Abstract ▼ AI-Helper

Bioremediation has been recognized as efficient, cost effective, and a suitable alternative to conventional methods for removing contaminant by use of fungi, bacteria and microalgae. In contrast to other organism, microalgae are unique to have the ability to do photosynthesis like plant and to utili...

Bioremediation has been recognized as efficient, cost effective, and a suitable alternative to conventional methods for removing contaminant by use of fungi, bacteria and microalgae. In contrast to other organism, microalgae are unique to have the ability to do photosynthesis like plant and to utilize organic / inorganic carbon substrate, the process termed as phycoremediation. Microalgae can populate reaction site quickly and enhance bioremediation efficiency. In this study, three kinds of microalgae, Chlorella vulgaris, Scenedesmus obliquus, and Ankistrodesmus bibraianus, were used to evaluate the removal potentials of nutrients, total nitrogen (T-N) and total phosphorus (T-P), and heavy metals (Cu and Zn) from the synthetic and swine wastewater. The optimum growth condition for three microalgae and their removal capacity of T-N, T-P, Cu and Zn from synthetic wastewater were investigated. Optimal growth conditions of the three microalgae were established at 28℃, pH 7, and light and dark cycle of 14:10 h. The removal efficiencies of T-N by microalgae in the single treatments of T-N (500, 1 000, 5 000, 10 000 mg/L) were as follows: Ankistrodesmus bibraianus (84%, 75%, 24%, 21%) > Chlorella vulgaris (80%, 71%, 23%, 20%) > Scenedesmus obliquus (70%, 60%, 21%, 18%). Also, the removal efficiencies of T-P by microalgae in the single treatments of T-P (500, 1 000, 5 000, 10 000 mg/L) were as follows: Chlorella vulgaris (50%, 23%, 18%, 18%) ≧ Ankistrodesmus bibraianus (50%, 20%, 18%, and 18%) > Scenedesmus obliquus (34%, 9%, 9%, 8%), respectively. The removal efficiencies of T-N and T-P by microalgae in the mixed treatments of T-N and T-P (500, 1 000, 5 000, 10 000 mg/L) were in the order of Ankistrodesmus bibraianus > Chlorella vulgaris > Scenedesmus obliquus, respectively, as those in the singly T-N and T-P treatments. Based on the results obtained from this experiment, it appears that the effective species of microalgae for T-N and T-P removal were Ankistrodesmus bibraianus and Chlorella vulgaris rather than Scenedesmus obliquus. The removal efficiencies of Cu by microalgae in the singly Cu treatments (10, 30, 50 mg/L) were in the order as follows: Ankistrodesmus bibraianus (86%, 33%, 24%) > Chlorella vulgaris (63%, 23%, 16%) > Scenedesmus obliquus (40%, 20%, 14%), respectively. The removal efficiencies of Zn by microalgae in the singly Zn treatments (10, 30, 50 mg/L) were as follows: Chlorella vulgaris (50%, 20%, 16%) > Ankistrodesmus bibraianus (40%, 17%, 14%) > Scenedesmus obliquus (30%, 10%, 10%), respectively. The removal efficiencies of Cu and Zn by microalgae in the mixed treatments of Cu and Zn (10, 30, 50 mg/L) were in the order of Ankistrodesmus bibraianus > Chlorella vulgaris > Scenedesmus obliquus as those in the singly Cu and Zn treatments. In addition, the removal efficiencies of Cu were higher than those of Zn by all three microalgae. When three kinds of microalgae were applied to swine wastewater, Ankistrodesmus bibraianus had the highest removal efficiencies of nutrients (T-N and T-P) and heavy metals (Cu and Zn) as those in the synthetic wastewater. In conclusion, there was no significant differences in the growth of three kinds of microalgae and the removal efficiencies of nutrients and heavy metals in both synthetic and swine wastewater. Therefore, the results obtained from the study has shown that all three kinds of microalgae could be used in the wastewater treatment for removal of nutrients and heavy metals present in swine wastewater and in particular, Ankistrodesmus bibraianus had the highest adaptability to swine wastewater with a higher removal capacity of nutrients and heavy metals.

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