Azo Dyes, Their Environmental Effects, and Defining a Strategy for Their Biodegradation and Detoxification

Intenzivan industrijski razvoj popraćen je sve većom kompleksnošću sastava otpadnih voda, što u smislu učinkovite zaštite okoliša i održivog razvoja nalaže potrebu pospješivanja kvalitete postojećih te uvođenjem novih postupaka obrade otpadnih voda, kao iznimno važnog čimbenika u interakciji čovjeka i okoliša. Posebnu znanstveno-tehnološku pozornost zahtijevaju novosintetizirani ksenobiotici, poput azo-boja, koji su u prirodi veoma teško razgradivi. Azo-boje podložne su bioakumulaciji, a zbog alergijskih, kancerogenih, mutagenih i teratogenih svojstava nerijetko su prijetnja zdravlju ljudi i očuvanju okoliša. Primjenu fi zikalnokemijskih metoda za uklanjanje azo-boja iz otpadnih voda često ograničavaju visoke cijene, potrebe za odlaganjem nastalog štetnog mulja ili nastanak toksičnih sastojaka razgradnje. Biotehnološki postupci su, zbog mogućnosti ekonomične provedbe i postizanja potpune biorazgradnje, a time i detoksifi kacije, sve zastupljeniji u obradi svih vrsta otpadnih voda, pa tako i onih koje sadržavaju azo-boje.Intense industrial development has been accompanied by the production of wastewaters of very complex content, which pose a serious hazard to the environment, put at risk sustainable development, and call for new treatment technologies that would more effectively address the issue. One particular challenge in terms of science and technology is how to biodegrade xenobiotics such as azo dyes, which practically do not degrade under natural environmental conditions. These compounds tend to bioaccumulate in the environment, and have allergenic, carcinogenic, mutagenic, and teratogenic properties for humans. Removal of azo dyes from effl uents is mostly based on physical-chemical methods. These methods are often very costly and limited, as they accumulate concentrated sludge, which also poses a significant secondary disposal problem, or produce toxic end-products. Biotechnological approach may offer alternative, lowcost biological treatment systems that can completely biodegrade and detoxify even the hard-to-biodegrade azo dyes