Advanced Materials Research Vols. 781-784

Abstract: The anaerobic-aerobic processes and membrane module was combined to be an A/O MBR used for treatment of dyeing wastewater. The running parameters, such as the removal of COD_cr, DO, MLSS and HRT have been studied. Through experimental analysis, when the MLSS is between 2000 and 6000mg/L, DO is nearby 2.5mg/L, HRT is between 8h and 9h, the treatment efficiency is the highest.

Abstract: For effective utilization of sulfate slag, the content of iron (Fe) should higher than 60%, while the content of asenic (As) should lower than 0.05%. A sulfate slag pretreated by magnetic separation-gravity separation, contains Fe 58.61% and As 0.33%, and the forms of Fe and As are mainly Fe₂O₃ and FeAsO₄. To obtain qualified Fe ore concentrate product, chemical leaching conditions was used to remove As. Results show that the the optimal conditions are-0.074mm 75% grinding fineness, 30 °C, 15 g/L initial acid, 5/1 liquid-solid ratio, 350 rpm mixing intensity and 60 min leaching time. The obtained qualified product contains Fe 61.85%, As 0.045%, and Fe recovery rate is 98.63%.

Abstract: Chromium is extremely toxic and considered a priority pollutant. It is compulsory to control the discharge of chromium compounds into aquatic systems in order to prevent severe environmental problems. Among all the treatment methods, adsorption has been proved to be a substantial method for the removal of chromium from wastewater. Recently, a variety of starch-based materials have been used as chromium adsorbents. The present review provides the recent development in the sorption capacities of starch-based sorbents for chromium, new starch-based materials and their advantages for the removal of chromium from the wastewater. Moreover, the adsorption mechanisms of Cr (III) or Cr (VI) on starch-based adsorbents are reviewed, and the sorption efficiency and capacities of starch-based adsorbents are compared with that of other low cost adsorbent materials. The primary objective is to provide the recent information about the starch-based materials as absorbents, and propose that the starch-based microsphere materials as absorbents will develop greater function in removal of chromium from wastewater in future.

Abstract: TiO2 photocatalytic membrane reactors (PMRs) are prospective technology of treating dyeing and printing wastewater. The type and structure of the PMRs currently used for dyes wastewater treating were introduced. In these systems TiO2 was successfully separated from water by means of excellent separation performance of membrane, reducing TiO2 loss, enhancing the utilization ratio of catalysts and improving effluent water quality. At the same time dyes and other macromolecular substances were degraded photocatalyticly, greatly improving the stain resistance to membrane and extending membranes service life.

Abstract: Nitrogen doping TiO₂ was prepared and used to degrade acrolein wastewater under simulated solar irradiation acrylic acid. The results showed that the removal of acrolein, hydroquinone and acrylic acid were 0.73, 0.64, 0.26 after 4 hour degradation by TiO₂/UV system. The degradation of acrolein, hydroquinone and acrylic acid using TiO₂/UV system followed pseudo first-order kinetics. It results indicated that this proposed method can be useful for the pretreatment acrolein wastewater.

Abstract: The seven typical plots were sampled and the contents of As, Cd, Cr, Cu, Ni, Pb and Zn were analyzed in order to investigate the heavy metal pollution of farmland soils surrounding scale pig farms in Nanchang. The heavy metal pollution was evaluated by using single pollution index and comprehensive index methods. The results were addressed that Cd and Pb were the major two pollutants in the farmland soils. The sequence of single pollution index was Cd, Pb, Ni, Cu, Zn, As and Cr. The competitive pollution index was 1.55, and the farmland soils were a slightly polluted grade. The correlation among heavy metals As, Cd, Pb, Cu and Zn were highly significant or significant, but the correlation among Cr, Ni and other heavy metals were not relevant.

Abstract: Phosphorus removal from wastewater has always been given serious attention in sewage treatment. Eutrophication can happen if phosphorus wastewater is directly discharged into natural water and high phosphorus-contained irrigation water may lead crops beat down. The research investigated the phosphorus removal efficiency in wastewater by shell powder. The experiment results showed that the best removal effect could meet the Wastewater Treatment Plant Discharge Standard (GB18918-2002) Grade I-A in China, which can be achieved under the conditions of the dosage of shell powder solution 1 ml, pH > 11 and precipitation one to four hours at the initial phosphorus concentration of about 3 mg/L.

Abstract: The different ratios (PVA and SA) of PVA/SA blend films with cross-linking structure are successfully prepared by coagulating the mixture of sodium alginate (SA) and polyvinyl alcohol (PVA) in aqueous solution, then by treating with crosslinking agent CaCl₂ solution. The Surface morphology and flexibility of PVA/SA blend films were studied. The results indicate there is some strong interaction and good compatibility between sodium alginate and polyvinyl alcohol molecular. The physical and chemical properties of the PSA-80(PVA:SA=4:1) blend films are obviously improved owing to a molecular force and hydrogen bond interaction. The effects of parameters of the blend film was investigated in relation to its adsorption capability for low concentration ions Cr (VI) including such as SA content of the PVA/SA film, contact time, solution pH and temperature of solution. The results indicate that the maximum adsorption rate is 95.86% at the temperature 50°C under optimized pH 4 for 60min by PSA-80 films.

Abstract: The effects of pH on the advanced treatment of mid-stage pulping effluent with potassium ferrate were studied. Firstly, the effect of pH on the stability of the potassium ferrate solution was studied, which indicated that potassium ferrate was more stable in alkaline conditions than in acidic and neutral conditions, and the most stability was achieved at pH of 9-10. Then the effect of pH on the mid-stage pulping effluent treatment with potassium ferrate showed that the oxidation increased firstly and then decreased with the increase of the pH. The best treatment efficiency was at pH=4, under which COD removal efficiency reached 40%. The flocculation experiment was conducted using Fe³⁺ produced by the oxidation reaction as flocculant and PAC as extra flocculant and PAM as coagulant aid. Effect of pH on the flocculation process was studied, which showed that the flocculation effect first increased and then decreased with pH increasing. When pH was 9, COD removal efficiency reached 60%. The final effluent of COD concentration was less than 60mg/L, which met the requirements from the national first-order discharge standard.

Abstract: Takovite, a kind of hydrotalcite-like compounds (HTlcs), was used for boron removal from water. It was prepared by coprecipitation method and characterized by X-ray diffraction technique (XRD). The equilibrium time of boron sorption by takovite as well as its boron uptake capacities was determined by the reaction kinetic experiments and isotherm sorption experiments. The effects of experimental conditions on boron removal efficiency were also evaluated. Generally, the boron uptake by takovites increases with increasing initial boron concentration in solution. The isotherm sorption data match well with the Freundlich model, indicating that the anion exchange contributes a lot to solution deboronation. Moreover, at higher temperature, greater boron removal by takovite was observed. As compared to calcined takovite, uncalcined takovite has better performance in terms of boron uptake, since the structural restoration of calcined takovite didnt happen during its contact with boron-containing solution, which is quite different from the behavior of other HTlcs as reported.