Specialist Group on Use of Macrophytes in Water Pollution ... - IWA

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Although the Buffalo design had anticipated the need for nutrient addition, establishment of effective treatment was slow, and the system began to experience foaming associated with the formation of polysaccharide slimes by the resident bacteria. Foaming and slime formation is known to occur at wastewater treatment plants subject to severe nutrient limitations (Arias et al., 2008; Ayati and Ganjidoust, 2008). Owing to the observed slime formation at Buffalo, estimates on the yield ratio had to revised upwards, and was finally estimated by the authors to be at least 0.3. This had profound implications on the rate of nutrient addition, as the Buffalo wetland was designed to process 4,500 kg/d of BOD; a yield ratio of 0.3 implies 1,350 kg/d per day of microbial biomass production. Based on the information in Table 5, this amount of biomass production would require 115 kg/d of nitrogen and 23 kg/d of phosphorus, in addition to micronutrients. After feeding the appropriate amount of nutrients, slime formation ceased and treatment performance improved dramatically. FULL-SCALE OPERATION Operation of the full-scale treatment wetland was continued through the 2010/2011 de-icing season (with improved nutrient addition). The full-scale system consists of four subsurface flow wetland beds (saturated vertical downflow), each sized at 4,640 m 2 with a bed depth of 1.5 m. The distribution piping is buried under an insulating level of compost such that no water is exposed during the treatment process (Figure 2). Figure 2. Full-scale treatment wetland at Buffalo Niagara International Airport. The subsurface vertical flow wetlands have an internal array of aeration tubes to enhance oxygen transfer as a means of intensification. The enhanced oxygen transfer rate allows for the aerobic degradation of glycol compounds. Each wetland can be supplied with air up to 140 m 3 /min, which allows an oxygen transfer rate approximately 60 times greater than what would be supplied through passive atmospheric diffusion. ___________________________________________________________________________ 40 IWA <strong>Specialist</strong> <strong>Group</strong> on Use of Macrophytes in Water Pollution Control: Newsletter No. 37
During the 2010/2011 de-icing season, influent BOD5 concentrations were in excess of 15,000 mg/L. Generally, the system had very low effluent values, which averaged 77 mg/L (based on a correlation between online total organic carbon measurements and laboratory BOD5 values), as shown in Figure 3. Figure 3. Influent and effluent BOD5 values for the intensified wetland at Buffalo Niagara International Airport. The wetland system also experienced BOD5 loadings well in excess of the original design parameters. While the design was based on a BOD5 loading rate of 4,500 kg/d, actual loadings exceeded 20,000 kg/d. BOD5 removals remained in the range of 90 to 100% (with an average removal rate of 98.3%), and reductions in treatment efficiency were only observed at the heaviest organic loadings (Figure 4). Figure 4. BOD5 loadings and treatment efficiency for the intensified wetland at Buffalo Niagara International Airport ____________________________________________________________________________________________________ IWA <strong>Specialist</strong> <strong>Group</strong> on Use of Macrophytes in Water Pollution Control: Newsletter No. 38 41
Page 1 and 2: Specialist <strong
Page 3 and 4: MESSAGE FROM THE CHAIR Dear Members
Page 5 and 6: The Proposers The Environmental Tec
Page 7 and 8: MD6677-5-11 Printed on environmenta
Page 9 and 10: You mention Kenya, and I should tal
Page 11 and 12: APPLICATION OF VERTICAL FLOW TREATM
Page 13 and 14: So we knew: 1. We wanted to do some
Page 15 and 16: All these analysis were done by thi
Page 17 and 18: NUTRIENT RELEASE FROM INTEGRATED CO
Page 19 and 20: Collected samples were analysed for
Page 21 and 22: Concentration (mg/l) 160 140 120 10
Page 23 and 24: CONSTRUCTED WETLANDS AS PART OF ECO
Page 25 and 26: Figure 3. Filter baskets as wastewa
Page 27 and 28: RESULTS AND DISCUSSION Physico-chem
Page 29 and 30: Heavy metals The analysis for heavy
Page 31 and 32: AREA AND ENERGY REQUIREMENTS: COMPA
Page 33 and 34: The ‘French design’ system. Bas
Page 35 and 36: References Austin D.C., Lohan E. an
Page 37 and 38: Constructed wetlands are an attract
Page 39: The BOD5 removal rate coefficients
Page 43 and 44: TREATMENT OF SISAL WASTEWATER USING
Page 45 and 46: References APHA (2000). Standard Me
Page 47 and 48: CW is not only utilized for treatin
Page 49 and 50: Table 2. Process characteristics an
Page 51 and 52: Table 3. the basic information of t
Page 53 and 54: Dr Yosihiro Natuhara, Nagoya Univer
Page 55 and 56: Further details of this year‘s co
Page 57 and 58: NEWS FROM IWA HEADQUARTERS IWA Deve
Page 59 and 60: ___________________________________
Page 61 and 62: Environmental Technologies to Treat
Page 63 and 64: exceed the strict definition of ana

Specialist Group on Use of Macrophytes in Water Pollution ... - IWA

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