Adsorption of Trace Estrogens in Ultrapure and Wastewater Treatment Plant Effluent by Magnetic Graphene Oxide

Response of constructed wetland for wastewater treatment to graphene oxide: Perspectives on plant and microbe

The wide application of graphene oxide (GO) increases its release into environment with less known on environmental effects. This work investigated 120-day interaction between GO (500 and 5000 μg/L) and constructed wetlands (CWs) planted with Iris pseudacorus. CWs showed the effective retention for GO via mature biofilm but less biodegradation. GO significantly induced enzyme activities (urease, neutral phosphatase, and catalase), which was attributed to increases in ecological association and enzyme abundance. GO decreased microbial biomass on day 30, but it had no impacts on day 120. The microbial community showed gradual self-adaption with time due to protection of antioxidant defense system (L-ascorbate oxidase, superoxide reductase, and glutathione related enzyme). The antioxidant enzymes (superoxide dismutase and peroxidase) and lipid peroxidation of Iris pseudacorus were increased by GO, accompanied by reduction on chlorophyll biosynthesis. Overall, the separate effects of GO on micro-regions and individual bodies in CWs were obvious, but it was acceptable that variations in pollutant removal were not evident due to synergetic role of plant-substrate-microbe. Organic matter and phosphorus removals reached to above 93%, and ammonia and total nitrogen removals in GO groups were reduced by 7-8% and 9-13%, respectively.

Adsorption of estrone, 17β-estradiol, and 17α-ethinylestradiol from water onto modified multi-walled carbon nanotubes, carbon cryogel, and carbonized hydrothermal carbon

Carbon materials of different structural and textural properties (multi-walled carbon nanotubes, carbon cryogel, and carbonized hydrothermal carbon) were used as adsorbents for the removal of estrone, 17β-estradiol, and 17α-ethinylestradiol from aqueous solutions. Chemical modification and/or activation were applied to alter surface characteristics and to increase the adsorption and desorption efficiency of carbon materials. Surfaces of treated and untreated carbon materials were characterized through the examination of the textural properties, the nature of surface functional groups, and surface acidity. It was found that the adsorption capacity of tested carbon materials is not directly proportional to the specific surface area and the content of surface oxygen groups. However, a high ratio of surface mesoporosity affected the adsorption process most prominently, by increasing adsorption capacity and the rate of the adsorption process. Adsorption of estrone, 17β-estradiol, and 17α-ethinylestradiol followed pseudo-second-order kinetic model, while the equilibrium adsorption data were best fitted with the Langmuir isotherm model. Calculated mean adsorption energy values, along with the thermodynamic parameters, indicated that removal of selected hormones was dominated by the physisorption mechanism. High values of adsorption efficiency (88-100 %) and Langmuir adsorption capacities (29.45-194.7 mg/g) imply that examined materials, especially mesoporous carbon cryogel and multi-walled carbon nanotubes, can be used as powerful adsorbents for relatively fast removal of estrogen hormones from water.

Study on the Release Potential of BPA and Steroid Estrogens in the Sediments of Erhai Lake, a Typical Plateau Lake of China

On-site sampling analysis and laboratory-scale experiments were conducted to study the pollution status and release potential of EDCs in Erhai Lake. We found that nitrogen and phosphorus pollution in Erhai Lake sediment were both at a high level, as well as EDCs pollution. The concentrations of BPA, E2α, E1, E2β, EE2, and E3 were 36.84 ng/g(DW), 13.04 ng/g(DW), 128.97 ng/g(DW), 52.57 ng/g(DW), 18.48 ng/g(DW) and 5.36 ng/g(DW), respectively. The concentrations of E2α, E1, E2β and EE2 in the bottom water were higher than the surface water due to the impact of sediment release. The results of the 20 days release test indicated that BPA release from the sediment had a greater correlation with the original concentration and the particle size of sediment, while the steroid EDCs had no obvious correlation with these two factors, probably due to the difference in hydrophobicity between them. Under hydraulic disturbance and aerobic conditions, the release process of EDCs was accompanied by a large amount of microbial degradation, and degradation amount > released amount. BPA was released quickly, 9.56% was released in 20 days, but only 3.37% of steroid EDCs released. In comparison, the release process of steroids was longer and posed a greater threat to aquatic ecology.

Effective column adsorption of triclosan from pure water and wastewater treatment plant effluent by using magnetic porous reduced graphene oxide

The ubiquitous presence of triclosan (TCS) in aquatic systems is of great concern. In the present work, magnetic porous reduced graphene oxide (MPrGO) was synthesized via in situ chemical co-precipitation of Fe³⁺and porous graphene oxide and, was used as an adsorbent for the removal of TCS with μg/L level from both pure water and wastewater treatment plant (WWTP) effluent by conducting with continuous flow fixed column. The BET surface area of MPrGO (1070 m²/g) was about tenfold higher than that of commercial powder activated carbon (PAC). Fast adsorption equilibrium can be reached within 20 s, the maximum adsorption capacity of TCS on MPrGO reached 1105.8 mg/g, and the sorbent can be regenerated for reusability about 5 cycles. The breakthrough time was 50 days for the bed depth of 2.3 mm at the inlet TCS concentration of 100 μg/L. MPrGO exhibited a much higher affinity toward TCS than PAC as the breakthrough time for MPrGO was 6.5 times longer than that for PAC. The Thomas and Yoon-Nelson models provide a better fitting curve than that by the Adams-Bohart model. High TCS adsorption capacity of 935.3 mg/g was calculated from WWTP effluent.

Fate of environmental pollutants

This annual review covers the literature published in 2018 on topics related to the occurrence and fate of environmental pollutants in wastewater. Due to the vast amount of literature published on this topic, we have discussed only a portion of the quality research publications, due to the limitation of space. The abstract search was carried out using Web of Science, and the abstracts were selected based on their relevance. In a few cases, full-text articles were referred to understand new findings better. This review is divided into the following sections: antibiotic-resistant bacteria (ARBs) and antibiotic-resistant genes (ARGs), disinfection by-products (DBPs), drugs of abuse (DoAs), estrogens, heavy metals, microplastics, per- and polyfluoroalkyl compounds (PFAS), pesticides, and pharmaceuticals and personal care products (PPCPs), with the addition of two new classes of pollutants to previous years (DoAs and PFAS).