Grey Water Treatment Using Constructed Wetlands

This assignment delves into the importance of using constructed wetlands as a treatment system for grey water. It highlights various types of wetlands, such as free water surface, surface flow, and vertical flow systems, with a focus on hybrid systems that offer multiple capabilities in improving land habitats and reusing effluence. The use of constructed wetlands is considered a low-cost, chemical-process-free method that enhances treatment efficiency and reduces pollution. Relevant references are provided from books and journals to support the discussion.

ENVIRONMENTAL GREY WATER
TREATMENT SYSTEMS

TABLE OF CONTENTS
ENVIRONMENT GRAY WATER TREATMENT SYSTEM......................................................1
CONSTRUCTED WETLANDS (CW)...........................................................................................1
Free water surface wetlands (FWSW).........................................................................................1
Surface flow wetlands (SSFW)...................................................................................................2
Vertical flow system (VFS).........................................................................................................2
Combination, hybrid and tandem systems...................................................................................2
COST...............................................................................................................................................3
Capital cost..................................................................................................................................3
Operating cost..............................................................................................................................3
WATER USE...................................................................................................................................3
REFERENCES................................................................................................................................5

ENVIRONMENT GRAY WATER TREATMENT SYSTEM
Gray water is released in rivers, then it increases pollution but use of such water in plants
can act as a valuable fertilizer. Gray water recycling is helpful in minimising need of freshwater.
One of most common gray water treatment system is wetlands. It is the distinct ecosystem which
is saturated with water (ElZein, Abdou and ElGawad, 2016). This is engineered system that
naturally treats waste water. This method is used for the treatment of centralised and on site
waste water. Initially septic tanks or primary treatment process is applied and then these
wetlands are used. Use of constructed wetlands is environmental friendly process for treatment.
It reduces load of BOD, suspended solids by 98%. It is fact that use of this process is beneficial
in raising water quality and it is also valuable for lands and animals as well. Various wetlands
and their features are explained as below:
CONSTRUCTED WETLANDS (CW)
Reuse of gray water is beneficial for environment It is considered as essential treatment
system for the environment gray water (Mojiri and et.al., 2017). They are designed in such
manner, that they can take advantage of naturally occurring energies (Wurochekke and et.al.,
2016). It is simple and natural wetland with small variation in soil and plant types. This has
pollution resistance capacity. It needs limited natural resources to use this treatment system. The
main advantages of applying constructed wetlands are that it is technically simple process,
require low maintenance and have high pollution removal efficiency. CW is the procedure in
which physical, biological, mechanical and chemical things are applied for environment gray
water treatment (Filho and et.al., 2018). Before implementing constructed wetland system
government uses primary treatment system in order to remove solids, oil and grease, etc.
Enhancing planting improves habitat in root zone. The treatment process includes filtration,
oxidation, biochemical degradation, etc. (Patil and Munavalli, 2016).
Free water surface wetlands (FWSW)
This is another type of wetland, this is generally containing open water area and
vegetation rooted below water surface. It supports in minimising freshwater extraction and
energy as well. It is essential that these wetlands remain saturated so that velocity of water flow
can be low above and within soil. This is beneficial in saving electricity because in this treatment
no electricity is required (Zipf, Pinheiro and Conegero, 2016). Operating cost of FWSW is very
low as compare to other wetlands treatment system. But free water surface wetland system is
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requiring close supervision and it cannot be applied in small land areas. FWSW are considered as
one of the most effective engineering system to remove organics. Nitrification and ammonia
volatilisation system are used to remove nitrogen and ammonia from water. Such type of
treatment systems are generally used in North America, Australia(Filho and et.al., 2018).
Figure 1example of Free water surface wetlands
Surface flow wetlands (SSFW)
This is another type of wetland which is used for the treatment of waste water and storm
waters. This type of process is generally applied for Ph stabilisation, flow balancing, BOD
polishing. This is also designed horizontally but water level is kept below media surface
(Chrispim and Nolasco, 2017). It is structured in such manner in which water is passes through
root zone and media but it does not touch surface.
Vertical flow system (VFS)
The major difference between VFS and SSFW is its flow path. It is beneficial in
reduction of BOD. Operating cost such wetland is also quit low. But in such type of treatment
system requires frequent maintenance and constant electrical energy. Vertical flow system can be
used with other system for environment gray water treatment (Yadav, Chazarenc and Mutnuri,
2018).
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Figure 2example of Vertical flow system (VFS)
Combination, hybrid and tandem systems
There are many other types of constructed wetlands that have high treatment efficiency. It
is multiple stage system in which vertical and horizontal both process of treatment is used for
waste water recycling. Though single CWs are used in most of the places because of their cost
efficiency but simple constructed wetlands are unable to reach to high pollution removal
efficiency level (Mojiri and et.al, 2017). Thus, such type of hybrid systems is used for high
removal of nitrogen’s. Vertical system has capability to remove ammonium and horizontal
system has capability to remove organic things. By using hybrid system efficiency level of
treatment can be increased. Hybrid rainwater grey water system has advantage of treating water
in cost efficient and resource friendly manner. Otherwise use of other wetlands sometimes
increases cost of treatment (ElZein, Abdou and ElGawad, 2016).
COST
There are various environment gray water treatment system and they all are designed in
various sizes with different configurations. Many of CW has size of 18m2 and 4500m2
. But due to difference in size cost of applying this system gets changes. But use of wetlands for
grey water treatment is low, it includes: low consumption, maintenance, energy costs. Thus, it is
fact that such type of treatment system is considered as most cost effective as compare to other
centralised systems (Patil and Munavalli, 2016). Generally, there are two main types of expenses
include: operating and capital cost.
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Capital cost
Such type of cost is highly depended upon local product, labour, pricing etc (Filho and
et.al., 2018). If such system is applied on large projects, then per unit cost gets reduced. But it
also depends upon site; if sit is large then it will require huge expenditure. There are various
activities that are included in estimation of cost such as land cost, site investigation, earthworks,
plants, piping, water control structure etc (Zipf, Pinheiro and Conegero, 2016). If this system is
applied in urban areas where cost of land is high, then overall capital cost of this treatment will
get increased to great extent.
Operating cost
It is another major component of price; traditional system requires low operating cost as
compare to other modern systems. One of the main reasons of cost difference is that these
traditional treatment systems can work by using limited resources and low maintenance is
required as well (Chrispim and Nolasco, 2017).
WATER USE
Captured wetlands can be reused in household activities, by this way daily water
consumption can be minimized to great extent. Furthermore, excess reused water can also be
used in landscape irrigation because this will support in planting. Such type of effluent can also
be used in gardens, watering parks etc (Mojiri and et.al, 2017). Restoration of polluted rivers can
be minimised by using this CWs treatment system. This is beneficial in improving environmental
condition and creating dynamic ecosystem. Use of constructed wetlands is considered as most
effective treatment system for the gray water because it can reduce water pollution in cost
effective and resource friendly manner (Wurochekke and et.al., 2016). CW is highly depended
upon biological process which is low cost consuming. In this process no chemical process is
being used thus, it does not spread pollution in environment. constructed wetlands are the
essential treatment system for grey water. Hybrid wetland system has multiple capabilities that
can be beneficial in improve land habitats and enhancing reuse of effluence. There are various
types of wetlands such as free water surface wetlands, Surface flow wetlands, Vertical flow
system (VFS) but use of hybrid system is helpful in improving water quality and enhancing
treatment efficiency (Filho and et.al., 2018).
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REFERENCES
Books and Journals;
Chrispim, M. C. and Nolasco, M. A., 2017. Greywater treatment using a moving bed biofilm
reactor at a university campus in Brazil. Journal of Cleaner Production. 142. pp.290-296.
ElZein, Z., Abdou, A. and ElGawad, I. A., 2016. Constructed wetlands as a sustainable
wastewater treatment method in communities. Procedia Environmental Sciences. 34.
pp.605-617.
Filho, F. J. C. M. and et.al., 2018. Hydraulic and hydrological aspects of an evapotranspiration-
constructed wetland combined system for household greywater treatment. Journal of
Environmental Science and Health. Part A. 53(6). pp.493-500.
Mojiri, A. and et.al., 2017. Ammonia, phosphate, phenol, and copper (II) removal from aqueous
solution by subsurface and surface flow constructed wetland. Environmental monitoring
and assessment. 189(7). pp.337.
Patil, Y. M. and Munavalli, G. R., 2016. Performance evaluation of an Integrated On-site
Greywater Treatment System in a tropical region. Ecological Engineering, 95, pp.492-
500.
Wurochekke, A. A and et.al., 2016. Household greywater treatment methods using natural
materials and their hybrid system. Journal of water and health. p. wh2016054.
Yadav, A., Chazarenc, F. and Mutnuri, S., 2018. Development of the “French system” vertical
flow constructed wetland to treat raw domestic wastewater in India. Ecological
Engineering. 113. pp.88-93.
Zipf, M. S., Pinheiro, I. G. and Conegero, M. G., 2016. Simplified greywater treatment systems:
Slow filters of sand and slate waste followed by granular activated carbon. Journal of
environmental management. 176. pp.119-127.
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