1-STEP® filter-

Ultimate One-Step Total Effluent Polishing

Ultimate one-step total effluent polishing filter

Previously the removal of suspended solids, nutrients, heavy metals, and organic micro pollutants from treated effluent of wastewater treatment plants required successive conventional processes to be implemented at the WWTP, leading to high investment and operational costs.

The 1-STEP® filter, developed by Nijhuis Industries, Witteveen+Bos and Waternet, is an innovative compact fixed bed activated carbon filter operated at a relatively high rate downward flow combining four processes in one single additional treatment unit.

Besides the removal of suspended solids by filtration, it performs excellently on nitrogen removal by simultaneous biological denitrification (using a selective carbon source), chemical phosphate and heavy metals removal (by coagulation and flocculation with a low dose of metal salt), and if required, removal of organic micropollutants by adsorption to the activated carbon.

Nijhuis innovative technologies to polish your wastewater to stringent discharge standards or for reuse.
Nijhuis Polishing 1-STEP Filter for wastewater treatment for reuse

Customer benefits

  1. The 1-STEP® filter produces filtrate of excellent quality.
  2. Stable performance and great stability of treated effluent.
  3. The compact design results in significant savings on construction cost and plot size.
  4. Operational costs are low due to the intelligent monitoring and control philosophy delivering low chemicals and energy consumption.
  5. The filter bed can effectively be cleaned by gently backwashing it.
  6. The 1-STEP® filter is future-proof since it removes a broad spectrum of high-priority and emerging substances.


Comprehensive tertiary treatment of treated effluent for final polishing, advanced nitrogen and priority substances removal, and removal of phosphorous to a standard < 0.25 mg P/l. Enabler for successfully addressing water scarcity when implemented in treated effluent recycling schemes.

One-Step Total Effluent Polishing Filter

The 1-STEP® filter combines four treatment processes into one additional single treatment unit:

  1. Removal of suspended solids by filtration.
  2. Nitrogen removal by simultaneous biological denitrification using a selective carbon source dosed to the influent of the 1-STEP® filter.
  3. Chemical phosphate and heavy metals removal by coagulation and flocculation with a low dose of metal salt (also dosed to the influent of the filter).
  4. If required, removal of up to 90% of the incoming organic micropollutants by adsorption onto the activated carbon.

The 1-STEP® filter is easy to implement and extend since it can be added to existing wastewater treatment plants or function as a pre-treatment unit in treated effluent recycling facilities.

Nijhuis 1-STEP filter pilot plant for wastewater treatment


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