Model for predicting the performance of membrane bioadsorber reactor process in water treatment applications

Gene expression programming for process parameter optimization during ultrafiltration of surfactant wastewater using hydrophilic polyethersulfone membrane

Surfactants are the emerging contaminant and cause a detrimental effect on the ecosystem. In this study, an attempt is made to removal anionic surfactant Sodium dodecyl sulfate (SDS) containing wastewater using hydrophilic polyvinylpyrollidone (PVP) (5-15 wt%) modified polyethersulfone (PES) ultrafiltration membrane. The influence of operating variables on membrane performance was also sequentially analyzed using tests and three numerical modeling methods such as multiple linear regression (MLR), multiple Ln-equation regression (MLnER), and gene expression programming (GEP). Contact angle value of 10 wt% PVP modified PES membrane decreased up to 23.8°, whereas the neat PES membrane is 70.7°. This study indicates that the required hydrophilic property was improved in the modified membrane. The water flux and porosity also enhanced in PVP modified PES membranes. In performance evaluation, the optimum operating variable condition of transmembrane pressure (TMP), feed concentration, and the temperature is found to be 3 bar, 100 ppm, and 25 °C, respectively. Among the models, GEP has a good correlation with experimental anionic surfactant SDS filtration data. GEP performs better than other model with respect to statistical parameter and error terms. This study provides an insight into an adaptation of novel numerical modeling methods for the prediction of membrane performance to the treatment of surfactant wastewater.

Modeling of Wastewater Treatment Processes in Membrane Bioreactors Compared to Conventional Activated Sludge Systems

Membrane techniques constitute an interesting alternative to conventional activated sludge systems (CAS). In membrane bioreactors (MBR), the biomass separated on membranes is retained independently of sludge sedimentation properties. As a consequence, a high biomass concentration as well as low food to microorganisms ratio can be obtained. Moreover, the development of a characteristic activated sludge population is stimulated by the specific conditions prevailing in MBRs. In the study, the operation and treatment efficiency of the MBR and CAS processes were examined and compared. Simulation was performed with the use of GPS-X software. The effluent quality obtained for the MBR system was either better or comparable to that of CAS. The most significant difference concerned the elimination of total suspended solids, which amounted to 99.8% in the MBR. Regarding nutrients, a low concentration of total phosphorus in the effluent from CAS and MBR was obtained (0.67 gP m−3 and 0.50 gP m−3, respectively). Greater differences were achieved in the case of total nitrogen. Although almost complete nitrification took place in both systems, a lower concentration of nitrate in the effluent from MBR in comparison to CAS, i.e., 11.2 gN m−3 and 14.1 gN m−3, respectively, allowed us to obtain a higher removal of total nitrogen (80.8% and 76.1%, respectively).

The effect of activated carbon addition on membrane bioreactor processes for wastewater treatment and reclamation - A critical review

This review concentrates on the effect of activated carbon (AC) addition to membrane bioreactors (MBRs) treating wastewaters. Use of AC-assisted MBRs combines adsorption, biodegradation and membrane filtration. This can lead to advanced removal of recalcitrant pollutants and mitigation of membrane fouling. The relative contribution of adsorption and biodegradation to overall removal achieved by an AC-assisted MBR process can vary, and "biological AC" may not fully develop due to competition of target pollutants with bulk organics in wastewater. Thus periodic replenishment of spent AC is necessary. Sludge retention time (SRT) governs the frequency of spent AC withdrawal and addition of fresh AC, and is an important parameter that significantly influences the performance of AC-assisted MBRs. Of utmost importance is AC dosage because AC overdose may aggravate membrane fouling, increase sludge viscosity, impair mass transfer and reduce sludge dewaterability.

Comparison of the performance of submerged membrane bioreactor (SMBR) and submerged membrane adsorption bioreactor (SMABR)

This study focuses on comparing the performance of submerged membrane bioreactor (SMBR) and submerged membrane adsorption bioreactor (SMABR) over a period of 20 days at a hydraulic retention time (HRT) of 3.1h. The effects of PAC on critical flux and membrane fouling were also investigated. The SMABR exhibited better results in terms of mixed liquor suspended solids (MLSS) growth, DOC removal (over 96%), COD removal (over 95%), transmembrane pressure (TMP) and oxygen uptake rate. Nearly 100% of bacteria and 100% of total coliforms were removed in both systems. The addition of PAC could maintain the critical flux at a lower TMP value (7.5 kPa), while irreversible fouling caused by PAC occurred when the filtration flux exceeded critical flux.