USING VENTURI TUBE FOR AIR SUPPLY IN SEQUENCING BATCH BIOREACTOR TO TREAT DOMESTIC WASTEWATER

Abstract

The purpose of the study aims to assess the ability of venturi tubes combined with mixers to provide oxygen to microbes in the aerobic biological treatment of suspended growth to remove total suspended solids, organic matters and nutrients in domestic wastewater. The experimental system consists of 2 tanks using HDPE plastic barrels with a working volume of 60 L and are operated in batches with hydraulic retention time of 5.5 hours. The experiment was conducted in parallel with 2 types of air supply including venturi tubes combined with mixers and conventional aeration through a porous tube into each tank. The experiment was firstly conducted to evaluate the efficiency of dissolving oxygen into water. Then, two types of air supply are applied to provide oxygen to the two experimental systems of activated sludge chambers that have been cultured with microorganisms. The experimental results showed that the removal efficiencies of TSS, organic matters and nutrients by the 2 experimental systems was most likely similar. The COD and BOD₅ removal efficiency is about 80% and NH₄⁺-N is about 90%. The venturi tube air supply type combined mixer has a lower TSS removal efficiency than the conventional aeration type. Overall, the average concentrations of TSS, COD, BOD₅, NH₄⁺-N, NO₃^--N, PO₄^3- in the treated wastewater of both experimental systems were 26.7 ± 4.2 mg/L and 18.3 ± 5.8 mg/L, 36.7 ± 15.5 mg/L and 34.3 ± 11.5 mg/L, 24.0 ± 6.5 mg/L and 21.1 ± 5.1 mg/L, 1.4 ± 0.11 mg/L and 1.26 ± 0.05 mg/L, 6.26 ± 0.74 mg/L and 6.07 ± 1.44 mg/L, 2.9 ± 0.3 mg/L and 3.0 ± 0.37 mg/L respectively and meet the column A of the national technical regulation on domestic wastewater QCVN 14:2008/BTNMT. Ultimately, the research results shown that the venturi tube combines with the mixer is able to supply oxygen sufficiently to microbes in an activated sludge system for domestic wastetwater treatment.