seen from Figure 11 the pumping station and associated odour control is located

within a 2.4 km long waterfront park, 50 metres away from an open-air arts and crafts market

and outdoor dining areas. There are also high pedestrian traffic multi-use trails that are only 1

metre away from the exhaust stack of the biofilter. Given the high visibility of the biofilter and

the limited space available for odour control, Biorem designed a biofiltration system that is

inconspicuous, with a small footprint and high efficiency. Table 7 gives an overview of the

design parameters for the odour control system.

Table 7: Ankeny biofilter design parameters

Parameter Value

Airflow 12 750 m3/h


BF Media XLD (Biorem proprietary engineered media)

BF EBRT 25 seconds

Performance Guarantee 99% H2S




The biofilter system was designed to be completely below grade with an underground vault for

the exhaust fan, humidification system, control panel, instrumentation and control valves. The

concrete vault and biofilter vessel were covered with top soil and grass seed such that the only

evidence that the odour control system is even there are access hatches and a brushed stainless

steel exhaust stack. Figure 7 through Figure 10 show some drawings and pictures of this odour

control facility.

Figure 12: 3D Rendering of the Ankeny biofilter

Figure 13: Outside view of the Ankeny biofilter

Figure 14: Plumbing and access hatch in the Ankeny

biofilter below grade mechanical room

Figure 15: Headspace above the Ankeny biofilter

media

CONCLUSIONS As was discussed in the introduction, public works engineers are more frequently having to

design wastewater treatment plants and collection systems with nearby residential and

commercial properties in mind. It is becoming very important that equipment be aesthetically

pleasing, quiet, and focused on total odour control, not just one or two odorous compounds.

The case studies presented have achieved these goals by incorporating the following elements:

Custom, site specific, below grade installations. While addressing aesthetics, these

design features also ensure that noise levels of operating equipment do not have a

negative impact on the surrounding communities.

Engineered biofilter media that allow lower EBRT’s and higher total odour removal.

Smaller footprints and the permanent nature of the engineered media allow for fully

enclosed, underground designs.

Multi-stage systems using different media types customize the process design to the

expected foul air makeup. This ensures long term, predictable performance.

Design emphasis on aesthetics, blending the biofilter installations into the surroundings.

This is increasingly important as urban growth rates necessitate integration with

municipal infrastructure.




Integrated approach to design, customizing the layout to the specific site requirements

rather than providing off-the-shelf biofilter solutions. No single piece of equipment is

suited for every site and application. Understanding the application is paramount to

ensure the right solution selection.

Incorporating these elements in odour control design can improve the quality of life of

neighbors nearby wastewater treatment plants, virtually eliminating complaints and

maintaining property values.

REFERENCES De Heyder, B., Ockier, P., Jansen, R., & Huiberts, R. (2001). Predicting the sound power and

impact of a wastewater treatment plant. Water Science and Technology, 44(2-3), 231-

241.

Forcemains in Quick Time. (2013, July 4). Water Canada.

Giuliani, S., Zarra, T., Naddeo, V., & Belgiorno, V. (2013). A novel tool for odor emission

assessment in wastewater treatment plant. 13th International Conference on

Environmental Science and Technology. 55. Athens, Greece: Balaban Desalination

Publications.

Lasaridi, K., Katsabanis, G., Kyriacou, A., Maggos, T., Manios, T., Fountoulakis, M., . . .

Stentiford, E. I. (2010). Assessing odour nuisance from wastewater treatment and

composting facilities in Greece. Waste Management & Research, 28(11), 977-984.

Lazarova, V., Abed, B., Markovska, G., & Dezenclos, T. (2013). Control of odour nuisance in

urban areas: the efficiency and social acceptance of the application of masking agents.

Water Science & Technology, 68(3), 614-621.

Lebrero, R., Bouchy, L., Stuetz, R., & Muñoz, R. (2011). Odor Assessment and Management

in Wastewater Treatment Plants: A Review. Critical Reviews in Environmental Science

and Technology, 47(7), 915-950.

Leson, G., & Winer, A. (1991). Biofiltration: An Innovative Air Pollution Control Technology

for VOC Emissions. Journal of the Air & Waste Management Association, 41(8), 1045-

1054.

McGinley, C., McGinley, M., & McGinley, D. (2000). "Odor Basics", Understanding and

Using Odor Testing. The 22nd Annual Hawaii Water Environment Association

Conference. Honolulu, Hawaii.

McGinley, M., & McGinley, C. (2008). Odor Threshold Emission Factors for Common WWTP

Processes. Water Environment Federation / Air & Waste Management Association.

Phoenix, AZ.

Tchobanoglous, G., Burton, F., & Stensel, D. (2003). Wastewater Engineering, Treatment and

Reuse (4th ed.). New Delhi, India: McGraw Hill Education.

The City of Portland Oregon. (2015). Ankeny Pump Station Upgrade. Retrieved from The City

of Portland Oregon Website: https://www.portlandoregon.gov/bes/article/394265

Best Design Practices for Odour Management of High Profile ...€¦ · 6th IWA Conference on Odours...

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