UPGRADING THE EFFLUENT QUALITY OF AN AERATED LAGOON WITH HORIZONTAL ROUGHING FILTRATION

Removal of suspended solids and microorganisms from an aerated lagoon effluent with a horizontal roughing filter (HRF) was investigated. The aerated lagoon receives Qom municipal wastewater. The HRF was operated at three filtration rates of 0.5, 1.0 and 1.5 m super(3)/(m super(2)[middot]h) during four month operation period. The measured values of turbidity, TSS, COD, pH, temperature and flow rate of HRF at the former filtration rate were 79+ or -12 NTU, 100+ or -11 mg/dm super(3), 190+ or -12 mg/dm super(3), 7+ or -0.1 [degrees]C, 17+ or -8 [degrees]C and 0.82 dm super(3)/min, respectively. The differences between inlet and outlet values of pH and temperature were not significant (P > 0.05). Measures turbidity, TSS and COD in HRF final effluent were 15+ or -13.7 NTU, 37+ or -295 mg/dm super(3), 64+ or -39.7 mg/dm super(3), respectively, which corresponds to 81.1%, 63% and 66.3% removal efficiencies, respectively. A decrease of removal efficiency was observed upon increasing filtration rates. The Spearman correlation coefficients between the head-loss and removal efficiencies ranged from 0.578 to 0.968 pointing to a direct relationship. Results of modeling approach revealed appropriate compliance between the values of the observed and predicted TSS for higher filtration rates.