Textile wastewater treatment model using non-thermal plasma
Dyes play an important role in modern life, being used in many industries such as textile, printing, leather and paper. These industries consume a large amount of water and also generate a large amount of wastewater. This wastewater contains hundreds of chemicals: dyes, electrolytes, starch, yeast and oxidants. Furthermore, because the dyes are anti-microbial, light resistant and chemically stable, textile wastewater (TW) is difficult to treat.
A lot of research has been conducted to create appropriate technologies to treat TW. Research focuses on developing advanced oxidation processes (AOPs). The AOPs generate highly reactive agents, notably hydroxyl radicals (OH•) which are non-selective oxidizing agents capable of mineralizing most organic compounds.
Recently, the AOPs process based on non-thermal plasma (NTP) for water treatment has attracted scientific attention. NTP can simultaneously and locally create physical effects (electric field, UV rays, shock waves...) and strong oxidizing agents (OH•, O•, O3, H2O2) without adding any chemical agents. The mutual combination of these agents creates the ability to effectively treat organic compounds in TW. To access new technologies to effectively handle TW, MSc. Quan Thi Thu Trang and the research team of the Institute of Chemistry carried out the project "Research on the decomposition of dyes in water, using non-thermal Plasma combined with Feo/bentonite catalyst" (code: VAST07.01/20 -21).
The research results confirm the ability to effectively decompose two typical dyes: Azo dye (represented by methyl orange - MO) and reactive dye (RY-145 dye) on the self-made NTP reaction equipment system in the presence of catalyst and without catalyst.
The catalytic material IFMB (nZVI/(Fe-Mn) binary oxide/bentonite) has been manufactured by the research team with the following characteristics: specific surface area 218m2/g, zero charge point PZC = 6.67, the adsorption amount of dye RY-145 reached qmax = 344.8mg/g. IFMB exhibits performance as an effective catalyst for the fenton-like process. The research team produced 05 kg of catalyst for research.
The experimental scale dielectric barrier discharge NTP reactor system has been designed and manufactured by the research team. Research on the decomposition of azo dyes and reactive dyes on manufacturing equipment systems has been carried out in all three models: i) Intermittent operation model, ii) Continuous operation model and iii) Model Continuous operation combined with catalyst.
Image of Plasma reaction system combined with catalyst working in continuous mode and image of Plasma reaction chamber
To explore the ability to treat actual wastewater, wastewater samples General Textile Garment Joint Stock Company Hanoi (Hanosimex) were used to run on an experimental system with a 100mm high IFMB catalytic column supplemented with 5mM/l H2O2. The results showed that COD treatment efficiency increased to 92% (compared to 69% when running only through plasma system). A preliminary assessment of the system's applicability shows that this method can be applied to treat textile wastewater.
MSc. Quan Thi Thu Trang said that wastewater treatment containing persistent organic compounds (including TW) is an issue of concern to scientists and businesses. NTP is a new method for water and wastewater treatment, with outstanding advantages such as being able to create a variety of highly reactive physical and chemical agents on site without using any chemicals, which substances and their effect create the opportunity to thoroughly oxidize difficult-to-decompose organic compounds. Combining NTP with catalyst can enhance wastewater treatment efficiency. However, the main technical barriers for the practical application of this technique are the lack of high-capacity, energy-efficient plasma reactors. Therefore, to be able to develop this research direction for large-scale application, the research team hopes to continue receiving support for research on process techniques and the development of highly efficient plasma reactors.
The research team has published 01 article in a prestigious international journal (SCIE) and 01 article in a domestic journal. The project has been graded excellent by the Acceptance Council of VAST.
Translated by Tuyet Nhung
Link to Vietnamese version