Pine Creek WWTP
City of Calgary, Alberta (Canada)
The 100 ML/d Pine Creek WWTP is a state-of-the-art BNR facility that serves the City of
Calgary, Alberta. A delay in the construction of the primary sludge fermenters allowed a
comparison of the performance of the BNR process with and without fermentation for
extended periods of time, and facilitated a life-cycle cost analysis in which the cost of
primary sludge fermentation was compared with alternative forms of primary sludge
thickening and meeting the effluent total P limit by chemical addition. Data from the first 20
months of plant operation indicated that, with primary sludge fermentation, the plant is
capable of reliably meeting its stringent effluent total P target of <0.3 mg/L. Without
fermentation, the plant required the in-plant addition for approximately 50 mg/L of alum to
meet this same effluent quality standard. The life-cycle cost comparison between primary
sludge fermentation and enhanced biological phosphorus removal (EBPR), and two
alternative forms of primary sludge thickening and chemical P removal, indicated that
primary sludge fermentation is a cost-effective method of reliably meeting a stringent
effluent total P standard. Using a 20-year net present value (NPV) analysis, primary sludge
fermentation was found to be approximately 8 percent cheaper than mechanical primary
sludge thickening and chemical P removal, and 22 percent cheaper than gravity thickening of
primary sludge and chemical P removal.
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Posted: May 20th, 2011 | Filed under: 100K-500K, Waste Water Treatment | Tags: Biological Nutrient Removal, Phosphorus Removal, Sludge Handling | No Comments »
Metropolitan Syracuse Wastewater Treatment Plant
Syracuse, New York
The 84.2 mgd Metropolitan Syracuse Wastewater Treatment Plant (Metro) has recently
undergone a major upgrade to provide advanced ammonia-nitrogen and phosphorus removal.
Seasonal limits for ammonia are 1.2 mg/L NH3 summer and 2.4 mg/L NH3 winter, and the limit
for phosphorus is a 12-month rolling average of 0.12 mg/L. Biological aerated filters (BAFs) by
Krüger were added for ammonia removal and the ballasted flocculated settling process,
ACTIFLO (also by Krüger) was added for phosphorus removal.
To address the increased biosolids produced at Metro, Environmental Engineering Associates,
LLP (EEA – a joint venture of Stearns & Wheler, LLC, O’Brien & Gere, and Blasland, Bouck &
Lee [now ARCADIS]) was retained to develop the necessary biosolids handling improvements.
The project includes:
• Replacing existing belt filter press dewatering system with high solids centrifuges
• Installing gravity belt thickeners (GBTs) to thicker WAS
• Provide sludge blend tanks to blend thickened primary sludge and thickened WAS prior to
digestion
• Provide a cogeneration system that utilizes digester gas to generate electricity and recover
heat.
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Posted: May 3rd, 2011 | Filed under: 100K-500K, Waste Water Treatment | Tags: Improved Digestion, Improved Sludge Drying, Nitrogen Removal, Phosphorus Removal, Plant Optimization, Reduced Odors | No Comments »
Parkway WWTP and Henrico County WRF
Laurel, Maryland and Richmond, Virginia
Nitrogen removal to increasingly strict discharge standards requires, in many cases, the use of supplemental carbon (methanol, glycerol, acetate, sugar water, etc). The supplemental carbon provides the driving force for further biological denitrification and is typically applied as a polishing treatment such as to a post anoxic zone or a tertiary denitrification filter. The practical use of supplemental carbons has attracted substantial attention from both process optimization and cost minimization perspectives. This paper presents the operational experiences gained with the secondary and indirect impacts of supplemental carbon addition to BNR/ENR treatment facilities at the Parkway WWTP, located in Laurel, Maryland, and at the Henrico County WRF, located in Richmond, Virginia. The focus of the paper deals with the sometimes unexpected beneficial secondary effects of supplemental carbon addition to post anoxic zones in the BNR/ENR treatment processes. This paper has demonstrated secondary impacts from supplemental carbon addition for nitrogen removal. The benefits demonstrated included improved biological phosphorus removal, improved anoxic zone performance, increased biosynthesis for P and N removal, lower residual DO in the internal recycle, and improved utilization of influent rbCOD. Additionally various ways of calculating by the CODadded/Nremoved ratio was developed using effluent TN with and without supplemental carbon. The impact of lower NOx-N load in the RAS when the pre-anoxic zone is not fully utilized was shown to be a significant factor in the resulting CODadded/Nremoved ratio. These impacts illustrate the importance of considering the whole system response rather than an isolated portion of a reactor when evaluating supplemental carbon. Source: WEFTEC 2009 Proceedings
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Posted: August 27th, 2010 | Filed under: 50k-100k, Waste Water Treatment | Tags: Environmental Impact, Improved Anoxic Zone Performance, Lower Residual DO, Nitrogen Removal, Phosphorus Removal | 1 Comment »
The algae-to-biofuel industry requires a cost effective means for separating a relatively dilute algae suspension from a large flow of water. Ideally, algae recovery should be economical and result in a thick algae concentrate with minimal extraneous and inert materials that would detract from the value of the resource. To a large extent, the economy of microalgae production depends on the method employed for harvesting and concentrating the algae. This paper discusses some of the possible algae separation techniques with an overview of the advantages and disadvantages of each. Emphasis is placed on the dissolved air flotation process because it still remains the most effective means of separating a relatively low concentration of algae from a large body of water. Some of the important design features of dissolved air flotation that promote effective algae separation and harvesting, as well as thickening of the separated algae, are discussed. The efficiency of recovery is a significant issue because it relates to the economics of the separation technique. However, it is not necessarily of overriding importance since the water from the separation unit can be recycled back to the algae growth units. The efficiency of recovery and operation of the separation technique depends to a large extent on the means by which the algae is conditioned. The paper discusses various inorganic and organic chemicals for algae coagulation, to facilitate algae separation by dissolved air flotation, or by other means. Inorganic coagulants tend to be the most effective, although some natural and synthetic polymers are effective. Chitosan is a natural polymer that does not detract from the animal feed option for the co-product from algae biofuel processing, although it does introduce significant quantities of inert material. Other organic polymers that are GRAS certified should be used preferentially to those products that are not certified. Source: WEFTEC 2009 Proceedings
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Posted: August 27th, 2010 | Filed under: Waste Water Treatment | Tags: Ammonia Removal, Effective Algae Separation Technique, Environmental Impact, Improved Algae Recovery, Improved Thickened Algae Concentrate, Phosphorus Removal, Plant Sustainability, Reduced Greenhouse Gas Emissions | No Comments »
High rate algae ponds fed clarified domestic wastewater and CO2-rich flue gas are expected to remove nutrients to concentrations similar to those achieved in mechanical treatment technologies, such as activated sludge. However, the energy intensity of wastewater treatment with CO2-supplemented high rate ponds (HRPs) would be less than that of mechanical treatments. In conjunction with anaerobic digestion of algal biomass and co-substrates, the algae-based system would produce a substantial excess of electricity. Greenhouse gas abatement from such CO2-HRP/digestion systems would stem mainly from energy conservation and the offset of fossil fuel electricity with biogas-derived electricity. Laboratory experiments showed nutrient removals of >98% for ammonium and >96% for phosphorus with mixed culture microalgae grown on CO2-supplemented primary wastewater effluent. An engineering numerical model for CO2-HRP/digestion facilities (based in part on large-scale algae production under southern California conditions) indicates a potential energy surplus of 330 kWh/ML (1,200 kWh/MG) from biogas-derived electricity, compared to the net energy consumption of about 760 kWh/ML (2,900 kWh/MG) at typical activated sludge facilities with nitrification/denitrification. Considering the net electricity production and energy savings of the CO2-HRP/digestion systems, a greenhouse gas abatement potential of 660 kg CO2eq/ML (2,500 kg CO2eq/MG) treated is expected for a 100-ha facility treating 20 MGD. Source: WEFTEC 2009 Proceedings
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Posted: August 27th, 2010 | Filed under: Waste Water Treatment | Tags: Energy Savings, Environmental Impact, Improved Algae Recovery, Nitrogen Removal, Phosphorus Removal, Plant Sustainability, Reduced Greenhouse Gas Emissions | No Comments »
Walton Wastewater Treatment Plant
Walton, New York
The CBUDSF tertiary treatment systems installed throughout the New York City water supply watershed have proven to be robust, reliable and easily maintained. The anticipated lifespan of the CBUDSF systems are 40-50 years with proper maintenance and replacement of supporting equipment (Delaware Engineering, 2008) and are in place at nine WWTP’s in the NYC water supply Catskill and Delaware watershed districts. Over the last 6 years, the CBUDSF system has met its design and operational objectives and continues to perform an integral role in optimizing the Walton WWTP effluent which in turn benefits water quality in the West Branch Delaware River, the Cannonsville Reservoir and the NYC water supply in general. Following installation of the system in January 2003, significant reductions in effluent turbidity (99.99%), total suspended solids (99.95%), phosphorus (99.98%) and fecal Coliform (99.99%) were realized. Plant discharge routinely meets discharge parameter limits for TSS, phosphorus and fecal Coliform. Improvements in water quality below the Walton WWTP as well as other WWTP’s discharging into the West Branch Delaware River have been detected following the regulatory upgrades. NYCDEP stream water quality monitoring operations has measured “drastic” reductions in nutrient loading in the West Branch Delaware River below the Walton WWTP since 2003 when the tertiary system became operational (NYCDEP, 2006). The increased TSS removal facilitated by the tertiary filtration system creates additional TSS loading at the head of the plant since the reject waste stream is directed there. This increase in influent TSS load resulted in a 30% net increase in the weight of residuals generated. Walton WWTP and other watershed WWTP’s operators find that the CBUDSF systems run with relative ease, tolerate variations in input flow composition and are not prone to malfunction (Delaware Operations, 2009). Source: WEFTEC 2009 Proceedings
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Posted: July 6th, 2010 | Filed under: Waste Water Treatment | Tags: Phosphorus Removal, Tertiary Treatment | No Comments »