Process for the Biological Removal of Fe (II) from Reconstituted Waters on a Support of Filter Material with Coated Jujube Seeds

Three beakers for removing Fe (II) in reconstituted water (doped with FeSO4) were built and tested. Given the set operating conditions ([O2] > 4 mg·L-1, Patm = 1.013 bar, T = 25°C ± 1°C and [Fe2+]0 = 0.5 to 2 mg·L-1), removal of iron was caused by biological and possibly physical and chemical oxidation because there is a quantity of free oxygen in the medium. The extent of each type of oxidation has not been evaluated as it specifically studies the biological degradation of iron in these beaker tests by setting the operating conditions (pH > 6.5, dissolved oxygen from 0 to 8 mg·L-1, Redox Potential from 100 to 400 mV). The experimental studies focused particularly on the measurements of maximum wavelength, conversion efficiencies from Fe (II) to Fe (III), the effect of the Fe (II) concentration, the influence of pH, the action of the temperature of the prepared solutions and the effect of O2 concentration under specified operating conditions. It noticed precipitated amounts of iron deposited at the bottom of the beakers. Thus, the low concentrations of Fe (II) detected in the influent after the biological oxidation operation could be attributed to microorganisms that consume iron as a substrate.

In situ characterization of natural pyrite bioleaching using electrochemical noise technique

An in situ characterization technique called electrochemical noise（ECN） was used to investigate the bioleaching of natural pyrite.ECN experiments were conducted in four active systems（sulfuric acid,ferric-ion,9k culture medium,and bioleaching solutions）.The ECN data were analyzed in both the time and frequency domains.Spectral noise impedance spectra obtained from power spectral density（PSD）plots for different systems were compared.A reaction mechanism was also proposed on the basis of the experimental data analysis.The bioleaching system exhibits the lowest noise resistance of 0.101 MΩ The bioleaching of natural pyrite is considered to be a bio-battery reaction,which distinguishes it from chemical oxidation reactions in ferric-ion and culture-medium（9k） solutions.The corrosion of pyrite becomes more severe over time after the long-term testing of bioleaching.

STUDY ON BIOLEACHING OF PRIMARY CHALCOPYRITE ORE WITH THERMOACIDOPHLIC ARCHAE

A high temperature-tolerating thermoacidophilic archae （TA） was isolated from water samples collected from a hot sulfur-containing spring in the Yunnan Province, China, and was used in bioleaching experiments of a low-grade chalcopyrite ore. The TA grow at temperatures ranging from 40 to 80℃, with 65℃ being the optimum temperature, and at pH values of l.5 to 4.0, with an optimum pH value of 2.0. The bioleaching experiments of the chalcvpyrite ore were conducted in both laboratory batch bioreactors and leaching columns. The results obtained from the bioreactor experiments showed that the TA bioleaching rate of copper reached 97% for a 12-day leaching period, while the bioleaching rate was 32.43% for thiobacillus ferrooxidans （Tf） leaching for the same leaching time. In the case of column leaching, tests of a two-phase leaching （196 days）, that is, a two-month （56 days） Tf leaching in the first phase, followed by a 140-day TA leaching in the second phase were performed. The average leaching rate of copper achieved for the 140-day TA leaching was 195mg/（L.d）, while for the control experiments, it was as low as 78mg/（L .d） for the Tf leaching, indicating that the TA possesses a more powerful oxidizing ability to the chalcopyrite than Tf Therefore, it is suggested that the two-phase leaching process be applied to .for the heap leaching operations, whereas, the TA can be used in the second phase when the temperature inside the heap has increased, and the primary copper sulfide minerals have already been partially oxidized with Tf beforehand in the first phase.

Profiling of microbial communities in a bioreactor for treating hydrocarbon-sulfide-containing wastewater

A technology of polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)was used to profile the structure and dynamic changes of microbial communities in a bioreactor for treating hydrocarbon-sulfide-containing(HSC)wastewater.The results showed that the heterotrophic genus of Acinetobacter and the autotrophic genera of Thiobacillus and Thiomonas could survive well in all of three operating conditions.Some special genera were also observed with changes of micro-ecoenvironment in the reacto...

Field experiment on biological contact oxidation process to treat polluted river water in the Dianchi Lake watershed

In this study two types of biological contact oxidation processes(BCOP),a step-feed(SBCOP)unit and an inter-recycle(IBCOP)unit,were designed to investigate the treatment of heavily polluted river water.The Daqing River,which is the largest pollutant contributor to the Dianchi Lake,one of the most eutrophic freshwater lakes in China,was taken for the case study.It was found that the SBCOP had higher adaptability and better performance in the reduction of COD,TN,and TP,which made it applicable for the treatment of polluted river water entering the Dianchi Lake.Nitrification rate was observed to be greatly affected by the influent temperature.During each season,the nitrification in the SBCOP was higher than that in the IBCOP.TN removal efficiency in the SBCOP was higher than that in the IBCOP during the winter and spring but poorer during the summer,possibly due to the inhibition of denitrification by higher dissolved oxygen level in the summer.Moreover,symbiotic algaebacteria growth may be conducive to the removal of pollutants.

The endogenous antioxidant ability of royal jelly in Drosophila is independent of Keap1/Nrf2 by activating oxidoreductase activity

Royal jelly(RJ)is a biologically active substance secreted by the hypopharyngeal and mandibular glands of worker honeybees.It is widely claimed that RJ reduces oxidative stress.However,the antioxidant activity of RJ has mostly been determined by in vitro chemical detection methods or by external administration drugs that cause oxidative stress.Whether RJ can clear the endogenous production of reactive oxygen species(ROS)in cells remains largely unknown.Here,we systematically investigated the antioxidant properties of RJ using several endogenous oxidative stress models of Drosophila.We found that RJ enhanced sleep quality of aging Drosophila,which is decreased due to an increase of oxidative damage with age.RJ supplementation improved survival and suppressed ROS levels in gut cells of flies upon exposure to hydrogen peroxide or to the neurotoxic agent paraquat.Moreover,RJ supplementation moderated levels of ROS in endogenous gut cells and extended lifespan after exposure of flies to heat stress.Sleep deprivation leads to accumulation of ROS in the gut cells,and RJ attenuated the consequences of oxidative stress caused by sleep loss and prolonged lifespan.Mechanistically,RJ prevented cell oxidative damage caused by heat stress or sleep deprivation,with the antioxidant activity in vivo independent of Keap1/Nrf2 signaling.RJ supplementation activated oxidoreductase activity in the guts of flies,suggesting its ability to inhibit endogenous oxidative stress and maintain health,possibly in humans.

Impact of dissolved oxygen on the production of nitrous oxide in biological aerated filters

Polymerase chain reaction-denaturing gradient gel electrophoresis （pCR-DGGE） and microelectrode technology were employed to evaluate the Nitrous oxide （N2O） production in biological aerated filters （BAFs） under varied dissolved oxygen （DO） concentrations during treating wastewater under laboratory scale. The average yield of gasous N2O showed more than 4-fold increase when the DO levels were reduced from 6.0 to 2.0 mg·L^-1, indicating that low DO may drive N2O generation. PCRDGGE results revealed that Nitratifractor salsuginis were dominant and may be responsible for N2O emission from the BAFs system. While at a low DO concentration （2.0 mg·L^-1）, Flavobacterium urocaniciphilum might playa role. When DO concentration was the limiting factor （reduced from 6.0 to 2.0 mg·L^-1） for nitrification, it reduced NO2^--N oxidation as well as the total nitrification. The data from this study contribute to explain how N2O production changes in response to DO concentration, and may be helpful for reduction ofN2O through regulation of DO levels.

Comparison and modeling of two biofilm processes applied to decentralized wastewater treatment

In order to control water pollution in the rapidly urbanizing South China area,biological contact oxidation(BCO)process and biological aerated filter(BAF)process were applied in a pilot-scale experiment for decentralized wastewater treatment.An investigation to find the optimal parameters of the two biofilm systems was conducted on hydraulic loading,organic loading,and aeration rate.The results indicated that the water reuse criteria required a maximum hydraulic and organic loading of 30.0 m^(3)/(m^(2)·d)and 4.0 kg COD/(m^(3)·d),respectively,as well as a minimum effluent DO of 4.0 mg/L.The utilization of a new media allowed BAF to perform better than BCO.The kinetic description of the COD removal process for BAF and BCO are Se=S0e^(-0.639t)/(1+1.035t),and S_(e)=S_(0)/[(1+0.947t)(1+1.242t)],respectively.The correlativity analysis showed that the two models could predict the effluent water quality based on the hydraulic retention time.Thus,the appropriate hydraulic loading for certain effluent water quality demands could be determined.The two models could be applied to wastewater treatment practice.

Aerobic N_2O emission for activated sludge acclimated under different aeration rates in the multiple anoxic and aerobic process

Nitrous oxide（N_2O） is a potent greenhouse gas that can be emitted during biological nitrogen removal. N_2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600 m L/min sequencing batch reactor（SBRL） and 1200 m L/min（SBRH）.The nitrogen removal percentage was 89% in SBRLand 71% in SBRH, respectively. N_2O emission mainly occurred during the aerobic phase, and the N_2O emission factor was 10.1%in SBRLand 2.3% in SBRH, respectively. In all batch experiments, the N_2O emission potential was high in SBRLcompared with SBRH. In SBRL, with increasing aeration rates, the N_2O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification（SND）. By contrast, in SBRHthe N_2O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N_2O emission during biological nitrogen removal.