Beiping Zhang

Efficient and microbial communities for pollutant removal in a distributed-inflow biological reactor (DBR) for treating piggery wastewater

To treat piggery wastewater with a low C/N ratio, a novel distributed-inflow biological reactor (DBR) was developed that assures the proper organic flow for an efficient denitrification process. The operation of the DBR featured the use of continuous feeding and bypass flow rates (x = 0.2–0.5). Results demonstrated that under low C/N ratio conditions (3.8–5.4), bypass rates of 0.3–0.4 were desirable and resulted in COD, NH4+–N, and TN removal efficiencies of 89.2%, 97.4%, and 86.2%, respectively. Track studies elucidated the removal and transformation of organic matter and nitrogen in the DBR. High-throughput sequencing showed that Proteobacteria and Bacteroidetes were dominant in both the DBR and the sludge obtained from a wastewater treatment plant (WWTP) for seeding the DBR. Compared with the seed sludge, the populations of aerobic heterotrophic bacteria (Filimonas and Chryseolinea) and heterotrophic denitrifiers (Thauera, Halomonas, and Ottowia) were apparently enriched in DBR, and were mainly responsible for the removal of COD and NO3−–N. In contrast, the populations of ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) decreased sharply. Although stable nitrification was achieved, autotrophic nitrifiers such as AOB and NOB were unexpectedly present as minor species, probably due to the synergistic effects of autotrophic AOB and heterotrophic nitrifiers.

Feasibility Study on the Pyrolysis Production for Hydrogen-Riched Fuel Gas from the Wet Sewage Sludge

The feasibility of producing hydrogen-riched fuel gas from wet sewage sludge was assessed in this paper, which consist in carrying out the pyrolysis of dewatered residual activated sludge as it is produced in the wastewater treatment plant with a moisture content of above 70%, without subjecting it to any previous thermal drying process. In order to establish the most favorable conditions for the production of hydrogen-riched fuel gas, the effects of moisture content, heating rate and temperature were analyzed. It was found that the natural moisture of the sludge was converted into steam at high temperature, which can take part in the partial gasification of the sludge, leading to an increase in the gas production and the yield of hydrogen. In addition, pyrolyzing wet sludge at high temperature with high heating rates could maximize the gas yield productivity and raise its quality as a fuel and as a source of hydrogen or syngas as well. In this process, the drying, pyrolysis and gasification of wet sewage sludge were completed in a single thermal process, and resulting in a considerable amount of gases with potential value as fuels due to the relatively high calorific values they contain.

Nitrate and COD Reduction Contrast of Biofilm-Electrode Reactor in Different Position of Denitrogenation Process

To achieve effective combination of hydrogen autotrophic denitrification and traditional biological denitrogenation, two groups of experiments were designed with a self-made experimental biofilm-electrode reactor (BER) put ahead or behind in biological denitrogenation process for the treatment of domestic wastewater from septic tank. On different conditions, the nitrate and the COD reducing efficiency of the biofilmelectrode reactor were contrasted. The experimental results implied that the position of BER in denitrogenation process would strongly affect the reduction rate of the nitrate of BER. With the optimum current intensity of 20mA, the highest nitrate reduction rate of 68.5% would be achieved as the BER was put behind in denitrogenation process, with 29% increased compared with the condition of putting ahead. The highest COD reduction rate of the BER was respectively 27%(with BER put behind) and 17.9%(with BER put ahead), which implied the presence of heterotrophic denitrification process in BER device. Further analyses were given from the view of microbe nutrition. It can be inferred that the denitrogenation process with the BER put behind may provide better nutrition conditions for denitrifying micro-organisms on which autotrophic and heterotrophic denitrification process might be carried out in combination. Keywordshydrogen autotrophic denitrification; BER; nitrate and COD reduction efficiency; nutrition conditions of denitrifying micro-organisms

Primary Research on the Disposal of Organic Wastewater of Low C/N Ratio with Electrode-Membrane Biological Reactor

The paper gave a brief introduction to electrode- membrane biological reactor (EMBR) and its denitrogenation mechanism. A experimental EMBR device was used to treat organic wastewater of low C/N ratio taken from septic tank. 9 groups of experiments were carried out to investigate the performance of the device with the variations of COD concentration and the C/N ratio of the influents as well as the electric current density of the reactor. According to the experiment results, the experimental EMBR had higher denitrogenation efficiency than traditional MBR owing to the cooperation of autotrophic and heterotrophic denitrification occurred in the anoxic chambers of the device. The change of electric current density and the C/N ratio of the influents had notable influence on denitrogenation process. On the conditions of the experiments, with the current density of 0.025 mA/cm 2 , the experimental device had the highest nitrogen removal rate of 73.1 percents. The contribution of the heterotrophic denitrifying chamber and autotrophic denitrifying chamber to total nitrogen removal is respectively 57.8 percents and 42.1 percents. EMBR had the advantage of steady and high COD removal efficiency as traditional MBR did. The COD removal rate of the experimental device was above 97 percents.

Preliminary Research on Ammonia Reclaim from Landfill Leachate by Vacuum Technique

In this paper, landfill leachates and vacuum technique were investigated. Conditions for the removal and reclaim of high content ammonia from landfill leachates were studied by vacuum method; the device made on the spot was used to find the optimal experimental procedures. While the operating time was 1.5 hours, the temperature was of 50degC, a vacuum degree was 1.5 m water column, and the highest removal rate for ammonia could be obtained, but the primary ammonia contents of landfill leachates could hardly influence on the efficiency of ammonia removal. In despite of the same condition , adsorption of ammonia by injector was better than by vacuum pump ,that the methods of adsorption are very important for the reclaim of ammonia was demonstrated by the tests. In the work , both the characteristics without adjusting the pH value of 8.5 , and the reclaiming of ammonia, distinguished from others by special quality.

Study on Removal of Nitrogen and Phosphorus by the Integrated Intermittent-Aeration Membrane Biological Reactor

Pollutants removal efficiency of the Integrated Intermittent-aeration Membrane Biological Reactor (MIBR) was investigated in this paper. And four different working conditions were researched by the laboratory-scale experiment. The results showed that the working condition III in which the periods of aeration and agitation are 2h and 2h was considered optimal for under this condition the pollutants removal efficiency of MIBR were better. Under the condition of the optimal working condition, the concentrations of COD, TN, NH4+-N and TP in the effluent of MIBR were 12.55-40.92 mg/L, 3.66-10.10 mg/L, 0.50- 6.89 mg/L and 0.18-0.98 mg/L respectively. It indicated that effluent quality of MIBR could meet the standard of the reused water quality criterion (CJ/48-1999).