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SYLLABUS (As per CBCS Scheme)

Module -5:

Advanced Wastewater Treatment: Need and technologies used. Nitrification and Denitrification Processes, Phosphorous removal. Advance oxidation processes (AOPs), Electro coagulation.

Rural Sanitation: Low cost treatment process: Working principal and design of septic tanks for small community in rural and urban areas, two-pit latrines, eco-toilet and soak pits.

8 Hours

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Module Planning

Class 01	Advanced Wastewater Treatment: Need and technologies used.
Class 02	Nitrification and Denitrification Processes
Class 03	Phosphorous removal
Class 04	Advance oxidation processes (AOPs),
Class 05	Electro coagulation
Class 06	Rural Sanitation: Low cost treatment process:
Class 07	Working principal and design of septic tanks for small community in rural and urban areas,
Class 08	Two-pit latrines, eco-toilet and soak pits.

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RURAL SANITATION

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OBJECTIVE

Develop critical thinking and/or observation skills, and apply them to the analysis of a problem or question related to the rural water sanitation.

Lack of adequate sanitation is a pressing challenge in rural India.

The first national program to increase access to rural sanitation on a large scale

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APPLICATION

Improvement of health by minimizing the introduction of pathogens from human excreta into the water cycle

Promotion of safe, hygienic recovery and use of nutrients, organics, trace elements, water and energy

Preservation of soil fertility

Contribution to the conservation of resources through lower water consumption, substitution of mineral fertilizer and minimization of water pollution

Preference for modular, decentralized partial-flow systems for more appropriate cost-efficient solutions adapted to the local situation

Promotion of a holistic, interdisciplinary approach

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RURAL SANITATION

Introduction

If water is life, sanitation is surely a ‘way of life’ and access to such facilities has an impact on the quality of human life and health.

A holistic definition of sanitation includes safe drinking water, liquid and solid waste management, environmental cleanliness and personal hygiene.

Environmental cleanliness and sanitation were subjects closest to Mahatma Gandhi’s heart who proclaimed that “cleanliness is next only to godliness”.

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The concept of sanitation was expanded to include personal hygiene, home sanitation, safe water, garbage disposal, excreta disposal and waste water disposal.

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A public toilet, frequently called a restroom, is accessible to the general public. It may be within a building that, while privately owned, allows public access. Access to a public toilet may require a fee, (pay toilet), or may be limited to business's customers.

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Problems we currently face: (Ground)-water pollution…

On-site wastewater disposal systems like pit latrines or soak pits can contaminate groundwater (infiltration of wastewater) when the groundwater table is high

Source: (4)

🡪 Health risk: Polluted well-water

However, shortcomings also conventional on-site wastewater disposal systems have their shortcomings. Very often, they lead to groundwater contamination, which gets worse with increasing population densities. In many densely populated areas this has led to nitrate concentrations in groundwater, which exceed the maximum level recommended by the WHO for drinking water and which have been linked to serious health problems, particularly for babies.

Shallow groundwater is still a major source of water supply in rural and peri-urban areas, especially for the poor. The design of the conventional “drop and store” pit-latrine (and of most other on-plot systems) is not compatible with this practice as it deliberately aims to retain only solid matter in the pit and infiltrate as much of the liquids as possible into the subsoil. As these liquids contain all the soluble elements of the excreta as well as viruses and pathogens, this type of sanitation, depending on the hydro-geological situation, can be a highway to groundwater contamination. There may also be topographical constraints against the construction of pit latrines, for example where the ground is rocky or on sites that are subject to flooding (1).

Pit toilets may be a solution only when the infiltration cannot possible endanger water sources. This depends on the infiltration capacity, the distance to the drinking water source, the kind of the drinking water source etc. To be really on the safe side, pit latrines should therefore only be constructed in close collaboration with experts – which is often very difficult.

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Problems we currently face: Conventional Waterborne Sanitation

…are “flush and forget” sanitation solutions, where human wastes are flushed away with huge amounts of scarce freshwater, polluting rivers and the drinking water of people living further downstream.

What happens at the end of the pipe?

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Problems we currently face: Conventional Waterborne Sanitation

What happens at the end of the pipe?

If we are very lucky, there might be a “state of the art” conventional Sewage Treatment Plant:

Which will need:

Long sewer network & pumps to get the wastewater to the plant
Electricity for aeration, pumps and other moving parts
Skilled (and thus expensive) operation & maintenance staff
Backup generator for powercuts
Diesel for generator

🡪 Who will pay for this?

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Alternative, sustainable solutions are needed!

Sustainable sanitation solutions :

should be eco-friendly (no pollution of ground- and surface water)
need to be user-friendly
should need low maintenance
should be cost effective
should produce and not require energy (e.g. biogas)
are usually decentralized
should reuse nutrients, and water contained in wastewater

J. Heeb

K. Conradin

J. Heeb

P. Jenssen

K. Conradin

We need to rethink our sanitation approach; a new philosophy is needed!

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Ecological Sanitation as a Sustainable Solution

NUTRIENTS

closing the loop

between sanitation and agriculture

FOOD

Pathogen destruction

Source: (4)

The basic principle of ecological sanitation is to close the loop between sanitation and agriculture without compromising health

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Closing the Loop: Urine as Fertilizer

Urine is an excellent nitrogen-rich fertilizer!

Sugar cane without urine

Sugar cane with urine

“Urine is a complete fertiliser that is rich in nitrogen. It can be used in the same way as a nitrogen rich liquid chemical fertiliser. For biological fertilisers, the plant availability of the urine nutrients is uniquely high. In experiments, the phosphorous effect has been as good as that of chemical fertiliser and the nitrogen effect has varied from around 70% to more than 100%, compared to chemical fertiliser.

On average, the nitrogen effect has been around 90%, after deduction of the nitrogen lost as ammonia. In Swedish experiments, the nitrogen loss in the form of ammonia has varied from less than 1% to more than 10%. On average it has been around 5%. To keep the ammonia loss low, it is important to mix the urine into the soil as quickly as possible. The best method is probably to apply it in furrows or holes, which are then covered over immediately after application.“

Source: (20)

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Closing the Loop: Other Reuse Possibilities

Biogas as a sustainable energy source from wastewater:

For cooking
For heating
For lights
For electricity production

Reuse of water after treatment:

Irrigation in agriculture
Industry, flush for toilets
Recharge of groundwater

Other Reuse Possibilities:

Other forms of reuse in ecosan

While ecosan aims to close the nutrient loop between sanitation and agriculture through the reuse of nutrients, organics, water and energy contained in wastewater, the reuse options of such an ecosystem approach are not limited to agriculture.

“There are a whole range of other reuse options which can and should be integrated into ecosan systems wherever possible. These include the domestic reuse of grey water, following suitable treatment, for example for flushing toilets, or possibly its use as service water in industry, or used to recharge groundwater. Rainwater use could also be incorporated into this, with rainwater possibly being treated and being used for drinking water. The energy contained in wastewater can be recuperated and put to an array of uses, for example for cooking, for electricity generation, for heating purposes or even for industrial use. Organic material can also be recovered and put to use outside of agriculture, to generate biogas, or perhaps even as a general soil improver.” (1)

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Advantages of ecosan Systems

Improvement of health
Promotion of recycling
Conservation of resources
Preference for modular, decentralised partial-flow systems
Contribution to the preservation of soil fertility
Improvement of agricultural productivity and hence contributes to food security
Increasing user comfort/security, in particular for women and girls Promotion of a holistic, interdisciplinary approach.
Cyclic Material-flow instead of disposal.

Source: (18)

ecosan approaches are based on the systematic realisation of a material-flow-oriented recycling process spanning the full range from strictly low-tech solutions to expressly high-tech solutions. Elements of ecosan systems can range from compost latrines or dehydrating latrines with urine separation to complex, mainly decentralised solutions (see modules M3-1 and M3-2). These may consist, for example, of urine diversion toilets, vacuum transport systems and anaerobic or membrane treatment technology, combined with near-natural greywater treatment, e.g. in wetlands.
Even if ecosan approaches chiefly comprise semi-centralised or non-centralised sanitation systems, they can - especially in urban areas - also be represented by a combination of centralised sewerage systems and downstream sewage treatment plants. However, the treatment technology would then have to be oriented to rendering the effluent hygienically safe instead of to eliminating the nutrients, and the hygienically safe wastewater would then have to be used for agricultural irrigation.
ecosan approaches aim not only at closing the nutrient cycles and rendering them safe, but also at closing local water cycles and minimising the outlay of resources, including the possibility of energy gain. Principally every approach that ultimately leads to closing the loops and to the reuse of nutrients, water and energy should fall under the term ecosan.
ecosan systems offer appropriate and sustainable solutions for different circumstances and demands. They permit acceptable and affordable sanitation for poor and rural areas, as well as for high-income areas and industrialised countries

Source: 18

Ideally, ecological sanitation systems permit the complete recovery of all nutrients from faeces, urine and greywater, benefiting agriculture and minimising water pollution, as well as allowing economical use of water and its maximal reuse, particularly for purposes of irrigation. An even broader understanding of the term could also include the use, storage and infiltration of rainwater, treatment and recycling of solid organic wastes, minimisation of the energy input for wastewater disposal and utilisation of the energy content of solid and liquid wastes (18).

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There is not only one Ecosan Technology…

…many technology components can be used for Ecosan!

Urine-diversion flush toilets

Urine-diverting �dehydration toilets

Constructed Wetlands

Toilet-linked Biogas Plants

…and many more!

Decentralized Wastewater Treatment Systems

“Urine is a complete fertiliser that is rich in nitrogen. It can be used in the same way as a nitrogen rich liquid chemical fertiliser. For biological fertilisers, the plant availability of the urine nutrients is uniquely high. In experiments, the phosphorous effect has been as good as that of chemical fertiliser and the nitrogen effect has varied from around 70% to more than 100%, compared to chemical fertiliser.

On average, the nitrogen effect has been around 90%, after deduction of the nitrogen lost as ammonia. In Swedish experiments, the nitrogen loss in the form of ammonia has varied from less than 1% to more than 10%. On average it has been around 5%. To keep the ammonia loss low, it is important to mix the urine into the soil as quickly as possible. The best method is probably to apply it in furrows or holes, which are then covered over immediately after application.“

Source: (20)

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Conclusion - Ecological Sanitation Approach

Ecosan…

…regards all (dry and wet) “wastes” as resources

…is all about reuse, recovery and recycling of nutrients & water

…is a new holistic way of thinking, not a specific technology!

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Twin Pits for Pour Flush

This technology consists of two alternating pits connected to a [Pour Flush Toilet]. The blackwater (and in some cases greywater) is collected in the pits and allowed to slowly infiltrate into the surrounding soil. Over time, the solids are sufficiently dewatered and can be manually removed with a shovel.

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SOAKAGE PIT

The septic tank effluent disposed off in any one of the following ways:

By subsurface irrigation

By surface irrigation

By discharging in to near by water courses

By soil absorption system

Soakage pit: This is also known as sewage pit. There are circular pits more than one meter in diameter and 1 m in depth below the invert of the inlet pipe. These pits are lined with dry bricks or stone and are filled with brick-bats or coarse aggregate more than 7.5 cm, size. In the case of large pits the top portion is reduced in size for the reduction in the size of R.C.C cover.