A membrane bioreactor for an innovative biological nitrogen removal process

Abstract

A hybrid system has been developed for biological nitrogen removal through nitrification-denitrification. The system includes an aerobic tank and an anoxic tank with an intermediate sludge settler connected to a membrane bioreactor (MBR) with a submerged 0.4 microm hollow-fiber membrane module. The laboratory system has a total working volume of 6.5 L treating a glucose-based synthetic wastewater. The experimental results demonstrate that the new process is highly effective for simultaneous organic and nitrogen removal. During the stationary operation, a sludge SS (suspended solids) concentration of 6 g/L or higher can be maintained in the reactors. The system has a COD (chemical oxygen demand) loading rate of up to 2,100 mg/L-d and a total nitrogen loading rate of up to 170 mg N/L-d. More than 95% COD can be degraded, and the total nitrogen removal efficiency can be 90% or higher as the nitrogen is reduced from 100 to around 7.5 mg/L. A high quality effluent is produced with a SS of less than 1 mg/L. With the MBR, organic degradation, nitrogen removal and sludge-liquid separation can be well achieved within a short HRT of about 10 hr.

Biofilm Fixed Film Systems

“…Chen et al [96] also developed a hybrid biological nitrogen removal system, consisting of an aerobic tank and an anoxic tank with an intermediate sludge settler connected to an MBR, which provided both nitrification and denitrification. Hwang et al [97] investigated total nitrogen removal in a two-step membrane biofilm reactor (MBfR) system incorporating sequential nitrification and hydrogen driven autotrophic denitrification in order to achieve nitrogen removal by autotrophic bacteria alone.…”