Evaluation of Commercial Reverse Osmosis and Nanofiltration Membranes for the Removal of Heavy Metals from Surface Water in the Democratic Republic of Congo

Abstract

This study evaluates the performance of commercial reverse osmosis (RO) and nanofiltration (NF) membranes for the removal of metal ions from synthetic water and surface water carried from the north-west of Lake Tanganyika in the city of Uvira, in the east of the Democratic Republic of Congo. Metal ion analyses were performed by the standardized ICP-MS and ICP-OES methods. The RO membrane showed higher metal ion rejection in high-concentration solutions (synthetic samples) prepared in the laboratory as well as in low-concentration samples from real raw water collected near Lake Tanganyika. Rejection levels were higher than 98% for Cr3+, Pb2+, Cd2+, As3+, Ni2+, and Sb+3 ions in the synthetic solutions, and 99.2, 98.8, 98.6, 99.2, 98.4, and 98.8%, respectively, in the real samples. The concentrations of metals in the permeate varied depending on the feed concentration and were 0.15 to 1.02 mg/L, 0.33 to 22 mg/L, and 0.11 to 22 mg/L in RO, NF90, and NF270 membranes, respectively. Regarding the NF membranes, the rejection of Cr, Ni, and Cd ions was interesting: 98.2, 97.8, and 92.3%, respectively. However, it was lower for Pb, As, and Sb ions: 76.9, 52.5 and 64.1%, respectively. The flux of NF was 329 to 375 L/m2.h, much higher than for RO membranes, which had a flux of 98 to 132 L/m2.h. The studied membranes are thus a feasible solution to remove the studied metals from real water sources at low concentrations since they meet the standards of the World Health Organization on specific values assigned to chemicals from industrial sources and human habitation areas where these ions are present in drinking water.

A Comprehensive Review on Wastewater Nitrogen Removal and Its Recovery Processes

“…RO and NF were originally developed for the purification and recovery of drinking water from brine and brackish water. In recent years, both have gradually been used to remove pollutants such as heavy metals, nitrogen, and phosphorus [ 149 , 150 , 151 ]. Compared to other membrane technologies, they are more flexible, easy to operate, and relatively easy to maintain [ 152 ].…”

Biosorption of Technologically Valuable Metal Ions on Algae Wastes: Laboratory Studies and Applicability

“…Physical methods (such as membrane processes, osmosis, etc.) require expensive equipment and are inefficient when the concentration of metal ions is higher than 100 mg/L [8,9]. Biological methods (such as bioaccumulation or phytoremediation), although characterized by high selectivity, have a modest efficiency in removing heavy metals and a high risk of contamination [10,11].…”

Application of Unsupervised Learning for the Evaluation of Aerogels’ Efficiency towards Dye Removal—A Principal Component Analysis (PCA) Approach

“…It functions on the principle of settling velocity; this term can be simply defined as the speed at which a particle settles. At this step of the process, the slightly treated waste, which is referred to as effluent, is free of solids larger than 10 µm and should be all organic matter, which will be treated further [ 3 , 4 ]. The top layer of the clarified water flows over a weir wall and into the next basement process called the aeration basin.…”

“…Several approaches can rise, following the particle dissolved in water size: UltraFiltration (UF), NanoFiltration (NF), and Reverse Osmosis (RO). The latter removes up to 99% of the water contaminants [ 3 , 4 ].…”