By B. Bosshard, PE

NOWECO wastewater has been in operation for over 100 years. During this period, NORWECO has continuously improved wastewater products from basic residential septic tank designs, and then extended aeration systems which have evolved into the NORWECO SINGULAIR line of products. The SINGULAIR line of products has superior wastewater treatment performance, including built-in:

  • Robust effluent filtration
  • Wastewater De-nitrification
  • Chlorination capabilities
  • De-chlorination capabilities
  • UV Disinfection
  • Flow Equalization
  • Wastewater treatment capabilities to U.S. drinking water standards.
  • Low costs
  • 50-year warrantee exchange program

BnB Alternative Septic Solutions, LLC chooses NOWECO SINGULAIR as the top residential wastewater treatment system on the market today. NORWECO is also teamed with GEOFLOW drip irrigation systems and provides integrated wastewater reuse systems. The best wastewater treatment performance, including de-nitrification (NSF 40 certified) sets NORWECO well above competing extended aeration systems.

We consider NORWECO’s demonstrated performance, price and the technical -principles of the SINGULAIR design when rating NORWECO SINGULAIR as the top residential wastewater treatment system on the market today.

General Discussion

To provide a robust wastewater treatment system you need to incorporate the following included in the basic design:

  1. One-day pretreatment
  2. One-day aeration/extended aeration
  3. Flow equalization
  4. Filtration
  5. Tertiary treatment for dentrification
  6. Built-in Chlorination and De-Chlorination

One-day pretreatment

All NORWECO SINGULAIR systems include a minimum of 1-day wastewater pretreatment. Pretreatment is accomplished by requiring a minimum of 1-gallon solids separation tank capacity for each gallon of maximum daily wastewater flow. SINGULAIR designs ensure that larger packaged systems increase solids tank capacity accordingly. The basic SINGULAIR systems are 600, 750, 1,000, 1,250, and 1,500 gallons per day (GPD). Each configuration mandates that pretreatment tank capacity is increased accordingly.


One-Day Aeration

Similar to pretreatment tank capacities, minimum aeration tank volumes are increased according to maximum estimated GPD flows. The increase in aeration tank size promotes a minimum of 1-day aeration. Also, as aeration volumes are increased, the number of aerators are increased to ensure adequate aeration capacity (1,000, 1,250, and 1,500 GPD units have two aerators.). NORWECO SINGULAIR utilizes a stirring technology (only moving parts) which minimizes the airflow into the system. The low airflow (2-4 cubic feet per minute (CFM) minimizes odors which are generally associated with extended aeration systems. The aeration flow dissipates into the surrounding soil, which minimizes smells from the systems. Competing systems use excessive air-flow (over 20 CFM) to stir the wastewater. This high airflow rate causes bad odors in the general area of the pipe outlet. Also, when the tank is continuously aerated, there is no possibility for de-nitrification, since the anoxic conditions are required for de-nitrification.

Flow Equalization

The flow equalization is accomplished by maintaining the Bio-Kinetic (BK) module height within +/- one inch. Each 6,000 GPD treatment node consists of four 1500 GPD Singulair units with a 6,000 gallon pre-treatment tank. Surges to the treatment nodes are regulated by the patented BK modules. Each BK module has ¼ inch holes at two elevations which will incorporate any surges and equalize flow between BK modules. The slow throughput promotes equal flow between the four 1,500 GPD units.

Filtration and De-nitrification

The second function of the BK-Module(s) is to filter particulates from the wastewater stream. The BK-Module has a series of contact plates which cause most particulates to precipitate out of the wastewater stream. Also, the BK-Modules are generally operating in the absence of oxygen (anoxic conditions), which promotes the buildup of de-nitrification bacteria. These bacteria eliminate total nitrogen from the wastewater stream. Once again, this patented configuration minimizes surges in the residential wastewater flow rates, which minimizes exceeding of wastewater treatment effluent goals. The NORWECO SINGULAIR aerators cycle 1-hour on and 1-hour off, promoting anoxic conditions for about 50 percent of the time. During the anoxic cycles, de-nitrification of the residential wastewater stream occurs.




Built-in Chlorination and De-Chlorination

Each BK-Module has the built-in capability to insert chlorination and de-chlorination tablet holders. This low-cost residential wastewater disinfection option (about $75) is quite unique. Since the chlorinator is built into the BK-module, wastewater flows are equalized and generally flow through tow ¼ holes. This slow contact rate with the chlorinators ensures reliable chlorination of the residential wastewater stream.


The NORWECO SINGULAIR systems are distributed locally by authorized NOWECO distributors. Costs (controlled locally by the NORWECO distributor), for a single family residence (up to 600 GPD wastewater flow) range from $3,500 to about $5,000 per unit. The NORWECO SINGULAIR GREEN systems cost approximately $800 to $1,000 more per system, depending on location. The advantage of the SINGULAIR GREEN system is that it can be transported to remote areas and placed with a standard backhoe (weighs approximately 1,000 pounds). Please send us a comment; if you are interested in SINGULAIR or SINGUAIR GREEN systems, we directly service the northern Arizona, southern Nevada and California areas ( Please contact us or NORWECO directly at



  1. Jolyn says:

    And to think I was going to talk to someone in perosn about this.

  2. Lauretta Irving says:

    I have a Singulair Model 780 aerator I need to replace. Do you still make this model or is there a replacement. Current unit is 115 V 1P 3 amp. I have the serial number if that would be required.

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