How to tackle the stringent sulfate removal requirements in mine water treatment—A review of potential methods

Abstract

Sulfate (SO) is a ubiquitous anion in natural waters. It is not considered toxic, but it may be detrimental to freshwater species at elevated concentrations. Mining activities are one significant source of anthropogenic sulfate into natural waters, mainly due to the exposure of sulfide mineral ores to weathering. There are several strategies for mitigating sulfate release, starting from preventing sulfate formation in the first place and ending at several end-of-pipe treatment options. Currently, the most widely used sulfate-removal process is precipitation as gypsum (CaSO·2HO). However, the lowest reachable concentration is theoretically 1500 mg L SO due to gypsum's solubility. At the same time, several mines worldwide have significantly more stringent sulfate discharge limits. The purpose of this review is to examine the process options to reach low sulfate levels (< 1500 mg L) in mine effluents. Examples of such processes include alternative chemical precipitation methods, membrane technology, biological treatment, ion exchange, and adsorption. In addition, aqueous chemistry and current effluent standards concerning sulfate together with concentrate treatment and sulfur recovery are discussed.

Modular Chitosan-Based Adsorbents for Tunable Uptake of Sulfate from Water

“…Currently, sulfate remediation does not generally employ adsorption-based methods, even though adsorbent technology can provide benefits in terms of cost, environmental and maintenance over other types of physical and chemical removal methods [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Adsorption-based removal of sulfate offers a relatively low-cost approach with variable efficiency and selectivity [ 16 ].…”

“…Sulfate as a competitor anion is supported by a recent study of mixed anions (Cl − , HCO 3 − , and SO 4 2− ) [ 41 ]. Similar to chitosan, sparse reports are available for chitin materials in the form of shrimp shells and grafted composite materials have been reported for sulfate removal from aqueous sources [ 15 ]. The chitosan bead systems offer various benefits over its pristine form, e.g., reduced back pressure in column application and increased flow rate [ 42 ].…”

Sequestration of Sulfate Anions from Groundwater by Biopolymer-Metal Composite Materials

“…The natural sources include dissolution and oxidation of sulfate minerals such as gypsum and pyrite along with precipitation and volcanic activity. On the other hand, anthropogenic sources include sewage streams, synthetic detergents, industrial wastewater, mining drainage and mineral tailings, where levels can reach 10,000 mg/L [1][2][3][4]. The sulfate anions can exist in various forms with varying concentrations according to the water source and the nature of the industrial activities of the region [4,5].…”

“…The sulfate anions can exist in various forms with varying concentrations according to the water source and the nature of the industrial activities of the region [4,5]. The toxicological effects of sulfate in humans and animals have been reported to include catharsis, diarrhea, and dehydration as well as changes in methaemoglobin and sulfhaemoglobin levels [1,6]. In freshwater species, sulfate can be lethal at elevated concentrations due to osmoregulatory stress [7,8].…”

Economia circular na indústria de mineração: barreiras para difusão da inovação ambiental

“…várias técnicas para a remoção de sulfato dos efluentes de mineração que podem ser divididos em passivos -são processos que utilizam a força da gravidade, produtos químicos naturais e processos biológicos -e ativos -são métodos que necessitam de dispositivos mecânicos, fornecimento contínuo de eletricidade, químicos e manutenção. Para a remoção do sulfato pode-se destacar os métodos: precipitação -por meio de gesso, calcário e polímeros; adsorção -por meio de carvão ativado, cinzas volantes, zeólitos modificados, biomassa, resíduos de papel e celulose, entre outros; troca iônica por resina; tratamentos biológicos e tecnologias de membranas(RUNTTI et al, 2018). incrustações nos equipamentos industriais ou adsorção para a extração de íons cromo hexavalente, como forma de reduzir o custo com agentes redutores -químicos e bioredutores (CETEM/MCT, 2010).Os métodos tradicionais para o tratamento de efluentes da indústria de mineração incluem a neutralização, precipitação química, tratamento microbiológico e separação de membrana.…”