Yanzhen Yu

The characteristics and effect of grain-slag media for the treatment of phosphorus in a biological aerated filter (BAF)

Abstract Haydite and grain-slag, a new type of filter media made of grain slag, were used as filter media for biological aerated filter (BAF) to treat synthetic wastewater in parallel. The aim of this study was to compare the phosphorus removal performance of two BAF reactors at the different influent pH values, hydraulic retention time (HRT), and phosphorus load rates. It demonstrated that the BAF packed with grain-slag showed higher phosphate removal efficiency than with haydite. The removal of phosphate by the grain-slag BAF was in the range of 75.21–84.98%; 63.10–70.44%; 40.49–48.02%; and 26.10–33.11%, respectively, under the HRT of 12, 8, 5, and 1 h. The results obtained from the study of phosphate removal rate vs. pH values indicated that grain-slag BAF could remove phosphorus effectively by biologically induced chemical precipitation and the sediments do not affect the effluent turbidity.

Stimulation effect of electric current density (ECD) on microbial community of a three dimensional particle electrode coupled with biological aerated filter reactor (TDE-BAF).

Improving the stimulation effect of electric current density (ECD) on microbial community is critical in designing and operating TDE-BAF. This study investigated the effect of ECD at 0.00, 4.08, 6.12, 12.20, 14.25, 16.30 and 20.20A·m-2 on the removal performance, diversity and structure of microbial community in TDE-BAF. Results indicated that the ECD of 14.25A·m-2 exhibited the highest COD, TOC and NH4+-N average removal rates with 93.33%, 91.26% and 93.87%, respectively; Under high ECD, especially exceeding 14.25A·m-2, the inhibition of growth and activity because of plasmatorrhexis was in agreement with the sharp biomass decline; there was no significant relation between community richness and diversity and removal efficiency below optimum ECD, while above optimal ECD, it was just the opposite; Microbial communities mainly including Hydrogenophaga, Saprospiraceae_uncultured, Delftia, Enterobacter, Pseudomonas, Pseudoxanthomonas, and Nitrosospira and physicochemical properties well explained the excellent removal performance at the optimum ECD.

Optimization and modeling of preparation conditions of poly-Si-Fe-Zn (PSFZ) coagulant from industrial wastes using response surface methodology

AbstractA new composite coagulant poly-Si-Fe-Zn (PSFZ) was synthesized using industrial wastes as main raw materials and parameters affecting the coagulant performance, such as polymerization temperature, time, and Si/(Fe + Zn) moral ratio in this study, were examined. In addition, to obtain the optimum preparation conditions resulting in the maximum turbidity and ammonia nitrogen (NH3-N) removal, response surface methodology was used to assess their interactive effects on coagulation performance, and quadratic models based on the high value (>0.97) of determination coefficient (R2) were conducted for the response variables: turbidity and NH3-N removal efficiency. The results showed that optimum preparation conditions were found to be polymerization temperature of 65°C, polymerization time of 80 min, and Si/(Fe + Zn) moral ratio of 0.73, corresponding to predicted turbidity and NH3-N removal percentages of 96 and 77.03, respectively. Besides, the structure and morphology of PSFZ were characterized by X-ra...

Preparation of particle electrodes from manganese slag and its degradation performance for salicylic acid in the three-dimensional electrode reactor (TDE)

Salicylic acid (SA) is a class of trace pollutants widely presented in the environment belonged to pharmaceuticals and personal care products. It is difficult to remove SA by the traditional treatment processes because of its toxicity. In this paper, the degradation of SA by Mn-loaded Cu/Fe particle electrodes was studied. Firstly, the particle electrodes were prepared by impregnation-roasting method and then characterized by SEM, XRF and XRD. The diffraction peaks of Fe2O3 and CuO in the XRD patterns of the particle electrodes which had the dense spherical particles were significantly increased and the content of CuO and Fe2O3 increased by 1.9% and 3.6% respectively. Secondly, single factor experiments were carried out under conditions of cell voltage, electrolyte concentration, pH, HRT, inter-electrode distance and initial pollutant concentration. Under the optimum conditions of all the factors, the degradation rate of SA reached 76.9%. Then, HPLC and GCMS were employed to deduce the degradation pathways of SA by the TDE with Mn-particle electrodes (Mn-PETDE). Under the action of •OH, SA underwent decarboxylation and substitution reactions and then mineralized after the ring-opening reaction. All results demonstrated that this Mn-PETDE was effective for degradation of SA.

In-Situ Ion Exchange Electrocatalysis Biological Coupling (i-IEEBC) for Simultaneously Enhanced Degradation of Organic Pollutants and Heavy Metals in Electroplating Wastewater

The goal of this research was to develop a new process for simultaneously removing organics and heavy metals of electroplating wastewater by in-situ ion exchange electrocatalysis biological coupling (i-IEEBC). The study evaluated the removal efficiency of coexisting refractory organics and heavy metal ions, and investigated the effects of current density (CD) on the removal performance of the i-IEEBC method. The results indicated the i-IEEBC reactor exhibited higher average removal rates of COD, TOC, Cr and Cu ions, i.e. 87.23%, 80.42%, 91.25%, and 95.97% in that order, which represented an increase by 32.59%, 40.10%, 31.86%, and 33.82%, respectively, compared with BAF. The optimum CD for simultaneously removing organics and heavy metals of electroplating wastewater in i-IEEBC was 0.40 mA/(cm)2. The change of biodegradability and the presence of short chain organic compounds also indirectly confirmed the excellent removal organic pollutants performance of i-IEEBC at the optimum CD. In addition, the composition and construction of CER before and after the application, under the optimum CD, SEM, EDS and FT-IR spectroscopy also showed that the cation exchange properties of CER improved the catalytic lifetime of the particle electrodes. This research provides a highly efficient new alternative to electroplating wastewater treatment technology.