Efficient removal of imidacloprid from sewage by Scenedesmus sp. TXH and the effects of environmental factors on its removal

Abstract

BACKGROUND: With the rapid development of modern industry and agriculture, large amounts of sewage of various types are being discharged into water bodies every year, causing huge environmental pressure and posing a threat to organisms. Amongst different solutions to this problem, microalgae can remove pollutants including pesticides and antibiotics from water. In this work, an algal strain designated as Scenedesmus sp. TXH. was isolated from the Tangxun Lake Sewage Treatment Plant (Wuhan, China) and used to remove imidacloprid (IMI) from sewage. The removal efficiency, degradation products, removal of conventional contaminants [total dissolved nitrogen (TDN) ammonia nitrogen (NH 4 + -N), total dissolved phosphorus (TDP)], the biochemical response of the microalgae, and the effects of environmental factors such as light intensity and temperature were investigated. RESULTS:The results showed that: (i) the highest IMI removal efficiency of ≈60% was achieved under 80 ∼mol m −2 s −1 at 25 °C;(ii) the removal of NH 4 + -N, TDP and TDN in the sewage reached 90%, 90% and 65%, respectively; (iii) there was a significant linear relationship between the concentration of total chlorophyll and the removal of IMI in the sewage; and (iv) finally, based on the analysis of degradation products by mass spectrometer, three potential IMI degradation pathways were proposed.CONCLUSION: In summary, our results showed that Scenedesmus sp. TXH can remove IMI and conventional nutrients efficiently from sewage, implying a potential application in sewage treatment in the near future.

Photocatalytic degradation of imidacloprid using Ag2O/CuO composites

“…15. 38 The CuO nanoparticles exhibit a narrow bandgap of 1.2 eV which offers easy recombination of photo-generated electronhole pairs. But, the doping of silver improves the band gap to 2.6 eV which restricts the electron-hole recombination rate and improves the charge separation.…”