Objectives Sludge cake produced in paper mill industries is disposed into a landfill and may cause the environmental and health problems. Now many researchers have tried to recycle rigid materials from it for the purpose of decreasing its volume. The aims of this study were to clarify three hypotheses: (1) whether a flower pot would be economically made from sludge cake, (2) whether it would be safe for environment, and (3) when vegetables would grow enough in it, whether they would be safe for human consumption. Methods Sludge cake was mixed with soil (soil texture: heavy clay). The circular plaster mold was used as a fixed mold. As the toxicological testing, leaching test and seed germination test were used. Heavy metal concentrations in vegetables grown in the flower pot were measured. Results The flower pot was sufficiently formed by drying in natural open air. The results of leaching test showed three heavy metals, lead, nickel and copper, were lower than the standard in Thailand. The seed germination test suggested no negative effects of the flower pot on the germination of Chinese kale. Lead concentrations in the Chinese kale were higher than the recommended maximum level in leafy vegetables. ConclusionThe new flower pot can be made from sludge cake with soil. It has the possibility to have no negative effect on the environment. Although the vegetables grown in this flower pot are not suitable to eat, this flower pot has the possibility to solve the environmental and health problems.

Hearing loss induced

Objectives Now, a lot of researchers have tried to make recycled rigid materials from the sludge cake produced in paper mill industries for the purpose of decreasing its volume. In this study, the researchers tried to make economically a disposable bin and to examine whether it is toxic or not to the outside environment. Methods To make a disposable bin, the researchers used the sludge cake, a plastic basket, as a fixed mold, white cloth or newspaper, as a removable supporter for wrapping around the mold, and latex or plaster, as a binder. The strength of the samples was measured by tensile-stress testing. The water absorption was evaluated by Cobb test. As toxicological tests, leaching test and seed germination test were selected. Results It was possible to form the disposal bin from the cleaned sludge cake. They seemed safe to carry garbage in the industry judging from the results of tensile-stress testing. Some of them showed less water absorptiveness (higher water resistance) in the results of Cobb test. The results of leaching test showed small values of three heavy metals, lead, nickel and copper, in the leachate. The seed germination test suggested no adverse effects of the bins in the clay and sand on the tomato growth. Conclusions The results of these tests suggest that the bins have good strength, sufficient water resistance and no toxicological effect on the environment. This new recycled bin has the possibility to solve the environmental and health problems at disposing the sludge cake.

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