## 7 Mitigation Strategies for MPs in the Environment
The best way to avoid the environmental risks of MPs is to remove them from the environment and then recycle or completely degrade them [75]. Technologies for removing MPs from the environment are intensively studied [69]. The efficiency of MP removal from water can be improved by sedimentation, flocculation, advanced filtration (e.g., disk filter, bio filter or sand filter), membrane bioreactor technology, adsorption (synthetic or natural sponge, biochar, graphene, metal complexes, organic chemicals, untreated coffee grounds or magnetic adsorption), coagulation or innovative procedures of electrocoagulation, electrochemical oxidation and magnetic separation [53; 75; 113; 114]. Flocculation, sedimentation and coagulation technology is applicable for drinking water treatment [113]. There are possibilities of biological removal of MPs from the aquatic environment (Figure 10), such as adsorption on green algae and aggregation, flocculation using jellyfish mucus, decomposition by microorganisms (fungi and bacteria) and ingestion (zooplankton, corals and bivalves) [98; 113; 114]. Despite the great potential of marine organisms to remove MPs from the environment by ingestion or filtration, it is currently not considered as an elimination strategy [114] because in this way, the MPs are only moved in the environment and introduced into food chains instead of efficient removal [113]. The combination of different removal techniques can achieve better efficiency [114]. However, all suggested MP removal techniques have both positive and negative effects and were mainly investigated in a laboratory rather than under natural environmental conditions [75]. Figure 9: Means of individual contribution to reduce microplastic pollution (adapted from [66; 75]). Abiotic (photocatalytic) degradation of MPs occurs spontaneously in the environment under the influence of UV radiation, temperature, air, water and mechanical force. Such mechanical decomposition reduces the size of the particles while their relative weight remains the same. The total amount of MPs is reduced by chemical decomposition. Biotic decomposition is desirable and safe for the environment because it enables complete mineralization of MPs if the appropriate environmental conditions are enabled. In addition, useful intermediate products can be formed in the process [113]. Some polymer types are molecules with a large molar mass and stable covalent bonds, so decomposition takes decades or even centuries [115]. No signs of PVC degradation were found in the soil after 35 years in natural environmental conditions [14]. It is known that many enzymes have the ability to depolymerize MPs, but the mechanism of complete mineralization is still unclear and unexplored [69]. Recently, various complex compounds are being synthesized that would catalyze the degradation of MPs [105]. Most of the abiotic and biological degradation technologies of MPs have been studied under laboratory conditions; therefore, further research and technical improvements are needed before their field application [113]. Some scientists see a possible solution of the MP pollution in biodegradable plastics and bioplastics as alternatives to conventional plastic materials [114; 116]. Biodegradable plastics are produced from petroleum resources but can be degraded by microorganisms [8; 69], e.g., _Staphylococcus_, _Bacillus_, _Psudomonas_ and _Rhodococcus_[64; 113]. On the other hand, the term bioplastics refers to polymeric materials derived from plants, animals and microorganisms [54], i.e., renewable natural resources that are environmentally benign (e.g., thermoplastic starch) [109]. Bioplastics comprise about 1% of the annual amount of 390.7 million tons of plastic produced in 2021 [36; 117]. MPs with a half-life shorter than it are defined by the REACH persistence criteria in a particular environmental compartment and are considered degradable [114]. Aliphatic polymers as well as aliphatic-aromatic polymers with a small number of aromatic units are classified as biodegradable [115].