Water reuse, especially from municipal wastewater treatment plants, is becoming an increasingly important for a variety of
applications. The presence of Trace Organic Compounds, primarily from pharmaceuticals and personal care products
are increasing in wastewater effluents. While the current levels do not seem to present a threat to human health
presently, forward looking utilities are studying processes that can be added to the current treatment train to reduce the
presence of these materials in the effluent streams. It has already been demonstrated that aquatic life can be and has
been effected by these compounds. So, there is strong interest in studying processes to treat these compounds.
The presence of the compounds in wastewater is due to two factors: The increased use of pharmaceuticals and personal care products by consumers and because standard wastewater treatment processes are not effective in removing these compounds. So, wastewater treatment plant operators are looking for polishing steps to remove these compounds from the wastewater effluent
Reverse osmosis combined and UV/peroxide has been one treatment option used for water reuse. While effective for removal of trace organic compounds concerns exist regarding discharge of concentrate, chemical costs and energy requirements.
Ozone has recently become more interesting since it provides a comparable efficacy in removing trace organic compounds to the UV/peroxide process without the need for chemical additions and lower energy costs. Ozone can generate hydroxyl radicals via side reactions with compounds found in the wastewater creating an advanced oxidation process. The ozone process can be optimized for trace contaminant removal, if necessary, with the addition of peroxide.
Ozone is also well know to public water utilities since it is used extensively for drinking water disinfection. It is also a well known disinfecting agent for wastewater, especially in Europe. This is important for regulatory compliance, e.g. California Title 22 requirements for recycled water.
Combining ozone with biological filtration may create the optimal method for removing the trace compounds with the reduced presence of byproducts and lower toxicity. Ozone bio filtration is a process that is employed in pretreatment of surface water for drinking water treatment. So, it is both familiar and reasonably well understood.