Environmental implications of aggregation phenomena: Current understanding

Maximova, Natalia; Dahl, Olli

doi:10.1016/j.cocis.2006.06.001

Cited by 109 publications

(43 citation statements)

References 151 publications

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“…Our results were similar to those reported elsewhere for ZnO ENPs, e.g. Mu and Chen (2011), Xiong et al (2011), and Thwala et al (2013, whereas the dosing concentration increase led to enhanced aggregation (Maximova and Dahl, 2006), which is expected because of a higher probability of particle collisions -which ultimately leads to a decline in the dissolution rate (Xiong et al, 2011;Thwala et al, 2013). (b) Figure 6 shows biomass removal during wastewater treatment at different ZnO ENP dosing concentrations.…”

Section: Effect Of Concentration On Zno Enp Removalsupporting

confidence: 79%

Fate, behaviour, and implications of ZnO nanoparticles in a simulated wastewater treatment plant

Chaúque¹,

Zvimba²,

Ngila³

et al. 2016

WSA

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Increased use of engineered nanoparticles (ENPs) has resulted in their entry into municipal wastewater treatment plants (WWTPs) as their final sinks. However, the adverse impact of ENPs on the bacterial activity in the activated sludge WWTPs is not yet well understood, despite their increased release into such systems. In this study, the impacts on WWTPS associated with the disposal of zinc oxide (ZnO) ENPs was investigated using a simulated WWTP developed as per the prescribed Organization for Economic Co-operation and Development (OECD 303A) specifications. Analyses were done to determine zinc concentrations at various stages of the setup, mainly in the raw wastewater and treated effluent, using inductively coupled plasma optical emission spectrometry (ICP-OES). The results obtained indicated low levels of zinc residue (about 50-200 µg/L) in the treated effluent compared to relatively high concentrations of Zn in the sludge (about 3 000 mg/kg). Results reported herein imply precipitation of ZnO ENPs during wastewater treatment processes and hence its high levels in the sludge. The presence of solid Zn in the sludge was determined using X-ray diffraction spectroscopy (XRD). Overall, no significant impact of ZnO ENPs on the performance of the simulated WWTP was observed, in terms of the removal levels of chemical oxygen demand (COD) during the treatment process

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Section: Effect Of Concentration On Zno Enp Removalsupporting

confidence: 79%

Fate, behaviour, and implications of ZnO nanoparticles in a simulated wastewater treatment plant

Chaúque¹,

Zvimba²,

Ngila³

et al. 2016

WSA

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“…This can be brought on either by constriction of the electrical double layer in high ionic strength solutions, or bridging between particles by oppositely charged counter ions in solution. [72][73][74] Many unique 'nano' effects are a function of the size and surface area of the ENMs (i.e. fluorescence, surface plasmon resonance), these properties, and thus their use for ENP detection, may be lost upon aggregation.…”

Section: Transformation Of Enmsmentioning

confidence: 99%

Current status and future direction for examining engineered nanoparticles in natural systems

et al. 2014

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Environmental context. The detection and characterisation of engineered nanomaterials in the environment is essential for exposure and risk assessment for this emerging class of materials. However, the ubiquitous presence of naturally occurring nanomaterials presents a unique challenge for the accurate determination of engineered nanomaterials in environmental matrices. New techniques and methodologies are being developed to overcome some of these issues by taking advantage of subtle differences in the elemental and isotopic ratios within these nanomaterials.Abstract. The increasing manufacture and implementation of engineered nanomaterials (ENMs) will continue to lead to the release of these materials into the environment. Reliably assessing the environmental exposure risk of ENMs will depend highly on the ability to quantify and characterise these materials in environmental samples. However, performing these measurements is obstructed by the complexity of environmental sample matrices, physiochemical processes altering the state of the ENM and the high background of naturally occurring nanoparticles (NNPs), which may be similar in size, shape and composition to their engineered analogues. Current analytical techniques can be implemented to overcome some of these obstacles, but the ubiquity of NNPs presents a unique challenge requiring the exploitation of properties that discriminate engineered and natural nanomaterials. To this end, new techniques are being developed that take advantage of the nature of ENMs to discern them from naturally occurring analogues. This paper reviews the current techniques utilised in the detection and characterisation of ENMs in environmental samples as well as discusses promising new approaches to overcome the high backgrounds of NNPs. Despite their occurrence in the atmosphere and soil, this review will be limited to a discussion of aqueous-based samples containing ENMs, as this environment will serve as a principal medium for the environmental dispersion of ENMs.

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“…A flocculant is a substance that causes the suspended particles in a fluid to aggregate and form discrete flocs (Piazza et al, 2011). Most flocculants are polymeric and are used to accelerate or improve the settling of suspended solids in various types of wastewater (Patil et al, 2011), such as during wastewater clarification (Maximova & Dahl, 2006). These flocculants are also used as filtration and centrifugation aids (Lewellyn & Avotins, 1988).…”

Section: Introductionmentioning

confidence: 99%

An improved method for determining phytoplankton chlorophyll a concentration without filtration

Qin

2012

Hydrobiologia

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The common and routine procedure for the quantification of chlorophyll a (chl a) in aquatic studies has a series of steps. Here, we sought to find optimal conditions for phytoplankton cell harvesting, chl a extraction, and chl a measurement and calculation, to find an effective, cost-saving, safe, and environment-friendly procedure for determining phytoplankton chl a concentration. We replaced the traditional GF/C filters with inorganic polymer flocculants (IPFs) and clay for phytoplankton harvesting, and then various solvents (acetone, ethanol, DMF, and DMSO), IPFs (PAC, PFS, and PAFS) and clay were tested for their suitability for chl a extraction, with or without homogenization at different temperatures for different extraction durations. About 0.3-1.0 g l -1 of PAC or PFSA combined with 1.0-2.5 g l -1 clay were found to provide optimal conditions in terms of yield and cost for phytoplankton cell harvesting from water samples. Based on our results, we recommend flocculation and centrifugation instead of glass-fiber membrane filtration for harvesting phytoplankton cells from environmental water samples, 95% ethanol for chl a extraction without homogenization and heating, and spectrophotometry to determine chl a concentration.

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Environmental implications of aggregation phenomena: Current understanding

Cited by 109 publications

References 151 publications

Fate, behaviour, and implications of ZnO nanoparticles in a simulated wastewater treatment plant

Fate, behaviour, and implications of ZnO nanoparticles in a simulated wastewater treatment plant

Current status and future direction for examining engineered nanoparticles in natural systems

An improved method for determining phytoplankton chlorophyll a concentration without filtration

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