General SepticNET™ Process Description

The new Septic Nutrient Elimination Technology (SepticNET™) is an innovative, patent-pending, modular septic treatment system designed for use with new home construction or as an upgrade to existing on-site septic systems. Based on pilot-scale testing and full-scale test model operation, the SepticNET™ out-performs existing systems by more than 300%.

The SepticNET™ modular wastewater treatment system is designed to remove nutrients, primarily nitrogen, from on-site septic systems. The heart of the SepticNET™ is an Aerobic Treatment Unit (ATU) nitrification reactor, featuring an up-flow/up-flow aerated, packed-column, fixed-film bioreactor which converts ammonia to nitrate through a process called nitrification. Ammonia is the primary form of nitrogen leaving a standard septic tank, which is converted to nitrate beneath the leaching field, where no further treatment occurs in many geologic conditions. The nitrification step, frequently overlooked by other technologies, is often the limiting step in total nitrogen removal.

The innovative design of the nitrification reactor allows for the complete conversion of ammonia to nitrate without clogging from biomass production, a critical improvement over existing technologies. Wastewater and air enter the column from the bottom and pass through a bed of engineered plastic bio-filter growth media. The agitation from the air keeps the bio-film healthy and prevents clogging. The air/water/excess bio-film mixture exits the nitrification reactor and enters the initial clarifier.

In the next step of the SepticNET™ process, the nitrate-rich water produced in the aerated bio-filter flows through the initial clarifier. The innovative clarifier design allows for solids generated in the nitrification process to be collected and pumped back to the septic tank, which prevents clogging and minimizes maintenance of the system.

The next step in the SepticNET™ process is a packed column, fixed-film bio-reactor used for de-nitrification. The de-nitrification process requires an environment without oxygen and a source of organic carbon. Since all of the existing organic carbon is removed in the nitrification process, an external source of carbon is needed for complete de-nitrification. A patent-pending carbon-based bio-film carrier is used for the de-nitrification process. This carrier is insoluble in water and slightly buoyant, thus creating optimum conditions for de-nitrification and at the same time minimizing plugging and channeling of the wastewater.

The final step in the SepticNET™ process is a settling chamber used to reduce total suspended solids (TSS) in the final effluent. The innovative design allows for solids generated in the nitrification process to be pumped back to the septic tank, which prevents clogging and minimizes maintenance of the system. The resulting total nitrogen (TN) levels in the final discharge of the SepticNET™ system are well below drinking water standards (10 mg/L). Following the final settling tank, the wastewater is sent to the drain field.

SepticNET™ also has the capability to remove phosphorus, a significant nutrient of concern in surface water bodies. Phosphorus is removed by biological methods to about 50% of the incoming concentrations. If further reduction is required, a phosphorus removal media can be placed in the final settling tank which can remove phosphorus below surface water trigger levels. The flexibility of the SepticNET™ system is also demonstrated by the ability to add additional modules to facilitate the removal of current or future contaminants as required by regulatory agencies.

Table 1. EPA/Montana Approved Septic Treatment System Effluent Data versus the SepticNET™

Treatment Technology	Final Effluent Nutrient Concentration
	Ammonia (mg/L)	Nitrate-Nitrite (mg/L)	Kjeldahl Nitrogen (mg/L)	Total Nitrogen (mg/L)
MDEQ Regulatory Trigger	N/A	N/A	N/A	7.50
Standard System	50-80	N/A	50-80	50-80
Bioclere™	6.2	5.65	10	15.65
ReCip®	10	1.88	13	14.88
RetroFAST®	5.9	8.46	11	19.46
Amphidrome™	7.0	6.67	8.5	15.17
SeptiTech®	5.1	7.02	6.8	13.82
Waterloo Biofilter®	2.4	10.2	3.7	13.90
SepticNET™	<0.1	0.4	4.2	4.60

Note: Removal concentrations based on similar wastewater influent composition.

Research and Commercialization Funding

Research funding for the SepticNET system has been provided by WET, as an extension of its existing land development and water treatment business lines. In addition, WET was awarded a research grant through the Montana Board of Research and Commercialization Technology in 2008-2009. This grant assisted WET in the construction and installation of six full-scale SepticNET systems for testing purposes. This grant was integral in allowing WET to finance the full-scale testing of our systems, and we would like to sincerely thank the MBRCT for this grant assistance.

WET is currently seeking approval for the SepticNET treatment technology from the Montana DEQ as a Level II system. Once approved, WET will offer commercially available SepticNET treatment systems to the public. For more information on the SepticNET system, please contact us at 782-5220.