Applied Mechanics and Materials Vols. 675-677

Abstract: Concentrated leachate obtained from landfill leachate by membrane separation was treated using technique of aerobic recharge. Variation of effluent COD, NH₃-N and pH in concentrated leachate during aerobic recharge was studied. The impact of hydraulic loading on the removal rate of COD and NH₃-N was investigated. The results indicate that, after passing through the three stages of rapid declining, smooth declining and stabilization, the variation of effluent COD of the concentrated leachate versus time maintains in the range of 900~2000 mg/L, and the corresponding removal rate is 88%~92%. The variation of effluent NH₃-N versus time indicates a trend that it climbs up initially and then declines. The effluent NH₃-N starts from 700 mg/L. After 35 days, it declines down to 18 mg/L and maintains in the range of 93%~99% with a corresponding removal rate up to 98%. Aerobic recharge reduces the build up of organic acids in the early stage. After 10 days, the pH value of the leachate maintains in the range between 7.5 and 9.0. The COD removal rate decreases from 94.39% down to 75.75% when the hydraulic loading increases from 12.5 mL / (L·d) to 75mL / (L·d), indicating a strong trend. In the mean time, the NH₃-N removal rate decreases from 98.14% down to 90.11%, indicating a weak tread.

Abstract: Biosorption of dyeing wastewater is most widely used method so far. The adsorption of methylene blue (MB) with bamboo shoot shell (BSS) as biosorbent was investigated. Orthogonal test was used to optimize the adsorption process, and adsorption capacity and color removal efficiency were used to judge the adsorptivity of BSS. Results showed that maximum adsorption capacity was 225.71 mg·g^-1, and color removal efficiency could achieve to 98.96% during the test. To obtain best adsorption capacity, the optimized conditions of temperature, initial concentration of dye, BSS dosage, pH value and adsorption time were 45 °C, 400 mg·L^-1, 10 mg/10 mL, 9.6 and 30 min, respectively. As to another target color removal efficiency, the best parameters were 100 mg·L^-1, 200 mg/10 mL, 11.5 and 120 min, respectively. The results reveal that the agricultural by-product BSS is an effective biosorbent.

Abstract: In order to provide an effective and economic method for the yeast wastewater′s treatment, this study taken yeast wastewater as objection, and applied immobilized micro-aerobic microorganism technology into yeast wastewater′s treatment, then explored the degradation effect of major pollutants in yeast wastewater. The immobilized carrier was analyzed by scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR), and dominant species in immobilized carrier were identified. The results showed that immobilized carrier was a composite carrier with porous structure, and removal rate of chemical oxygen demand (COD), ammonia nitrogen (NH₃-N), total nitrogen (TN) and total organic carbon (TOC) of yeast wastewater by using the immobilized micro-aerobic microorganism technology were 71.1%, 99.7%, 61.4% and 67.0%, respectively. Moreover, the dominant bacteria which attached in the carrier included Sphingomonas paucimobilis, Pseudomonas putida, Acinetobacter lwoffii and Pseudomonas stutzeri.

Abstract: In order to improve the biological oxidation and phosphorous removal in BAF, compound inoculation method was introduced to start two stage biological filters by alternative aeration. The two stage biological filters were connected by serial way, and three phases "batch aeration phase, the phase of small flow water for gradually increasing in the load, the alternative aeration phase" were adopted as the start up procedure. The experimental results showed that: COD removal rate was 83.3% after the former two stages; Ammonia nitrogen removal rate was stable at 81.5% while the TP removal efficiency was 68.9% and COD removal rate reached above 80% at the end of the third phase. Totally, 25 days were necessary for the biofilm formation in two stages BAF.

Abstract: Aerobic activated sludge was more appropriate for APMP(Alkaline Peroxide Mechanical Pulp) effluent treatment than anaerobic processes because the high content of toxic wood extractives in the effluent. In this article, Eucalyptus APMP effluent was treated with activated sludge and the process conditions was optimized. The optimized conditions were: the initial pH value was 6.0, SV₃₀ of activated sludge was 35%, and loading volume of flask was 150ml (250ml flask), cultured shakily for 3 days at 35°Cand 150rpm. The removal of COD was 66.75%, from 4181mg/l to 1390mg/l, and the color of the effluent and treated water were 2541C.U. and 1557C.U. under the optimized conditions, respectively. In most cases, the color of treated wastewater was increased compared with the initial effluent, but the removal of COD was significant.

Abstract: Concentration of 4 heavy metals (Cu, Pb, Zn, Cd) and petroleum hydrocarbon in the surface sediments collected from Chenglingji, Dongting Lake, were quantitatively analyzed. Distribution characteristics and possible sources of the heavy metals and petroleum hydrocarbon were discussed. Methods of single-factor index and geoaccumulation index were adopted to evaluate the potential ecological risks of heavy metal. The results showed that Cd was seriously polluted and in a strong ecological risk level; Cu, Pb and Zn pollution was mild in Chenglingji Port, Dongting Lake. Petroleum hydrocarbon content of nearshore sediment was low exclude of area near Chenglingji Port, which significantly exceeded the standard value. And the content of petroleum hydrocarbon decreased with the distance far away from the harbor.

Abstract: Under the laboratory condition, use the mixture of coal cinder and soil, the mixture of fine sand and soil , and simple soil as the matrixes; use the Acorus calamus, the Typha angustata Bory et Chaub, and the Scirpus validus Vahl as the plants. Three groups of ditch systems are built to study the effect of different group of ditches in removing nitrogen and phosphorus pollution of paddy fields drainage ditch. The results show that the plants significantly improve the purification performance of ditches, the removal rate to TN of the ditch system based on the mixture of fine sand and soil and the Acorus calamus is 50.9% which is higher than other groups; the removal rate to TP of the ditch system based on the mixture of coal cinder and soil and the Acorus calamus is 48.1% which is higher than other groups.

Abstract: ZnS/TiO₂/Chitosan nanocomposite thin films were prepared by entrapping zinc ions and nanosized TiO2 in chitosan films under mild conditions. The surface structure and morphology of the film were characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Methyl Orange was selected to evaluate the photocatalytic activity under simulated solar irradiation. The HRTEM results show that TiO2 and ZnS were dispersed uniformly with diameters of 20–30 nm. The prepared film exhibits high photocatalytic activities. About 93.5% Methyl Orange(3.6×10-5 mol/L) were photodegraded by 0.6 g L−1 photocatalyst at pH 4.0 with 120 min irradiation. The influence of the reaction pH, stability and reusability of the film have also been investigated. It can be developed as a economically feasible and environmentally friendly photocatalyst for the practical industrial waste water treatment.

Abstract: In order to develop a new substrate filler for wetland, Fly ash and soil was mixed and modified in different mass ratio, then, static adsorption and seepage purification experiments were carried out to choose four appropriate modified fillers for wetland model experiment. Experimental results showed that when the mass proportion of fly ash and soil was 3:7, the best treatment effect was achieved. While using this modified wetland for wastewater treatment, the removal rate of total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH₄-N) and COD was 57.52%, 97.58%, 93.78% and 89.53% respectively. The effluent concentration of TN could meet the priority standard (level B) of Discharge standard of pollutants for municipal wastewater treatment plant (GB18918-2002), while the effluent concentration of TP, NH₄-N and COD could meet the priority standard (level A).

Abstract: The study used self-made nutshell activated carbon and took catering wastewater as research object. After pretreatment, the catering wastewater was adsorbed by nutshell activated carbon.Throught investigating the adsorption value of methylene blue and iodine,the effect of Peach pit shell activated carbon is higher than others.The optimal conditions are determined: proper time of reaction 4 h, Peach shell activated carbon dosage 30 mg/L, pH 6.0, reaction temperature 30°C. Under this optimum, the removal rate of COD_cr as well as grease can be as high as 92.75% and 87.05%, respectively.