Arsenic removal from drinking water

Toksičnost arsena poznata je već stoljećima, a njegova je prisutnost u vodi za piće velik problem milijuna ljudi. Povišena koncentracija arsena utvrđena je i u mnogim vodama za piće istočne Hrvatske. Visoka koncentracija arsena uzročnik je mnogih bolesti i može dovesti do oštećenja živaca, kože i do pojave raka. Metode određivanja arsena u vodi su najčešće spektrometrijske. Spektrometrijskim metodama sa srebrovim dietilditiokarbamatom i borhidridom ili elementarnim cinkom dobivamo arsin koji se mjeri spektrometrijski. Koriste se i suvremene metode kao što su induktivno spregnuta plazma u kombinaciji s masenom spektrometrijom i induktivno spregnuta plazma u kombinaciji s atomskom emisionom spektrometrijom. Metode uklanjanja arsena dijelimo na konvencionalne metode, adsorpcijske metode i membranske procese. Konvencionalne metode su flokulacija, mekšanje vode i uklanjanje Fe/Mn. Adsorbensi za uklanjanje su metalni oksidi, aktivirana glinica, aktivni ugljen, ionska izmjena, itd. Moguće je direktno uklanjanje visokotlačnim membranskim procesima i kombinirano uklanjanje adsorpcijom i niskotlačnim membranskim procesima.The toxicity of arsenic has been known for centuries, and its presence in drinking water is a huge problem for millions of people. Increased concentration of arsenic was found in drinking water of eastern Croatia. High arsenic concentration can cause many diseases, and can cause nerve and skin damage and increase the risk of cancer. Most common methods for arsenic determination in drinking water are spectrometric. Silver diethylditiocarbamate spectrophotometric methods with sodium borohydride or zinc are used for reduction of arsenic to arsine, which is determined spectrophotometrically. Modern methods for arsenic determination are inductively coupled plasma in combination with mass spectrometry and inductively coupled plasma in combination with atomic emission spectroscopy. Methods for arsenic removal are conventional methods, adsorption processes and membrane processes. Conventional methods are coagulation, softening and Fe/Mn removal. Adsorbents for removal are metal oxides, activated alumina, activated carbon, ion exchange, etc. Direct removal with high pressure membrane processes is possible as well as combined removal by adsorption and low pressure membrane processes