New Technology Selection Of Residential Wastewater Treatment Packaged Plants

by Bruce Bosshard, PE

BnB Engineering conducted a review of residential wastewater treatment systems on the market today. Our review picked Norweco Singulair as the top manufacturer. Norweco 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; 1)Robust effluent filtration, 2) Wastewater De-nitrification, 3) Chlorination capabilities and UV Disinfection, 4) De-chlorination capabilities, 5) Flow Equalization, 6) Wastewater treatment capabilities to U.S. drinking water standards., 7) Low costs, 8) 50-year warranty exchange program

BnB views NORWECO SINGULAIR as the best residential wastewater treatment packaged plant on the today’s market. GEOFLOW, a leader in drip irrigation products, is teamed with NORWECO to provide add on drip irrigation products. GEOFLOW recognizes that SINGULAIR’s top residential wastewater treatment performance is unparalleled. The best wastewater treatment performance, including de-nitrification (NSF 40 certified) sets NORWECO well above extended aeration competing systems. In BnB’s final decision, we included NORWECO SINGULAIR’s competitive pricing, demonstrated NSF-40 certified performance, a long track record (100 years) in continuous improvement and innovation as key factors.

The following is a general Discussion on our Pick. To provide a robust wastewater treatment system you need to incorporate the following into the basic design; 1) One-day pretreatment, 2) One-day aeration/extended aeration, 3)Flow equalization, 4) Filtration, 5) Tertiary treatment for de-nitrification, 5) Built-in Chlorination and De-Chlorination

All NORWECO SINGULAIR systems include a minimum of 1-day wastewater pretreatment. NORWECO requires stringent quality assurance. One key to SINGULAIR success is that standard precast tank molds are used by all distributors. This standardization makes certain that there are little variations from one caster to another. Competing systems often allow concrete tank casters to use existing molds. Holes are generally cut in each tank and their one-size fits all units are placed in the holes. These competing systems lack the conformity of SINGULAIR systems, therefore, their performance is not always consistent. In SINGULAIR systems, 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. NORWECO provides ALL distributors with approved concrete molds which ensure tanks are always the same. This mandate ensures adequate stage-one residential wastewater treatment and consistent NSF-40 performance.

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 (the 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, that we looked at, use excessive air-flow (over 20 CFM) to stir the wastewater. This continuous-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 is accomplished by maintaining the Bio-Kinetic (BK) module height within +/- one inch. The SINGULAIR TANKS are constructed with about 6-inches of minimum free board. The BK-module has a series of small holes in each side of the module. As tank level increases, slow flows of wastewater are allowed through the holes. The systems can easily be expanded to multiple treatment units, if designs ensure that all the treatment units are at the same elevation. BnB refers this configuration as a treatment node. Here the SINGULAIR system can be expanded to much larger treatment nodes, with limits at about 6,000 GPD.

The BK module also promotes superb filtration and de-nitrification. To reach stringent NSF performance requirements for total suspended solids (TSS), SINGULAIR BK modules possess a robust group of contact discs which in turn precipitate out the vast majority of TSS. Once again, the BK module design and style is patented and can’t be integrated into competing systems. We’ve observed effective BK module filtration up to 1. 5 years of operations, without servicing. The comprehensive filtering capability in the SINGULAIR BK module provides this robust promise. Competing devices evaluated depend on straightforward filtration for example bags or filters which are high priced as well as require quarterly check up, cleansing and-or replacing. The SINGULAIR BK modules have numerous “stacked plates” that are comparable to commercial clarifiers. The stacked pates enable de-nitrifying bacteria (anaerobic bacteria -absence of oxygen) to fill the plates. The FE, slowly and gradually flowing residential wastewater flow, passes within the plates and the micro organism decreases the nitrogen or de-nitrifies the treated wastewater flow. This revolutionary approach has demonstrated, in some designs, to lower total nitrogen to under 5 mg/L (drinking water standard is less than 10 mg/L total nitrogen).

BK-modules can be readily converted to include both chlorination and de-chlorination. The top of the BK-modules are constructed to receive tubes which can be fitted with chlorination or de-chlorination tablets. Since the BK-modules provide low-equalized-flows, the tubes utilize specially formulated tablets that function well at low flow rates. The Chlorination/de-chlorination tubes cost about $75 each. Therefore, for about $150 the systems can be converted to chlorination disinfection units. This is a very cost-effective option. A few states, including TX requires that FE, reliable chlorination, and filtration devices be added to the effluent of most competing systems. NORWECO gladly provides them BK-2000 modules. The BK-2000 is a small tank that contains one BK-module. In re-use applications, this add-on allows the competing systems to perform at more-reliable and higher standards.

We consider NORWECO SINGULAIR costs as highly competitive. The NORWECO SINGULAIR systems are distributed locally by authorized NORWECO 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 SINGULAIR GREEN systems. We directly service the northern Arizona, southern Nevada and California areas ( Please contact us or NORWECO directly at