Aiming to achieve simultaneous good performances of in-situ sludge reduction and effluent quality,an integrated repeatedly coupling aerobic and anaerobic and oxic-setting-anaerobic system( r CAA + OSA) is developed to reduce sludge production and enhance nutrient removal. Considering the mechanism of in-situ sludge reduction in this r CAA +OSA system,the combined effect of energy uncoupling metabolism and sludge cryptic growth maybe attributed to the higher reduction of biomass. Results show that the maximal sludge reduction in this r CAA + OSA system is obtained when the hydraulic retention time( HRT) is controlled at6. 5 h,which an increase in 16. 67% reduction in excess sludge is achieved compared with OSA system( HRT of 6. 5 h). When compared the performances of effluent qualities,the enhanced nutrient removal efficiencies also can be observed in this r CAA + OSA system. Three-dimensional excitation emission matrix( 3D-EEM)fluorescence spectroscopy is applied to characterize the effluent organic matters( Ef OM) under different HRTs in the OSA and the r CAA+OSA systems. Analyses of 3D-EEM spectra show that more refractory humic-like and fulvic-like components are observed in the effluent of the OSA system. On the basis of these results,simultaneous enhanced in-situ sludge reduction and improved nutrient removal can be obtained in the r CAA +OSA systems.
This study aims at investigating the effects of ultrasonic and acid pretreatment on food waste( FW)disintegration and volatile fatty acid( VFA) production. Single-factor experiments are carried out to obtain optimal conditions of individual ultrasonic and acid pretreatment,and response surface method( RSM) is applied to optimize the conditions of the combination of ultrasonic and acid( UA) pretreatment. Results show that the optimal acid,ultrasonic and UA pretreatments conditions are individual pH 2,individual ultrasonic energy density of 1. 0 W / mL and the combination of ultrasonic energy density1. 11 W / mL and pH 1. 43,respectively. Correspondingly,the maximum disintegration degrees( DD) of 46. 90%,57. 38% and68. 83%are obtained by acid,ultrasonic and UA pretreatments,respectively. After optimizing pretreatment conditions,batch experiments are operated to produce VFA from raw and pretreated FW under anaerobic fermentation process. Both the maximum VFA production( 976. 17 mg COD / gV S) and VFA / SCOD( 72. 89%) are obtained with ultrasonic pretreatment, followed by UA pretreatment, non-pretreatment and acid pretreatment,respectively. This observation demonstrates that a higher acidity on acid and UA pretreatments inhibits the generation of VFA. Results suggest that ultrasonic pretreatment is preferable to promote the disintegration degree of FW and VFA production.
The colloidal properties of biogenic elemental sulfur(S^0)cause solid–liquid separation problems,such as poor settling and membrane fouling.In this study,the separation of S^0 from bulk liquids was performed using flocculation.Polyaluminum chloride(PAC),polyacrylamide(PAM)and microbial flocculant(MBF)were compared to investigate their abilities to flocculate S^0 produced during the treatment of sulfate-containing wastewater.A novel approach with response surface methodology(RSM)was employed to evaluate the effects and interactions of flocculant dose,pH and stirring intensity,on the treatment efficiency in terms of the S^0 flocculation and the supernatant turbidity removal.The dose optimization results indicated that the S^0 flocculation efficiency decreased in the following order PAC>MBF>PAM.Optimum S^0 flocculation conditions were observed at pH 4.73,a stirring speed of 129 r/min and a flocculant dose of 2.42 mg PAC/mg S.During optimum flocculation conditions,the S^0f locculation rate reached 97.53%.Confirmation experiments demonstrated that employing PAC for S^0 flocculation is feasible and RSM is an efficient approach for optimizing the process of S^0 flocculation.The results provide basic parameters and conditions for recovering sulfur during the treatment of sulfate-laden wastewaters.
Fan ChenYe YuanChuan ChenYoukang ZhaoWenbo TanCong HuangXijun XuAijie Wang
Aims our study quantified the combined effects of fertilization and inoculation with arbuscular mycorrhizal fungi(AMF)on grain yield and allocation of biomass and nutrients in field-grown rice(Oryza sativa l.).Methods a two-factor experiment was conducted at a field site in northeast of China(in shuangcheng,Heilongjiang Province,songhua river basin):six nitrogen-phosphorus-potassium fertilizer levels were provided(0,20,40,60,80 and 100%of the local norm of ferti-lizer supply),with or without inoculation with Glomus mosseae.at maturity,we quantified the percentage of root length colonization by AMF,grain yield,shoot:root ratios,shoot N and P contents and nutrients allocated to panicles,leaves and stems.Important Findingsas expected,inoculation resulted in greatly increased AMF colo-nization,which in turn led to higher shoot:root ratios and greater shoot N contents.shoot:root ratios of inoculated rice increased with increasing fertilization while there was a significant interaction between fertilization and inoculation on shoot:root ratio.additionally,a F inoculation increased panicle:shoot ratios,panicle N:shoot N ratios and panicle P:shoot P ratios,especially in plants grown at low fertilizer levels.Importantly,inoculated rice exhibited higher grain yield,with the maximum improvement(near 62%)at the lower fertilizer end.our results showed that(i)AMFinoculated plants conform to the functional equilibrium theory,albeit to a reduced extent compared to non-inoculated plants and(ii)AMF inoculation resulted in greater allocation of shoot biomass to panicles and increased grain yield by stimulating N and P redis-tribution to panicles.
Bioflocculant-producing bacteria Agrobacterium tumefaciens F2 and Bacillus sphaeicus F6 were immobilized onto mycelial pellets to investigate the bioflocculant-producing potential of this combined organism and the corresponding flocculating efficiency. The atomic force microscope ( AFM) images of mycelial surface indicate that the mycelia pellet can immobilize bioflocculant-producing bacteria F2 and F6 as a biomass carrier. The flocculating efficiency of bioflocculant produced by this combined organism was studied under the optimum flocculating conditions obtained by Response Surface Methodology ( RSM ) . The fermentation yield of the combined mycelial pellet is about 2. 6 g / L,which is higher than that of the free bacteria ( only 2. 2 g / L) . Flocculating efficiency of the combined mycelial pellet was comparable with that of bioflocculant generated by the free bacteria. The bioflocculant yield is enhanced and the flocculating efficiency of the co-culture is uninfluenced after immobilized with mycelial pellet as a carrier. In conclusion,the mycelial pellet is feasible as a biomass carrier for the immobilization of bioflocculant-producing bacteria.
Jin-Na WangFang MaJing-Bo GuoJi-Xian YangAng LiJi-Hua Wang
Carbamazepine is frequently detected in waters and hardly eliminated during conventional wastewater treatment processes due to its complicated chemical structure and resistance to biodegradation. A carbamazepine-degrading bacterium named CBZ-4 was isolated at a low temperature(10°C) from activated sludge in a municipal wastewater treatment plant. Strain CBZ-4, which can use carbamazepine as its sole source of carbon and energy, was identified as Pseudomonas sp. by the 16S rRNA gene sequence. The composition and percentage of fatty acids, which can reveal the cold-adaptation mechanism of strain CBZ-4, were determined. Strain CBZ-4 can efectively degrade carbamazepine at optimal conditions: pH 7.0, 10°C, 150 r/min rotation speed, and 13% inoculation volume. The average removal rate of carbamazepine was 46.6% after 144 hr of incubation. The biodegradation kinetics of carbamazepine by CBZ-4 was fitted via the Monod model. Vmax and Ks were found to be 0.0094 hr 1and 32.5 mg/L, respectively.
Ang LiRui CaiDi CuiTian QiuChanglong PangJixian YangFang MaNanqi Ren
