A Proposed Sanitation and Methane Production System

Article Tools

Image Gallery

Print

E-mail

Comments

RSS

Several alternatives to the flush septic system have been proposed. The problem with most such methods of waste treatment is that they require their operators to come in direct contact with the excreta before it has been made sanitary. This is neither wise nor legal.

In the case of the compost privy, for instance, the contents must be stirred several times in the course of decomposition to ensure that all the waste materials spend time "cooking" in the middle of the pile. For this process to be legal (i.e., guaranteed safe) the stirring would have to be done mechanically rather than with a shovel.

A notable exception is the Clivus system (Fig. 1) . . . essentially a large (and expensive) fiberglass chamber-with a sophisticated vent arrangement-which holds sewage for gradual composting. Instead of dumping human wastes into the water table, the Clivus transforms them to humus by an aerobic process and releases the gases of decomposition into the air. An excellent fertilizer is produced (over a long period of time . . . the first excreta to enter the chamber are ready to enrich your garden soil some two or three years later). The system is installed indoors and requires very little tending. (For more details on the Clivus, see page 118 of MOTHER N0. 31.—MOTHER.)

Many homesteaders, however, are more attracted to the idea of treating wastes by anaerobic digestion. . . a lower-cost, faster-acting process which produces not only fertilizer but methane gas. In times like these, a homemade fuel supply which can't be affected by transportation costs or international politics is an "extra" with a very strong appeal.

The problem with the methane sanitation systems that have been proposed is one of getting the waste from the toilet to the digester. This step can make the facility either very expensive (if elaborate machinery is used) or illegal (if the transfer is done by hand).

In his book Composting (1956 edition available for $5.00 from the American Public Health Association, 1015 18th Street N.W., Washington, D.C. 20036), H.B. Gotaas suggests eliminating this transfer problem by placing an outhouse directly over the input pipe to the methane digester tank (Fig. 2). It's unlikely that such a facility would pass inspection under the sanitary codes, however, since disease organisms could breed freely in the chamber's entrance. The formation of unpleasant odor is another drawback of this design. Also—as with any continuous-feed digestion system—care would be needed to prevent waste from "short-circuiting". . . passing straight through the digester. Since at least 30 days are required to guarantee complete destruction of dangerous microorganisms by an anaerobic culture at temperatures of less than 90° F, the privy's owner would have to be sure that all excreta were treated for at least that length of time.

Incidentally, if your homestead or community produces a considerable amount of animal manure, you may find it efficient to set up a continuous-feed digestion system that incorporates your own wastes . . . but the input of human sewage would have to be automated, or the human excreta digested separately. Unless you're raising a large number of livestock (more than you need for your own food), the generator's gas yield probably still won't be able to provide for your total energy requirements.

RSS | Comments | E-mail | Print