Effects of metal oxide nanoparticles on nitrification in wastewater treatment systems: A systematic review

Abstract

While the variety of engineered nanoparticles used in consumer products continues to grow, the use of metal oxide nanoparticles in electronics, textiles, cosmetics and food packaging industry has grown exponentially in recent years, which will inevitably result in their release into wastewater streams in turn impacting the important biological processes in wastewater treatment plants. Among these processes, nitrification play a critical role in nitrogen removal during wastewater treatment, however, it is sensitive to a wide range of inhibitory substances including metal oxide nanoparticles. Therefore, it is essential to systematically asses the effects of metal oxide nanoparticles on nitrification in biological wastewater treatment systems. In this review we discuss the present scenario of metal oxide nanoparticles and their impact on biological wastewater treatment processes, specifically nitrogen removal through nitrification. We also summarize the various methods used to measure nitrification inhibition by metal oxide nanoparticles and highlight corresponding results obtained using those methods. Finally, the key research gaps that need to be addressed in future are discussed.

Engineered metal oxide nanomaterials inhibit corneal epithelial wound healing in vitro and in vivo

“…Metal oxide engineered nanomaterials (ENMs) are commonly used in various industrial applications and daily consumer goods including sunscreens (Burnett and Wang, 2011), cosmetic products (Lu et al, 2015), antimicrobial coatings (Raghunath and Perumal, 2017), solar cells (Singh et al, 2016), semiconductors (Jo et al, 2015), pigments and UVabsorption filters (Singh and Nanda, 2014;Kim and Min, 2013), filling materials in food production (Kapoor et al, 2018), as well as toothpastes, and sanitary ware coatings (Contado, 2015). In spite of the widely publicized benefits of metal oxide ENMs, recent concerns have been raised regarding potential adverse effects of these ENMs on human health and the environment.…”

The effects of engineered nanoparticles on nitrification during biological wastewater treatment

“…AOB 16S-rRNA), and the decreased abundance of the active players in wastewater N-removal is often found to correlate with nitrification inhibition. Coupling different types of techniques is more frequently adopted in recent studies, and this will eventually provide a holistic picture of ENP effects on the nitrification process in WWTPs (Kapoor et al, 2018). At the current stage, many gaps remain to establish meaningful and unambiguous connections between performance deterioration data and cellular and molecular damaged data.…”

Long-Term Toxicity of ZnO Nanoparticles on Scenedesmus rubescens Cultivated in Semi-Batch Mode

“…The increasing use of NPs in daily products leads to their release in WWTPs and natural systems. Although the environmental concentrations of NMs are still unknown, there is evidence of the presence of NPs in WWTPs [27], from which some of them escape into water bodies [28]. NPs may remain in the environment for a long period and can be potentially toxic to aquatic life [28].…”

“…It is important to assess the effects of metal nanoparticles on nutrient removal in biological wastewater treatment processes [27]. During the exposure of S. rubescens to ZnO NPs, it was observed that nutrient removal was analogous to biomass concentration, and nutrient uptake was not affected by the presence of NPs.…”

“…Many studies have reported that the major toxicological concern is that some of the manufactured nanomaterials are transported across algal cell membranes, especially into mitochondria [28]. Concequenlty, NPs may cause damage of algal cells due to the accumulation of nanoparticles in the membrane, and ROS production, which subsequently impact macromolecules, including DNA, lipoproteins, and enzymes [27]. Agarwal et al [40] reported that ZnO NPs interact with the cell membrane and may form pits with intracellular leakage, which eventually causes cell death.…”