Xenobiotics are becoming an increasing problem in wastewater treatment systems because they are relatively new substances and difficult to remove, and they appear in the environment in amounts that are unnatural due to human activity. The consequence of their ineffective removal from wastewater is their bioaccumulation in food chains, which poses a direct threat to ecosystems and human health. The conventional biological method of activated sludge treatment, which is mostly used in wastewater treatment plants, is ineffective for removing xenobiotics. The low efficiency of their removal is the result of the partial retention of xenobiotics in the sludge or their metabolism into more hydrophilic and stable forms that pass through wastewater treatment plants. Therefore, it is necessary to direct the development of new technologies that will facilitate their removal in wastewater treatment systems. An alternative to conventional wastewater treatment is represented by membrane bioreactors combining biological treatment with activated sludge and membrane separation processes. This paper aims to provide an overview of the application of wastewater treatment technology with membrane bioreactors and to examine the effectiveness of removing the anthelmintic febantel and the pesticides acetamiprid and thiacloprid by membrane biodegradation. The process of biodegradation of xenobiotics is carried out for 48 h, and analytical monitoring of xenobiotics was carried out by high-performance liquid chromatography. The influence of xenobiotics on the activity of activated sludge was examined by monitoring the Colony Forming Units. Membrane biodegradation of xenobiotics during 48 h achieved the highest removal efficiency of febantel at 98.5 %, acetamiprid at 57 %, and thiacloprid at 42 %. During biodegradation, new degradation and/or transformation products were detected. The low removal efficiency of acetamiprid and thiacloprid is a consequence of their toxicity to organisms present in activated sludge, which makes them unsuitable for membrane biodegradation processes.