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Casino Rama Achieving 0.15 mg/l Total Phosphorous in Tertiary Effluent in anABJ ICEAS Wastewater Treatment System

Ed Salenieks, Marshal Macklin Monaghan Ltd.Les Szpunar, Marshall Macklin Monaghan Ltd.

Ralph Tulipano, Cjippewas of Mnjikaning First Nation

Rosemary Leslie, Chippewas of Mnjikaning First Nation

IntroductionCasino Rama, located in the Mnjikaning (Rama) First Nation near Orillia, Ontario is serviced by an ABJ ICEASwastewater treatment system. The plant is designed for biological phosphorous removal, followed bychemical addition and effluent filtration, to achieve tertiary quality effluent, with target total phosphorouslevels of less than 0.15 mg/l and 3 mg/l total ammonia. The 2,100 m3/d capacity plant was put into serviceat the end of July 1996. The results of the first year of operation for the plant are presented in this paper.

Design effluent requirements were consistently met on a year-round basis under varying flow, totalphosphorous and organic loading conditions. A high degree of nitrogen removal was also routinelyachieved, concomitant with biological phosphorous removal in the SBR system.

BackgroundIn December 1994, the Chippewas of Mnjikaning (Rama) First Nation was selected by the Province of Ontarioto develop a full service Casino on community lands. The Mnjikaning First Nation is located approximately10 km northeast of Orillia in Simcoe County. The Casino facility is located off of Rama Road (County Road44) just east of Lake Couchiching. Marshall Macklin Monaghan was retained in April 1995 to undertake theenvironmental assessment under the Canadian Environmental Assessment act (CEAA) for infrastructureservicing of the Interim Casino site. The CEAA process applies to land used development proposals, forwhich the federal government holds decision-making authority, whether as proponent, land administrator,

source of funding or regulator. Indian and Northern Affairs Canada (INAC) was identified as the responsibleauthority of this project.

The Casino Rama project was designed and constructed over a 10-month period. Infrastructure design byMMM started in September 1995, with construction of the wastewater treatment plant underway byDecember 1995. The Casino and plant were fully operational by July 30, 1996.

The new wastewater collection, treatment and disposal system was designed for the Interim Casino andrelated community facilities, including an arena, seniors complex, community centre and industrial mall.The current design capacity of 2,100 m3/d makes provision to service other developments including a future


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permanent casino and hotel. Capacity and capability was also provided at the plant to accept septic tankpump-outs and landfill leachate. Allowance was made in the plant layout and design to permit readyexpansion by 50 percent.

Criteria for the discharge of effluent to Lake Couchiching were developed based on discussions with theOntario Ministry of Environment. Effluent quality that could be achieved by the best-proven availabletechnology, economically achievable, was used as the basis for establishing the required level of treatment.Water quality and dispersion studies were subsequently performed to identify the preferred outfall locationand the required diffuser design. Effluent from the plant is pumped via forcemain approximately 2,200 m toLake Couchiching, with the outfall extending 550 m into the lake. The inland location of the plant therebypreserves the shoreline area for possible future development of a permanent casino and hotel complex.

Total phosphorous (TP) and un-ionized ammonia were identified as the two key parameters most likely toimpact Lake Couchiching water quality and fish habitat. In addition, chlorine was to be absent in the finaleffluent.

To minimize potential environmental impact, design effluent requirements for the Rama Wastewater

Treatment Centre (WWTC) of 0.15 mg/l TP and 3 mg/l total ammonia were conservatively established, whichreadily meet Provincial Water Quality Objectives within the diffuser mixing zone.

Based upon a subsequent review of available technologies, the sequencing batch reactor (SBR) treatmentprocess, incorporating biological phosphorous removal, followed by tertiary treatment for phosphorousremoval using chemical addition and effluent filtration, was established as the preferred treatment system.Filtered effluent receives disinfection by ultraviolet radiation, thereby precluding the discharge of chlorine tothe lake.

Rama Treatment ProcessThe Rama WWTC is designed to produce tertiary quality effluent on a consistent year round basis using thesequencing batch reactor process and continuous backwash filtration. The plants present average design

flow capacity is 2,100 m3/d with provision for ready expansion to 3,150 m3/d. Currently the plant providesservice mainly to Casino Rama and the Mnjikaning Arena and Seniors Complex.

The plant was designed based on the following influent and final effluent discharge criteria.

Design Influent CriteriaBOD5 260 mg/lTSS 250 mg/lTKN 65 mg/lTotal P 8 mg/lAlkalinity 210 mg/l (as CaCO3)

Temperature (min) 10 C

Design Effluent CriteriaBOD5


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Design influent criteria were developed taking into consideration information available on several standalone casinos in the United States and from projected visitations to Casino Rama and associated waterconsumption.

The Rama WWTC consists of two parallel treatment trains, each capable of independently handling 50% ofthe design flow (i.e. 1,050 m3/d each). The following is a general description of the facility.

Screened sewage is pumped directly into a continuous inflow/intermittent discharge SBR. The modified SBRused at Rama is an ABJ ICEAS process. The SBR process provides organic carbon (BOD5) removal,nitrification, biological phosphorous and concomitant nitrogen removal. SBR cycles are controlled by aprogrammable logic controller. The system operates on a 4.8-hour normal cycle and 3.0 hour storm cycle.In the 4.8-hour cycle, the first 168 minutes of each cycle is intermittently aerated. During the rest of thecycle, each basin is in a settle or decant mode. During the oxic/anoxic phase of the cycle, each basin isalternately aerated. Aeration is controlled by dissolved oxygen levels measured in the tanks. A total of threeblowers are provided for aeration, with one unit dedicated to each aeration basin and the third unit forstandby duty. SBR effluent discharge at the end of the decant cycle flows by gravity from the decanter toequalization tanks located below the floor of the Control Building.

Presently, there are two upflow continuous backwash filters installed in concrete tanks located in the ControlBuilding. The Dynasand model filters, supplied by Parkson were designed to handle the initial design flow of2,100 m3/d (1,050 m3/d per filter). A third concrete tank was provided for installation of a future filter toaccommodate the ultimate design flow of 3,150 m3/d.

Alum for chemical phosphorous removal is injected into the filter feed line immediately upstream of a staticmixer to provide complete mixing. The 2.0 meter deep bed sand filters provide tertiary phosphorous removalthrough in bed coagulation, flocculation and solids removal of the chemically bound phosphorous.

Polymer can also be added as needed to improve particle removal. A separate injection point and staticmixer is provided for polymer addition to the filter feed line after the alum addition point.

Construction and Start-UpThe short time frame mandated for development of the Casino required fast track design and constructionof the project. A construction management approach for project implementation was used, whichpermitted tendering and construction of portions of the work (i.e. foundations) at the same time as designwas still on-going. In the case of the Rama WWTC, all major process equipment was evaluated and pre-purchased as the design of the plant progressed.

Start-up of the plant presented a challenge, as a key objective was to achieve compliance with effluentcriteria within a very short time, due to sensitive nature of Lake Couchiching and the time of year the plantwas being commissioned. To achieve this goal, the plant was seeded approximately 1 week in advance of

startup with waste activated sludge from the City of Orillia WWTC. The sludge was conditioned prior to thefirst day of operation by intermittent aeration in the SBR, with limited sewage inflow as associated withstart-up of the casino. Effluent quality was within design values, with biological phosphorous removal beingachieved from the first day of operation of the plant, after Casino Rama opened.

SBR PerformanceGeneral Theory of Biological Phosphorous RemovalA brief description of the mechanisms of biological phosphorous removal in the SBR system used at theRama WWTC follows:


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Biological P removal in this application incorporates intermittent aeration so that cyclic aerobic andanaerobic conditions are created, resulting in the growth of a biological population that has a much highercellular phosphorous content. The total phosphorous content of waste sludge is typically in the range of 3-6percent in bio-P removal systems, compared to 1.5-2.0 percent in conventional activated sludge systems.The process of wasting sludge solids removes phosphorous from the system. The basic principles ofbiological P removal are summarized below:

1. Certain microorganisms, when subjected to anaerobic conditions, assimilate and store fermentationproducts produced by other facultative bacteria. These microorganisms derive energy for thisassimilation from stored polyphosphates, which are hydrolyzed to liberate energy. The free phosphorousthat results from the hydrolysis is released to the mixed liquor.

2. These same microorganisms, when subsequently exposed to aerobic conditions, consume bothphosphorous (which is used for cell synthesis and stored as polyphosphates) and oxygen to metabolizethe previously stored substrate for energy production and cell synthesis. The organisms take up thephosphorous in excess, to remedy their former phosphorous starved condition. That is, they take inmore phosphorous than they previously released. The phosphorous is removed form the wastewaterstream by wasting of excess sludge generated in the treatment process.

Bio-P Removal in Rama WWTCPhosphorous removal due to excess uptake by organisms was demonstrated in the Rama SBR system. Thefollowing formula (from ABJ) was used to calculate theoretical effluent TP concentration:

TP removed = TPin ((BODin-BODout) x Y x TPps)Where:

Tpremoval = Total Phosphorous removed from the system, mg/lTpin = Total Phosphorous in the influent wastewater, mg/lBODin = Influent BOD5 in the wastewater, mg/lBODout = Effluent BOD5 in the wastewater, mg/l

Y = Sludge Yield, kg MLSS/kg BOD removedTPps = Phosphorous content in the sludge, percent

As shown, the SBR effluent TP concentrations were significantly lower than that from a theoreticalconventional activated sludge plant. As expected, the controlled intermittent oxic/anaerobic conditionsdevelopment in the SBR resulted in a luxury phosphorous uptake by bacteria and as a result greater TPremoval through sludge wasting. A direct relationship is inferred between influent BOD levels and thedegree of phosphorous removal. High influent BOD levels resulted in greater bio-P removal. SBR designeffluent criteria of 1.0 mg/l TP was achieved without chemical addition at influent TP concentrations as highas 15 mg/l as associated with high influent BOD levels.

Chemical Phosphorous RemovalAn alum metering system was provided to allow for chemical phosphorous precipitation within the SBR, in

case the design effluent criteria could not be reached by bio-P removal. An SBR effluent TP concentration of1.0 mg/l was used in design of the effluent filtration system in order to achieve 0.15 mg/l TP in the finaleffluent. Alum can be added to the raw sewage at the inlet chamber of the SBR when daily laboratoryanalysis indicates higher than design values of influent and/or SBR effluent TP. Alum dosage rates that wereoccasionally used only accounted for TP not removed biologically, and as such, alum addition onlysupplemented biological phosphorous removal. Alum addition to the SBR inlet chamber was suspendedwhenever influent concentrations returned to design values.

Biological phosphorous removal was occasionally supplemented by alum addition to the SBR in March toJune of 1997. When practiced, combined biological and chemical P removal resulted in SBR effluent TPconcentrations of between 0.3 0.4 mg/l. Such low concentrations were not observed on a continuous


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basis when only biological phosphorous removal was practiced. Alum addition did not appear to result inany adverse effect on biological activity and did not reduce the ability of bacteria to uptake phosphorouswhen alum addition was suspended.

Nitrogen RemovalBiological nitrogen removal was achieved in the SBR by cyclic anoxic and oxic conditions created a s part ofthe bio-P removal process within the SBR reactor. The design sludge age in the Rama system was 23 days.Essentially complete nitrification was achieved year round. SBR effluent was well below 3.0 mg/l of totalammonia, as required in order to achieve the design un-ionized ammonia concentration. Although therewas no design requirement for denitrification, concomitant nitrogen removal was observed along with bio-Premoval in the SBR system.

Tertiary Effluent FiltrationSBR effluent is stored in a two-compartment equalization tank and pumped at a constant rate to thecontinuous backwash filters. Alum is added to the filter feed to precipitate the remaining phosphorous toachieve the desired final effluent TP concentration of 0.15 mg/l. Occasionally, polymer was added toenhance flocculation of precipitated matter. TP concentration in the final effluent as low as 0.05 mg/l was

achieved when biological phosphorous removal in the SBR was enhanced by chemical addition.

Side Stream Processes

Aerobic DigesterAerobic digestion is used at the Rama WWTC for waste activated sludge stabilization. The second stage ofthe digester is employed as a gravity thickener when the aeration is intermittently turned off in thiscompartment. The resulting supernatant is decanted to the digester supernatant clarifier. The clarifieroverflow is returned to the head of the plant, while sludge within the clarifier is returned to the aerobicdigester.

There was a concern during a course of design that significant amounts of phosphorous might be solubilized

due to anoxic conditions in the aerobic digester during settling. The solubilized P would be then be returnedto the plant resulting in overloading the system with recycled phosphorous. To eliminate this possibility, analum addition point was provided ahead of supernatant clarifier to permit chemical phosphorous removal.The digester supernatant and supernatant clarifier effluent phosphorous concentrations were routinelymonitored and excessive phosphorous release was not observed.

Septage/Leachate Holding TankA septage/leachate holding tank was included in the plant to provide for flow equalization of septagecollected from domestic tanks located in Rama lands, as well as future leachate. A submersible pump wasinstalled to meter the stored septage/leachate to the head of the plant.

Operational ProblemsOver time, significant accumulations of grease was observed in the influent pumps wet wells and ultimatelyin the SBR, equalization tanks, filter pump discharge header and the effluent filter beds. The design of theplant does not provide for separate grease removal, as grease traps were installed in the various casinorestaurants. Accumulation of grease in various points of the WWTC process train resulted in additional laborand expenses associated with cleaning and on some occasions, higher than desired final effluent suspendedsolids and phosphorous concentrations due to degraded effluent filter performance. The problem waseventually addressed by the installation of additional grease traps in the Casino, which resulted in lowergrease concentrations being received at the plant.


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ConclusionsJuly 1997 marked the first anniversary of operation of the Rama Wastewater Treatment Centre. Theanalytical data collected during this period documents the plants performance both under varying flow,BOD and nutrient loadings and seasonal conditions. The following conclusions can be drawn form the firstyear of operation of this facility:1. Biological phosphorous removal in the SBR, followed by continuous backwash effluent filtration with

alum addition achieved an annual average TP concentration of 0.15 mg/l in the final effluent.2. TP concentrations of 0.3 0.4 mg/l were routinely observed in the SBR effluent when biological

phosphorous removal was supplemented by alum addition to the incoming wastewater.3. By inclusion of an anoxic sequence in the SBR operating cycle, concomitant removal of nitrogen was

achieved along with biological phosphorous removal.4. Excessive phosphorous release was not observed in aerobic digester supernatant.

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