Co-occurrence of microplastics and triclosan inhibited nitrification function and enriched antibiotic resistance genes in nitrifying sludge

Evaluation of Triclosan Effects on Cultured Swine Luteal Cells

Simple Summary

A great concern has been raised against many chemicals, both natural and man-made, that can mimic or interfere with the hormones. Among these, using swine ovarian cells, we were aimed to explore the potential effect of triclosan, an antimicrobial agent widely used in cosmetics and home products. Our results demonstrate that triclosan disrupts cellular function, in particular interfering with hormone production and proliferation, thus suggesting a critical evaluation of its effects.

Abstract

Triclosan is a chlorinated phenolic, used in many personal and home care products for its powerful antimicrobial effect. Several studies have shown triclosan toxicity and the American Food and Drug Administration (FDA) in 2016 has limited its use. It has been recently included in endocrine-disrupting chemicals (EDCs), a list of chemicals known for their ability to interfere with hormonal signaling with particular critical effects on reproduction both in animals and humans. In order to deepen the knowledge in this specific field, the present study was undertaken to explore the effect of different concentrations of triclosan (1, 10, and 50 µM) on cultured luteal cells, isolated from swine ovaries, evaluating effects on growth Bromodeoxyuridine (BrDU) incorporation and Adenosine TriPhosphate (ATP) production, steroidogenesis (progesterone secretion) and redox status (superoxide and nitric oxide production, enzymatic and non-enzymatic scavenging activity). A biphasic effect was exerted by triclosan on P4 production. In fact, the highest concentration inhibited, while the others stimulated P4 production (p < 0.05). Triclosan significantly inhibited cell proliferation, metabolic activity, and enzymatic scavenger activity (p < 0.05). On the contrary, nitric oxide production was significantly increased by triclosan (p < 0.01), while superoxide anion generation and non-enzymatic scavenging activity were unaffected.

Effect of microplastic particle size to the nutrients removal in activated sludge system

Microplastics as emerging environmental pollutants, its effect to the bioprocess of water and wastewater treatment has aroused concern. This study investigated the effects of microplastic polystyrene (PS) particle size to the activated sludge nutrient removal process. The ammonia, nitrite, nitrate and phosphorus removal under various PS particle size during nitrification and denitrification process was tested. The results indicated that with PS particle size 150-300 μm, the ammonia oxidation during nitrification process was inhibited to 71%, 92%, and 80% as compared with the blank reactor, for PS concentration at 0.01 g/L, 0.05 g/L and 0.10 g/L, respectively. The nitrite accumulation during nitrification process was also high at PS particle size 150-300 μm and concentration no less than 0.05 g/L. The nitrate reduction during the denitrification process was all inhibited to 69%-94% as compared with the blank, except for reactor No.4. The phosphate removal during nitrification process was not affected by the existence of microplastics PS, the average removal rate was over 80% after 2 h and over 95% after 3 h, respectively. The microplastics particle size plays important role in affecting the activated sludge nutrient removal process.

Evaluation of microplastic polyvinylchloride and antibiotics tetracycline co-effect on the partial nitrification process

This study investigated the co-effect of microplastic polyvinylchloride and antibiotics tetracycline to partial nitrification process in treating high ammonia wastewater. The average ammonia oxidation rate of all reactors was 53.58, 56.17 and 42.08 mg·N/L·h in round 1, round 7 and round 13, respectively. The ammonia oxidation rate was reduced to 89.40%, 79.08%, 80.60%, 73.37%, 69.50%, 75.72%, 98.93% and 66.04% from 1st round of test to 13th round of test at reactor R1 to R8. The average nitrosation rate was always over 80% in all conditions tested. Tetracycline removal rate was attributed to sludge adsorption in all reactors and was increased continuously with the increment of tetracycline concentration. The nitrous oxide emission was keep decreasing from round 1 to round 13 in all reactors tested. The microbial community results revealed that with the existence of tetracycline and microplastics, the relative abundance of Bacteroidetes were reduced and Proteobacteria were increased.