Sustainable wastewater treatment report

Introduction
Wastewater
What is wastewater? Wastewater is any water that has been affected in quality. It can be
described as contaminated water or “sick Water”. Wastewater can originate from homes,
industrial and factory waste, commercial or farming activities, surface runoff or storm water.
Surface run off can include anything from harmful substances that wash off from roads,
parking lots or rooftops. Wastewater is harmful to human health if not treated properly after
being disposed into the environment. Sewage is usually treated at a wastewater treatment
plant. Wastewater begins from toilets, shower room, laundry room and kitchen sinks. In
addition, water used for washing and cleaning purposes suchas for gardens, swimmingpools,
washing machine and storm water is included in wastewaterbut not specifically sewage water.
Wastewater includes dissolved contaminants, suspended solids and micro-organisms.
Various levels of wastewater treatment separate the wastewater into sludge and a dissolved
fraction containing much of the water, organic material, bacteria and salts. What is left behind
is called sludge or bio solids. It is important to see sludge as one of the wastewater
management issues for your community. Often sludge is ignored as a wastewater problem
because community attention is solely focused on treating the remaining water to a level that
reduces harm to waterways, and the nutrient cycle in particular. Liquid waste, especially
wastewater containing human wastes, will also produce an odor (from gases and aerosols).
Odor is not a public health issue, but it can be a major source of nuisance and concern in a
community. It will be part of your wastewater management challenge.
Wastewater from farming tends to be dealt with separately. Increasingly, farmers are being
required to set up on-site treatment systems for such things as animal effluent. Households,
industries and commercial businesses can all use on-site systems, but often, depending on
the size of the community, their wastewater will be combined and managed together. This
means that the wastewater in your area will be unique. An essential factor in determining the
kinds of wastewater you will need to deal with will be the kinds of industries and processing
businesses in your area. If there is a metal-processing factory, your system may have to deal
with water that has been used to washdown machinery. Wastes from industry and businesses
are known as trade wastes. It will be important to take account of these trade wastes when
designing your system, and important to take account of initiatives being undertaken by
industry to reduce the volume and toxicity of their wastes.It would be worth working with these
industries in order to help them to deal with their own waste streams.

Wastewaters can be categorized as domestic wastewater aka municipal/sanitary wastewater,
simply sewage -which used water discharged from the residential, commercial and industrial
area of a city and collected though the sewage system. It generally is 99.9% water and
contains only 0.1% of organic and inorganic solids and also microorganism(bacteria). There
is also industrial wastewater which generated from medium to large scale industries or
manufacturing industries produce a large volume of wastewaters.
Wastewater Issues
What is in wastewater that causes problems? One of the problems is the suspended solids
that does not dissolve but remains suspended in the water. The level of suspended solids in
untreated wastewater is around 200 g/m3. (Ferguson, 2003) If effluent is discharged into
streams untreated, any solids it contains will tend to settle in quiet spots. Oxygen levels will
soon be depleted in the area of the contamination, causing it to decompose anaerobically. If
there are high concentrations of this contamination the water in the stream will go septic
because the oxygen will be used up. This will not only smother the fish, but will also kill off the
life at the bottom of the stream, creating dead zones.
Next, human gut produces a huge quantity of bacteria, which are excreted as part of faeces
on a daily basis. The most common and easily measured organism is E.coli , which is referred
to by wastewater scientists and engineers as ‘faecal coliform’ bacteria. This is called an
‘indicator’ because its presence indicates the presence of faecal matter from warm-blooded
animals. More extensive testing is required to tell if the source is human or not. Many of the
faecal coliform bacteria in human waste are harmless. However, there are disease organisms
– or ‘pathogens’ – that can cause harm. Direct contact with these pathogens or pollution of
the water supply can cause infections. For example, wastewater can pollute shellfish-
gathering areas and, if eaten, the shellfish will cause illness.

Effective wastewater management is very important to reduce the level of pollutants in
wastewater before it is being discharged into the environment without harming human health
or to the natural environment. Wastewatertreatment is a process that coverts wastewaterfrom
its unusable state into an effluent that can be either returned to the water cycle with minimal
environmental issues or reused for another purpose. In rural settings, water is discharged
naturally by the sun, vegetation and soils. In urban settings water needs to be discharged by
appropriate technology because of nature’s inability to handle large volumes of wastewater.
The increase in human population and boom in industry all over the world means the discharge
of wastewater is also increasing at a rapid level. Therefore, the management of wastewater
should be more sustainable and efficient. A wastewater system will include technologies, but
will also include the processes that occur within and between the different technological
components. Wastewater systems also include people and their actions and behaviour, as
well as the natural ecosystem processes within which the technologies operate.
Wastewater management is not only about the provision of a wastewater service. It is also
linked to water supply and stormwater services. Wastewater management is also about the
wise use of our natural resources such as water, nutrients and even energy. The ecosystem,
social and resource problems in urban settings are all interrelated.
Water is essential to life. However, as we place more and more demands on our local water
supplies, it becomes vital to ensure that wastewater treatment procedures are put in place to
avoid problems with contamination, pollution, spreading disease and poisoning.
Sustainability
Definition of sustainable is the quality of not being harmful to the environment or depleting
natural resources, and thereby supporting long-term ecological balance. A sustainable
approach gives many benefits not only to the environment but also improve food security,
health and a country’s economy as a whole. A sustainable way to manage wastewater is to
recycle and re-use water. For example: waste water can be used over and over again for a
cooling plant, also recycled wastewater can be used for construction and concrete mixing.

Types of Wastewater Systems
Domestic wastewater system
This is a wastewater system that processes wastewater from a home, or group of homes. The
system includes the source of wastewater in the home, technologies for treating the
wastewater, and technologies and processes for returning the processed wastewater to the
ecosystem. Total wastewater system for a single home are listed down below:
• The home itself – how it is built may affect how wastewater is created
• The technologies in the home, such as washing machines and toilets
• ‘Inputs’ – such as food (nutrients), household cleaners and water
• The people and their behavior
• The resulting wastewater
• Recycling and treatment – on-site or off-site
• The ecosystem within which the home is embedded
Industrial wastewater system
This is a system that processes wastewater from an industrial unit, such as a factory. As with
the homesystem,the boundaries extend from the wastewatersource(the industrial processes)
through to the technologies and processes for returning the processed wastewater to the
ecosystem. It differs from the home system in terms of:
• The types of technologies producing the waste
• The way wastewater is managed at the source
• What goes into the processes (eg, chemicals/metals)
• The kind of waste produced
The system is similar in that it includes people, recycling, the treatment technologies and the
ecosystem within which the industry sits. There are four stages or parts to any wastewater
management system:
1. Managing wastewater at source (including water conservation and recycling)
2. Collection and treatment

3. Re-use of treated wastewater and sludge
4. Re-entry of treated waste into the ecosystem
Instead of the traditional end-of-pipe approach, a systems approach involves considering the
total physical wastewater system, from the source to eventual return of the wastewater to the
environment. This can offer more economic and sustainable solutions. For example, it may be
more appropriate and sustainable to reduce the amount of wastewaterat the source by looking
at the types of technologies (eg, washing machines,toilet systems)used.Orit may be cheaper
and better in long term to change the types of household cleaners used in the home to ones
that do not damage your septic tank, rather than pay for complex and expensive treatment.
The scale of wastewater treatment systems
Cutting across these stages is the issue of the scale of the physical technical solutions –
whether the solutions deal with one house, a business, a farm, a group of sites, or a whole
community. There are three general categories of overall technical framework:
• individual: serves separate households, farms or businesses
• cluster: designed so that treatment of wastes serves groups of households or
businesses, but not a whole community
• central: usually designed so the treatment of wastes for an entire community is
managed at once in one place.
Variation is possible within these. For example, a cluster framework can have some on-site
pre-treatment and the final treatment plant can be located off-site, or on-site among the houses.
By ‘on-site’ it meant treatment or re-entry on the site where the wastewater was originally
generated; ‘off-site’ means treatment away from where the waste was treated. Re-entry of
wastes can occur on-site or off-site. A centralized overall technical system can have some on-
site pretreatment, while individually focused technical solutions will always be on-site. Cluster
and centralized systems tend to be managed by an overall central agency, such as a local
authority. In contrast, technical systems focused on individual households or business can be
managed by their users, or can be managed and maintained as a group by a central agency.

Wastewater Treatment Process
For the water to be recycled it has to run through several stages that will process and treat the
water. These stages contain equipment that are necessary for that particular process. After
the waste water is processedit can be passed back into nature or some other designated use.
The treatment varies depending on the type of wastewater that the plans have to process and
what they will be used for after they have been recycled. Sometimes industries need them for
certain products or for consumption, and other plants will release the water back into the rivers
and streams, or oceans. The four main stages that the waste water will pass through in order
to recycle back to reusable water are:
1. Preliminary Treatment
2. Primary Treatment
3. Secondary Treatment
4. Tertiary Treatment

1. Preliminary Treatment
Bar Screener
The first stage of processing wastewater is the preliminary stage; this is when the water first
comes into the plant. Here is where physical screening takes place. Screening is the first part
in the preliminary stage. Here, large objects like plastics, sticks and rags occur and then they
are removed and disposed in landfills. This is so that the other stages will not be disturbed by
the debris from the sewage. The screening is done by a bar screenand many of the unwanted
large objects will get caught and removed. Bar screens stop the dirt by having bars with gaps
in between. So, the objects that can’t fit into the gap will be stopped and removed. The bar
screen will vary in size starting from larger gaps to smaller ones, as to remove the bigger
objects to the smaller ones later.
A screener is a device with openings (usually uniform in size) to remove the floating materials
and suspended particles. Objects such as rags, paper, plastics, and metals are removed to
prevent damage and clogging of downstream equipment, piping, and appurtenances.
2. Primary Treatment
After preliminary treatment, wastewater will reach the settling tank and is allowed to settle for
a long period. Resulting in heavy solids settling down and the much lighter substances such
as oil and grease will float on the surface. Then the chemical coagulant like alum is added
here. Now smaller particles will aggregate and form floc, which settle down easily. This
eliminates settled and floating materials in the primary treatment. Now the secondary
treatment can begin. This process removes about 40-60% of solid waste. Some people
consider the preliminary treatment as part of the primary treatment, because it is a small step
before the primary step.

Grit Chambers
Next, water passes through the grit chamber where velocity of wastewater is adjusted to a
lower speed, this permits the settlement of medium sized particles. This step can occur once
all the larger waste materials are removed by the bar screens. They are primarily to remove
anything that is “heavier” than the organic biodegradable solids in the wastewater. For
example, materials such as sand, stone, grit and broken glasses settled to the bottom and are
removed in this step. The technicality of the grit chamber may vary depending on different
locations. Different places contain different types of sewage water. Grit chamber may not be
necessary for small plants but it’s very important for larger plants. After this process is done
and the grit is removed from the wastewater then next step begins. The waste water is
subjected to primary treatment next.

Skimming Tanks
Skimming tanks are used after grit is removed. The wastewaters flow into a chamber arranged
so that the floating matter like oil, fat, grease etc., rise and they stay on the surface of the
fluids (sewage) until they are removed, while the liquid flows out continuously under baffles.
The floating matter must be removed from sewage otherwise it shows up in the appearance
in of the unsightly scum on the top of the settling tanks. If they aren’t removed they may also
interfere with the activated sludge process of wastewater treatment.
The skimming tank is a lengthy trough structure split up into two or three lateral
compartments by vertical baffle walls having slots for a short distance below the sewage
surface and permitting oil and grease to escape into stilling compartments.
3. Secondary Treatment
Even though the wastewater is free from most physical contaminants, there are still other
suspended and biological contaminants. And in this stage those organic matters which has
been dissolved and missed in primary stage will be processes with biological treatment.
Secondary treatment removes 85 percent or more of the organic matter in sewage.

Secondary or biological treatment is performed in a tank where air is pumped in. It contains
starved microbes called activated sludge that require air to live. Microorganisms in this
aeration tank use the dissolved and particulate organic matter as food, producing more
microorganisms.Therefore, the waste materials are converted into microorganisms whichcan
be collected and separated from the water in the secondary clarifier. In the secondary clarifier,
the collected return activated sludge are sent back to the aeration tank and recycled. The level
of oxygen in the wastewateris changed at different stages - to produce aerobic and anaerobic
environments. Aerobic and anaerobic processes are the biological treatment processes of
sewage. Aeration tank provides oxygen which allows the growth of aerobic bacteria. Organic
compounds are removed in this step by aerobic bacteria using effluent as their food. Now the
waste water is moved to the tertiary treatment.
Aerobic processes use bacteria that require oxygen, so air is circulated throughout the
treatment tank. These aerobic bacteria then break down the waste within the wastewater.
Anaerobic bacteria (bacteria that live in environments that contain no oxygen) broke down
organic matter in the wastewater into biogas that contains large amounts of methane gas and
carbon dioxide.

4. TertiaryTreatment
The tertiary treatment specifically removes any component that was not removed in the
previous steps. It varies depending on the industry. After this stage, usable water is produced.
It may include additional removal of organic matter or solids, reductions in the concentration
of nutrients such as nitrogen and phosphorus or treatment of toxic substances. The tertiary
treatment stage can remove up to 99 percent of the impurities from the wastewater. This
produces effluent water that is close to drinking water quality. Tertiary treatment is needed
under the following circumstances:
1. When standard requirements are not met by the quality of the effluent to be recycled.
2. When there is a need for the sewage/wastewater usually due to water shortage, and
it being a cheaper alternative.
3. For nitrogen and phosphorus compounds to be removed.
The first stage in tertiary treatment is to filtrate the water. This helps primarily to remove
leftover suspended matter in the wastewater. Sand filtration is the usual method that is used
for this purpose.

The second stage is the removal of high nutrient concentration. Nutrients such Nitrogen and
phosphorus which are usually found in the high concentrations. Nitrogen can be removed in
the form of ammonia is first oxidized to form nitrates and then nitrates to nitrogen gas which
is released to the environment. On the other hand, phosphorus can be removed biologically
as well by chemical precipitation with salts of iron, aluminum, or lime. Accumulating bacteria
can accumulate high percentage of phosphorus and the biomass thus generated can further
be of good value as fertilizer.
The last stage is disinfection. After the primary treatment stage and the secondary treatment
process, there are still some diseases left in the remaining treated wastewater. In order to
eliminate them, for at least 20-25 minutes in tanks, the wastewater must be disinfected, with
a mixture of chlorine and sodium hypochlorite. The effluent (treated wastewater) is later
released into the environment through the local waterways. This disinfection stage is an
important part of the treatment process because it ensures that when the recycled water is
released to into a fragile ecosystem it will be safe.
After everything else, the sludge still has to be dealt with. We have removed solids at
various points in the wastewater treatment process: primary sludge composed of the
sewage solids collected in the primary clarifier and waste activated sludge from the
secondary clarifier.
The sludge presents two problems. First, it is rich in organic matter and will consume oxygen
and create foul odors if delivered to the environment without further treatment. Second, even
though it is called sludge, it is mostly water and is difficult to handle in final disposal. It needs
to be digested to break down the organic matter and also it needs to dewatered to reduce the
water content and make it easily handled. The sludge is then treated and sent back into the
environment and can be used for agricultural use.

Advantages
Enhances and upgrading quality of water
Untreated wastewater will bring negative impact to the community and environment such as
health problem and eutrophication of the lakes. It is essential to provide clean water to the
people because water is used every day for domestic (indoor and outdoor household
purposes), industrial and agriculture purposes. The quality of water will depend on the
wastewater treatment system. Thus, the government has the responsibility to maintain the
public sewage treatment plant so that water source is efficient, clean and drinkable by the
people for daily use.
Preserve and protect natural environment
As you know that the demand for water is unlimited as it is important to our daily life. Therefore,
there is always an increased percentage of water consumption and waste water every day.
For instance, water for domestic uses such as drinking, bathing, cooking and many other
activities. It is predicted that one litre of untreated wastewater can pollute 8 litres of freshwater.
So, in any case of poor management of water treatment system, it will contribute damages to
the natural environment suchas water pollution. When polluted water flows to the river or sea,
it will lead to environmental issue that affects fish and wildlife. Besides that, wastewater
treatment plant produces by products such as treated bio solids (organic matter recycled from
sewage, especially for use in agriculture) and methane. Treated sludge is utilized as a dirt or
soil conditioner for tree cultivation whilst methane is being utilized for electricity, power,
required to work the plant. Due to the fact that wastewater management removes harmful
waste, microorganism and chemicals in a water supply. Thus, fish and wildlife will be protected
by the uncontaminated streams or lake. Apart from that, unwanted event such as storm water
can be prevented if the system is utilized effectively. Thus, it can lessen the damages and
financial consequences resulting from flood.
Waste reduction – saving and processing waters
Biodegradable material can be removed through the wastewater treatment plant before
discharging to environment, hence amount of waste will reduce. In addition, wastewater
treatment can reduce a country expenditure on projects to overcome the polluted environment
such as water.

Energy Production
During the wastewater treatment process, the sludge is collected, treated by anaerobic
bacteria and heated at 35 degree Celsius in a fully enclosed digester as it contains a lot of
biodegradable material. These anaerobic microorganism carries out anaerobic process in the
absence of oxygen. The gas created during anaerobic digestion contains carbon dioxide and
methane. The methane gas is gathered to generate electricity. This will reduce the
dependence on non-renewable energy such as fossil fuels, hence minimize the country’s
consumption on energy production. For instance, this system had been utilized in the Middle
East and can be found in al-Samra wastewater treatment plant in Jordan. Based on
government officials, the wastewater treatment plant produces 40% of the required energy
through burning the methane produced by the treatment process.
Fertilizer Production
These biodegradable materials can contribute to the agricultural sector as it can be used as a
natural fertilizer in local crop fields which minimize the usage of pesticides that are harmful to
the ocean, human health as well as environment.
Economics
Operators are required to collect and examine wastewater sample in order to ensure that
wastewater has proper disinfection and purification process. Sometimes, when there is heavy
rainfall, the water supply and sewer pipes might be flooded which exceeded the capacity of
the treatment plant to handle that amount of waste water. Thus, it is important to have a few
operators during emergency because they are trained to use special equipment to protect
public health and facility. Since operation of wastewater treatment plant requires many skilled
workers and professionals, more job opportunities available for researching and processing.
Treatment facilities, for example, require regular maintenance and human operation.
Furthermore, production of clean water helps the environment for recreational water activities
which will further boost tourism. Therefore, it will increase economic growth of the country.

It prevents disease
Scientists believe there may be hundreds of disease-causing organisms present in sewage
and wastewater that have yet to be identified. Untreated water that contain bacteria, viruses
and chemicals would cause harmful effect to people that consume it. 97% of contaminants in
water is removed by wastewater treatment plant. In this process, contaminants in water will
be filtered to ensure no bacteria or pathogens are present that can be hazardous to people,
plants and animals. Thus, disease like typhoid has been gradually eliminated due to less
contaminated drinking water and better sanitation system in developed countries.
Disadvantages
High Capital cost
Wastewater treatment system is undeniably expensive. Government will have high
expenditure to install the wastewater treatment as there are many factors that contribute to
high capital cost. For instance, the up-front planning of wastewater treatment plant
infrastructure. Installation cost can range between 15-40 % of the total project cost but it
depends on the amount of civil work needed. In addition, high labour cost when recruiting
professionals who are well-versed in this field. They are knowledgeable on method and
procedures to operate, handle and control the machineries used, hence achieving high
efficiency throughout the process. Apart from that, regulatory cost in terms of waste disposal.
Prior to discharging any waste, you’ll need to ensure your facility have approval to release
waste, otherwise you will be fined. However, it is better to spend more to install and
maintaining wastewater treatment plant than handling the aftermath problems such as water
pollution that may cause environmental and health issues to the society.
Public perception
Drinking recycled water will face public opinions and critics. This is because society found it
disgusting drinking treated wastewater even if they knew that it is highly purified after going
through many stages of treatment process. People usually have this in mind that recycled
water is referring to purified sewage. Thus, people fear to drink recycled water.

Various chemical substances and waste product from the process
Although chemicalsubstances are important to treat the wastewaterbut if it is used to a certain
extent that exceeds the required amount then there will be problems occurring. During the
disinfection in chemical unit processes, there can be too much chlorine present in the water
that will contribute negative effect on human health if proper measures not taken by the
specialized workers. Besides that, if waste product not discharged or handled effectively, it
can cause environmental impacts to wildlife in sea. Thus, government should involve in
research and development on inventing new technology that can minimize harmful waste
product before allowing it to flow to the nearest river.
Decentralised Wastewater System
The contrast between decentralized and centralized systems is in the conveyance structure.
In decentralized wastewater system, waste water is treated, disposed and reused at close
vicinity to its source. Therefore, conveyance of waste water network is small and sometimes
limited to one pipeline. However, there are advantages and disadvantages of this system.
Advantages
 Decentralized wastewater treatment is considered as “green” and “sustainable”. If it is
well maintained and designed, it should be able to minimize the water pollution in the river
or lake as well as encouraging the reuse of sewage for “green” solution.
 The wastewater does not need to flow or transport at a long distance as it can be treated
close to the source of generation.
 Reusing water can lead to lower consumption of fresh water.
 This system can be independent from corrupted local government.
 Lastly, decentralized wastewater treatment do not need large investment as compared to
centralized wastewater treatment.
Disadvantages
 In a large number of treatment units, it can be difficult to carry out proper maintenance.
Thus, there will be risk for human health issues arise.
 It is expensive to build the treatment, storage and disposal units along with extra piping
system for the gray water and the water to be reused. This will further increase the cost of
the building and cannot be recovered by the saving water cost.

Case Study 1
Rio de Janeiro’s Wastewater Treatment (Municipal wastewater)
About Rio de Janeiro
It is the 2nd most populated area in Brazil and the 3rd biggest metropolis in South America.
Rio de Janeiro was the hostof the 2016 SummerOlympics and the 2016 Summer Paralympics,
making the city the first South American and Portuguese-speaking city to ever host the events,
and the third time the Olympics were held in a Southern Hemisphere city. The Maracanã
Stadium held the finals of the 1950 and 2014 FIFA World Cups, the 2013 FIFA Confederations
Cup, and the XV Pan American Games. Due to the events, they have to reduce the raw
sewage spilling into the Guanabara Bay which located in Southeast Brazil.
Problems faced in Rio
The level of water cleanliness is at a critical point and the wastewater from homes and
commercialbuildings are left untreated and they bypass into the sea. 70% of the sewage from
12 million inhabitants of Rio de Janeiro now flows into the water system untreated. The bay
is, environmentally, in relative distress. The raw sewage and garbage can be seen floating in
the water. Thus, the growth of super bacteria has increased. A particular concern was to
reduce the amount of domestic sewage flowing into the WestZone rivers and Guanabara Bay,
an especially urgent issue since the Olympic sailing events were to be held there.

Solution to the problem
As part of the efforts to clean up the bay, €164 million has been invested, which aims to
develop a number of sanitation works to improve the health of the local population and the by
building a new water waste treatment plant based on a Dutchtechnology known as the Nereda
technology. Nereda is technique for water purification, based on a technological solution which
uses aerobic granular mass. The technology uses less energy than current systems and has
a small footprint. The groundbreaking technology took twenty years to develop and perfect,
and provides a leap forward for water treatment options.
This technology was developed in the Netherlands by Delft University, the Dutch Foundation
for Applied Water Research (STOWA), the Dutch Water Boards and Royal Haskoning DHV.
This sustainable treatment process treats wastewater by using aerobic biological action to
purify it before returning clean water to the environment. Its main priority was to cater the
visitors during the Olympics in 2016. ("Water industry step change | Envirotec", 2016) The first
phase of the plan included 200km of new sewage networks, 11 pumping stations and
connections for 25 thousand households.
How does Nereda works ?
Biomass in Nereda develops as fast settling aerobic granular sludge. These granules have
excellent settling properties and therefore Nereda does not require a separate time-consuming
decant phase like conventional SBR's. Further, all the biological treatment processes take
place simultaneously in the granules, requiring only one tank.
Due to the distinctive characteristics of aerobic granular biomass, Nereda technology uses an
optimised SBR cycle:
1. Simultaneous influent feed and effluent discharge.
2. Simultaneous biological removal of organic, nitrogen and phosphorous components.
3. Fast settling phase, in this phase the biomass is separated from the effluent and
Nereda is ready for a new cycle.

Since the effluent is pushed out of the tank, discharge of the effluent does not require
moving decanters. ("Nereda municipal wastewater treatment plant | Rio de Janeiro -
Deodoro, Brazil", n.d.)
The outcome
During the opening in 2016 the Deodoro WwTw was the largest Nereda plant built so far
anywhere in the world and the first of its kind in South America, with a further five planned in
Brazil. Designed to treat eventually the wastewater of 480,000 people, the equivalent to
86,400m3 per day, the plant serves two fifths of the population of Rio de Janeiro’s West
Zone.With 10 times the capacity of the original plant, the flow of domestic sewage into the
local rivers and bay has been massively reduced. One of the most significant legacy projects
from the 2016 Olympic Games, the Deodoro plant will continue to bring benefit to the local
population and the environment for generations to come.

Figure 1 Nereda WWTP Rio de Janeiro-Deodoro
Figure 2 Nereda WWTP Rio de Janeuro-Deodoro

Figure 3 Nereda WWTP Rio de Janeiro-Duodoro
Figure 4 Nereda WWTP Rio de Janeiro- Duodoro

Case Study 2
Treatment of Wastewater For Re-Use in the Drinking Water System of Windhoek
About Windhoek, Namibia
Situated in one of the most arid countries in Africa, at the heart of Namibia, Windhoek has a
large dependency on water that is located very far away. With perennial rivers in excess of
500 km to the North or South, Windhoek depends on water supply from 60 to 200 km away,
where boreholes and three surface dams ephemeral rivers are. The city is prompted to look
for alternatives to augment the water supply due to shortages. With a capacity of 4,800 m3/d,
the first reclamation plant began operations in 1968. There has been many changes and
improvements that have taken place since then. In September 2002 the New Goreangab
Reclamation Plant (NGRP) was commissioned having a 21,000 m3/day capacity. The old
plant is now treating effluents for irrigation of parks and sports fields.
Problems
In Namibia, part of the problem was their low average rainfall, which was 250 mm per year,
thus there was a problem of water shortages. Also, the population’s growth rates were high,
numbering over the past 100 years, this continued to increase the need for water. Supply
authorities needed new resources as the sources were being depleted. Direct reclamation
continued to play an important role to augment the Windhoek water supply, because of
repeated periods of erratic rainfall ensured it.

Solutions
To a large extent, easily accessible natural resources had been fully exploited. Also, the
demand management measures successfully implemented. Extended reclamation proved to
be the logical choice to augment supply. However, it would not be cost effective to upgrade
the existing reclamation plant. The prevailing drought at the time precluded the interim loss of
production from the old plant. Thus, the City of Windhoek obtained loan finance from European
Financial Institutions to construct a new 21,000 m3
(~5.5 MG) a day reclamation plant, on a
site adjacent to the old plant. Completed in 2002, this plant can now provide 35% of the daily
potable requirements of the City.
Reclamation Process
Reclamation of treated effluent Considerations for the design of the New Goreangab
Reclamation Plant (NGRP) Drinking water treatment has three main goals:
 To provide safe water
 To provide aesthetically pleasing water
 To ensure that the technology applied will last long into the future with minor problems.
Process steps:
1. Oxidation and pre-ozonation: The raw water mix is treated with the off gas and access
ozone.
2. Powdered activated carbon dosing: can be added as back up capacity for adsorption
should the ozone process fail.
3. Coagulation and flocculation: Ferric chloride is added as primary coagulant in dosages
to achieve enhanced coagulation for maximum organic removal in the first solids
separation step. Hydrochloric acid can be added if required for pH control. If needed,
a polymer can also be added.

4. Dissolved air flotation (DAF): used for solids separation. This process is used since
1984 in Windhoek and is regarded as the “heart” of the reclamation process.
5. Dual media filtration: Dual media filters with anthracite and graded sand. The filters are
equipped with slow start and filter-to-waste facility for maximum cyst/oocyst removal.
6. Main ozonation: Oxygen is produced on-site with a Pressure Swing Adsorption (PSA)
plant. Ozone is dosed at three dosage points. Dosage is regulated for maximum
Dissolved organic carbon (DOC) removal.
7. Biological activated carbon filtration (BAC): During ozonation organics with high
molecular weight and especially the refractory organic matter are oxidized to produce
molecules that are readily biodegradable. These are removed by the biological
activated carbon.
8. Granular activated carbon filtration (GAC): Consist of primary and secondary filters
with a contact time of EBCT = 30 minutes at maximum flow to remove organic
molecules from the water.
9. Ultrafiltration: Chlorinated water is filtered through ultra filtration membrane modules
to remove bacteria, protozoa and virus.
10. Disinfection and stabilisation:Breakpoint chlorination, free residual of 1 mg/l and
contact time of 1 hour. Adding of caustic to raise the pH to ascertain positive
precipitation potential of 4 mg/l.

Outcome
Over the pastsix years, the water quality of the distribution system has improved considerably.
Windhoek has become an excellent example, proven over 35 years, that it is possible today
to augment drinking water supplies through direct reclaimed water in a safe and responsible
way. However if it is allowed by geographical circumstances, it is recommended rather to use
an indirect reclamation scheme such as storing reclaimed water in an aquifer.
A multi disciplinary team approach should be used if a reclamation/reuse scheme. It is going
to be implemented to ensure that the technology employed is operating properly and that the
necessary monitoring is conducted. This is to ensure that the treated water is safe for its
intended use. To ensure the long-term safety and sustainability of such projects, policies and
regulations on a national and local level are needed for proper support.

Possible Problems to The System
Carbon Footprints & Greenhouse Gas
Nowadays, the increase in water demand, population growth, resource scarcity and the
impacts of climate change have led to a growing need for demand management and water
supplies. Modern wastewater treatment systems have been able to treat the water, but they
are not very environmentally conscious. For example, carbon dioxide (CO2) are produced in
wastewater treatment system during the burning of fossil fuels for power production and the
general decomposition of the materials in the wastewater. The gas emitted during the process
will leads to high carbon footprints left on the environment.
Studies on waste water treatment plants (Stokes and Horvath, 2006; Ortiz et al., 2007;
Friedrich et al., 2009; Lyons et al., 2009; Pasqualino et al., 2010; de Haas et al., 2011) found
that energy consumption is a dominant factor contributing approximately 68 to 92% of the
carbon footprint (Tangsubkul et al., 2005; Stokes and Horvath, 2009). Many studies confirmed
that using conventional activated sludge (CAS) during wastewater treatment led to high
electricity consumption (Friedrich et al., 2009; Pasqualino et al., 2010; Zhang et al., 2010) and
consequently high emissions during the operation phase. Other than that, replacing higher
quality water leads to greater energy and carbon offsets than. Since treating water to a higher
level requires more energy and resource inputs, the carbon footprint offset potential of
reclaimed water typically increases with higher-value end uses. (Pasqualino et al., 2010;
Shehabi et al., 2012; Tong et al., 2013).

Carbon footprint is defined as the total set of greenhouse gas emissions caused by an activity
or product expressed as carbon dioxide equivalent. It is a measure of the total amount of
carbon dioxide (CO2), methane (CH4) and Nitrous Oxide (N2O) emissions of a defined system
or activity, considering all relevant sources and sinks within the system or activity (G.Vijayan,
R. Saravanane, T. Sundrarajan, 2017).
Global warming and climatic change is being viewed as an international problem and several
studies establish the significance of greenhouse gas emissions from the wastewater process
and the impact on the ecosystem. Wastewater treatment systems are also one of the source
of greenhouse gas emissions. This include direct emission of greenhouse gas from
wastewater treatment comprising emission of CO2 due to degradation of organic matters,
emission of N2O during the process of nitrification and denitrification and emissions of CH4
and N2O from anaerobic digestion during sludge treatment; indirect emissions of greenhouse
gas from sludge treatment, usage of electrical power and chemicals during the operation and
maintenance of the treatment plant and disposal of sludge. Anaerobic digestion is a biological
process where microorganisms break down biodegradable material in the absence of oxygen.
Aerobic treatment systems produceprimarily CO2, while anaerobic systems producea mixture
of CH4 and CO2. Apart from these, the production and transportation of constructionmaterials
can also cause indirect emissions of greenhouse gas (G.Vijayan, R. Saravanane, T.
Sundrarajan, 2017).

Today, a number of challenges must be dealt with to achieve sustainable wastewater
treatment. Carbon footprint and greenhouse gas emissions are both important issues related
to wastewater management. Many local and state governments around the world have taken
action to reduce greenhouse gas emissions to address the problem of elevated carbon
footprints and climate change impacts (Cornejo, Pablo K; 2015). For example, since 2009
more than 825 cities are participating in the United States Mayors Climate Protection
Agreement, which would reduce greenhouse gas emissions in accordance with the Kyoto
Protocol goals (Newman et al., 2009).
Human Health & Environmental Risk
Wastewater treatment system that are not managed well may cause negative effects to the
environment such as human health, fish and wildlife populations, oxygen depletion, beach
closures and other restrictions on recreational water use, restrictions on fish and shellfish
harvesting and consumption and restrictions on drinking water consumption.
When wastewater system is not properly managed or treated, the first danger is usually to
aquatic life in rivers, lakes or streams. Some examples of the pollutants that can be found in
wastewater are chemicalcontaminants suchas chlorine compounds and toxic metals suchas
mercury, lead and cadmium will kill fishes and aquatic plants. Water naturally contains metals
such as iron, zinc and manganese, but industrial processes can introduce higher
concentrations. If the concentrations are high enough, exposure to some metals and
chemicals may have an impact on human body system. For example, manganese can also
be used in the production of batteries paints, and cosmetics. Exposure to manganese in large
quantities can cause damage to the nervous system, leading to slowness and behavioral
changes/poor concentration.
Other than that, regular organic waste that provides excessive nutrients such as nitrates and
phosphates, they contain large amounts of phosphorus that can stimulate an overgrowth of
algae and other aquatic plants (weeds) that will cause eutrophication. When eutrophication
happens, oxygen will be used up. This will cause oxygen depletion and other aquatic life such
as fish will die.

Decaying organic matter and debris can use up the dissolved oxygen in a lake or river as the
bacteria responsible for decomposition will consume oxygen. When the amount of
decomposition is manageable, the bacteria will do their job and there is plenty of oxygen left
over for fish and aquatic animals. When the environment is unbalanced, then the bacteria
multiply to large amounts and consume more oxygen in the water and causes depletion of
oxygen (Proud Green Home, 2017). The bacteria will continue to decompose the waste in
anaerobic metabolism and produces more noticeable waste compounds and smelly gases
(smells of rot decomposition).
Wastewater that are not treated well in the wastewater treatment system can spread disease
and contaminate drinking water sources through bacteria viruses and disease-causing
pathogens. Bacteria, viruses, and parasites (including worms and protozoans), are the types
of pathogens in wastewater that are hazardous to humans. They pollute beaches, contaminate
shellfish populations, leading to restrictions on human recreation, drinking water consumption
and shellfish consumption. Contaminated water is a common cause of outbreak of
wastewater-related diseases such as Cholera and Typhoid.
Pollution
From the investigations that had been carried out previously indicated that wastewater and
sewage effluent from treatment plant and deteriorating infrastructure is a major source of
pollution. Moreover, groundwater is also at risk of being polluted by chemicals discharging
from stationary effluent leaking from treatment plants which is known as leachate. In 2008, a

number of incidents of water pollution due to sewage discharges from municipal wastewater
and sewage treatment plants were reported. Municipal raw water or treated effluent is
discharged from specific point-sources and channeled into the receiving waters such as
streams, rivers, lakes, ponds and ground water.
Point-source pollution problems not only increase treatment costs considerably, but
also introduce a wide range of potentially infectious agents to water that may be supplied
to many rural communities, thus resulting in incidences of waterborne diseases with far
reaching socio-economic implications.
Incur High Cost
The operator is incurring costs as a result of the grit that is present as final results. This applies
throughout a treatment plant, both for maintenance activities and routine operations, and also
unscheduled maintenance tasks. The impact can be as routine as having to ensure that
channels are kept clear. At the other end of the scale, an anaerobic digester can build up
sediment in it over time, reactor space will then be slowly diminished and impact the
performance. The task of taking the digester offline and removing the sediment is an
unpleasant, time-consuming and costly one.
Diagram shows an aerobic digester

These impacts accumulate for the plant as a whole. They place a burden on the overall annual
operations and budgets – even if these budgets don’t specifically include an allocation for
dealing with grit. More than this, the costs accumulate over the lifespan of the treatment plant.
Ultimately they can shorten the overall lifespan of the asset, meaning there are capital
expenditure requirements also. There are also potentially wider costs, not least an increased
risk of incurring a fine and damaging the environment if plants are not functioning fully during
maintenance or if there is an equipment failure (Hydro International, 2018).
Electricity cost is expected to increase over the years as the number of plot ratio and density
of developments within regional wastewater treatment plant keeps increasing more than is
allowable in urban areas to connect to the existing sewer line (Ramli and Abdul Hamid, 2016).

Recommendation for Future Improvements
Waste water treatment is still having very high potential to be improve especially at the
sustainable and environmental friendly issue. Nowadays, there are a lot of research or
technology about wastewater treatment that are focusing on saving cost, using renewable
energy and increasing efficiency. There are a few recommendations for future improvement
to the current waste water system:
1. Reducing conveyance distances and using gravity rather than pumps, water and
wastewater utilities can reduce energy costs.
2. Decentralizing new treatment facilities are able to achieve additional savings.
Small, local treatment facilities can reduce the energy costs of conveyance and make
treated wastewater available for local reuse.
3. Using landfill gas energytechnologiesto capture renewable energy from anaerobic
digesters. One of the end products of anaerobic digestion is biogas, which can be used
for combustion to generate electricity and heat or turn it into a renewable natural gas.
Landfill gas energy technologies capture methane from landfills to prevent it from being
emitted to the atmosphere, thus reducing landfill methane emissions by 60–90%.
Methane collected from landfill are flammable gas that can be used to produce heat
and electricity. The process of landfill gas recovery and use is similar to the recovering
of methane from anaerobic digesters. This can also be applied to water and
wastewater treatment facilities situated near landfills. When the wastewater treatment
facilities are near to the landfill, they can share the same facilities to transfer the
methane to be usable and it can save more cost.
Example of small treatmentfacilities thatavailable for
local use

4. On-Site Renewable EnergyGeneration installed such as wind turbines, solar panels
or solar water pump to increase the energy efficiency and reduce greenhouse gas
emission.Solar WaterPumpdoes not require any battery for storage and the produced
energy is fully used to pump water from well. This solar water pump is design for the
cold water supply system but it can also be used for renewable energy generation in
waste water system.
5. Improve efficiency of operations by installing Supervisory Control and Data
Acquisition (SCADA) software. This can increasethe efficiency of process monitoring
and operating control. SCADA is a type of software application program for process
control. These systems are used to monitor and control the equipment in the industrial
process which include manufacturing, production, development and fabrication.
A simple illustration of how SCADA function
Solar Water Pump

6. Reduction in wastewater treatment costs by use of natural adsorbent like Neem
leaf and orange peel is an eco-friendly effort for freshwater conservation.
7. Changes in biological treatment processes from aerobic to anaerobic or anoxic
microbes to increase the potential of reduce the energy demand at a treatment works.
Aerobic and anaerobic treatment is two types of biologically-based wastewater
treatment process to prevent waterborne disease and maintain health.
8. Comparison between Aerobic and Anaerobic Biological Treatment:
Aerobic Anaerobic
How it Works Use bacteria that require
oxygen to break down the
organic matter and remove
other pollutants like
nitrogen, so air is circulated
throughout the treatment
tank.
Anaerobic bacteria is a type
of bacteria that does not
require oxygen to growth
and it transform/break down
organic matter in the
wastewater into biogas that
contains large amounts of
methane gas.
Energy Used or Produced  Electricity is required for
system operation.
 Uses less energy than
aerobic treatment.
 Biogas produced can be
used for a renewable
energy source
Advantages and
disadvantages
 Requires air input and
generate more sludge
 More expensive to
maintain
 More expensive to
operate than typical
septic(anaerobic)
systems.
 No air input required and
generate lesser sludge
 Less expensive to
maintain
 Require lower costs to
handle sludge than
aerobic treatment
systems
 Sludge is safe to use as
a soil enrichment

8. Improved Screening. Screening is the first unit operation used at wastewater
treatment plants removes objects such as rags to prevent damage and clogging of
downstream equipment, piping, and appurtenances. Some modern wastewater
treatment plants use both coarse screens and fine screens. By using fine screens on
collection mains or trunks to prevents the loss of chemical energy, reduces the need
for new facilities, and improves process and infrastructure sustainability.
9. Ammonia in wastewater act as a renewable energy. Ammonia can be burned
directly in an internal combustionengine, converted to electricity in an alkaline fuel cell,
or decomposed to provide hydrogen for a non-alkaline fuel cell. The temperature
required for the process depends on the catalyst. High conversion efficiencies are
achieved at temperatures of 650-700ºC. There is the potential at wastewater treatment
plants to use the ammonia from high-strength, high-temperature side streams as a fuel
source to produce electrical energy, heat, and/or hydrogen.
New Technology to Replace Current Waste Water Treatment:
Microbial fuel cells (MFCs)
Microbial fuel cells (MFCs) generate electricity from the organics present in wastewater and
are a promising innovative approach to renewable energy from wastewater. MFCs utilize the
bacteria commonly found in biological wastewater treatment processes to harvest the
chemical energy stored in contaminants and convert it to electricity. The system that using
MFC are called Bioelectrochemical systems (BESs), this system is relatively mild conditions
compared with conventional fuel cells and use a wide variety of organic substrates and mostly
do not use expensive precious metals as catalysts.
Screen for Wastewater Treatment Plant

In the waste water treatment, MFCs are used to harvest energy utilizing anaerobic digestion.
During the process it also reduce the pathogens at the same time. However, the temperature
should be at least 30 degree Celsius or higher to covert the biogas to electricity. Spiral spacer
is used to increase electricity generation by creating a helical flow in the MFC.
A great amount of research effort has been invested to test MFCs at the bench scale level
for wastewater treatment, yielding increasingly effective power generation rates; however,
full-scale use of MFC will be in the future. Also, chemical hydrogen peroxide (H2O2) can be
produced from a bio electrochemical system.
Nanofiltration (NF) Hollow Fiber Membrane
Hollow fiber membranes require much lower pressure to having an effective filtration
compared with others system.This membrane doe not require any additional processes such
as ultrafiltration to having complete treatment and it will resulting in overall treatment costs
far lower than similar processes. The technology is still in an initial commercialization phase.

Learning Outcome From The Group Work Project
As a student, we feel happy and appreciate for having this experience of doing this project.
We also feel very fortunate to have a group of responsible, helpful, diligent and attentive
groupmates. We distribute the works equally and every groupmates are active in every
discussion also. Doing this assignment is undoubtedly a memorable and interesting
experience sincethey are humorous and also make great effort on helping each other. Without
each other, we believe we are impossible to finish this project which has an important and
recondite topic to the environment.
The topic we choose to do is Sustainable Wastewater Treatment. Throughout this project, we
realized the importance of waste water treatment that we never focus on before. Without waste
water treatment or technology in our life there will be a lot of trouble and health problem occur
including the food chain since water is essential to every organism. Doing case study and
research about other country or area’s waste water treatment is helping us to understand our
own country waste water system also. This is because we will discover and understand the
weakness or strength of our system. This also helps us to know where we should improve
while doing the comparison.
This assignment let us learn to appreciate what we have from where we live while we are
doing research and comparison with some other countries that do not have a proper waste
water treatment. We also realized the importance of “sustainable” waste water treatment
which provides people clean water in long term and it is also environmental friendly in terms
of using renewable energy while running the system and changing the waste water to potable
water. After knowing the importance of having a sustainable waste water treatment and doing
some research about advantages, disadvantages and future improvements of the treatment,
we feel grateful to every scientist who had invented or modify the waste water technology.
During the process of research, we realized that one of the major problems of improving
sustainable waste water system is costing. To have an advance waste water technology it
requires high investment as low cost water treatment technologies will have some
inefficiencies that need to be addressed. Hence, majority of the current research is trying to
address these issues by modifying existing wastewater technologies to make them efficient,
saving more money and energy.

In conclusion, after learning and understanding the importance of sustainable waste water
treatment, we should pay more attention on waste water treatment’s issue and also convey
the awareness of sustainable wastewater treatment to the people. As sustainable waste water
treatment is a serious issue that can affect our life easily, we should be paying more attention
on it, so that improvement or modification of this system can be made with more efficient.

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