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

0.7- to 1.3Avolt potential (29). Conventional absorption trenches are
constructed and a mineral rock-filled anode is installed immediately
adjacent to the trench. Coke-filled cathodes with graphite cores are
installed some distance from the trench (see Figure 7-18). The water
that moves to the cathode is claimed to be removed by evapotranspiration
(30). These systems have been used successfully in California, Iowa,
Minnesota, and Wyoming (29).
7.2.7.2 Site Considerations
Electra-osmosis systems were developed to enhance wastewater absorption
in slowly permeable soils. They are used in soils with percolation
rates slower than 60 min/in. (24 min/cm). Criteria for soil absorption
trench or bed are presented in Table 7-l.
7.2.7.3 Design and Construction
The electro-osmosis system is patented. Design and construction of sys-
tems are done by licensees.
7.2.7.4 Operation and Maintenance
Once installed, no routine maintenance of the electrodes has been re-
ported. Maintenance techniques for the. soil absorption trench are
presented in Section 7.2.2.5.
7.2.8 Effluent Distribution Network for Subsurface
Soil Absorption Systems
Several different distribution networks are used in subsurface soil
absorption systems. They include single line, closed loop, distribution
box, relief line, drop box, and pressure networks. The objective of
each is to apply the pretreated wastewater over the infiltrative
surface.
The choice of one network over another depends on the type of system
proposed and the method of wastewater application desired. Networks for
the various types of systems versus the method of wastewater application
are given in Table 7-12. Where more than one network is suitable, they
are listed in order of preference.
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