Application of Modified Bentonite in Water Treatment (II)
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2.3 Treatment of organic sludge Due to the strong adsorption capacity of sludge for organic pollutants, it is difficult to achieve the treatment effect by biodegradation or traditional methods. If more organic pollutants is added to the organic adsorption capacity of clay minerals, contaminants redistribution, it is possible to remove organic contaminants in the sludge. Based on this idea, the scholars used a monovalent anionic surfactant to modify Fe 2 O 3 and applied it to phenanthrene-containing sludge. The phenanthrene was transferred from the sludge to the organic phase around Fe 2 O 3 and reused. magnet which is separated, the sludge removal phenanthrene up to 98% to 99%. In addition, Irfan et al., in the treatment of oily sludge, first extract the oil by means of refining and separation, and then decolorize the oil with 2.5% bentonite and 0.75% oxalic acid to make it an available oil.
2.4 Decolorization Printing and dyeing wastewater is a kind of industrial wastewater that is difficult to treat. In recent years, modified bentonite has made some progress in the decolorization treatment of printing and dyeing wastewater. The adsorption mechanism is mainly physical adsorption. Chen Tianhu et al reported that when the dosage of sodium bentonite and inorganic polymer modified bentonite adsorbent was 0.1%, the decolorization rate of red printing and dyeing wastewater was over 88%, and the decolorization rate of treated blue wastewater was 98%. Yan Jingping's bentonite adsorbent modified with sodium and hydroxy iron at a dosage of 5-6 g/L, the acid red COD removal rate was 45%, the active bright red COD removal rate was 71%, and the acid black COD removal rate was Up to 60%. Studies by Hang Hu et al. showed that the use of 0.01% bentonite plus 0 5% of polyaluminium chloride can reduce the decolorization rate of cation-based printing and dyeing wastewater by 94% to 100%.
2.5 In addition to high levels of phosphorus phosphorus in water can cause eutrophication, severe algae blooms, smelly water, fish kills, seriously affect the aquatic environment and to human beings bring direct economic losses. Chemical or biological methods are often used for the purification of phosphorus-containing wastewater. Although the former has high removal efficiency and stable operation, it has a large amount of sludge and high operating cost; the latter has complicated operation and low removal efficiency. In recent years, research on modified bentonite adsorbents has provided a new way for wastewater dephosphorization. Sun Jiashou et al. used aluminum cross-linked montmorillonite to adsorb dephosphorization. When the amount of adsorbent was 9g/LH 2 O, the phosphorus adsorption dose was 5 56mg/g, and the removal rate was 100%.
2.6 Groundwater Remediation Since the 1970s, European and American countries have made great progress in groundwater pollution control technology. Bentonite and soil modified with quaternary ammonium surfactants are tens to hundreds of times more capable of removing organic pollutants than natural clay minerals and soils, and can effectively inhibit the migration of organic pollutants in the environment. Simple, effective, economical, and practical environmental repair tool. At present, some foreign scholars use clay minerals such as bentonite to easily form the properties of organoclay, simulate the environment of soil and aquifer containing organic pollutants, and add quaternary ammonium salt cationic surfactant to form organic pollutants. The adsorption zone can effectively intercept the flowing organic pollutants and fix the organic pollutants in the adsorption zone, thereby controlling the migration of pollutants in the groundwater. Reuse or remove organic pollutants enriched in the adsorption zone by microbes or chemical methods existing in nature to completely eliminate the organic pollution of groundwater.
3 Conclusion Bentonite has been studied for many years at home and abroad, and has achieved certain results, but the research in water treatment has only begun, and these studies are limited to the laboratory stage. Currently. No public reports of the practical application of modified bentonite in water treatment have been seen. In the future, improving the selectivity of modified bentonite for specific pollutants and finding a suitable regeneration method is the next step to solve. In addition, it is necessary to develop and improve the modified bentonite adsorption water treatment process to solve the problem that the adsorption performance of the modified bentonite may be interfered by other pollutants in practical applications. Nevertheless, through previous studies, we can still see that modified bentonite as a water treatment material has the following points: (1) abundant reserves and low prices; (2) simple preparation method; (3) high Chemical and biological stability; (4) easy to regenerate. Therefore, it is an ideal choice to replace traditional water treatment materials and will be widely used.