How are Antibiotics Removed from Wastewater?

Antibiotics are widely used in the treatment of human and livestock diseases and in promoting the growth of livestock and poultry, but only a small amount of antibiotics are absorbed by the body after ingestion, and more than 85% are excreted in the form of original drugs or metabolites, and finally enter the ecological environment. Long-term exposure to low-dose antibiotics induces resistance genes in environmental microbes. Microorganisms with drug resistance genes participate in the material energy cycle and may eventually enter the human body, causing humans to develop resistance to antibiotics.

Municipal wastewater treatment plants are often considered a line of defense against pollutants entering the environment. At present, most of the treatment processes of urban sewage treatment plants are designed for conventional organic pollutants and nutrients, and trace antibiotics can not be effectively removed in urban sewage treatment plants. The effluent from the sewage treatment plant enters the natural water body, making the effluent of the urban sewage treatment plant one of the main sources of antibiotics in the environment.

After antibiotics enter the sewage treatment system, a series of physical and chemical reactions occur, and some antibiotics are degraded or separated from the water phase, reducing the concentration of antibiotics in sewage. The removal of antibiotics in municipal wastewater treatment plants usually involves the following ways:

1. Photolysis

Photolysis is considered to be the primary abiotic removal of antibiotics in surface water. Most of the structures in the treatment process of sewage treatment plants are set up in the open air. Under the action of sunlight, photolysis can occur. Photolysis can be divided into direct photolysis and indirect photolysis. Direct photolysis means that antibiotics directly absorb photons to degrade, while indirect photolysis means that some natural photosensitive substances in water will produce some groups under the irradiation of sunlight. After these groups absorb photons, they act on the antibiotic and trigger the degradation of the antibiotic.

2. Membrane Filtration

The basis of membrane filtration technology is a membrane with selective permeability. Since the pore size of the membrane is very small and the cost is high, in order to prevent the membrane from being polluted, the sewage will be treated to a certain extent before membrane filtration. Commonly used membrane filtration technologies can be divided into microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), dialysis (Dialysis), electrodialysis (ED), pervaporation (PV), etc.

Hongtek provides a series of microfiltration products, such as Melt Blown Cartridges, string wound cartridges and Pleated Filter Cartridges, that are suitable for pre-filtration of antibiotics filtration with high removal efficiency and simple operation.

3. Sludge Adsorption and Activated Carbon Adsorption

Sludge adsorption and activated carbon adsorption did not degrade the antibiotics and reduce the total amount of antibiotics, but transferred the antibiotics from the water phase to the sludge or activated carbon. Activated sludge is a combination of microbial community and its attached organic and inorganic substances, which is porous and flocculent; activated carbon is a porous carbon material, both of which have a large specific surface area and are easy to adsorb antibiotics.

4. Biodegradable 

Antibiotics are toxic to microorganisms and may affect the treatment efficiency of biological treatment units, but biodegradation is still the most important way of antibiotic degradation. The degradation of antibiotics mainly depends on resistance strains, and it is particularly important to domesticate strains that are resistant to antibiotics. The transformation and degradation of antibiotics by microorganisms are mainly through two effects: co-metabolism and mixed substrate growth. The difference between the two is whether antibiotics are used as carbon sources.