Biodegradation of bezafibrate by the activated sludge under aerobic condition:Effect of initial concentration,temperature and pH

Lab-scale experiments were conducted to investigate the effect of initial concentration,temperature and pH on the removal of bezafibrate(BF)by activated sludge under aerobic condition.The results showed that adsorption of BF onto activated sludge was negligible,and biodegradation was the main removal mechanism of BF.The removal of BF in the aqueous phase by the activated sludge can be described by a pseudo-first-order reaction.The reaction rate constants had a negative relationship with the initial concentration of BF,and dramatically reduced from 0.050 to 0.007 h^-1,when the temperature dropped from 20℃to 10℃.Variation of pH between 5.0 and 9.0 did not have significant influence on the removal of BF,indicating a high adaptation of microorganism in the activated sludge responsible for BF degradation to a wide pH range.The findings of this study are helpful to improve the removal of pharmaceuticals during the wastewater treatment plants by selecting the appropriate process variables,and eventually eliminate their release to the environment.

Stepwise superposition approximation approach for analytical solutions with non-zero initial concentration using existing solutions of zero initial concentration in contaminate transport

Analytical solutions for contaminant transport are widely used for both theoretical and practical purposes.However,many existing solutions are obtained subject to an initial condition of zero concentration,which is often unrealistic in many practical cases.This article proposed a stepwise superposition approximation approach to solve the non-zero initial concentration problem for first-type and third-type boundary conditions by using the existing zero initial concentration solution.Theoretical examples showed that the approach was highly efficient if a proper superposition scheme with relative concentration increments was constructed.The key parameter that controlled the convergence speed was the time increment（△t） multiplied by the rate constant（λ）.The approach served also as an alternative way to make a convenient concentration calculation even if the non-zero initial concentration solution of a problem was known.

Evaluating the effects of granular and membrane filtrations on chlorine demand in drinking water

In this study, chlorine decay experiments were conducted for the raw water from Nakdong River that is treated by Chllseo Water Treatment Plant （CWTP） situated in Haman, Korea as well as the effluents from sand and granular activated carbon （GAC） filters of CWTP and fitted using a chlorine decay model. The model estimated the fast and slow reacting nitrogenous as well as organic/inorganic compounds that were present in the water. It was found that the chlorine demand due to fast and slow reacting （FRA and SRA） organic/inorganic substances was not reduced significantly by sand as well as GAC filters. However, the treated effluents from those filters contained FRA and SRA that are less reactive and had small reaction rate constants. For the effluents from microfiltration, ultrafiltration, and nanofiltration the chlorine demand because FRA and SRA were further reduced but the reaction rate constants were larger compared to those of sand and GAC filter effluents. This has implications in the formation of disinfection by products （DBPs）. If DBPs are assumed to form due to the interactions between chlorine and SRA, then it is possible that the DBP formation potential in the effluents from membrane filtrations could be higher than that in the effluents from granular media filters.

Effects of sludge retention time,carbon and initial biomass concentrations on selection process:From activated sludge to polyhydroxyalkanoate accumulating cultures

Four sequence batch reactors（SBRs） fed by fermented sugar cane wastewater were continuously operated under the aerobic dynamic feeding（ADF） mode with different configurations of sludge retention time（SRT）, carbon and initial biomass concentrations to enrich polyhydroxyalkanoate（PHA） accumulating mixed microbial cultures（MMCs） from municipal activated sludge.The stability of SBRs was investigated besides the enrichment performance. The microbial community structures of the enriched MMCs were analyzed using terminal restriction fragment length polymorphism（T-RFLP）. The optimum operating conditions for the enrichment process were： SRT of 5 days, carbon concentration of 2.52 g COD/L and initial biomass concentration of3.65 g/L. The best enrichment performance in terms of both operating stability and PHA storage ability of enriched cultures（with the maximum PHA content and PHA storage yield（YPHA/S） of61.26% and 0.68 mg COD/mg COD, respectively） was achieved under this condition. Effects of the SRT, carbon concentration and initial biomass concentration on the PHA accumulating MMCs selection process were discussed respectively. A new model including the segmentation of the enrichment process and the effects of SRT on each phase was proposed.

Humic acid transport in saturated porous media:Influence of flow velocity and influent concentration

Understanding the transport of humic acids（HAs） in porous media can provide important and practical evidence needed for accurate prediction of organic/inorganic contaminant transport in different environmental media and interfaces. A series of column transport experiments was conducted to evaluate the transport of HA in different porous media at different flow velocities and influent HA concentrations. Low flow velocity and influent concentration were found to favor the adsorption and deposition of HA onto sand grains packed into columns and to give higher equilibrium distribution coefficients and deposition rate coefficients, which resulted in an increased fraction of HA being retained in columns.Consequently, retardation factors were increased and the transport of HA through the columns was delayed. These results suggest that the transport of HA in porous media is primarily controlled by the attachment of HA to the solid matrix. Accordingly, this attachment should be considered in studies of HA behavior in porous media.

Effects of strain,nutrients concentration and inoculum size on microalgae culture for bioenergy from post hydrothermal liquefaction wastewater

Cultivating microalgae in post hydrothermal liquefaction wastewater(PHWW)offers many benefits,including nutrients recovery and reuse,wastewater purification and biomass production.However,the high nutrients concentration and toxic substances in PHWW undermine the efficiency of biomass production and nutrient recovery.This study aimed to investigate the effects of the microalgae strains,initial nutrients concentrations and inoculum sizes on biomass production and nutrient recovery using PHWW as the cultivation medium.Results indicated that both biomass production and nutrients recovery were successfully improved by using the screened microalgae strain at the desirable initial nutrient concentration with the suggested algae inoculum size.Chlorella vulgaris 1067 probably demonstrated the strongest tolerance ability among the five microalgae strains screened,and performed well in the diluted PHWW,of which initial TN concentration was approximately 500 mg/L.The desirable inoculum size was determined to be 0.103-0.135 g/L.The biomass daily productivity was increased by 15.67-fold(reached 0.13 g/(L·d)).With the above optimal conditions,high biomass production and nutrient recovery from the PHWW to produce microalgae biomass for bioenergy production were achieved.

Study on aerosol agglomeration using the airborne ultrasonic transducer

Acoustic agglomeration technology use high-intensity acoustic field to make aerosol particles collide and condense rapidly. Existing studies have shown that 70%–90% of fine particles can be eliminated within minutes using compression drives and air-jet generators. Currently, there are limitations to the sound sources used. In this paper, an airborne ultrasonic transducer with a resonant frequency of 15 kHz is designed, followed by the corresponding numerical simulation and experiments for the evaluation of the vibration modal and sound pressure field. The sound pressure levels (SPL) of the open space and the agglomeration chamber can reach 150 dB and 156 dB, respectively. The agglomeration effect of water droplets, liquid phase smoke, solid phase smoke and mixed smoke is experimentally investigated, and the light transmittance rapidly increases from 8% to 60% within 4 s, 8 s, 5 s and 6 s, respectively. Agglomeration is also effective in the high-frequency range, and we infer that the acoustic wake effect is the predominant mechanism. The elimination effect is promoted with the increasing of SPL until the corresponding secondary acoustic effect is enhanced. Moreover, the agglomeration rate of higher concentration aerosol is significantly better than that of diluted aerosols in ultrasonic agglomeration process.

Pre-treatment of pyridine wastewater by new cathodic–anodic-electrolysis packing

A novel cathodic–anodic-electrolysis packing（CAEP） used in the treatment of pyridine wastewater was researched, which mainly consisted of 4,4′-diamino-2,2′-disulfonic acid（DSD acid） industrial iron sludge. The physical properties and morphology of the packing were studied. The CAEP was used in a column reactor during the pretreatment of pyridine wastewater. The influence of p H, hydraulic retention time（HRT）, the air–liquid ratio（A/L）and the initial concentration of pyridine were investigated by measuring the removal of total organic carbon（TOC） and pyridine. The characterization results showed that the bulk density, grain density, water absorption percentage and specific surface area were 921 kg/m3,1086 kg/m3, 25% and 29.89 m^2/g, respectively; the removal of TOC and pyridine could reach50% and 58% at the optimal experimental conditions（p H = 3, HRT = 8 hr, A/L = 2）. Notably,the surface of the packing was renewed constantly during the running of the filter, and the handling capacity was stable after running for three months.

A chemical oscillating reaction in NaBrO_3-pyruvic acid-H_2SO_4-[Ni(Me_2[14]1,3-diene N_4)]^(2+) system

In this paper we report a chemical oscillation catalyzed by [Ni(Me2[14]1,3-diene N4)]2+ (Me2[14]l,3-diene N4 denotes 2,3-dimethyl-l,4,8,ll-tetraazacyclotetradeca-1,3-diene) in BrO3--pyruvic acid-H2SO4 system.The domain of the existence of the oscillation was obtained.The effects of initial concentration of the components on the oscillation were studied.The features of the oscillations were described in detail.We also examined the effects of Ag+,Hg2+,CCl4,free radical inhibitors,etc.on the osillations.