The article studies the occurrence of microplastics in the inlet and outlet wastewater streams at wastewater treatment plants in the Saigon-Dong Nai river basin, Vietnam and provide a suitable removal solution. The sampling method is suitable for the actual conditions of Vietnam combined with the application of Fourier-transform infrared spectroscopy to analyze the microplastic composition in the sample. The results show that microplastics exist in many different shapes and colors. Density of microplastics in the inlet stream is from 10.188-15.074 gL -1 . Density of microplastics in the outlet stream is from 0.684-2.107 gL -1 . In which, filaments with an average length of 524.68 μm and an average radius of 100.4 μm; slender form with an average length of 229.49 μm and an average width of 101.3-120.6 μm; granules with an average radius of 113.81μm. The removal efficiency of microplastics in the wastewater stream at the surveyed wastewater treatment plants ranges from 85.4% to 93.7% through the following main processes: pre-settlement, flotation, moving bed biofilm reactor, sedimentation, filtration. Solutions for the removal of microplastics from wastewater treatment plants in the Saigon -Dong Nai river basin were proposed and discussed.

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The study was conducted to evaluate 5 main river basins: Long Song River, Luy River, Cai Phan Thiet River, Ca Ty River and Phan River in Binh Thuan province has a great impact on the province's socio-economic development. By method of survey, sampling and analysis of physico-chemical parameters and WQI method with hydrological regimes, typical minimum flow, the research has carried out the following contents: (1) An overview analysis of the water quality situation in the study area in the years 2018-2020;(2) Calculating the WQI index to determine the overall status of the water environment of 5 river basins; (3) Determine the environmental flow that needs to be maintained in the river to ensure the daily activities and production of people in the area. The research results have determined the current status of the water environment in rivers and canals and assessed the responsiveness of water sources to socio-economic activities in the locality. From there, propose solutions to effectively use surface water in river basins of Binh Thuan province in the direction of sustainable development.

Tóm tắt: Chỉ số chất lượng nước Water Quality Index (WQI) là một chỉ số được tính toán từ các thông số quan trắc chất lượng nước, dùng để mô tả định lượng về chất lượng nước và khả năng sử dụng của nguồn nước đó được biểu diễn qua một thang điểm. Hiện nay có rất nhiều quốc gia/ địa phương xây dựng và áp dụng chỉ số WQI. Thông qua một mô hình tính toán, từ các thông số khác nhau pH, DO, BOD5, COD, NH4 + , PO4 2-, Coliform...ta thu được một chỉ số duy nhất. Sau đó chất lượng nước có thể được so sánh với nhau thông qua chỉ số WQI. Theo Quyết định 879/QĐ-TCMT, ngày 01 tháng 7 năm 2011 của Tổng cục Môi trường. Bài báo trình bày, bằng công cụ tin học tác giả đã nghiên cứu và xây dựng phần mềm WQI_Serepok nhằm tính toán nhanh chỉ số chất lượng nước WQI, góp phần vào công tác quản lý chất lượng nước sông Serepok.

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Solar energy has now been applied to provide energy in many different fields around the world. In Vietnam, many solar energy projects are being implemented. In this transdisciplinarity research, research team and local stakeholders participate in designing a solar application to power a fruit and vegetable refrigerator located at Cu lao Rua, Thanh Hoi commune, Tan Uyen Town, Binh Duong province, Vietnam for the poor worker living in the disadvantaged localities with difficulties due to the impact of the Covid-19 pandemic. This is considered a community development project with the use of renewable energy, contributing to environmental protection of the new rural commune.

The Groundwater Quality of Tay Ninh province was studied applying monitoring of 24 wells from 2016 to 2019. Based on this research there were determined 8 sites with very bad water quality, mostly due to the low pH index, high iron and ammonium contents. The remaining 16 wells preserve very good water quality. To determine the relationship between Groundwater Quality and peat deposits, the authors studied the map of these deposits in Tay Ninh province and compared it with monitoring points. The results show source of pollution mainly related to peat deposits and human activity. Due to the sustainable development, Tay Ninh province needs planning and the reasonable exploitation of the groundwater in the next 30–50 years, as well as the water resources partition and their management in each district.

Electro-hydraulic actuators have been widely applied in the industry because they have several major advantages. In this paper, we focused on controlling the mini motion package electro-hydraulics actuator. First, a mathematical model of the electro-hydraulic actuator (EHA) was implemented to apply the control process to the proposed system. Second, we applied the linear quadratic regulator (LQR) controller to a linear model that is converted from the nonlinear EHA system. Finally, the numerical simulation results were performed in which the results obtained from the LQR controller were compared with the PID controller to show the superiority of the proposed solution.