R. Pishgar1*, J. H. Tay1, R. A. Hamza1
1 Department of Civil Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4 Canada
(free)This study investigated the feasibility of using freeze-dried granular sludge in lagoon basins for reducing the treatment interval. Series of laboratory-scale batch studies were conducted to evaluate the effect of different operational conditions on treatment performance of granulebased lagoons with a focus on the detention time. The optimal dosage of 0.1 g/L granular sludge resulted in 80 – 94% removal of 1000 mg/L chemical oxygen demand (COD) in 7 – 10 days under anaerobic condition. For the aerobic treatment of the same level of organic matter, 0.2 g/L granular sludge was optimized. However, extra nutrients should be supplied concomitant with the aeration to encourage the growth of aerobic species. In the presence of sufficient nutrients, aerobic treatment interval was significantly shortened to 3 to 4 days. Aerobic activity of the granular sludge was optimized at ammonium nitrogen (NH4-N) concentration of 130 mg/L and phosphate (PO4-P) concentration of 8 mg/L, corresponding to COD/N/P ratio of 100/1/0.8. Under optimal condition, 91% removal of 1000 mg/L was aerobically achieved in 3 days. Inhibition effect of high concentrations of 5000 mg COD/L and 480 mg NH4-N/L was observed on the treatment capacity of the granular sludge. Mixing was a crucial measure to overcome mass transfer limitation. One-time inoculation of the lagoon was essential to achieve a satisfactory treatment capability. The results of this study suggested that application of granular sludge for augmenting lagoon plants is a feasible and sustainable technique and can lead to great treatment performance at short detention time
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