Particle Size Distribution in Permeate from a Pilot-Scale Membrane Bioreactor System under Actual Operating Conditions

Comparative study of the use of pure oxygen and air in the nitrification of a MBR system used for wastewater treatment

A MBR (membrane bioreactor) was performed to quantify the improvement in nitrogen removal terms when pure oxygen and air were used to supply the aerobic conditions at different HRT (hydraulic retention time) and mixed liquid suspended solids concentrations. The improvement in the efficiency was 8.0% and 13.5% when pure oxygen was used with 12h and 18 h of HRT respectively. The ammonium utilization rates with HRT of 18 h with pure oxygen was 1.23 mg N(t)/(L h) and with air 0.66 mg N(t)/(L h) and with HRT of 12h was 1.14 mg N(t)/(L h) and 1.18 mg N(t)/(L h) respectively. Model simulation (DESSAS software) confirmed the validity for nitrogen removal, hydrolysis constant was increased (106% and 184%), decay constant was decreased and Monod's constant was increased (190.4% to 324.1%), and a multivariate analysis with CANOCO v4.5 demonstrated that temperature and HRT have the higher influence in kinetics.

Kinetic study and oxygen transfer efficiency evaluation using respirometric methods in a submerged membrane bioreactor using pure oxygen to supply the aerobic conditions

The performance of a wastewater bench-scale ultrafiltration membrane bioreactor (MBR) treatment plant using pure oxygen to supply the aerobic conditions for 95 days was studied. The results showed the capacity of the MBR systems to remove organic material under a hydraulic retention time of 12h and a sludge retention time of 39.91 days. Aeration represents its major power input; this is why the alpha-factor of the aeration and kinetic parameters (design parameters) were determined when the mixed liquid suspended solids (MLSS) was increased from 3420 to 12,600 mg/l in order to understand the system. An alpha-factor in the range 0.462-0.022 and the kinetic parameters measured with the respirometric method (K(M) of 73.954-3.647 mg/l, k(d) of 0.0142-0.104 day(-1), k(H) of 0.1266-0.655 day(-1), and the yield mean coefficient of 0.941) were obtained. Our study suggested significant changes in the behaviour of the biological system when the concentration of MLSS was increased.