Eutrophication of surface water has become an environmental concern in recent decades. High concentrations of nutrients, especially nitrogen- and phosphorus-rich species, have contributed to the process of eutrophication, highlighting a demand for effective and economical methods of removing nitrogen and phosphorus from wastewater. This study aimed to investigate the ability of a green microalga species, Scenedesmus sp., to remove nitrogen and phosphorus, as well as chemical oxygen demand (COD) and biochemical oxygen demand (BOD5), from fertilizer plant wastewater. Different microalgae concentrations from 10 mg/L to 60 mg/L were used to assess the growth rate, biomass production, and removal ability. The results indicated that Scenedesmus sp. grew well in the wastewater (with a growth rate from 0.3 to 0.38/day) and produced up to 70.2 mg/L of dry biomass. The algal species was able to remove ammonium (NH4+), nitrate (NO3−), phosphate (PO43−), total phosphorus (TP), COD, and BOD5 with removal rates up to 93%, 84%, 97%, 96%, 93%, and 84%, respectively. Autobioflocculation (AFL) was observed in all cultures with flocculation activity of up to 88.3% in the highest algal biomass treatment. The formation of bioflocculation enhanced the removal of nutrients, COD, and BOD5 from wastewater effluent. The results indicated that wastewater from a fertilizer plant could be used as a cost-effective growth medium for algal biomass. The autoflocculation of microalgae could be used as a more practical approach for wastewater treatment using microalgae to eliminate eutrophication.

In order to find a new environmentally friendly coagulant that could partially replace conventional polyaluminum chloride (PAC), which was shown to be toxic to aquatic environments, gum extracted from the seeds of Cassia fistula Linn. (CF) was investigated for the decolorization of reactive dyes Blue 19 (RB19) and Black 5 (RB5) using jar-test experiments. The optimal results showed that crude CF gum did not achieve high degrees of decolorization of RB5 and RB19 when compared with PAC coagulant under the same conditions. Whereas when CF gum was used in combination with PAC, decolorization efficiencies of both dyes reached over high values at 40 % volume fraction of gum. These results indicated the potential of using CF gum as a "green" coagulant or as a contributing factor to color removal in textile wastewater.

Chitosan was combined with zeolites into composite membranes reinforced with glutaraldehyde crosslinking. The zeolite loading in the composite membranes was varied in the range 10-50 %, and the resulting membrane loading was varied at around 50 wt. %. The zeolite-loaded membranes showed better mechanical properties. The elimination of trace metal cations, Cr, As, Cd and Pb, by the chitosan-zeolite composite membranes was examined through the evacuation permeation process (EPP). In the permeability at each applied pressure, the selectivity of the composite membranes to the Cr ion was shown in the order of Cr > As > Cd > Pb at pH 5.5. It was noticed that the composite membrane with 20 wt. % zeolite loading showed the highest performance in the adsorption selectivity to the Cr cations. These results reveal the potential ability of the composite membrane to purify wastewater by removal of trace metal ions.

In this study, air flow controlled incinerator (AFCI) was used to treat medical solid waste in Vietnam. The experiment was conducted with solid waste samples that was weighed approximately 2.1–3.3 kg/h and had moisture content of 2.8–11.7%. The results showed that an increase in the airflow rate during the drying process accelerated the combustion time by 10–20%, and the optimal airflow rate was 1.1 m/s. The combustion time varied from 0–45 min. The highest temperatures recorded in the drying chamber, carbonisation chamber and combustion chamber after 25–35 min of operation were varied from 195°C, 775°C and 1275°C, respectively. The temperature of the stack was from 33–68°C after the treatment by the wet scrubber using 20% NaOH solution. The combustion capacity was 77.3–87.5%. The experimental results revealed the AFCI process advantages including low operation cost and suitability for treating hazardous waste on a small scale.

critical issue. It is necessary to identify the fate and sources of MPs in the environment, minimise their release and adverse effects. Compared to marine sediments, standardised methods for extracting and estimating the amount of MPs in freshwater sediments are relatively limited. The present study focuses on MP recovery efficiency of four commonly used salt solutions (NaCl, NaI, CaCl 2 and ZnCl 2 ) for isolating MPs during the density separation step from freshwater sediment.

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This paper analyzes the impact of country disclosure on the firm value of listed companies in Viet Nam. As the sharp increase in population and urbanization has led to the depletion of water resources, the issue of water management is having an impact on the sustainable development of businesses. These days stakeholders and investors are taking this issue more and more seriously, which leads to a business disclosing country information that has a positive effect on their firm value. We use the quantitative method through instrumental variables for a sample of 170 companies listed on the Ho Chi Minh Stock Exchange and conducted from 2015-2019. The results of our study have shown that there is a positive influence of information disclosure on corporate governance. Our research aims to provide additional information for the current literature by providing further evidence for the field and suggesting solutions for governments, stakeholders and companies.

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