A variety of non-biological methods can remove nitrate. These include methods that can destroy nitrogen compounds, such as chemical and electrochemical methods, and those that selectively transfer nitrate to a concentrated waste stream, such as ion exchange or reverse osmosis. Chemical removal of nitrate can occur through advanced oxidation processes, although it may produce hazardous byproducts. Electrochemical methods can remove nitrate by via a voltage applied across electrodes, with degradation usually occurring at the cathode. Effective cathode materials include transition metals, post transition metals, and semi-conductors like TiO. Electrochemical methods can often avoid requiring costly chemical additives, but their effectiveness can be constrained by the pH and ions present. Reverse osmosis is highly effective in removing small charged solutes like nitrate, but it may also remove desirable nutrients, create large volumes of wastewater, and require increased pumping pressures. Ion exchange can selectively remove nitrate from water without large waste streams, but do require regeneration and may face challenges with absorption of undesired ions.