Chunrong Wang

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.

Electrochemical Oxidation Using BDD Anodes Combined with Biological Aerated Filter for Biotreated Coking Wastewater Treatment

Coking wastewater is characterized by poor biodegradability and high microorganism toxicity. Thus, it is difficult to meet Grade I of Integrated Wastewater Discharge Standard of China by biological treatment technology; specifically, COD cannot meet above standard due to containing refractory organics. A novel coupling reactor, electrochemical oxidation using BDD anodes and biological aerated filter (BAF), has been developed for carbon and nitrogen removal from biotreated coking wastewater, focusing on COD, BOD5, -N, and -N removal on operation over 90 days with average effluent value of 91.3, 9.73, 0.62, and 13.34 mgL−1, respectively. Average value of BOD5/COD and BOD5/ -N was enhanced from 0.05 to 0.27 and from 0.45 to 1.21 by electrochemical oxidation, respectively, with average energy consumption of 67.9 kWh kg−1 COD. In addition, the refractory organics also were evidently mineralized in the unit based on the data of the three-dimensional fluorescence spectra. Meanwhile, its effluent provided excellent substrate for biological denitrification in BAF. At hydraulic retention time (HRT) of 13.08 h, about 12 mgL−1   -N was depleted through denitrification, and it mainly occurred at top of 0.25 m height of BAF. Therefore, it is feasible to apply the coupling reactor for biotreated coking wastewater treatment and achieve desirable effluent quality.

The Organic Pollutant Characteristics of Lurgi Coal Gasification Wastewater before and after Ozonation

The effluent of distilled and extracted Lurgi coal gasification wastewater has been found to have low biodegradability and high toxicity, which inhibits further biodegradation. However, ozonation enhances the biodegradability and reduces the toxicity of this effluent, enabling further biological treatment and increased removal of organic materials. In this study, the dissolved organic matters in Lurgi coal gasification wastewater were isolated into six classes by resin adsorbents, after which TOC, UV254, UV-Vis, and 3D EEM were employed to quantitatively and qualitatively analyze organic materials in each part of the fractionated samples. The HoA and HiN fraction accounted for large amounts of the Lurgi coal gasification wastewater, and their TOC values were about 380.21 mg·L−1 and 646.84 mg·L−1, respectively. After ozonation, the TOC removal rates of HoA and HiN reached 42.85% and 67.13%, respectively. The UV254 of HoA was basically stable before and after ozonation, while that of HiN increased continuously because a portion of the humic macromolecular organic materials in HoA was oxidized to HiN. Additionally, UV-Vis analysis revealed that the larger molecular organics of HoA were oxidized during ozonation, resulting in high biodegradability. Finally, the 3D EEM spectra indicated that the macromolecular organics were oxidized to smaller molecules with the degradation of soluble microbial by-products.

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 7.76 mg/L, respectively, in IBAF effluent because of changes in the DO concentration at 30 days after system start-up. The bacterial community results revealed that the 40 cm 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.

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.

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.