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De Nora has over 50 years of experience removing nutrients, organic compounds, and solids in tertiary fixed-film biological filters. De Nora’s flagship biofilter with over 300 installations is the DE NORA TETRA Denite® system, which biologically reduces phosphorus and converts soluble nitrates to nitrogen gas in an anoxic environment. Existing De Nora media filters can be easily upgraded to biologically active mode as well.

Wastewater treatment facilities face both increasing regulations and tightening operating budgets. DE NORA TETRA biofilters can be designed in a variety of configurations to achieve optimal treatment for biological oxidation of organic compounds, nitrification , and denitrification. With DE NORA TETRA Denite biological denitrification systems, nitrogen, phosphorus, and suspended solids are removed in a single process solution. Ideal where space restrictions exist, the fixed-film process requires only one-tenth of the space needed for suspended growth systems, making it easy to expand or retrofit existing tertiary filtration systems. In addition to anaerobic systems, DE NORA TETRA ColOX™, SAF, and NSAF are aerobic biofilters that are used for BOD/COD oxidation and nitrification.

Why choose DE NORA TETRA biological filtration? Simplify your plant operations by removing soluble and particulate contaminants in a single step while increasing removal performance in a compact footprint. Avoid clogging with the rugged SNAP T® Block underdrain, which will not clog or lift in biological applications. • System exhibits excellent distribution of backwash air and water, keepings filter media clean and ensuring efficient operation of the filter. • With no small openings, nozzles, screens, or moving parts to clog or wear, filters provide a long service life, maximizing your investment. Enjoy maximum process flexibility and performance with a system that accommodates a wide range of media types and sizes. • Prefabricated modular or build-on-site designs are available to suit specific needs. Case Study: DE NORA TETRA Denite WATER POLLUTION CONTROL BOARD, Arlington, Virginia . Using a highly effective filtration system that stays clean in large part through automated backwash processes, the Arlington County Water Pollution Control Plant (WPCP) reports nitrogen effluent to below 2.0 mg/L, down from a 1985 level of 19.5 mg/L; and phosphorous levels below 0.1 mg/L. Innovations in the De Nora system used at Arlington County WPCP include using site-captured methanol to reduce effluent nitrogen and a flexible and scalable system design that can handle regular heavy wet weather events as effectively as normal flow. • Nitrogen removal: Reaction is time-dependent, varying according to the temperature of the wastewater. Filtration rates of 1-3 gpm/ft2 (2-7 m/h) are designed to achieve complete denitrification. Peak hydraulic rates up to 6 gpm/ft2 (12 m/h) are designed to efficiently handle wet weather events. • Suspended solid removal: TSS removal from wastewater effluent also lowers BOD by 1 mg/L or more while at the same time reducing nitrogen, phosphorous and heavy metals, which are also contained within the effluent solids. With proper chemical treatment, the plant is consistently achieving effluent total phosphorous concentrations of <0.2 mg/L. De Nora filters easily meet <2 NTU or < 5 mg/L TSS with typical results of <2 mg/L TSS.