Silver nanoparticle filter for domestic wastewater reuse

BACKGROUND Under scarcity of freshwater, the reuse and low-cost technological solutions applied to wastewaters seek to reduce contamination to the users and freshwater biota. RESULTS A low-cost cellulose membrane was doped with silver nanoparticles to filter urban wastewater (UW) from a city in Argentina. The total amount of coliforms and Escherichia coli in the filter decreased by 99.6% and 99.9%, respectively. The leak of silver from the filter was 275 ng L-1, analyzed by square wave anodic stripping voltammetry. Silver nanoparticles tested on HepG2 and A549 mammalian cell lines showed no toxicity in a broad concentration range. Calculation of the organic matter provided by dead bacteria post-filtration was 347 mu g L-1 proteins, 148 mu g L-1 nucleic acids, 57 mu g L-1 lipids, and 53 mu g L-1 polysaccharides, indicating high availability of organic matter. The retention of inorganic salts in the filter was 78.5% ammonia, 6.2% nitrates, 97.6% nitrites, and 19.2% phosphates. In post-filtered UW, the Lactuca sativa germination test showed early seed germination between 90% and 95% in all the dilutions tested. In the range of 6.25% to 50.0%, filtered UW showed no significant differences in the hypocotyl but the difference was significant in the radicle length (mm) compared to the control made of synthetic media (P < 0.05). CONCLUSION The development of a low-cost filter based on cellulose membranes doped with silver nanoparticles allowed the reuse of wastewater for domestic purposes and garden irrigation. (c) 2021 Society of Chemical Industry (SCI).

Automated summary

Under the background of freshwater scarcity, a low-cost cellulose membrane doped with silver nanoparticles was used to filter urban wastewater, reducing the amount of coliforms and Escherichia coli significantly. The filtered wastewater retained a high availability of organic matter and a significant percentage of inorganic salts, allowing it to be reused for domestic purposes and garden irrigation.