On-Site Wastewater Treatment and Disposal Systems - Forced ...

The treatment objective for nitrogen and phosphorus in wastewater is
dependent upon the ultimate means of disposal. Surface water quality
objectives may require limitations of total phosphate, organic and
ammonia nitrogen, and/or total nitrogen. Subsurface water quality
objectives are less well developed, but may restrict nitrate-nitrogen
and/or total phosphate.
6.6.1.2 Application of Nutrient Removal Processes to Onsite
Treatment
There are a number of nutrient removal processes applicable to onsite
wastewater treatment, but there are very little data on long-term field
applications of these systems. In-house wastewater management through
segregation and household product selection appears to be the most
practical and cost-effective method for nitrogen and phosphorus control
onsite. Septic tanks may remove a portion of these nutrients as flot-
able and settleable solids. Other applicable chemical, physical, or
biological processes may also be employed to achieve a given level of
nutrient removal. Although these supplemental processes may be very
effective in removing nutrients, they are normally complex and energy
and labor intensive.
Since the state-of-the-art application of onsite nutrient removal is
limited, the discussion that follows is brief. Processes that may be
successful for onsite application are described. Acceptable design,
construction, and operation data are presented where they are available.
6.6.2 Nitrogen Removal
6.6.2.1 Description
Table 6-26 outlines the potential onsite nitrogen control options. In
many instances, these options also achieve other treatment objectives as
well, and should be evaluated as to their overall performance. The
removal or transformation of nitrogen within the soil absorption system
is described fully in Chapter 7.
6.6.2.2 In-House Segregation
Chapter 4 provides a detailed description of the household wastewater
characteristics and sources of these wastewaters. Between 78 and 90% of
the nitrogen in the wastewater discharged from the home is from toilets.
Separation of toilet wastewaters would result in average nitrogen levels
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