Ceramic filters are widely used for sustainable point-of-use water treatment in developing countries. It has remained a great challenge, however, for ceramic filters to simultaneously achieve high flow rate and effective bacterial removal. In this work, we reported the use of recycled paper fiber (greenfiber) as combustible material for the development of effective and fast-flow ceramic filters and compared their performance to filters that were fabricated using starch and rice husk, two common combustible materials used in previous studies. The clean ceramic filters made using 15% greenfiber achieved >4 log removal of bacteria (>99.99% removal) and an equivalent flow rate of 5.9 L/h (37.5 L/m2-h); the filters made using 20% greenfiber exhibited a fast flow rate of 13.9 L/h (87.1 L/m2-h) while maintaining a log microbial removal efficiency of >2 (>99% removal of bacterial cells). The two flow rates were ∼100% and >300% higher than the flow rates of mainline ceramic filters currently in use. The filters were characterized using mercury intrusion porosimetry, scanning electron microscopy, X-ray fluorescence analysis, and Fourier transform infrared spectroscopy. Our results suggested that the pore size distribution pattern played critical roles in the microbial removal efficiency. A mathematical framework was developed to provide a semiquantitative analysis of the relationship between filter bacterial removal efficiency and pore size distribution.

The development of economical, low-maintenance, environmentally friendly and effective water filtration techniques can have far-reaching public health, social and economic benefits. In this research, a cost-effective La-modified granular ceramic material made of red art clay and recycled paper fiber was developed for the removal of two major anionic contaminants, As(V) (arsenate) and Cr(VI) (chromate). La modification temperature significantly impacted the resulting composition and properties of the adsorbents, and thus played a crucial role in the adsorbent performance. The La-modified ceramic materials were extensively characterized through scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area measurement, thermal gravimetric analysis (TGA), zeta potential measurements, and Fourier-transform infrared spectroscopy (FTIR) analysis. The characterization results suggested that surface coating by LaONO 3 -related compounds was critical for As(V) and Cr(VI) adsorption. At the modification temperature of 385 °C, the adsorption of As(V) and Cr(VI) reached maximum, which were 23 mg/g and 13 mg/g, respectively, under circumneutral conditions that are relevant to various aquatic systems. The adsorption kinetics and isotherm, the influence of pH, ionic strength and coexisting anions on As(V) and Cr(VI) adsorption were investigated to further understand both As(V) and Cr(VI) adsorption behavior. Findings from this research showed that La-modified ceramic material made of recycled paper waste represents a cost-effective adsorbent for anionic contaminant removal under environmentally relevant conditions.

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In designing optical systems for synchrotron radiation, one is often led to conclude that optimal performance can be obtained from optical surfaces described by conic sections of revolution, usually paraboloids and ellipsoids. The resulting design can lead to prescriptions for three-dimensional optical surfaces that are dif®cult to fabricate accurately. Under some circumstances satisfactory system performance can be achieved through the use of more easily manufactured surfaces such as cylinders, cones, bent cones, toroids and elliptical cylinders. These surfaces often have the additional bene®ts of scalability to large aperture, lower surface roughness and improved surface ®gure accuracy. In this paper we explore some of the conditions under which these more easily manufactured surfaces can be utilized without sacri®cing performance.

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