Lab Scale Study of HRT and OLR Optimization in UASB Reactor for Pretreating Fortified Wastewater in Various Operational Temperatures

摘要

This study was carried out for examination of a lab-scale UASB reactor for optimization of organic loading rate and hydraulic retention time in various operational temperatures. The total volume of the reactor was 5 1 with an effective height of 160 cm and diameter of 5 cm. This reactor was used to treat fortified municipal wastewater at volumetric organic loadings of 3.6, 7.2, 10.8, and 14.4 kg m-3 d-1 at temperatures 30 °C and 20 °C and PH 7.6-8.4 for the treatment of high-strength enriched municipal wastewater of Ekbatan local treatment plant that located in west of Tehran. The COD of this wastewater have enriched by molasses and milk powder. To prevent PH fluctuation of the influent, NaHCO3 and K2HPO4 were added to wastewater. The result of present work indicated an optimum range for organic loading (7.2 to 10.8 kg m-3 d-1) at all temperature condition with COD removal efficiency of about of 85% and 73 % in UASB reactor at 30 °C and low temperature about 20 °C. Moreover, optimum HRT for influent COD concentration of 1200mg/l is shown to be only 4 hours. Furthermore nitrate removal efficiency was about 80% at optimized organic loading range, with a sharp decrease beyond this range (e.g. up to 30% decrease for 14.4 kg/m3.d and up to 45% decrease for 3.6 kg/m3.d)