Xuwen He

Cadmium adsorption characteristic of alkali modified sewage sludge.

This paper proposed a new biosorbent preparation method by alkali modification of sewage sludge. The cadmium ion (Cd(2+)) adsorption capacity of alkali modified sewage sludge (AMSS) was evaluated by equilibrium sorption experiments. The amount of released calcium ion (Ca(2+)) in sorption equilibrium experiment were measured in order to reveal the adsorption mechanism. In addition, Zeta potential, specific surface area and Fourier transform infrared (FTIR) spectra of AMSS were tested. The results showed that the cadmium adsorption isotherms of AMSS fitted well with both Langmuir and Freundlich models, and the maximum adsorption capacities increased by 0.713 mmol g(-1). The cadmium adsorption capacity of biosorbent increased with NaOH solution concentration (range from 0.25 to 7.5 mol L(-1)) for sewage sludge modification. The strong cadmium adsorption of AMSS was attributed to ion exchange effect, electrostatic attraction and complexation. This alkali modified sewage sludge may have a potential for serving as cadmium removal biosorbent.

Study on the treatment of wastewater containing Cu(II) by D851 ion exchange resin

AbstractA static adsorption experiment of copper ion was performed with D851 ion exchange resin to determine some optimum treatment parameters. The results of the experiment showed that the enthalpy value of the reaction was positive and the optimum reaction time was 60xa0min, while the optimum pH value and reaction temperature were 5.5 and 35°C, respectively. The adsorption equilibrium density of 0.1u2009g ion exchange resin was between 75 and 100xa0mg/L. With the condition of the hydraulic retention time of 60xa0min, wastewater containing 10xa0mg/L Cu(II) (pH ≈ 5.5) was treated by a dynamic ion exchange column, and the treatment effluent can meet the primary standard of the National Integrated Wastewater Discharge Standard (GB8978-1996). Meanwhile a desorption experiment with ion exchange resin was carried out, which determined that the optimum volume fraction of hydrochloric acid solution was 4% in the desorption solution. The figures of the scanning electron microscope showed that the resin saturated with Cu(II) ...

Impact of dissolved oxygen on the microbial community structure of an intermittent biological aerated filter (IBAF) and the removal efficiency of gasification wastewater

A novel IBAF system (altered conventional biological aerated filter (BAF) for intermittent aeration) was used to treat BDD anodes electrochemical oxidation gasification wastewater effluent, after which 454 pyrosequencing was applied to investigate the bacterial community of IBAF and demonstrate the relationship between dissolved oxygen (DO) and the bacterial community. The results showed that the concentration of COD, NH4+-N and NO3--N reached 55.08, 7.64 and 7.76u202fmg/L, respectively, in IBAF effluent because of changes in the DO concentration at 30u202fdays after system start-up. The bacterial community results revealed that the 40u202fcm sample had the highest bacterial diversity. The bacterial species were approximate in total samples at phylum and family level, but the relative abundance was significantly different because of change in DO concentration. In addition, sample distance analysis indicated that the similarity of different samples was related to the DO concentration at different heights.

Goaf purifying characteristic of mine water with high turbidity, high concentration of iron and manganese

Taking mine water with high iron and high manganese as research object, kinetic parameter experiment were carried out by goaf filling. The result shows that dispersion coefficient and adsorption coefficient of goaf filling are D=3.12m2/d, Kd (Fe)=11.07mL/g, Kd (Mn) =7.543mL/g respectively; Iron and manganese desorption rate is very low in goaf filling, and the highest desorption rates of iron, manganese are 29.29% and 33.85% respectively; Based on experiment result, iron and manganese fixed state adsorption capacity are 119.915 μg/g, 68.6 μg/g respectively.

Study on the preparation optimization and characteristics of modified media for coal-mine wastewater treatment with high iron and high manganese concentration

Nowadays, the coal-mine wastewater contained high concentration of iron ion and manganese ion was treated by filter process, in which manganese sand, as a kind of common filter media, was extensively applied, but its disadvantage is long set-up period for manganese ion removal. In this paper, for many advantages of hydrated manganese dioxide, such as high surface areas, abundant surface hydroxyl and strong absorption capacity, MnCl2 and KMnO4 solution were selected as modified agents for lava media in order to make its surface form the layer of hydrated manganese dioxide, thus it can enhance manganese ion removal efficiency and shorten set-up period. This paper firstly investigated the optimization of preparation parameters, namely 4times of soaking and oxidizing by modified agents and 1hour soaking-time were considered as optimal preparation parameters. Secondly, the pollutants removal efficiencies were compared among the modified lava media, lava media, modified manganese sand and manganese sand, results showed that modified lava media had high-efficiency and durable Mn2+ removal. Finally, the experiment of backwashing and generation for modified lava media showed that backwashing can recover the removal capacity for total iron and turbidity, and only generation can recover the removal capacity for Mn2+. The specific generation method was that the saturated media was submerged in 1mol/L NaNO3 solution for 15min.

Mine water pollutants migration and transformation in gob filling

Based on the experiment data, dynamic model of migration and transformation law was established. By comparison between predicted value and measured value, the result shows that model accuracy is very high and the greatest error is only 25.8%. By analyzing grain size, mineral composition and mineral cation exchange of gob filling, the treatment mechanism was studied. The result shows that SS, iron and manganese are removed by filtration, precipitation, biochemical reaction and sorption. Finally, above model was used to predict treatment effect of the mine water in the the coal mine. The result shows that the gob purifying greatly decreases pollution load with good pretreatment effect. Above research will establish theoretical base for determining design parameter in gob purifying project.

Advanced treatment of acrylic fiber manufacturing wastewater using electrochemical oxidation

Based on the characteristic of acrylic fiber manufacturing wastewater (AFMW), such as containing toxic and bio-refractory pollutants, the electrochemical oxidation is employed as an advanced treatment method, and the operating conditions such as current density, NaCl concentration, initial pH, are discussed. In addition, the bio-degradability prior to and after electrochemical treatment is evaluated. Under the optimal operating parameters of current density 10 mA/cm2, NaCl concentration 2 g/L, pH 7.1, the ammonia (NH3-N) and chemical oxygen demand (COD) are reduced by 100% and 50.8%, respectively. Under the condition of current density exceeds 10 mA/cm2 or NaCl concentration exceeds 2 g/L, the increment of current density and NaCl concentration accelerate the NH3-N remove process, but it can not greatly enhance the COD removal efficiency of electrochemical treatment. The neutral pH condition is optimal for COD removal.

Research on nitrogen removal of secondary effluent of wastewater treatment plant in horizontal subsurface-flow constructed wetlands

By investigating the nitrogen concentrations in effluents of the horizontal subsurface-flow constructed wetlands under the conditions of different kinds of substrates, residence time and heights, as well as the nitrogen concentrations changes along the flow in the wetlands, the nitrogen removal routes in the wetlands were analyzed. The results demonstrated that the wetland system with zeolites demonstrated greater efficiency in the removal of nitrogen. There was a higher nitrogen removal rates at the bottom of the wetland system owing to an aerobic-anoxic environment. In that a more efficient reoxygenation was attained at the front of the system, it achieved a higher nitrogen removal rates.