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Floating beds were used widely for improving water quality in aquaculture environments, but its effects on ammonia changes in aquaculture environments were still not clear. In this study, the Ipomoea aquatic floating beds were introduced into 2 intensive aquaculture ponds to investigate its effect on ammonia dynamics, and 2 similar ponds set as controls. Throughout the experiment, control ponds were higher than the corresponding floating bed ponds in ammonia concentration by 6.2 ~ 75.7%, and 12.4 ~ 43.2%, respectively. The unionized ammonia concentrations of the two control ponds were 2.58 ~ 8.86-fold higher than that of the corresponding experimental ponds. In the Ipomoea aquatica fibrous roots, the amoA copy numbers of ammonia-oxidizing bacteria (AOB) ranged from (1.16 ± 0.01) x 105 to (2.33 ± 0.24) x 106 copy g-1, and those of ammonia-oxidizing archaea (AOA) ranged from (5.41 ± 0.25) x 10³ to (3.82 ± 0.37) x 104 copy g-1. The Ipomoea aquatica floating bed can efficiently remove ammonia in intensive aquaculture pond, especially can decrease the unionized ammonia level and the unionized ammonia toxicity to fish. It was assumed that the decrease of the unionized ammonia level was resulted from the pH decrease, which was contributed by the floating bed through algal photosynthesis inhibition. High richness of AOB and AOA in the Ipomoea aquatica rhizosphere indicated that the rhizospheric ammonia-oxidizing microorganisms played a vital role in ammonia removal. [ABSTRACT FROM AUTHOR]

Floating beds with two different eutrophic Sphagnum mosses, Sphagnum fallax and Sphagnum squarossum, were used for heavy metal removal from fluctuating degraded riverine wetlands in Songhua River. Results indicated that Sphagnum moss was adapted to water quality fluctuation in the presence of toxic Cr. The increasing quantity or blue shift of the peak position in fulvic acid-like played a promoting role in the removal of heavy metals in degraded wetland water. The accumulation of five heavy metals in Sphagnum fallax was in order of Fe > Mn > Cr > Zn > Cu, with Sphagnum fallax retaining the greatest ability to accumulate Fe up to 1780.01 ug/g. While Sphagnum squarossum retained superior potential for Mn accumulation for a long time. This study could be useful for better understanding of heavy metals restoration in fluctuating degraded riverine wetlands by eutrophic Sphagnum mosses. [ABSTRACT FROM AUTHOR]

Abstract: A novel photocatalysis floating bed reactor was prepared to study for the degradation of textile wastewater. The reactor was assembled by short quartz tube loaded TiO2 film, showing a good catalytic activity. The decolorization rate of methyl orange can reach 98.7% by the photocatalysis floating bed reactor under UV light irradiation for 8hours. Scanning electron microscopy and EDS were used to characterize the structure of the photocatalyst. The results indicate that the TiO2 films of 1μm were loaded on short quartz tube in the photocatalysis floating bed reactor. [Copyright &y& Elsevier]

Abstract: The treatment capacity of an integrated constructed treatment system (CTS) was explored which was designed to reduce phosphorus (P) from secondary effluents. The integrated CTS was combined with vertical-flow constructed wetland, floating bed and sand filter. The vertical wetland was filled from the bottom to the top with gravels, steel slag and peat. Vetiver zizanioides (L.) Nash was selected to grow in the vertical constructed wetland while Coix lacrymajobi L. was grown in floating bed. The results suggested that integrated CTS displayed excellent removal efficiency for chemical oxygen demand (COD), dissolved phosphorus (DP), and total phosphorus (TP). The average COD removal efficiency of the integrated CTS was 90.45% after 40days of operation, the average DP and TP removal efficiencies of the integrated CTS were 97.43% and 96.40%, respectively. The integrated CTS has good potential in removing COD as well as P from secondary effluents. [Copyright &y& Elsevier]

• Pistia stratiotes has been used in design of floating bed. • Initial COD, vegetation coverage ratio and wastewater depth have been considered in designing process. • RSM based BBD model was utilized to optimize COD removal. • At the optimized conditions, highest COD removal efficiency of 96 % was obtained. Pollution of fresh water bodies is a global threat today and its the right time to take necessary steps to restore those contaminated lakes without disturbing the food web. Floating Bed (FB) is a green and sustainable technology, which can be used in treatment process. The present study aims to design a floating bed and assessing its performance for the treatment of domestic wastewater. Pistia stratiotes is considered as the plant of interest as it contains a plenty of aerenchyma tissues, which keep it in floating condition without any supporting material. Box-Behnken Design (BBD) was applied to develop the system and to study the effect of various parameters and their interaction effect on performance. The system was able to remove 96 % COD at an optimum condition : initial COD of 321.3 mg L-1, vegetation coverage ratio of 0.43 and wastewater depth of 29.4 cm. The plant also uptake significant amount of nutrient as effluents of the most experimental runs were contained below 2 mg L-1 of NH 4 +-N and 4 mg L-1 of and PO 4 3--P. A maximum Relative Growth Rate (RGR) of 0.0847 g g-1day-1 was obtained for Pistia stratiotes, when the vegetation coverage ratio was 0.25. In the kinetic analysis study, it was concluded that biodegradation followed the zero-order and first-order model with R2 value of 0.9765 and 0.9171, respectively. Overall, the system was working well and since it is one of the most eco-friendly technology, can be used in treatment of polluted water body. [ABSTRACT FROM AUTHOR]