Waste
All living systems must continuously process
materials for building and maintenance of their bodies. To do
this they must have inputs of energy through food and water and
must get rid of materials through respiration and excretement.
Humans, through the manufacture and use of goods, create additional
materials that are used and discarded. Collectively, the things
we think we don't need have been termed wastes. Waste collection,
processing and treatment systems must be part of every design.
Permaculture design is based on the premise of minimizing wastes.
What is often labeled as "waste" by society is indeed
a resource for us. The usual materials coming off a site are "hard"
construction and rock, "soft" plant organic matter,
"household" paper, plastics and cardboard and "human"
grey and black water.
The easiest to deal with is the "soft" organic plant
material. It gets composted, placed in worm boxes, fed to animals,
used for mulch, or otherwise placed back in the nutrient and soil
building cycle. In most developed world communities this resource
is lost to garbage disposal units and leaf bagging, becoming a
problem rather than a solution. Meat, the other household organic
waste, can be fed to animals; bone may be dried and pulverized
before composting.
The "hard" construction and rock materials are usually
not a problem as they are infrequently generated and much of it
can be used on site to make paved areas, subsurface drains and
water retention pits. The rock walls of New England provide an
excellent example of "waste" conversion to productive
function. Wood waste can be chipped and composted or burned for
the ash. I have a sturdy path constructed of the asphalt shingles
from an old roof.
"Household" materials are being more and more directed
to community recycling schemes. The first line of defense is to
try to stop generating it, a difficult task to do if one's name
is on mailing lists or if one must buy items in the normal consumer
market. However, one may purchase with attention to recycling
and some materials may be reused on site. For example, newspapers,
cardboard and such paper products may be incorporated into garden
walkways or sheet mulch where they eventually decompose to become
part of the soil.
The most difficult wastes are personal grey and black water mostly
because of the potential for carrying disease agents. Greywater,
water from showers or washing of clothes or dishes, can be used
on non-consumable herbaceous plants, berries, and orchards with
impunity. Black water, sewage, causes more difficulty.
Common sewage treatments have included surface disposal and direct
fertilization, a disease vector; outhouses and pits of various
scales, a potential ground water problem but a usable approach;
feeding of animals or fish, a problem of producing parasites;
septic fields, appropriate for small dispersed installations;
into the water after treatment, the typical urban solution causing
nutrification of receiving water bodies; and incineration, a high
user of energy creating ash as waste. Less common systems include
biodigestion, where sewage is turned into energy and fertilizer;
composting toilets, where the end product is a usable compost;
wetland treatment; with the benefit of biological purification
and use of nutrients prior to effluent release; and living machines;
where the process ends in pure water in a relatively small treatment
area because of intense biological activity.
The extent and type of system for treatment of human waste is
largely dependent upon the number of people and the nature of
the receiving environment. The trend is to develop systems that
use human waste as a resource and try to render in pathogenically
harmless while using its nutrient content. On a large scale, the
most promising systems seem to be wetland treatment and living
machines, both of which deliver higher quality of water at the
end than other systems. At the end of the cycle the water should
go onto land systems like forests rather than into water bodies.
For more information on wetland treatment and living machines
see: Todd, Nancy Jack and John Todd: From Eco-Cities to Living
Machines.
