Diatomite is a kind of natural low-cost mineral material. It has a number of unique physical properties and has been widely used as an adsorbent in wastewater treatment. This study was conducted to investigate the aer...Diatomite is a kind of natural low-cost mineral material. It has a number of unique physical properties and has been widely used as an adsorbent in wastewater treatment. This study was conducted to investigate the aerobic biodegradation of coal gasification wastewater with and without diatomite addition. Experimental results indicated that diatomite added in the activated sludge system could promote the biomass and also enhance the performance of the sludge settling. The average mixed-liquor volatile suspended solids （MLVSS） is increased from 4055 mg.L^-1 to 4518 mg.L^-1 and the average settling volume （SV） are changed only from 45.9% to 47.1%. Diatomite additive could enhance the efficiency of chemical oxygen demand （COD） and total phenols removal from the wastewater. The COD removal increased from 73.3% to near 80% and the total phenols removal increased from 81.4% to 85.8%. The mechanisms of the increase of biomass and pollutants removal may correlates to the improvement of bioavailability and sludge settlement characteristics by diatomite added. Micrograph of the sludge in the diatomite-activated sludge system indicated that the diatomite added could be the carrier of the microbe and also affect the biomass and pollutant removal.展开更多
In this study, biodiesel was produced from waste vegetable oil using a heterogeneous base catalyst synthesized by impregnating potassium hydroxide(KOH) onto diatomite. Response surface methodology based on a central c...In this study, biodiesel was produced from waste vegetable oil using a heterogeneous base catalyst synthesized by impregnating potassium hydroxide(KOH) onto diatomite. Response surface methodology based on a central composite design was used to optimize four transesterification variables: temperature(30–120 °C), reaction time(2–6 h), methanol to oil mass ratio(10%–50%) and catalyst to oil mass ratio(2.1%–7.9%). A quadratic polynomial equation was obtained to correlate biodiesel yield to the transesterification variables. The diatomite–KOH catalyst was characterized using X-ray diffraction(XRD), Fourier transform infra-red spectroscopy(FTIR) and a scanning electron microscope(SEM) equipped with an energy dispersive X-ray detector(EDS). A maximum biodiesel yield of 90%(by mass) was obtained. The reaction conditions were as follows: methanol to oil mass ratio 30%, catalyst to oil mass ratio 5%, reaction time 4 h, and reaction temperature 75 °C. The XRD, FTIR and SEM(EDS) results confirm that the addition of KOH modifies the structure of diatomite. During impregnation and calcination of the diatomite catalyst the K2 O phase forms in the diatomite structural matrix and the active basicity of this compound facilitates the transesterification process. It is possible to recycle the diatomite–KOH catalyst up to three times. The crucial biodiesel properties from waste vegetable oil are within the American Standard Test Method specifications.展开更多
基金Supported by the Shanghai Committee of Education (07ZZ158)
文摘Diatomite is a kind of natural low-cost mineral material. It has a number of unique physical properties and has been widely used as an adsorbent in wastewater treatment. This study was conducted to investigate the aerobic biodegradation of coal gasification wastewater with and without diatomite addition. Experimental results indicated that diatomite added in the activated sludge system could promote the biomass and also enhance the performance of the sludge settling. The average mixed-liquor volatile suspended solids （MLVSS） is increased from 4055 mg.L^-1 to 4518 mg.L^-1 and the average settling volume （SV） are changed only from 45.9% to 47.1%. Diatomite additive could enhance the efficiency of chemical oxygen demand （COD） and total phenols removal from the wastewater. The COD removal increased from 73.3% to near 80% and the total phenols removal increased from 81.4% to 85.8%. The mechanisms of the increase of biomass and pollutants removal may correlates to the improvement of bioavailability and sludge settlement characteristics by diatomite added. Micrograph of the sludge in the diatomite-activated sludge system indicated that the diatomite added could be the carrier of the microbe and also affect the biomass and pollutant removal.
基金support by the centre of research excellence(Vaal University of Technology)grant no 2188-2892 to fund this project is gratefully acknowledged
文摘In this study, biodiesel was produced from waste vegetable oil using a heterogeneous base catalyst synthesized by impregnating potassium hydroxide(KOH) onto diatomite. Response surface methodology based on a central composite design was used to optimize four transesterification variables: temperature(30–120 °C), reaction time(2–6 h), methanol to oil mass ratio(10%–50%) and catalyst to oil mass ratio(2.1%–7.9%). A quadratic polynomial equation was obtained to correlate biodiesel yield to the transesterification variables. The diatomite–KOH catalyst was characterized using X-ray diffraction(XRD), Fourier transform infra-red spectroscopy(FTIR) and a scanning electron microscope(SEM) equipped with an energy dispersive X-ray detector(EDS). A maximum biodiesel yield of 90%(by mass) was obtained. The reaction conditions were as follows: methanol to oil mass ratio 30%, catalyst to oil mass ratio 5%, reaction time 4 h, and reaction temperature 75 °C. The XRD, FTIR and SEM(EDS) results confirm that the addition of KOH modifies the structure of diatomite. During impregnation and calcination of the diatomite catalyst the K2 O phase forms in the diatomite structural matrix and the active basicity of this compound facilitates the transesterification process. It is possible to recycle the diatomite–KOH catalyst up to three times. The crucial biodiesel properties from waste vegetable oil are within the American Standard Test Method specifications.
