Enhanced antimony(V) removal using synergistic effects of Fe hydrolytic flocs and ultrafiltration membrane with sludge discharge evaluation

Abstract

a b s t r a c tThe integration of adsorbents with ultrafiltration (UF) membranes is a promising method for alleviating membrane fouling and reducing land use. However, a number of problems have become apparent concerning the granular adsorbents used currently, such as high running cost, high chance of causing membrane surface damage, low in situ chemical cleaning efficiency, etc. Herein, to overcome these disadvantages, loose in situ hydrolyzed flocs were directly injected into the membrane tank, providing strong adsorption ability at low cost. To test the feasibility of this method, the heavy metal pollutant antimony (Sb (V)) in a water plant was chosen at a test case, which is similar to arsenic and difficult to remove. We found that Fe-based flocs integrated with an UF membrane showed a large potential advantage in removing Sb(V), even after running for 110 days. We demonstrated that the observed slow transmembrane pressure development could be ascribed to the loose floc cake layer formed, even though some extracellular polymeric substances were induced during operation. We also found that the floc cake layer was easily removed by washing with feed water or dissolved by in situ chemical cleaning under strongly acidic conditions, and many primary membrane pores were clearly observed. In addition, a relative long sludge discharge interval was feasible for this technology and the effluent quality was good, including the turbidity, chromaticity and iron concentration. Based on the excellent performance, these flocs integrated with UF membranes indeed show potential for application in water treatment.

Evaluation of an ultrafiltration membrane for the removal of fish viruses and bacteria in aquaculture water

“…UF membrane pore size was previously reported to be influenced by temperature (8.9 -28.5 °C), where the pore size reduces at lower temperatures (Ma et al, 2017). In the current study, the UF performance was evaluated at a low (4 -7°C) and high (16 -19°C) temperature ranges for salmonid aquaculture, and both resulted in a 100% virus and bacteria removal.…”

“…In the current study, the UF performance was evaluated at a low (4 -7°C) and high (16 -19°C) temperature ranges for salmonid aquaculture, and both resulted in a 100% virus and bacteria removal. However, the pressure (bar) before the membrane was 11% higher at low temperature when compared to higher temperature, which may be a result on the effect of temperature on pore size as described by Ma et al (2017).…”

Titanium Coagulation Simplified Removal Procedure and Alleviated Membrane Fouling in Treatment of Antimony-Containing Wastewater

“…Coagulation with iron (Fe) salts is found to be an effective way for the removal of Sb. − However, because of the oxidizing properties, residual iron is a big threat to the subsequent reverse osmosis (RO) system. − Therefore, Fe coagulation is generally avoided in any sequential coagulation–RO filtration process.…”

Sb(V) Reduced to Sb(III) and More Easily Adsorbed in the Form of Sb(OH)3 by Microbial Extracellular Polymeric Substances and Core–Shell Magnetic Nanocomposites

“…Sb­(V) and Sb­(III) are two main valences of Sb in the environment. Sb­(V) exists mainly in electronegative Sb­(OH) 6 – , while Sb­(III) exists mainly in electroneutral Sb­(OH) 3 . , Due to the neutral characteristic in most cases, Sb­(III) has no electrostatic repulsion in contrast to the negatively charged Sb­(V), making the Sb­(III) more stable and hypothetically easier to remove from neutral and alkaline environments, but direct evidence of this property is lacking. ,− The speciation of Sb is more complicated for this metalloid than it is for ordinary metals, making research regarding Sb adsorption more difficult . As a result, recent trends in Sb remediation include determining the mechanism of Sb adsorption, as well as the development of novel adsorbents with high reducibility and adsorption capacity. , …”