Application and development of foam extraction technology in wastewater treatment: A review

With the advancement of technology, wastewater treatment has become a significant challenge limiting the clean and sustainable development of chemical and metallurgical industries. Foam extraction, based on interfacial separation and mineral flotation, has garnered considerable attention as a wastewater treatment technology due to its unique physicochemical properties. Although considerable excellent accomplishments were reported, there still lacks a comprehensive summary of process features and contaminant removal mechanisms via foam extraction. According to the latest research progresses, the principles and characteristics of foam extraction technology, the classification and application of flotation reagents are systematically summarized in this work. Then comprehensively commented on the application fields and prospects of iterative flotation technology such as ion flotation, adsorption flotation and floating-extraction. The shortcomings and limitations of the current foam extraction technologies were discussed, and the feasible process intensification techniques were highlighted. This review aims to enchance the understanding of the foam extraction mechanism, and provides guidance for the selection appropriate reagents and foam extraction technologies in wastewater treatment.

Recent advancements in the removal/recovery of toxic metals from aquatic system using flotation techniques

The paramount cause of water scarcity is pollution, which is becoming a massive issue since the last century. Besides, it is evident that water pollution is the main cause of emerging contaminants that are left untreated from industries, can cause serious threats to humans and biota as well. One of the best ways in remediating pollutants and finding a way for generating useable water is to use this contaminated water after the necessary treatment. Heavy metals are of major concern in treatment because of their toxicity, non-biodegradability, carcinogenicity, and they can cause inevitable damages even at low concentrations. In this review article, available different flotation techniques are discussed to address this issue. Flotation tends to be one of the promising techniques that have shown a high scope because of its high produce, low sludge formation, and ease of operation. From the several pieces of literature, it can be inferred that the flotation process can be conducted in one step, and that does not need any expensive materials. Further, this paper deliberates the versatility of each process in disclosing its advantages, limitations, further scope of research and fills the loopholes in the process for better effectiveness. Overall, flotation is a highly probable as well as effective treatment technology to eradicate noxious pollutants present in wastewater and thus helps to compromise environmental and social sustainability.

Iron removal by precipitate flotation

The water from several artesian wells in the metropolitan area of Recife presents high iron content, preventing its use in some industrial processes. The possibility of removing the iron by the use of precipitate flotation using sodium dodecyl sulphate (SDS) as collector was studied. The tests were carried out in a glass column 65 cm high, fed by a constant airflow. At pH 8, where the isoelectric point of colloidal iron hydroxide [Fe(OH)3] was observed, the size of the precipitate increases with conditioning time and facilitates the removal of iron ions by flotation. The results showed that an increase in conditioning time, from 5 to 20 minutes, resulted in a reduction of the residual concentration of iron from 13.2 to 0.2 ppm. The decrease in precipitate specific surface area rendered a decrease in the collector consumption possible. The iron ion removal process by flotation using SDS as collector was shown to be quite efficient. A removal of 99% of Fe3+ contained in the original solution was obtained.