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An adsorbent was prepared from Mangosteen shell using sulphuric acid and sodium bicarbonate as modifiers. Bicarbonate treated mangosteen shell (BTMC) was characterized using FT- IR, SEM, EDAX and XRD data. The Freundlich adsorption isotherm model gives a good fit. The maximum adsorption capacities of BTMC were found to be 58.48 mg g-1 and 49.75 mg g-1 for Pb (II) and. Hg (II). Adsorption of Pb (II) and Hg (II) followed pseudo-second-order kinetics. The adsorption mechanism was explained using the Weber and Morris's intra-particular diffusion process. Batch mode studies with synthetic wastewater suggest that BTMC can be efficiently used in wastewater treatment.

Water treatment ecosystem provides important habitats for various bacterial communities, but the response mechanism of this ecosystem under ultraviolet rays is not yet clear. For this reason, 16S rRNA gene sequencing is used to study the bacterial community structure and metabolic pathways under ultraviolet irradiation. Studies have shown that the bacterial communities under different ultraviolet irradiation are different, which indicates that the time of ultraviolet irradiation has an impact on the structure of bacterial communities. Analysis of driving factors shows that COD, pH, TN and NH3-N also have an impact on the relative abundance of key species. Key species under ultraviolet irradiation are Bacteroidetes, Proteobacteria, Actinobacteria, Firmicutes, Chloroflexi, and Chlamydiae, accounting for 96.69%～98.30%, and ultraviolet irradiation has a significant inhibitory effect on the relative abundance of the key species. As the dominant bacterial phyla in Plateau environment, Chlamydiae is discovered for the first time. The network co-occurrence diagrams constructed under different ultraviolet radiation show that each sample is composed of three independent network diagrams. There are 6 common dominant phyla and 33 common dominant bacterial genera in each sample, which reveals that the structure of the ecosystem is composed of more similar microorganisms, rather than random phenomena. It also reflects the competitive relationship between species and the adaptability of bacteria to the environment. Through the analysis of metabolic pathways, it is found that the dominant metabolic pathways in Plateau environment have certain changes under ultraviolet radiation. Further analysis of metabolic pathways of carbon, nitrogen and phosphorus shows that the relative abundance of related metabolic pathways has a certain change, but the difference in metabolic diagram is small, that is, the effect of ultraviolet radiation is mainly reflected in the relative abundance of metabolic pathways. These findings indicate that ultraviolet radiation in Plateau environment as an important influencing factor has an impact on microbial structure and metabolic pathways. This research provides an important theoretical basis for further understanding of water treatment ecosystem in Plateau environment, and also provides a new perspective for research on sewage treatment systems.

In this paper, the low-cost and practical adsorption for removing methylene blue (MB) dye has been developed by using recoverable natural zeolite that was magnetized with Fe3O4. The magnetization was conducted by co-precipitation technique. The adsorbents obtained from the magnetization were characterized by XRD, FTIR, surface area analyzer and turbidity meter machines. The MB adsorption on the recoverable adsorbent was performed by batch experiment. The effect of Fe3O4 fraction on adsorbent characters, recoverability, and adsorption ability was evaluated. The adsorption kinetic and isotherm were also determined. The research results attributed that recoverable zeolite/Fe3O4 adsorbent has been successfully produced. It was found that the increase of Fe3O4 fraction in the adsorbent, has improved the recoverability, but in the same time, it caused the adsorption decreased. The fraction of Fe3O4 as much 33.30%w displayed compromisingly good capacity and recoverability. The maximum MB dye adsorption was reached by a condition of 0.25 g L-1 of the adsorbent dose, pH 8, and in 60 mins of the contact time The adsorption kinetic well fitted with pseudo second-order with the adsorption rate of 0.0238 mg g-1 min-1. The adsorption strongly agreed with the Langmuir isotherm with adsorption capacity of 32.258 mg g-1 .

In this study activated carbon is produced from areca plant leaves, an agricultural waste material. The physical and chemical structural characterisation of the prepared carbon was carried out by FTIR, TGA and XRD analysis. FTIR study showed the presence of several functional groups, such as C=O, C=C, OH, NH on the surface of the activated carbon. To determine the adsorption efficiency, studies were carried out using cationic and anionic dyes and it was found to be dependent on contact time, temperature and concentration of the solution. The experimental data obtained were correlated with the Langmuir, Freundlich isotherm model. Kinetic data were obtained using second order rate equation. Probable mechanism of adsorption process with the dyes was analysed. As the prepared carbon is cost efficient, abundant and has high uptake capacity, it can be used as an adsorbent for fresh water or waste water treatment. It could be considered as promising material for the removal of dyes.