Removal effects of three aquatic plants on chemical oxygen demand(CODcr) in livestock breeding wastewater

ObjectiveThe ability of aquatic plants to remove chemical oxygen demand (CODcr) from livestock breed-ing wastewater was investigated , in order to provide theoretical basis for treating livestock breeding wastewater with ar-tificial wetland system. MethodThe reed, water hyacinth and water spinach, combination of reed and water hyacinth, combination of reed and water spinach was cultivated in artificial simulated breeding wastewaters with different concentra-tions, respectively, compared with different concentrations of livestock breeding wastewaters without planting aquatic plants. And the removing and purifying effects of reed, water hyacinth and water spinach on CODcr in livestock breeding wastewater were analyzed comparatively. ResultThe results showed that, three aquatic plants were ordered based on their abilities to remove and purify CODcr in livestock breeding wastewater, as follow: combination of reed and water hyacinth>combination of reed and water spinach>water hyacinth>water spinach>reed. After 15 days of culture , the removal rates of CODcr for three aquatic plants ranged from 43.8% to 87.3%, while the removal rate for control ranged from 28.9% to 66.4%. ConclusionThe reed, water hyacinth and water spinach have great ability to remove and purify CODcr in livestock breeding wastewater with a low concentration, while they have ordinary ability in breeding wastewater with a high concen-tration. Therefore, while building the artificial wetland plant system, plants should be combined properly to improve their removal effect according to actual situation.