Assessing the Effects of Silver Nanoparticles on Biological Nutrient Removal in Bench-Scale Activated Sludge Sequencing Batch Reactors

Abstract

Ag Analytical Methods. Briefly, samples were diluted in an acid solution to digest stabilizing coatings and other compounds that could interfere with ICP-MS measurements. An Agilent 7700 inductively coupled plasma mass spectrometer (ICP-MS, Santa Clara, CA) was used to measure total and dissolved Ag. First, total Ag was measured by dissolving a sample of wastewater in 2% HNO 3 and 0.5% HCl concentrated acid for at least 24 h. Samples were separately taken to measure the amount of dissolved Ag in the wastewater. Dissolved Ag samples were defined as the fraction of Ag filtrate that can be passed through and Amicon® Ultra-4 Centrifugal Filter Unit (Millipore, Billerica, MA) and centrifuged at 7,000 rpm for 35 min. The filtrate was then acidified with nitric and hydrochloric acid using a method amended from Wang et al. 1 . DNA extraction and PCR Conditions. Biomass samples were taken periodically from the SBRs and micro-centrifuged for 1 min at 13,000 x g. Biomass samples were then immediately stored at -20°C until DNA extraction. Duplicate samples were extracted for

Fate of metallic engineered nanomaterials in constructed wetlands: prospection and future research perspectives

“…There are some studies where the effects of ENMs on actual wastewater treatment processes have been investigated. Alito & Gunsch (2014) studied COD and ammonium removal efficiencies in laboratoryscale sequencing batch reactors (SBRs) which were spiked with citrate-and GA-coated Ag-NPs (0.2 mg/L). Although the treatment efficiency was recovered within h, the COD and ammonium removal efficiencies were initially affected by -30 % and by 1 -15 %, respectively.…”

Contradictory effects of silver nanoparticles on activated sludge wastewater treatment

“…Higher concentration of Ag-NPs often results in more significant adverse effects [2], [3], [4], [5]. Hormetic effects under sublethal concentration have been reported occasionally but stayed as a marginalized concept [6], [7], [8], [9], [10].…”

Implications of Engineered Nanomaterials in Drinking Water Sources

“…Typical wastewater treatment uses physical settling processes followed by biologically active reactors to remove suspended and dissolved pollutants, producing residual sludge (biosolids) that is predominately made up of microbial biomass. ENMs entering wastewater treatment plants (WWTPs) have been shown to be removed from wastewater through partitioning to biosolids, with removal typically exceeding 70% and ranging from 23 to 99.9%, depending on the ENM and wastewater treatment conditions (Alito & Gunsch 2014; Barton et al 2014; Kaegi et al 2013; Li et al 2013; Jeong et al 2012; Wang et al 2012; Kaegi et al 2011; Westerhoff et al 2011; Kiser et al 2010, 2009; Tiede et al 2010; Benn & Westerhoff 2008; Mueller & Nowack 2008). Although the majority of ENMs are likely to be removed through conventional biological wastewater treatment, ENMs have been detected in wastewater effluent in lab‐scale experiments (Wang et al 2012; Kiser et al 2010, 2009), pilot‐scale experiments (Kaegi et al 2011), and field sampling (Kaegi et al 2013, Li et al 2013, Johnson et al 2011a, Westerhoff et al 2011) at concentrations in the ranges of <12 ng/L (Li et al 2013) for silver nanoparticles; 3.2 ± 0.4 μg/L (Johnson et al 2011a), <5 to 15 μg/L (Kiser et al 2009), and <2 to 20 μg/L (Westerhoff et al 2011) for TiO 2 nanoparticles.…”