Lei Qin

Aerobic SMBR/reverse osmosis system enhanced by Fenton oxidation for advanced treatment of old municipal landfill leachate.

A novel combined process of Fenton oxidation, submerged membrane bioreactor (SMBR) and reverse osmosis (RO) was applied as an appropriate option for old municipal landfill leachate treatment. Fenton process was designed to intensively solve the problem of non-biodegradable organic pollutant removal and low biodegradability of leachate, although the removal of ammonia-nitrogen was similar to 10%. After SMBR treatment, it not only presented a higher removal efficiency of organics, but also exhibited high ammonia-nitrogen removal of 80% on average. The variation of extracellular polymeric substance (EPS) content, zeta potential, and particle size of flocs after Fenton effluent continually fed in SMBR was found to be benefit for alleviating membrane fouling. Finally, three kinds of RO membranes (RE, CPA, and BW) were applied to treat SMBR effluents and successfully met wastewater re-utilization requirement. Compared with simple RO process, the troublesome membrane fouling can be effectively reduced in the combined process.

Transformation of metal-organic frameworks for molecular sieving membranes

The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively.

Enhanced submerged membrane bioreactor combined with biosurfactant rhamnolipids: Performance for frying oil degradation and membrane fouling reduction

In this study, a novel submerged membrane bioreactor (SMBR) combined with rhamnolipids was developed to treat frying oil wastewater and control the problem of membrane fouling. To validate the feasibility of this new design, a hybrid SMBR with additional rhamnolipids (RSMBR) and a controlled SMBR (CSMBR) were run in parallel. Results demonstrated that RSMBR not only held high removal efficiency of oil up to 90% at short hydraulic time, but also exhibited 10 times higher membrane permeability in comparison to CSMBR. The presence of rhamnolipids greatly enhanced the contact and reaction between the microorganism and oil molecules. The great improvement in membrane filterability was associated with an increase in hydrophobicity of flocs as well as the increase of particle size from 53.06 to 145.54 μm. The oil strongly adhered to the surface of flocs by rhamnolipids, and consequently prevented larger oil droplets directly depositing on the membrane surface.

Anoxic oscillating MBR for photosynthetic bacteria harvesting and high salinity wastewater treatment

In this study, photosynthetic bacteria (PSB) were first harvested by MBR with pendulum type oscillation (PTO) hollow fiber module in succession and on a large scale. Based on unique properties of PSB, PSB/MBR was successfully applied for high-salinity wastewater treatment. Compared with control PSB-MBR (CMBR), PSB/PTO-MBR exhibited more excellent organics removal, which was mainly attributed to much higher biomass production for utilization. Meanwhile, the influence of light irradiation and aeration on activity of PSB was investigated in detail. Results showed that PTO-MBR with 12h light irradiation proved to be a promising and economical alternative. The cycle of dark/light and anoxic had a positive effect on PSB cultivating. Moreover, PTO-MBR exhibited much higher flux than CMBR even if large amounts of biomass existed, which demonstrated that the strong shear stress on interface of liquid-membrane played important roles on membrane fouling reduction.

A submerged membrane bioreactor with pendulum type oscillation (PTO) for oily wastewater treatment: Membrane permeability and fouling control

In this study, a novel submerged membrane bioreactor (SMBR) with pendulum type oscillation (PTO) hollow fiber membrane modules was developed to treat oily wastewater and control the problem of membrane fouling. To assess the potential of PTO membrane modules, the effect of oscillation orientation and frequency on membrane permeability was investigated in detail. The forces exerted on sludge flocs in the oscillating SMBR were analyzed to evaluate the impact of membrane oscillating on the cake layer resistance reduction. Results showed that the optimized PTO SMBR system exhibited 11 times higher membrane permeability and better fouling controllability than the conventional MBR system. By hydrodynamic analysis, it was found that the cooperative effect of bubble-induced turbulence and membrane oscillation in PTO SMBR system generated strong shear stress at liquid-membrane interface in vertical and horizontal direction and effectively hindered the particles from depositing on membrane surface.

One-Pot Synthesis of Mesoporous Anatase-TiO2(B) Mixed-Phase Nanowires Decorated with Sulfur and Fe2O3 Nanoparticles for Visible-Light Photochemical Oxidation

We present a facial one‐pot synthesis method for fabrication of mesoporous anatase‐TiO2(B) mixed‐phase nanowires (TNWs) decorated with sulfur and Fe2O3 nanoparticles (NPs). Through one‐pot calcination, control of morphology and crystal phase for TNWs was easily achieved. After calcined at 773u2005K, mixed‐phase heterostructured TNWs with mesoporous structure and high surface area were obtained. This can not only lead ultrafine NPs well‐disperse in porous matrix, but also greatly enhance interfacial separation and transfer of photo‐induced charges between various planes. Moreover, sulfur doping improved acid/light properties of solid and brought more orbital‐overlapping between active sites and H2O2. The prepared S‐Fe2O3/anatase‐TiO2(B) TNWs had excellent catalytic ability in visible‐light assisted Fenton oxidation at neutral pH, which was attributed to the synergistic effect of sulfur species, NPs and TNWs. The progresses are valuable in developing highly efficient and green heterogeneous catalysts.

Advanced membrane bioreactors systems: New materials and hybrid process design

Membrane bioreactor (MBR) is deemed as one of the most powerful technologies for efficient municipal and industrial wastewater treatment around the world. However, low microbial activity of activated sludge and serious membrane fouling still remain big challenges in worldwide application of MBR technology. Nowadays, more and more progresses on the research and development of advanced MBR with new materials and hybrid process are just on the way. In this paper, an overview on the perspective of high efficient strains applied into MBR for biological activity enhancement and fouling reduction is provided first. Secondly, as emerging fouling control strategy, design and fabrication of novel anti-fouling composited membranes are comprehensively highlighted. Meanwhile, hybrid MBR systems integrated with some novel dynamic membrane modules and/or with other technologies like advanced oxidation processes (AOPs) are introduced and compared. Finally, the challenges and opportunities of advanced MBRs combined with bioenergy production in wastewater treatment are discussed.

Oscillating membrane photoreactor combined with salt-tolerated Chlorella pyrenoidosa for landfill leachates treatment

In this study, a novel oscillating membrane (OM) photoreactor combined with salt-tolerated Chlorella was developed for old landfill leachates treatment, in which harvesting of highly-active algae was easily performed on large scale. Compared with control membrane photo-bioreactor (CMPBR), OM-MPBR exhibited excellent NH3-N removal efficiency as high as 94.0%. With light time prolonged, an increase in biomass production and NH3 removal rates was observed due to more energy provided for Chlorella cells. By comparison, it was found the highest membrane flux (99.6u202fL/m2u202fhu202fbar) was obtained in OM-MPBR, which was attributed to strong shear stress on interface of liquid/membrane effectively reducing bio-foulants. It was clear that energy consumptions of OM-MPBR on biomass productivity (0.68u202fkWh/kgu202fcell) and NH3 removal (0.0151u202fkWh/kgu202fNH3-N) were lower than CMPBR. The new coupling system opens a door to scalable development of promising and economical MBR for environmental pollution control and biomass energy production.

The Exploration of Integrated Practice Base Construction of “Industry-University-Research” to Cultivate High Quality Postgraduate

This paper explains and explores through the establishment of integration of industry-university-research and practice base, university and society joint training the postgraduate as a kind of combine theory study and practice of the new education pattern, change the previous traditional closed pattern of postgraduate education, improve the innovation ability and practice ability of postgraduate and help to improve the graduate students comprehensive quality and ability. The establishment of the integration of industry-university-research and practice base is giving full play to the advantages of university disciplines and talents, help enterprises to improve the level of technology and management, realize the service society, and as the effective ways to promote economic development.