Secondary treatment systems such as the "Bioclere" (Aquapoint), "Advantex" (Orenco) or the various peat systems may qualify for reductions in setbacks, groundwater seperation or loading rate per your local or state regulations. These systems can significant reduce effluent strength. However, the technology is not cheap and will likely require a certfied operator for periodic insepction and maintenance. A residential system can easily cost over $40,000, plus maintenance fees. As you suggested, land application measures may also qualify. Unfortunately, I have not worked with these systems and cannot be if much assistance, but they are typically in the form of a modifed irrigation hose.