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Lime mud is a kind of solid waste in the papermaking industry, which has been a source of serious environmental pollution. Ceramsites containing anorthite and gehlenite were prepared from lime mud and fly ash through the solid state reaction method at 1050°C. The objective of this study was to explore the efficiency of Ca 2 + and OH − release and assess the phosphorus and copper ion removal performance of the ceramsites via batch experiments, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that Ca 2 + and OH − were released from the ceramsites due to the dissolution of anorthite, gehlenite and available lime. It is also concluded that gehlenite had stronger capacity for Ca 2 + and OH − release compared with anorthite. The Ca 2 + release could be fit well by the Avrami kinetic model. Increases of porosity, dosage and temperature were associated with increases in the concentrations of Ca 2 + and OH − released. Under different conditions, the ceramsites could maintain aqueous solutions in alkaline conditions (pH = 9.3–10.9) and the release of Ca 2 + was not affected. The removal rates of phosphorus and copper ions were as high as 96.88% and 96.81%, respectively. The final pH values of both phosphorus and copper ions solutions changed slightly. The reuse of lime mud in the form of ceramsites is an effective strategy.

We used toxicity identification evaluation (TIE) method to confirm the combinational effects of identified toxic metals in a paper recycling mill effluent in inducing the decreased lifespan in nematode Caenorhabditis elegans. Exposure to Ca + Al caused more severely decreased lifespan than that exposed to Ca, or Al; and exposure to Ca + Fe induced more severely decreased lifespan than that exposed to Ca, or Fe. Exposure to Ca+Al+Fe caused more severely decreased lifespan than that exposed to Ca, or Ca+Fe. Moreover, the baseline toxicity on lifespan was doubled by doubling the concentration of combined metals (Ca+Al+Fe) in spiking test in original effluent (oe), and lifespan defects in oe+Ca+Al+Fe exposed nematodes were more severe than that in Ca+Al+Fe exposed nematode. Therefore, Ca+Al+Fe exposure may largely explain the formation of decreased lifespan induced by the examined industrial effluent. Furthermore, the observed reduction of lifespan induced by the combination of high level of Ca with other metals may be at least partially independent of the insulin-like pathway.