Environmental Engineering Reference
In-Depth Information
NO
3
−N and PO
4
−P were also increased from
65-84 % to 11-76 % in pre-established stage
(after 2 months) and fully established stage (after
6 months), respectively. Constructed wetland was
found to remove more than 90 %, 65 %, 78 %,
84 %, 76 % and 86 % of BOD, TSS, TDS,
NO
3
−N, PO
4
−P and NH
3
−N, respectively, from
inlet sewage after 36 h of retention time under
fully established condition. Therefore, vegetation
in a wetland provides a substrate (roots, stems
and leaves) upon which
microorganisms
can
grow as they break down organic materials. There
are more indirect ways in which plants contribute
to wastewater purification. Further, treatment
through fully established constructed wetland
resulted in reduction in metal contents in sewage
water, including Cr, Mn, Co, Ni, Cu, Zn, As, Se,
Cd and Pb.
Public perception of composting tends to be
positive insofar as there is a general acceptance
of the need to recycle or reduce waste, but there
are environmental issues which here become
driver or constraints, subsequent to the process −
rate/cost equation. The biogas plant is the perfect
fertiliser-making machine, and it has been tested
all over the world. There is no better way to
digest or compost manure and other organic
material than in a biogas plant. Bio-compost is a
100 % natural and organic fertiliser, thereby also
aids in the better establishment of plants. Bio-
compost is a cost-effective and eco-friendly sup-
plement to chemical fertilisers.
7
Conclusions
Continuous rise in the pollution of river Ganga
has been accompanied by mass apathy. Pollution
and public concern of Ganga seem to exist in
inverse ratios. The distressed river beckons all to
come to its rescue. Implementation of plant-based
green technology of constructed wetland for sew-
age treatment before mixing into Ganga river at
its source and popularisation in local public resid-
ing along the bank of Ganga river by awareness
among masses about pollution threats in the river
has to go hand in hand. A study conducted in
Shantikunj, Haridwar, India, showed that the
plants developed in fully established constructed
wetland have greater purifying potential for sew-
age from domestic sources as concentration of
different physico-chemical parameters was
reduced to an acceptable limit for discharging into
the river Ganga. Therefore, there is a need of a
new vision for a pristine and pure Ganga to pour
forth and translate on the ground. A new vision,
which needs churning of the spirit and mind,
inspires the masses to action and reconcile the
competing demands on the precious waters of the
river with sustainability. It needs to think of the
river as one organic entity where tinkering in one
part affects the entire body of the river. Use of the
constructed wetlands for filtration and remedia-
tion of water is currently a popular method; how-
ever, understanding the nature of plant-microbe
interactions may improve this process.
6
Utilisation
of Phytoremediated Biomass
In most of the composting processes, the focus is
on waste management and mass reduction.
Phytoremediated biomass of aquatic plant con-
tains high amount of toxic metals, which has
important role in biogeocycling via active and
passive transfer of elements into the food chain.
To overcome this problem, composting has been
found to be one of the most economical ways of
treatment because it combines materials recy-
cling and waste disposal at the same time. Several
wetland macrophytes such as
Spirodela polyr-
rhiza
,
Ceratophyllum demersum
,
Bacopa monn-
ieri
,
Alternanthera sessilis
,
Hygroryza aristata
,
Hydrilla verticillata
and
Vallisneria spiralis
have been utilised for postharvest composting.
Besides, key factors for a successful composting
such as temperature, aeration, moisture and nutri-
ents should be appropriately controlled. C/N and
C/P ratio is one of the important factors effecting
composting process and compost quality (Huang
et al.
2004
). Among the wetland plants,
V. spira-
lis
has been found as a potential plant for water
quality improvement, reduction of metal and
composting process having high C/N ratio
(Shukla et al.
2009
).
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