Leaching of nickel-molybdenum sulfide ore in membrane biological reactor

The bioleaching of molybdenum from its sulfide ore using a Mo-resistant thermophilic bacterium sulfolobus metallics combined with a membrane biological reactor（MBR） was studied.The experimental results showed that the concentration of Mo can be controlled by filter of the membrane in MBR and the toxicity of Mo to microorganism is decreased in the process of bioleaching.It was also evidenced that there were different leaching rates of Ni and Mo when the concentration of Mo was different.After leaching for 20 d in the MBR at Mo concentration of 395 mg/L,the leaching rates of Ni and Mo reached the maximum of 79.57% and 56.23% respectively under the conditions of 100 g/L of mineral density,65 ℃,pH=2 and 1.0 L/min of the aeration rate.While 75.59% Ni and 54.33% Mo were leached out in column without membrane under the same conditions.

Chloroplast Genetic Engineering in Higher Plants

Chloroplast genetic engineering, with several advantages over nuclear genetic engineering, is now regarded as an attractive new technology in basic and applied research, including deepening our understanding of plastid genome, engineering plant metabolic system, generating transplastomic plants with higher resistance to insect, disease, drought and herbicide and bioproducing of antibodies and vaccines. In this review, the principle and operating system for chloroplast genetic engineering and its application in higher plants have been discussed.

RESEARCH ON MEMBRANE BIOREACTOR TREATING DOMESTIC WASTEWATER AND RELATED MECHANISMS

Experiments on treatment of domestic wastewater by membrane bioreactors were carried out.The results showed that this process could produce good quality effluent with low COD,turbidity and total count of bacteria.With intermittent operation and continuous aeration,the membrane flux was kept steady.The mechanisms of removing COD through membrane,the structure of membrane and filtration resistance were also discussed.

STUDY AND SIMULATION OF AN ACTIVATED SLUDGE TREATMENT FOR METHYL VIOLET WASTE WATER

This paper researched a promising biological treatment of methyl violet waste water by methods of activated sludge.Effects of temperature and pH were studied on this process.Kinetic equation of the substrate biodegradation was investigated in the experimental range.It was studied and simulated that flow within the bubble region of this bioreactor according to the κ ε two fluid equation.Simulation results agree well with experimental data.

Effect of Flating Photobioreactor Light-path on the Growth and Organic Matter Accumulation of Isochrysis galbana Parke

[Objective] The paper aims to provide references to cultivate I.galbana in a large scale and explore its medical value.[Method] I.galbana had been cultivated in different light-path flat plate bioreactors,and the growth condition and content of organic matter within cells of I.galbana had been analyzed.[Result] Growth rate and volumetric productivity of I.galbana cells increased as light-path of flat plate bioreactors decreased,however,daily areal output rate rose with the increasing of light path.The smaller the light path of flat plate bioreactors was,the more content of total lipids,protein and polysaccharide it had in I.galbana cells.[Conclusion] It is an effective way to improve production efficiently and reduce the cost by selecting the suitable bioreactors.

Viable but Non-culturable Bacteria in Bioreactorbased Pharmaceutical Wastewater

We aimed to investigate the composition and phylogenetic rela-tionships of the viable but non-culturable （VBNC） state bacteria in pharmaceutical wastewater. [Method] Soil filter was used for constructing bioreactor. Based on the resuscitation- and growth-promoting function of Resuscitation Promoting Factor （Rpf） for VBNC bacteria, VBNC bacteria were isolated by most probable number （MPN） method and dilution-plating method and 16S rRNA gene phylogenetic analysis was carried out. [Result] In MPN culture system, Rpf could promote the resuscitation and growth of some bacteria. There were VBNC advantage floras that sensitive to Rpf in pharmaceutical wastewater. The culturable VBNC bacteria in pharmaceutical wastewater consisted of high-GC gram-positive actinomycetes including genera Mi-crobacterium, Gordonia and Leucobacter, and gram-negative bacteria including gen-era Candidimonas, Xanthobacter and Aminobacter. Four strains （ZYM1, ZYM3, ZYZR4, ZYXR1） could be potential novel species. [Conclusion] This research re-vealed there were VBNC bacteria in pharmaceutical wastewater. These results could provide important ideas and methods for further studies on VBNC bacteria in the pharmaceutical wastewater, especial y the formation mechanism and recovery mech-anism of VBNC bacteria and the advanced degradation process improvement of pharmaceutical wastewater.

Nitrogen Removal by Simultaneous Nitrification and Denitrification via Nitrite in a Sequence Hybrid Biological Reactor

Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification （SND） via nitrite. SND via nitrite was achieved in SHBR by controlling demand oxygen （DO） concentration. There was a programmed decrease of the DO from 2.50 mg·L^-1 to 0.30 mg·L^-1, and the average nitrite accumulation rate （NAR） was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L^-1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate. Nitrogen removal efficiency was increased with the increase in NAR, that is, NAR was increased from 60% to 90%, and total nitrogen removal efficiency was increased from 68% to 85%. The SHBR could tolerate high organic loading rate （OLR）, COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively,, and it even operated under low DO concentration （0.5 mg·L^-1） and maintained high OLR （4.0 kg COD·m^-3·d^-1）. The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index （SVI） of activated sludge in SHBR never hit more than 90 ml·L^-1 throughout the experiments.

Effects of nutrients and light intensity on the growth and biochemical composition of a marine microalga Odontella aurita

Algal biotechnology has advanced greatly in the past three decades. Many microalgae are now cultivated to produce bioactive substances. Odontella aurita is a marine diatom industrially cultured in outdoor open ponds and used for human nutrition. For the first time, we have systematically investigated the effects of culture conditions in cylindrical glass columns and fiat-plate photobioreactors, including nutrients （nitrogen, phosphorus, silicon, and sulfur）, light intensity and light path, on O. aurita cell growth and biochemical composition （protein, carbohydrate, β-1,3-glucan, lipids, and ash）. The optimal medium for photoautotrophic cultivation of O. aurita contained 17.65 mmol/L nitrogen, 1.09 mmol/L phosphorus, 0.42 mmol/L silicon, and 24.51 mmol/L sulfur, yielding a maximum biomass production of 6.1-6.8 g/L and 6.7-7.8 g/L under low and high light, respectively. Scale-up experiments were conducted with fiat-plate photobioreactors using different light-paths, indicating that a short light path was more suitable for biomass production of O. aurita. Analyses of biochemical composition showed that protein content decreased while carbohydrate （mainly composed of 15-1,3-glucan） increased remarkably to about 50% of dry weight during the entire culture period. The highest lipid content （19.7% of dry weight） was obtained under 0.11 mmol/L silicon and high light conditions at harvest time. Fatty acid profiles revealed that 80% were Cx4, C^6, and C20, while arachidonic acid and eicosapentaenoic acid （EPA） accounted for 1.6%-5.6% and 9%-20% of total fatty acids, respectively. High biomass production and characteristic biochemical composition profiles make O. aurita a promising microalga for the production ofbioactive components, such as EPA and D-1,3-glucan.

A system combining microbial fuel cell with photobioreactor for continuous domestic wastewater treatment and bioelectricity generation

A coupled system consisting of an upflow membrane-less microbial fuel cell (upflow ML-MFC) and a photobioreactor was developed, and its effectiveness for continuous wastewater treatment and electricity production was evaluated. Wastewater was fed to the upflow ML-MFC to remove chemical oxygen demand (COD), phosphorus and nitrogen with simultaneous electricity generation. The effluent from the cathode compartment of the upflow ML-MFC was then continuously fed to an external photobioreactor for removing the remaining phosphorus and nitrogen using microalgae. Alone, the upflow ML-MFC produces a maximum power density of 481 mW/m 3 , and obtains 77.9% COD, 23.5% total phosphorus (TP) and 97.6% NH4+-N removals. When combined with the photobioreactor, the system achieves 99.3% TP and 99.0% NH4+-N total removal. These results show both the effectiveness and the potential application of the coupled system to continuously treat domestic wastewater and simultaneously generate electricity and biomass.

Antioxidation Activities of Low-Molecular-Weight Gelatin Hydrolysate Isolated from the Sea Cucumber Stichopus japonicus

Gelatin extracted from the body wall of the sea cucumber （Stichopus japonicus） was hydrolyzed with flavourzyme. Low-molecular-weight gelatin hydrolysate （LMW-GH） of 700-- 1700 Da was produced using an ultrafiltration membrane bioreaetor system. Chemiluminescence analysis revealed that LMW-GH scavenges high free radicals in a concentration-dependent manner; IC50 value for superoxide and hydroxyl radicals was 442 and 285 μgmL-1, respectively. LMW-GH exhibited excellent inhibitory characteristics against melanin synthesis and tyrosinase activity in B16 cells. Furthermore, LMW-GH notably increased in- traeellular glutathione （GSH）, which in turn suppressed melanogenesis. LMW-GH performs antioxidation activity, holding the potential of being used as a valuable ingredient in function foods, cosmetics and pharmaceuticals or nutriceuticals.

Design and 3D Printing of Scaffolds and Tissues

A growing number of three-dimensional(3D)-print- ing processes have been applied to tissue engineering. This paper presents a state-of-the-art study of 3D-printing technologies for tissue-engineering applications, with particular focus on the development of a computer-aided scaffold design system; the direct 3D printing of functionally graded scaffolds; the modeling of selective laser sintering(SLS) and fused deposition modeling(FDM) processes; the indirect additive manufacturing of scaffolds, with both micro and macro features; the development of a bioreactor; and 3D/4D bioprinting. Technological limitations will be discussed so as to highlight the possibility of future improvements for new 3D-printing methodologies for tissue engineering.

Micro-Polluted Surface Water Treatment by PAC-MBR Process

A kind of hybrid membrane process, which integrated powdered activated carbon (PAC) with membrane bioreactor (MBR), was designed for bench scale experiment for micro-polluted surface water treatment. Molecular weight analysis was used to evaluate the efficiency of each unit process and the integration of them. The result of analysis indicated that organic molecules in the treated water from PAC-MBR process were concentrated on the section of below 1000, while PAC adsorption could enhance the removal efficiency of this section due to the high percent of biodegradation recalcitrant organic matter with low molecular weight. It was demonstrated that PAC adsorption and biological treatment promoted each other in PAC-MBR process, with a removal efficiency of 70% for COD Mn and UV 254, 100% for UV 410 and 92% for ammonia nitrogen in its stable stage.

Biological Nutrient Removal in a Full Scale Anoxic/Anaerobic/Aerobic/ Pre-anoxic-MBR Plant for Low C/N Ratio Municipal Wastewater Treatment

A novel full scale modified A2O （anoxic/anaerobic/aerobic/pre-anoxic）-membrane bioreactor （MBR） plant combined with the step feed strategy was operated to improve the biological nutrient removal （BNR） from low C/N ratio municipal wastewater in Southern China. Transformation of organic carbon, nitrogen and phosphorus, and membrane fouling were investigated. Experimental results for over four months demonstrated good efficiencies for chemical oxygen demand （COD） and NH4^＋-N removal, with average values higher than 84.5%and 98.1%, re-spectively. A relatively higher total nitrogen （TN） removal efficiency （52.1%） was also obtained at low C/N ratio of 3.82, contributed by the configuration modification （anoxic zone before anaerobic zone） and the step feed with a distribution ratio of 1：1. Addition of sodium acetate into the anoxic zone as the external carbon source, with a theoretical amount of 31.3 mg COD per liter in influent, enhanced denitrification and the TN removal efficiency in-creased to 74.9%. Moreover, the total phosphate （TP） removal efficiency increased by 18.0%. It is suggested that the external carbon source is needed to improve the BNR performance in treating low C/N ratio municipal waste-water in the modified A^2O-MBR process.

Removal of Di-n-butyl Phthalate Using Immobilized Microbial Cells

The biodegradation of di-n-butyl phthalate （DBP） using immobilized microbial cells was carded out in an internal airlift loop reactor with ceramic honeycomb supports. A strain that is capable of degrading DBP was isolated from the activated sludge and identified as Bacillus sp. using 16S rDNA sequential analysis. Bacillus sp. could be rapidly attached onto the ceramic honeycomb supports. The immobilized cells could effectively degrade DBP in batch and continuous experiments. When the influent concentration of DBP was 50mg·L^-1, the effluent DBP reached less than lmg.L i with 6h hydraulic retention time （HRT） in continuous experiment. The immobilized microbial cells could grow and accumulate through the biodegradation of DBP, and the rate of degradation is accordingly increased. The possible pathway of DBP biodegradation using immobilized cells was tentatively proposed.

Prevalence of porcine endogenous retrovirus in Chinese pig breeds and in patients treated with a porcine liver cell-based bioreactor

AIM： To determine the prevalence of porcine endogenous retrovirus （PERV） in various pig breeds raised in China including Chinese experimental mini-pigs by PERV-reverse transcriptase （PERV-RT enzyme）. Moreover, the potential for infection of PERV was investigated in patients treated with a bioreactor based on porcine liver cells （n = 3）. METHODS： Pig serum, liver and muscle cell-free supernatants were collected from various Chinese pig breeds. Porcine hepatocytes were isolated with a two-step perfusion method. Three patients with acute or chronic liver failure were treated with a bioartificial liver support system （BALSS） for 8-12 h and serum samples were collected from the patients before, immediately after and 30 d after treatment. RESULTS： The activities of PERV-RT enzyme in pig liver and muscle cell-free supernatants were higher than in normal human controls. PERV-TR enzyme activity did not increase in patients before and after 1 mo of treatment. PERV-RT activities were not significantly different when compared with pre-treatment group （1.544±0.155576）, the post-treatment groups （1.501±0.053507, 1.461±0.033808 and 1.6006667±0.01963 for 0, 14 and 30 d post-treatment, respectively, P〉0.05）, and normal control group （1.440±1.0641, P〉0.05）. RT enzyme activity in Chinese experimental mini-pigs was higher than in normal human control group （1.440±1.0641 U/mL, P〈0.05）, and not significantly different （P〉0.05） when compared with the pig breeds except in the muscle supernatants. All the samples including muscle and liver cell supernatants from the Chinese mini-experimental pigs and the four domestic Chinese pig breeds contained PERVs. CONCLUSION： These results suggest that the risk of PERV infection through BALSS containing porcine liver cells without immunosuppressants may be quite low. Although there were PERVs in Chinese experimental mini-pigs and porcine liver cell culture suspensions, we did not find any evidence of persistent PERV infection in patients treated with this porcine hepatocyte-based bioartificial liver.

Treatment of Benzene,Toluene and Xylene Contaminated Air in a Bioactive Foam Emulsion Reactor

A novel bioactive foam emulsion bioreactor for benzene,toluene and xylene(BTX)contaminated air streams treatment has been developed.The gas-liquid interfacial area by biocompatible foam and driving force for mass transfer by a water immiscible organic phase were increased in this reactor.The effect of several parameters such as gas residence time,oxygen content,and organic phase concentration on bioreactor performance was studied. Experimental results showed an average elimination capacity(EC)of 220 g·m3·h -1with removal efficiency(RE) of 89.59%for BTX inlet concentration of 1 g·m3at 15 s gas residence time in the bioreactor.The statistical developed model predicted that the maximum elimination capacity of the reactor for BTX could be reached to 423.45 g·m3·h -1.Continues operation of the bioreactor with high EC and RE was demonstrated by optimizing the operational parameters of the bioreactor.Overall the results suggest that the bioreactor developed can be very effective systems to treat BTX vapors.

Comparison of Fe^(2+) oxidation by Acidithiobacillus ferrooxidans in rotating-drum and stirred-tank reactors

Fe2＋ oxidation by Acidithiobacillus ferrooxidans（At.ferrooxidans） under different solid contents by adding inert Al2O3 powder was examined in rotating-drum and stirred-tank reactors.The results show that the bioactivity of At.ferrooxidans in the stirred-tank is higher than that in the rotating-drum in the absence of Al2O3 powder,but the biooxidation rate of Fe2＋ decreases markedly from 0.23 g/（L·h） to 0.025 g/（L·h） with increasing the content of Al2O3 powder from 0 to 50%（mass fraction） in the stirred-tank probably due to the deactivation of At.ferrooxidans resulting from the collision and friction of solid particles.The increase in Al2O3 content has a little adverse effect on the bioactivity of At.ferrooxidans in the rotating-drum due to different mixing mechanisms of the two reactors.The biooxidation rate of Fe2＋ in the rotating-drum is higher than that in the stirred-tank at the same content of Al2O3 powder,especially at high solid content.The higher bioactivity of At.ferrooxidans can be maintained for allowing high solid content in the rotating-drum reactor,but its application potential still needs to be verified further by the sulfide bioleaching for the property differences of Al2O3 powder and sulfide minerals.

Reconstruction of liver organoid using a bioreactor

AIM： To develop the effective technology for reconstruction of a liver organ in vitro using a bio-artificial liver. METHODS： We previously reported that a radial-flow bioreactor （RFB） could provide a three-dimensional highdensity culture system. We presently reconstructed the liver organoid using a functional human hepatocellular carcinoma cell line （FLC-5） as hepatocytes together with mouse immortalized sinusoidal endothelial cell （SEC） line M1 and mouse immortalized hepatic stellate cell （HSC） line A7 as non parenchymal cells in the RFB. Two × 10^7 FLC-5 cells were incubated in the RFB. After 5 d, 2 × 10^7 A7 cells were added in a similar manner followed by another addition of 10^7 M1 cells 5 d later. After three days of perfusion, some cellulose beads with the adherent cells were harvested. The last incubation period included perfusion with 200 nmol/L swinholide A for 2 h and then the remaining cellulose beads along with adherent cells were harvested from the RFB. The cell morphology was observed by transmission electron microscopy （TEM） and scanning electron microscopy （SEM）. To assess hepatocyte function, we compared mRNA expression for urea cycle enzymes as well as albumin synthesis by FLC-5 in monolayer cultures compared to those of single-type cultures and cocultures in the RFB. RESULTS： By transmission electron microscopy, FLC-5, M1, and A7 were arranged in relation to the perfusion side in a liver-like organization. Structures resembling bile canaliculi were seen between FCL-5 cells. Scanning electron microscopy demonstrated fenestrae on SEC surfaces. The number of vesiculo-vacuolar organelles （WO） and fenestrae increased when we introduced the actin-binding agent swinholide-A in the RFB for 2h. With respect to liver function, urea was found in the medium, and expression of mRNAs encoding arginosuccinate synthetase and arginase increased when the three cell types were cocultured in the RFB. However, albumin synthesis decreased. CONCLUSION： Co-culture in the RFB system can dramatically change the structure and function of all cell types, including the functional characteristics of hepatocytes. Our system proves effective for reconstruction of a liver organoid using a bio-artificial liver.

Effect of substrate concentration on stability of anammox biofilm reactors

Ammonium and nitrite are two substrates of anammox bacteria, but they are also inhibitors under high concentrations. The performance of two anaerobic ammonium-oxidizing (anammox) upflow biofilm (UBF) reactors was investigated. The results show that anammox UBFs become unstable under nitrogen loading rate (NLR) applied higher than 1.0 g/(L·d). The consumptions of acidity in the anammox reaction lead to the increase of pH, which is as high as 8.70-9.05. Free nitrous acid concentration is accompanied to be lower than the affinity constant of anammox bacteria, and then starvation effect appears. Moreover, free ammonia concentration increases to 57-178 mg/L, resulting in inhibitory effect on the anammox bacteria. Both negative effects contribute to the instability of the anammox bioreactors.