RECYCLING OF HUMAN WASTES : NEED OF THE HOUR
Shrikant M.Navrekar
Introduction
Every human being on this earth creates filth, if not anything else.
He starts taking his diet a few hours after his birth, which continues until
his death. Similarly, the acts of defecation & urination also continue
throughout his life. In addition to the wastes like feces & urine, which are
given out of a human body, two more inevitable wastes are produced in
our daily routine viz; waste water (sullage) & garbage (solid waste).
Feces, urine, wastewater & garbage are all, directly or indirectly,
harmful to human health.
If we peep into the history of human civilization, we find that in the
earliest era, man was a nomadic creature, his population was limited & he
used to live in the vicinity of forests. Therefore, there wasn’t any
accountable danger from his wastes. (In that era, wastewater & garbage
never existed). The problem of waste disposal started arising since man
started colonization, & the real hazards of human wastes came into light
only after the industrial revolution when very huge crowds of people started
settling around industries in an indiscriminate manner.
It is true that all the human wastes cause health hazards & hence
deserve destruction. The estimates show that about 80 % of the world’s
diseases are linked with inadequate sanitation & 10 to 25 million people
die of these diseases every year. Thus, sanitation is of prime importance
from the point of view of health. However, this is only one side of the coin.
The other side, which was hitherto neglected, has started coming into light
& environmentalists world over are realizing its importance. It is the ‘Reuse
potential of human wastes’. Thus in addition to the health aspect,
sanitation is also important from the economic point of view.
‘ Waste management ’ not ‘ waste disposal ’
In the modern era, especially in the western countries the health
aspect was over-emphasized resulting in the development of methods,
which aimed at mere destruction, or disposal of human wastes. However,
a time has now come when we must change our attitude from ‘ mere
destroying the wastes ’ to ‘managing the wastes’. It is an established fact
that most of the human wastes can best be converted into high quality
organic manures & energy. This has a direct bearing on our agriculture,
our village economy & ultimately on our national economy too! In fact, for a
developing country like India, with its limited resources & unlimited
challenges to meet, this recycling capability of wastes is a boon indeed!
The Nature’s Cycle
In nature, like all other systems, which maintain the ecological
balance, there exists a system to deal with various waste products. For
example, dead leaves of a tree in the forest fall down and accumulate
beneath it an d due to rains and moist conditions, get decayed adding to
the fertility of the soil. The droppings of animals get dried, decomposed
and mixed with the soil as manure.
So far as the dietary pattern of man and the cropping pattern
adopted for the same are concerned, there exists an implicit cycle which
must be maintained for a balanced ecosystem. Out of the crops grown,
the grain part is consumed by man and the straw by his animals. Hence,
the dung of the animals as well as the human excreta must be returned to
the soil in an appropriate manner. In fact, we owe it to the soil.
“If the night soil of a person (feces and urine) is properly converted
into manure, it provides sufficient plant nutrients to produce enough crops
to fulfill his dietary needs.”
Today, with the craze of modernity and with a greed for higher
yields, we have broken the above cycle and our agriculture has thus
become totally dependent on synthetic fertilizers, disadvantages and other
consequences of which are well known.
Reusability of human wastes
If the human wastes like feces, urine and garbage are scientifically
recycled, large quantities of organic manure can be obtained which is
evident from the following table.
Table 1- India : Plant nutrients obtainable from human wastes
Plant
Nutrient
Average quantity obtainable
From feces
& urine
gm /day/
head
(a)*
From
garbage
gm /day/
head
(b)*
Total
gm/day
/head
Total
Kg /Year
/Head
Qty. obtainable
only from rural
population
(million tons/year)
(c=a+b)
Nitrogen
12.90
3.00
15.90
4.06
Phosphorus
4.15
2.10
6.25
1.60
Potassium
3.04
3.90
6.94
1.80
* Note : (a) Ref.: Feachem et.al. – Appropriate Technology for water & sanitation
(b) Ref.: H.B.Gotaas – Composting
If we take into consideration the manure obtainable from the
livestock, we get the following statistics.
Table 2 – India: Plant nutrients obtainable from livestock waste
Total livestock in India
Dung production per day (@
10 kg / cattle)
Dung utilized for manure
(assuming 30 % use)
Qty. of manure obtainable per
day (50% of the fresh dung wt)
Qty. of manure obtainable per
year
240
million
2.4 mill.
tons
0.72 mill.
tons
0.36
mill.tons
131.4
mill. tons
Nitrogen
Qty.
obtainable
per year
1.7 mill.tons
Phosphorus
1.5 mill.tons
Potassium
1.3 mill.tons
Nutrient
Ref.: Handbook of Agriculture ICAR
Note : Plant nutrients from animal urine not considered.
Now let us compare the availability of plant nutrients from table 1& 2
with the total requirement of plant nutrients of India.
Table 3 – India : Comparison between the availability & requirement
of plant nutrients
Plant Nutrient
Nitrogen
Phosphorus
Potassium
Qty. removed
by all crops
per year
(million tons)
4.27
2.13
7.42
Qty. obtainable
from human
wastes
(million tons)
a
4.06
1.6
1.8
Qty. obtainable
from livestock
wastes
(million tons)
b
1.7
1.5
1.3
Total
(million
tons)
a+b
5.76
3.10
3.10
From the above table it can be concluded that almost all the
manurial needs of a nation can be compensated by recycling the wastes.
The techniques to achieve this are also very simple & low cost. It is the
need of the hour to explore the possibilities of propagating these
technologies along with the principles & thought behind it.
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