WWC-T and UV Odour Control

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SANITARY WASTEWATER COLLECTION SYSTEM & TREATMENTPLANT ODOURS

ULTRAVIOLET (UV) BASED ODOUR CONTROL TECHNOLOGY

INSTALLATIONS & PERFORMANCES

Presented by:George McGeachie. M.Sc., C.Eng., P.Eng.

Consult GeoConsulting EngineeringCalgary

403 247 4902

Alberta WW Operators Association SeminarBanff, Alberta

March 2007

The material in this paper reflects the authors best judgment, in the light of the information available to him, at the time of

preparation. Any use which a third party makes of this paper, or any reliance on or decisions to be made based on it, are theresponsibility of such third parties. The author accepts no responsibility for damages, if any, suffered by any third party as aresult of decisions made or actions taken based on this paper


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INTRODUCTION

Anaerobic or septic sanitary wastewater emits unpleasant odours, of which hydrogen

sulphide is the most noticeable. Hydrogen Sulphide (H 2S) is a gas, which smells likerotten eggs and which has a very low odour threshold (0.002 - 0.2ppm.) Even in smallconcentrations Hydrogen Sulphide can be smelt in a wide radius from manholes, airvalves, pumping stations and treatment plants. The odour is offensive and often results incomplaints from people living, working or just passing through the area. Furthermoreodour problems often give rise to media interest and lead to negative publicity for themunicipalities concerned.

The smell from septic wastewater produces a poor working environment for operationalstaff in sewer networks and at treatment plants. Entering manholes, inspecting pipes,working at pumping stations and treatment works are some of the operations in which

septic conditions create serious operational problems.

Septic sanitary wastewater, and in particular biosolids, can also form more complex,

volatile reduced sulphur and nitrogen compounds such as mercaptans and amines.For example, rotten cabbage odours are often associated with municipal biosoliods aredue to ethyl and methyl mercaptans. Putrid, fishy smells are attributed to methyl amines.

Septic sanitary wastewater gives off mainly Hydrogen Sulphide (and smalleramounts of other reduction compounds)

H2S has a very low odour threshold, as low as 2ppb Odour nuisance can quickly lead to public negative response in the form of

complaints, letters to MP's and media coverage.Hydrogen Sulphide is a toxic gas, about as toxic as Hydrogen Cyanide.In high concentrations it is deadly.


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Chemical Safety Data: Hydrogen Sulphide

Commonsynonyms

Hydrogen sulfide, sewer gas, stink gas, rotten eggs smell, sulfuratedhydrogen

Formula H2S

Physical properties

Form: colourless gas with a strong smell of rotten eggsStability: Stable, but highly flammableMelting point: -85 CBoiling point: -60 CCylinder pressure: typically around 17 barDensity: 1.539 g/l at 0C, 1 atmosphere pressureExplosion limits: Lower: 4.3%; upper: 46%

Principalhazards

*** Hydrogen sulphide is very toxic.*** Your ability to detect this gas via smell rapidly diminishes uponexposure, so you may be exposed to dangerously high concentrationswithout being aware of the danger.

*** Highly flammable and corrosive - hydrogen sulphide readily formsexplosive mixtures with air.

Safehandling

Wear safety glasses. Good ventilation is essential - this gas must be usedonly in a fume hood.


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Emergency

Eye contact: Immediately flush the eye with plenty of water. Call formedical help.Skin contact: Wash off with plenty of soap and water. Remove anycontaminated clothing. If the skin reddens or appears damaged, call formedical aid.If inhaled: Remove from exposure to the gas and call for immediatemedical help. This chemical is very toxic - a single breath of gascontaining 0.1% of hydrogen sulphide may cause coma. In addition,your sense of smell (which may initially detect hydrogen sulphide atlevels well below 1 part per million) will rapidly be dulled by exposureto the gas. As a result, you might seriously underestimate theconcentration of gas in the air.

Disposal

Small amounts of hydrogen sulphide can be vented through a fumecupboard, unless local rules prohibit this. Be aware, however, that the

detection limit is very low, and if you release more than tiny amounts ofthe gas those working in surrounding buildings may be exposed to theunpleasant smell. Where possible, you should chemically destroyhydrogen sulphide rather than release it into the environment.

Protection Wear safety glasses; work in a good fume cupboard.

Exposure

Exposure to lower concentrations can result in eye irritation, a sorethroat and cough, shortness of breath, and fluid in the lungs. Thesesymptoms usually go away in a few weeks. Long-term, low-level

exposure may result in fatigue, loss of appetite, headaches, irritability, poor memory, and dizziness. Higher concentrations of 700-800 ppmtend to be fatal.

0.0047 ppm is the recognition threshold, the concentration atwhich 50% of humans can detect the characteristic rotten eggodor of hydrogen sulfide [2]

10-20 ppm is the borderline concentration for eye irritation. 50-100 ppm leads to eye damage. At 150-250 ppm the olfactory nerve is paralyzed after a few

inhalations, and the sense of smell disappears, often together

with awareness of danger, 320-530 ppm leads to pulmonary edema with the possibility of

death. 530-1000 ppm causes strong stimulation of the central nervous

system and rapid breathing, leading to loss of breathing;o 800 ppm is the lethal concentration for 50% of humans


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for 5 minutes exposition (LC50).

Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.

ODOUR CONTROL TECHNOLOGY

In an effort to control the generation of the malodours and to mitigate the problemsresulting from the generation and emissions from sanitary sewageour industry commonly uses various methods which fall into two main categories :

1. Liquid Phase Control Methods to prevent or minimize the generation

and emission of the odourse.g. Oxygen addition Chemical addition Microbial supplementation Sediment control Control of mass transfer

2. Gas Phase Control Methods to mitigate the resulting problems causedby the odours and emissions.

e.g. Activated carbon adsorption Liquid scrubbing Biofiltration Iron filtration Control of ventilation

This paper deals with the Gas Phase Control Method using the Ultraviolet (UV)based technology, provided by Sol -Air Systems Inc., out of Kelowna , BritishColumbia.

Sol -Airs Ultraviolet Odour Control Technology


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A 48 UV lamp Sol-Air unit (C48LF) ; showing one of the six (6) lamp banks; eachbank is made up of eight (8) lamps.

In the simplest of terms The Sol-Air Unit consists of banks of UV lamps housed in aMarine Grade Aluminum housing


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The housing has an inlet and outlet duct connection. The odorous air is drawn through theunit to make contact with and the ultraviolet radiation and discharged from the unit withthe use of a fan also housed within the unit.(A typical Specification sheet for the Sol-Air C48XLF unit is attached to this paper.)

The wavelength frequency of the Sol-Air UV lamps is designed to affect the odorous gasmolecules of a wide range of compounds, including those containing sulfur, such asHydrogen Sulphide (H2S) and Mercaptans.The Ultraviolet Radiation catalyses the breaking of ambient oxygen and water vapourmolecules into O and OH (hydroxyl) radicals.These short lived free radicals oxidize the more complex molecules of the contaminatedair or gas with the hydroxyl radicals being consumed in the oxidation process. Thisreaction results in a sequential and instantaneous breakdown of the gaseous contaminantswith very little odorous by products - mainly traces of elemental sulphur CO2, watervapour, molecular oxygen and trace ozone.

The Sol-Air equipment is CSA approved and also approved as an explosion proofunit, suitable for installation in a confined space or a hazardous area as defined bythe Canadian Electrical Code.

Treatment Methodologies The versatility of the Sol-Air Systems UV technology allows the engineers to designthe application to suit the conditions that cause the odours and H2S and how thedecontaminated air is released to atmosphere. Several examples of treating odours andH2S gas emissions from a given headspace in a waste water collection or treatmentsystem are:

Injection Method:Using this method the ambient air is drawn through the Sol-Air unit and exposed to theUV technology. This processed air is then injected into the headspace from a distance ofno more than 10 feet creating a positive pressure in the head space. The injected

processed air contains powerful UV generated oxidizers ozone and hydroxyls with thehydroxyls being the most effective. The UV oxidizers then mix with the contaminatedair and the treated air is then vented to atmosphere in a controlled fashion.

Exhaust Method:Using this method the odours and H2S gasses are drawn from a vented headspacedirectly through the Sol-air unit creating a negative pressure. The contaminated air isexposed to the UV technology and this processed air mixture is exhausted to atmospherethrough a retention chamber. A variation to this method is to draw the odours and H2Sgasses into a sealed mixing room housing the Sol-Air unit. The contaminated air isdrawn through the Sol-Air unit and exposed to the UV technology. The processed air iscirculated in the room and vented to atmosphere through a gravity damper. There are nominimum distance requirements for the distance between the headspace and the Sol-Air


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unit.

Circulation Method:Using this method the odours and H2S gasses are drawn from the sealed head space intothe Sol-Air unit where the contaminated air is exposed directly to the UV technology and

then exhausted directly back into the sealed head space creating a neutral pressure. This process allows the UV technology to control the odorous peaks and valleys flowingthrough the headspace. Using this method there are no minimum distance requirements

between the sealed headroom and the Sol-Air unit but the system is more effective usingthe 10 foot maximum Rule i.e. a maximum 10 foot length of exhaust ducting from theSol- Air unit to the sealed head space

SOL-AIR SYSTEMS INC. (SASI)INSTALLATIONS:INVESTIGATIONS

Investigations were conducted by contacting and interviewing the personnel responsiblefor the selection and hands on operation and maintenance of the existing Sol AirSystems. Interviews were conducted by telephone and email.Some R&D performance data was obtained along with a report on a Major Odour ControlProject which used the Sol-Air equipment. Sol Air odour control applications andinstallations were investigated at the following facilities:CITY OF CALGARY WATER SERVICES

APPLICATION: To treat offensive odours from manholes on the Citys sanitary wastewater collection system.Air is drawn at a rate of 1000 cfm from the manholes using an exising ducting system tothe SASI equipment located in a shed adjacent to the manholes and exhausted toatmosphere through an exhaust duct.PERSONNEL INTERVIEWED:Bill HansonSupervisor Lift stations and Special ProjectsTel: 403 899 2783

COMMUNITY OF FIELD TERTIARY MBR WWTP BRITISH COLUMBIA

APPLICATION : To provide for treatment of odours from covered MBR / ActivatedSludge process and odours and any H2S from the Headworks / Screening room.These process areas are ducted and exhausted to a small sealed odour control room.The SASI equipment is located in this small room for treatment of all foul odoursdischarged to the room.Treated air is exhausted through a gravity damper to the outside environment. PERSONNEL INTERVIEWED:Darrell Fitzpatrick


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Parks CanadaMunicipal Services Manager,Field and Lake LouiseMartin BambullisChief Operator

Tel : 1 403 522 3623

CITY OF VERNON, WASTEWATER COLLECTION SYSTEM and WWTPBRITISH COLUMBIA.

APPLICATION: To provide treatment for various areas of the WWTP producing strongodours and H2S emissions , including headworks, covered primary clarifiers, solidshandling facilities etc.SASI equipment was recently used in an emergency when the

permanent activated Carbon Scrubber System had to be shut down for replacement of thecarbon media. Plans are in place to install a SASI system to pre-treat the foul air ahead of

the Carbon Media Scrubber System to extend the life of the scrubbers carbon media andsignificantly reduce ongoing costs to Operate and Maintain this system.The SASI equipment is used to treat the foul air and H2S emissions from two largesubmersible lift station wet wells on the Citys municipal collection system.

PERSONNEL INTERVIEWED:Serge KozinWWTPChief of OperationsTony Kopp Collection SystemWWTP : Tel:1 250 550 3627 ; COLLECTION SYSTEM : Tel: 1 250 550 1147

CRD NORTH SAANICH PENNINSULA WWTP, BRITISH COLUMBIA.

APPLICATION: Pretreatment of foul air from all sources of strong odours and H2Semissions in the WWTP; Headworks, Primary Clarifiers, Solids Handling etc.SASI equipment treats the foul air prior to the air being ducted to an Activated CarbonOdour Control / Scrubber System.The SASI equipment, has reportedly, increased the Activated Carbon Media life by afactor of 4.Media cost prior to introducing the SASI system were reported to be unsustainable.PERSONNEL INTERVIEWED: Dennis PerraultPenninsula WWTPChief of Operations.9055 Mainwaring Road

North Saanich BC V8L 5Z1. Tel: 1 250 656 2425 Ext 2.


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CITY OF KAMLOOPS WASTEWATER COLLECTION SYSTEM, BRITISHCOLUMBIA.

APPLICATION: Treatment of the foul air in a large submersible lift station wet well on the collection system. The station is close to a condo development whose

residents were seriously impacted by the foul odors and H2S emissions from the station, prior to the introduction of the SASI treatment.PERSONNEL INTERVIEWED:Mike Warren P.Eng.City Engineer.Frank Noel

Chief of Operations Collection SystemEngineering: Tel: 1 250 828 3467Collection System: Tel: 1 250 214 0301

NORTH JUAREZ WWTP MEXICO ODOUR CONTROL PROJECT Hydrogen

Sulphide Emission Control: APPLIED ENVIRONMENTAL SERVICES INC.

APPLICATION: Treatment of various sources of foul air and H2S emissions fromwithin the WWTP, including influent Archimedian screw pumps, channels, headworks,

primary clarifiers etc. PERSONNEL INTERVIEWED:Alec Felhaber. P.E.PresidentApplied Environmental Services Inc.Manager and Author of the NORTH JUAREZ WWTP MEXICO ODOUR CONTROLPROJECT : Hydrogen Sulphide Emission Control Report.140 N Cotton StreetEl Paso, TEXAS 79901 USA. Tel: 1 915 533 1147

SOL-AIR SYSTEMS INC

PERSONNEL INTERVIEWED:

BERNIE LAMBERTSol-Air Systems Inc.Vice Presidenthttp://www.solair.caToll free number: 1-866-880-2479tel. (250)763-7034fax. (250)763-7023E mail Bernie@ solair.ca


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KERRY M. SAUNDERSSol-Air Systems IncPresident/CEOtel. 250-763-7034fax. 250-763-7023

E mail. [email protected].

FINDINGS

Effectiveness:All existing installations reported that the Sol-Air equipment was effective in treating thefoul air and H2S gas emissions at the locations listed above.All installations reported that the Sol-Air units were performing to meet the operator andowners requirements, mitigating and satisfactorily addressing the odour complaints fromthe public, prior to or in the absence of the Sol-Air equipment being in operation.

Effectiveness was rated from satisfactory to very effectiveThe total Juarez WWTP Mexico Odour Control Project was funded by the USEnvironmental Protection Agency (EPA).

O&M:The O&M labour requirements were characterized as minimal at each location listedabove. Operation involves turning on the number of UV lamps one requires and settingthe speed of the equipments fan to achieve the desired air flow through the banks of UVlamps. When the unit is fitted with an intake filter then this should be cleaned regularly.

The UV lamps need to be kept clean using 50:50 % hot water and alcohol from a spray bottle and a soft clean cloth. Lamps are rated by Sol-Air for a 9000 hour (1Year)continuous life span

INSTALLATION EXAMPLES


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Biosolids Building Installation

Sanitary Lift Station Installation

Trickling Filter Installation.


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TYPICAL EQUIPMENT DATA SHEET


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WWC-T and UV Odour Control

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