Nelson Environmental - Lagoon Aeration - Nitrification - Wastewater Treatment - Canada - United States

Effluent Filtration


Optaer - Nelson Environmental - Canada - United States

Effluent Filters, including disk filters and continuous backwash sand filters, may be used following facultative and aerated lagoons to provide final TSS removal where TSS levels of less than 25 mg/L are required and for lagoon systems that are prone to algae growth.

Sand filters with a chemical addition can be installed following a Lagoon or SAGR for phosphorus removal and may be combined with carbon for denitrification where a reduction in total nitrogen is required.

Disk Filter

The disk filter is a continuous operating system that utilizes a fixed disk and a rotating backwash system. All internal or submerged components are corrosion-resistant stainless steel or non-metallic materials. Use of the fixed disk design reduces overall horsepower and permits removal of each individual disk, while the filter remains in operation. Disk filters can be designed into concrete structures or fabricated with tanks constructed of steel or fiberglass.

Continuous Backwash Gravity Sand Filters

Optaer - Nelson Environmental - Canada - United States

Continuous backwash gravity sand filters are the best choice in virtually every application that requires granular media filtration for removal of colloidal and suspended solids.

In an upflow gravity sand filter, influent flows upward through the media bed before exiting the filter. Solids captured in the filter bed are drawn downward with the sand into the suction of an airlift pump. The turbulent, upward flow in the airlift provides a scrubbing action that effectively separates the sand and solids before discharging into the filter washbox. The washbox is a baffled chamber that allows for gravity separation of the cleaned sand and the concentrated waste solids.

The continuous backwash sand filter has no internal moving parts, which results in minimal operation and maintenance costs. Adding a carbon source, such as a methanol, to the sand filter following a nitrifying SAGR process can attain final effluent denitrification.


Typical Applications and Performance are:

  • Wastewater reuse programs
  • Tertiary wastewater filtration
  • Algae removal (TSS reduction, typically <5 mg/L)
  • Phosphorous removal (can reliably achieve <0.02 mg/L TP)

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