Fungal cultures for the biodegradation of organic micropollutants in wastewater (a review)

Summary

Currently, the methods for removing organic micro-pollutions present in agricultural, industrial and domestic wastewater have been actively developed. The characteristic properties of these substances are chemical stability and potential toxicity. Organic micropollutants are believed to have a negative impact on the environment and human health, even in trace concentrations. Substances of this kind include pharmaceutically active substances, personal care products, endocrine disruptors, pesticides, industrial chemicals, etc. The traditional biological process based on bacterial cultures does not provide for the efficient biodegradation of these substances at the wastewater treatment facilities. Biodegradation using fungi that cause white rot of wood, represented mainly by basidiomycetes, including Pleurotus ostreatus, Phanerochaete chrysosporium, Trametes versicolor, Ganoderma lucidum, Irpex lacteus, is considered a relatively new, however, very promising method for removing organic micro-pollutants. In the environment, these fungi effectively destroy lignin to release the more easily metabolized carbohydrates – hemicellulose and cellulose. This process involves extracellular ligninolytic enzymes, organic acids, mediators and auxiliary enzymes. A distinctive feature of the enzymatic mechanism is its non-specificity, due to the action through the formation of free radicals. Owing to this property, fungal extracellular enzymes are able to transform a wide range of organic molecules including pollutants present in wastewater. Numerous studies have shown good results in the biodegradation of organic micropollutants, including on real wastewater, in a continuous mode and a wide range of operating conditions in the presence of autochthonous microorganisms.

Key words

wastewater , pharmaceuticals , biodegradation , fungi that cause white rot of wood , pesticides , endocrine disruptors

Pharmaceuticals in natural, drinking and wastewater
(review)

Summary

The presence of pharmaceuticals in the natural water environment is becoming a subject of focused attention. For the moment more than 180 pharmaceuticals (pain relievers and anti-inflammatory drugs, antibiotics, beta-blockers, contrast agents, Lipid-lowering agents, psychiatric medicines, hormones and antiseptics) and their metabolites that keep bioactivity have been registered in the water environment in many countries. Most often detected among them are diclofenac, carbamazepin, clofibric acid, ibuprofen, bizafibrate, sulfamethoxazole, trimethoprim, phenazone, ketoprofen, roxithromycin, triclozan, iopromide. The sources of pharmaceuticals ending up in municipal wastewater are residential sector, medical institutions, pharmaceutical factories, animal clinics and live stock breeding complexes. The concentration of separate pharmaceuticals can reach 40 µg/l. At the traditional wastewater treatment facilities pharmaceuticals can be removed in the process of biodegradation/biotransformation and activated sludge adsorption. However, the efficiency of removing many of them is typically low. The concentration of certain pharmaceuticals in surface waters can reach in average 10 µg/l, in underground waters – 1 µg/l. This results in bioaccumulation of most common medicines in the tissue of fish and other aquatic organisms. In the process of drinking water purification pharmaceuticals are removed in the processes of coagulation, filtration, activated carbon adsorption, chlorination and ozonation. Quite a number of medicines cannot be completely eliminated. As a result in many countries they are detected in drinking water in concentrations from several nanograms to 1 µg/l. For the moment there is a lack of reliable data on the toxicological effect of pharmaceuticals present in water environment; however this issue is extensively investigated.

Key words

potable water , wastewater , natural water , pharmaceuticals , toxicological effect , biodegradation , activated sludge adsorption