The wastewater treatment unit program is administered by a well-qualified, professional staff from offices in Ann Arbor, Michigan. Physical testing and analytical services for the program are performed in laboratory facilities located in Waco Texas, Baton Rouge Louisiana, Buzzards Bay Massachusetts, and Vancouver British Columbia at pre-approved locations in the field.
All test facilities provide a source of wastewater primarily from homes and commercial buildings with little industrial component. This characteristic is essential for testing the alternative onsite treatment technologies covered under Standard 40.
Typically at each facility, raw wastewater is pumped from an interceptor or take-out point at the source location, dosed to equipment being tested, and returned to the source for inclusion in the source treatment process. Some test facilities are designed for flows up to 10,000 gallons per day (gpd), and physically accommodate concurrently up to 10 residential treatment systems of any process type. The sites can also accommodate testing of package plants and marine sanitation devices or special devices. Provisions are made for concentrating the waste if high strength dosing is required by the testing protocol (e.g., USCG-MSD evaluations). Typically, raw wastewater passes through a comminutor or grinder pump to protect and prevent clogging of the dosing equipment, while insuring that all components in the wastewater are dosed to the test units.
Automatic dosing equipment, a small laboratory and an office are located on site for all testing facilities. Plants normally installed outside are tested outside, with installation in accordance with manufacturers' instructions, commonly below grade. By design, the onsite protocols are sufficiently long to assure operation and testing under varying climatic conditions.
Standard 41 and 46 protocols are performed in analytical laboratories located in Ann Arbor Michigan.
As an example of how one test facility operates, following is a detailed description of the process employed to access, transfer, dose and return wastewater used to administer Standard 40 test parameters at the NSF Waco test facility.
The NSF Waco test facility is located within the fenced perimeter of the Waco Metropolitan Area Regional Sewage System (WMARSS ) treatment facility site. The Waco facility receives an average of 30 million gallons per day of combined municipal and industrial/commercial waste. A closely monitored and strictly enforced pre-treatment program operated by the city eliminates concerns with the presence of metals, toxics and high-strength BOD in the influent to the treatment plant. The Waco treatment facility has a consistently loaded biochemical oxygen demand, averaging approximately 225 mg/L with a similar total solids concentration. This consistency provides nearly ideal testing input stream parameters that allow for more uniform performance comparisons.
The take-out point for the NSF influent is located at the head of one of four Waco plant primary clarifier or settling basins. The NSF raw wastewater influent dosing system is designed to pump influent from the Waco treatment plant primary clarifier into a receiving tank adjacent to the dosing lab building. A dosing pump located within the dosing tank feeds influent through a manifold and manual valve system to individual dosing buckets. The level of dosed wastewater in these containers has been calibrated to within one percent of the daily rated gallon capacity for each unit being tested. Each dosing bucket has a one-quarter turn motorized drain valve that, along with the dosing pump, receives its timed operational signal from a programmable electronic timer. The timer is a 24-hour clock timer and is set to repeat dosing as often as is necessary to accomplish correct capacity dosing in compliance with Standard 40 test parameters. The timing is sequenced to allow filling to the preset level and timed overflow of the feed water into a separate overflow drain to insure complete filling and consistent sample acquisition. Overflow is allowed to flow to the system effluent sump tank and is not reused for dosing.
After a timed delay, the motorized valve opens to allow the influent to flow down separate gravity flow lines to the tested units installed below grade in each test site. After processing through the units, the effluent flows through a site under-drain into a system return sump and is in turn pumped back to the Waco primary clarifier chamber at a point down stream of the take out point.
Each unit under test has its own fenced and gated 25' X 27' test site. Each site has a sampling enclosure, located next to the unit and to the tee cross from which effluent samples are collected proportionate to dosing volumes and schedules. Composite effluent samples are drawn via a timer-controlled peristaltic pump and stored in a refrigerated unit at 4 degrees C for daily retrieval and assessment in the Waco lab on site.
Additional testing services are also provided to clients for sampling parameters not currently addressed in NSF Standards, but which may be required in various regulatory jurisdictions, including, but not limited to nutrient reduction testing and analyses, fecal reduction and disinfection unit testing and other analytical parameters as may be required by clients.