Organic matters removal from hospital wastewater by EGSB: Influences of seeding sludge and up-flow velocity

Abstract

From Binh An hospital was treated by EGSB lab-scale model. It is found that both EGSB started up with granular sludge and septic sludge operated at organic loading rate of 0.2-1.8 kg COD/m3.day, with upward-flow velocity of 1.3 m/h can achieve greater than 65% COD removal efficiency and meet the current Vietnamese discharged standard for effluent from hospital wastewater (QCVN 28:2008/BTNMT). COD decreased from 148 ± 18 mg/L of the influent to 50 ± 18 mg/L of the effluent and BOD5 of the effluent bellowed 35 ± 12 mg/L. When the organic loading rate increased from 1.8 kg COD/m3.day to 2.3 kg COD/m3.day, corresponding to the up-flow velocity increased from 2.4 m/h to 2.8 m/h, COD removal efficiency reduced significantly. The up-flow velocity of 2.8 m/h leaded small and low density suspended solids and granular sludge flowing with effluent. With COD of the influent < 200 mg/L, EGSB can remove > 65% of COD if the up-flow velocity and the organic loading rate was controlled ≤ 2.4 m/h and about 1.8 kg COD/m3.day, respectively. EGSB with media F25 gave higher COD removal efficiency compared to that without media addition.