Final EcoDes Project

8/3/2019 Final EcoDes Project

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EDISON CHALLENGE 2011

BEAVERSReg No: 4102011193151919

Indian School of Mines, Dhanbad, Jharkhand

Abhishek Srivastava

07209832720 | [email protected]

Love Goyal


Mohit Jain


Vamsi Krishna


Vikas Vimal (Team Leader)09973468381 | [email protected]

Prof. Biswajit Paul (Mentor)09431125959 | [email protected]

[WATER EFFICIENT TECHNOLOGIES

FOR GREEN BUILDINGS]Technologies involved in the design of a water efficient building in an urban locale.


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AbstractCities and the number of people living there are growing at an unprecedented rate. Water sources

are at a decline and rate of consumption is growing by leaps and bounds. Several authoritative

studies have discussed an impending water crisis in near future. If we allow such a situation to arise,

we will be at a great disadvantage. The economy and food security of the nation will be strained and

people would have to suffer.

The following paper illustrates a few methods that buildings in urban and rural areas can incorporate

in order to utilize water more effectively and efficiently.

The first section focuses on the reuse of domestic grey water. It uses an intricately balanced process

in which the total amount of greywater entering the system becomes equal to the total amount of

clean water and sludge recovered. The process utilizes a cyclic system in which a certain mass on

water keeps on being recirculated. Greywater brings in nutrients and the system efficiently converts

it into biomass, eliminating over 700 substances found in greywater. The system is designed to

degrade difficult to remove substances by utilizing both anaerobic as well as aerobic techniques.

The next section focuses on rainwater harvesting techniques. It is crucial that we make efficient useof this free source of high quality water. The design of harvesting system ensures proper collection ,

filtration, and long term storage of high purity water. These high volume tanks can be placed in

unused parking space at a low cost. Underground tanks made of low cost materials can make use of

unused areas around buildings without affecting the landscape.

The third section deals with installing a simple but highly efficient blackwater treatment system. It

relies on giving back the nutrients that we borrowed from Mother Nature. The Biogas plant with

separate urine treatment realizes efficient conversion of our waste into biogas and manure. The

system is cheaper, more cost effective and a more natural way of disposing our waste in urban

context than any other system.


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The fourth section describes an efficient centralized method of measuring the resources that we use.

We noticed that a simple thing such as the knowledge of consumption patterns can change our

attitude towards the resources we use and waste. The system uses a central unit to display the

various parameters affecting your house and can be adapted to measure and improve your water,

electricity, HVAC usage among other parameters.

The final section discusses the measures we need to put in place to reap the benefits of the

proposals made in the report. The use of efficient fixtures, easily degradable substances in our day

to day activities and keeping in mind that we cannot steal from the future generations can go a long

way in making the Earth a better place to live in.

Keywords: Greywater, Blackwater, Rainwater Harvesting, Biogas, Usage, Water Management


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Contents

Abstract ............................................................................................................................................... 2

Section 1: Greywater Reclamation .......................................................................................................... 5

Introduction......................................................................................................................................... 5Needs Being Addressed ....................................................................................................................... 6

Existing Solutions ................................................................................................................................. 7

Proposed Solution ............................................................................................................................... 8

The Filter.......................................................................................................................................... 9

Anaerobic Baffled Reactor ............................................................................................................ 10

Rotary Biological Contractors ........................................................................................................ 11

Grey Water Additives .................................................................................................................... 12

Solids Separation ........................................................................................................................... 13

Ultrafiltration ................................................................................................................................. 14

Novelty and feasibility ....................................................................................................................... 15

Cost Analysis ......................................................................................................................................18

Conclusion .........................................................................................................................................21

Section 2: Rainwater Harvesting ........................................................................................................... 22

Introduction.......................................................................................................................................22

Needs Being Addressed ..................................................................................................................... 23

Existing Solutions ...............................................................................................................................23

Proposed Solution ............................................................................................................................. 24

The Catchment Surface ................................................................................................................. 25

Transfer of water ........................................................................................................................... 26

First Flush diverters ....................................................................................................................... 26

Filtering of rainwater ..................................................................................................................... 27

Rainwater Storage ......................................................................................................................... 29

Novelty and feasibility ....................................................................................................................... 30

Cost Analysis ...................................................................................................................................... 31

Conclusion ......................................................................................................................................... 31

Section 3: Blackwater Reclamation ....................................................................................................... 32

Introduction.......................................................................................................................................32

Needs being addressed ..................................................................................................................... 33

Current Technologies ........................................................................................................................ 33

Proposed Solution ............................................................................................................................. 34

Novelty and Feasibility ...................................................................................................................... 35

Cost Analysis ...................................................................................................................................... 37

Conclusion ......................................................................................................................................... 37

Section 4: Smart Metering and Billing ................................................................................................... 38

Introduction.......................................................................................................................................38

Needs Being Addressed ..................................................................................................................... 38

Existing Solutions ...............................................................................................................................39

Proposed System ............................................................................................................................... 39

Novelty feasibility and cost analysis .................................................................................................. 41

Conclusion ......................................................................................................................................... 42

Section 5: Deploying supporting infrastructure .................................................................................... 43

References: ........................................................................................................................................ 44


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Section 1: Greywater Reclamation

IntroductionGrey water is defined as the wastewater devoid of any input from the toilets. Water from sources

like kitchen, basins, showers, washing machines etc is termed greywater. It comprises about 60-90%of total wastewater generated in homes. This fraction of waste water is considerably less polluted

than municipal wastewater and black water. The low amount of organics present makes it ideal for

recycling. There is an increasing global interest in reuse of water. The variations in climate pattern

and changes in rainfall make it essential to be prepared for water shortage.

Our process is designed to reuse a very large percentage of greywater and convert it to near potable

water. This would reduce the need of a municipal water supply mechanism. Assuming an average

80% of total water used is converted to greywater, our system aims to degrade the nutrients present

and converts it into removable sludge. This can lead to recirculation of purified water. Around 80%

of total water being supplied to the household is reclaimed from previous usage. The remaining 20%of the demand would be met by rainwater stored in storage tanks or by municipal water supply.

Greywater comprises of a multitude of organic chemicals, soaps, food particles, dissolved organics

etc. The composition of greywater is highly variable depending on lifestyle of occupants, water

distribution systems, water quality, etc. The major constituents of greywater are Metals,

microorganisms, food particles and XOCs (Xenobiotic Organic compounds). Metals are responsible

for hardness of water, growth of microorganisms, and are sometimes a health risk too.

Xenobiotic Organic Compounds are a group of comprising of chemicals like soap, detergents,

shampoos, perfumes, powders, oil, dyes, starch, glucose, dairy products and a multitude ofchemicals used in the house. While some of these chemicals are difficult to degrade, some even

retard the growth of microorganisms. Hence to completely understand processes leading to

degradation of greywater to an extent enough to render it near potable, we would need to

accurately sample over 700 or so chemicals found therein.

Microorganisms are also a major concern. Certain microbes can be detrimental to health such as E

Coli, Fecal Coliforms, Salmonellae, peptococcus, cholera, Fascicola, Ascaris, Entamoeba, and

Adenovirus etc. Precautions must be made to thoroughly clean water before it comes in contact

with any consumer.


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Needs Being AddressedOur design primarily addresses the concern of inefficient reuse of greywater. This design aims to

develop a cost effective and relatively simple process to reclaim high quality water from greywater.

A large fraction of average household demand of water can be met with an efficient Decentralized

Water Treatment (DWT) system.

The secondary aim is to reduce the dependence on municipal water supply through effective

reclamation and reuse. Additional reduction in municipal water demand can be achieved through

use of collected rainwater.

The aim is also to reach equilibrium in the flow sheet where the total amount of water, nutrients,

and other organics entering the system would be equal to the total amount of water and sludge

taken out of the system. This equilibrium would be responsible for creating steady load in the

system. The problems related to accumulation of certain chemicals in such a cyclic process have

been addressed by using novel techniques. The recirculating load would be same as amount of feedand thus a Circulating load ratio of >1 would be maintained.

The problem of accumulation of certain compounds is addressed too. The removal of 20% of water

as blackwater can help remove the most harmful fractions from the process.


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Existing SolutionsThe greywater treatment methods that are observed in India are as follows:

1. Municipal sewage system: A large fraction of urban population is dependent on municipalsewage system. The greywater gets released into conduits built near the houses which carrythem out to municipal treatment facilities. These facilities are huge and rely on complex

systems to process water before discharging it into water bodies.

At certain places where there is inefficient municipal participation, waste is channeled

untreated to nearest rivers or lakes where they degrade slowly and may cause groundwater

contamination.

2. Drainage to fields: In rural areas, the greywater is diverted to farms. Rural greywatercontains fewer amounts of toxic compounds and acts as a good fertilizer. A portion of it

seeps to groundwater and gets purified and reused in the process. It is a very efficient and

effective use of greywater. This method can rival some of the most technically advanced

methods of greywater treatment.3. Waste stabilization ponds: Smaller cities with less sophisticated treatment systems rely on a

series of waste stabilization ponds. The greywater seeps through the soil and reaches the

next pond in series. In this process, bacteria in the soil act aerobically as well as

anaerobically and systematically clean water enough to safely dispose in a river.

4. Constructed wetlands: These are wetlands covered by plants and weeds and are rich inbacteria. Wastewater passing through this wetland loses nutrients and emerges as relatively

pure water.

5. Aerobic digestion tanks: Large colonies often contain aerated tanks to degrade harmfulnutrients and improve water quality before releasing it into the waste water streams.

6. Some technologies such as Brac Greywater Recycling System emphasizes on reuse ofgreywater for flushing purposes after preliminary treatment.

7. Multistage RBC are used to degrade organic material and clean greywater to an extent. Aftersedimentation and UV filtration, it is used for toilets, irrigation, cleaning etc

8. Membrane Bioreactors immerse a membrane in a tank containing the greywater. The tank isactive and aerobic bacteria decompose nutrients. However, this process requires high

maintenance but is very compact.

9. Multi Stage Sequential Batch reactors are a part of a costly treatment technology.10.Other currently available greywater recycling solutions have prohibitive costs and have a

payback period of several decades and not feasible for Decentralized Waste WaterTreatment Systems.


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Proposed SolutionOur process utilizes a hybrid Reactor to treat the waste water. The design is derived from the fact

that a combination of Anaerobic and Aerobic treatment systems is required to degrade over 700

compounds present in greywater and reclaim the maximum percentage of water at a near potable

quality. The proposed design combines currently available Anaerobic Baffled Reactor with aerobicpost treatment with an RBC.

The grey water from the building is channeled through a belt filter to remove particulates which are

then sent to the biogas system for further processing. The filtered water is then introduced into a

settling chamber connected to a series of baffles. When water is added to the first chamber, the

water already present is forced to move through a series of baffles and coming in contact with active

biomass present there. Addition of Grey water additives is necessary to degrade the variety of

material present in grey water and ensure removal of hard to degrade material.

When the slurry passes through a defined number of baffles, it enters the Rotary BiologicalContractor and aerobic bacteria are added. This results in even larger extent of organic removal. A

flocculation tank/thickener follows aerobic treatment. The sludge is removed from the bottom of

the thickener and is recirculated through the filter press. The clear overflow is sent for ultrafiltration.

Ultra Filtration Membrane is assisted with ultrasonic vibrations to prevent clogging and increase life

of the membrane. UV treatment is done to remove remaining microbes and the water released is

near potable. The overflow of UV system is mixed with freshwater from rainwater harvesting or

municipal supply and flocculants and sent to thickener along with RBC discharge.

This process is designed to be technically advanced as well as robust and easy to maintain. The one-

time cost of this equipment is bound to be a high but it can return its investment in a few years.


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The FilterThe belt press filter is a rugged high capacity filter that can easily remove solids from grey water. Its

main purpose is to remove particulate materials from kitchen waste and sludge after final processing

in a single step. The solids would be sent to biogas plants for further treatment or disposed.

The operating principle of belt filter is focused on the cake being squeezed under two belts under

tension. The slurry is trapped in between two belts. The pressure applied on the belt increases

gradually, forcing water to separate out. This leaves the sludge on the behind which is removed

later.

The efficiency of these belts can be increased by addition of polyelectrolyte which flocculates them

and increases the sludge removal efficiency.

Features:

These are automatic and designed to operate with minimal operator assistance

Low initial investment and operating costs Small footprint and robust design

Setup:

The belt filter would be preceded by a small holding tank of, say, 3000 liters, to hold greywater for a

short period. The sludge from secondary sedimentation would be added to the tank. The flocculants

added during secondary sedimentation would make filtering easier.

A sensor in the tank would recognize if the tank is full and will automatically initiate the filter press.

This would provide settling time for proper flocculation and reduce energy required by using onlywhen necessary.

The filter press chosen would be something like V

fold belt filter press from Dayco Pty Ltd. It is cheap,

rugged, simple to operate and install. It can handle

slurries with highly variable solid liquid ratio.

The sludge formed would be compacted and sent

to biogas plant to recover nutrients and generate

fuel. Or, it can be directly sent to municipal wastedisposal.


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Anaerobic Baffled ReactorABR is an improvisation of the septic tank. It is designed to force the greywater to flow under and

over a series of baffles as it proceeds towards the outlet. This results in an enhanced contact with

the biomass already present in the reactor and increased degradation of pollutants. These machines

are robust and can treat a wide variety of pollutants.

Design: It consists of a tank with alternate hanging and standing baffles that force liquid to flow up

and down on its way to the outlet. The result is an enhanced localized mixing and contact with

microbe rich sludge settled at the bottom. It consists of 1 settling chamber and 2-5 up-flow

chambers.

The retention time for denser sludge is more

than that of the wastewater. This results in a

faster processing of water. The retention

time is in the order of a couple of days.

ABRs are suited for small to medium

residencies and can treat wastewater with

low amount of dissolved organics. It is not

feasible to be used in flood prone areas or

places with high water table.

It can achieve a reduction of 50-90% BOD,

60-90% COD, 60-90% TSS which is much

superior to conventional septic tank.

Features:

The installation cost is very low as it can be made from locally sourced materials. The operating cost is minimal as the flow is passive and requires no additional energy. Produces biogas that can be used in fuel cells. The design is a bit complex and requires expert guidance. It is however very robust and

resistant to changes in pH, Temperature and chemistry of system.

Automatic sludge removal at periodic intervals can reduce the amount of maintenancerequired, making it an automatic operation.

Only drawback seems that a longer time is required to achieve equilibrium performance. It can be installed easily in tropical climates.


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Rotary Biological ContractorsRBCs are fixed bed aerated reactors consisting of stacks of rotating disks mounted on a horizontal

motor driven shaft. These stacks are partially submerged in wastewater flowing through it. Microbes

attached to the disk soak up nutrients and digest them. The alternating exposure to air and nutrients

makes a higher rate of degradation possible. The system is very robust and has a minimum 10-20year design life.

This system can be used with low concentration

of nutrients found in greywater. It is particularly

effective for decentralized water treatment

plants.

Design: Rotating disks are designed of high

density plastic and have a large surface area.

The biomass growing on the surface is fed by

nutrients from water and adsorption of oxygen

from air. Nitrogen and other nutrients are

removed from water and added to biomass.

The disks are submerged 40-80% in water. The process is controlled by varying rotational speed and

submergence. The performance depends on pH, temperature, design and concentration of

nutrients.

Features:

Long design life, environmentally friendly, cost effective.

Silent and very stable operation, low level of supervision and maintenance required. Low per capita power requirement, to be met with power generated by sustainable sources. Faster processing than conventional treatment methods, lower residence time; 1 day. Simple in design and operation, materials are, however, not locally sourced. Better performance under low levels of loading. Fast settling and easily removable sludge. Degradation of nutrients left over by anaerobic bacteria. High BOD and COD removal efficiency, up to 90%.


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Grey Water AdditivesThe water treatment systems discussed above rely on conversion of available nutrients into biomass.

The composition of greywater is variable and it often lacks certain essential micronutrients

necessary for growth of microorganisms. It is a vastly overlooked concern as a deficiency of minerals

may lead to retarded growth of microorganisms and a decreased overall performance.

The nutrient deficiency can be tackled by adding a very small amount of Greywater additives. These

additives contain minerals such as Fe, Cu, Al, Mo, Co, Zn which are not usually found in greywater

but are essential for growth of bacteria. Lack of these micronutrients reduces the amount of specific

bacteria required to process different organics and may promote growth of ineffective bacteria.

Additionally, certain greywater additives currently available in market such as Bio Systems SA

contain high performance bacteria. A few grams of these additives per week can go a long way in

achieving a very high rate of removal of BOD and COD. The system when optimized, can achieve

over 98% reduction in load of nutrients and other dissolved elements.

Features:

Better degradation and emulsification of oils and greases in kitchen waste. Better performance on soaps, detergents and cosmetic wastes. Better odor management in the process. Specialized bacteria for difficult to degrade compounds. Replaces bacteria killed due to excess of detergents and other compounds. Better quality of final effluent. Provides micronutrients to sustain high performance. The cost of the system is moderate but improves the performance necessary to increase

efficiency of the operation.

Addition bacteria such as Achromobacter, Alcaligenes, Arthrobacter etc helps in flocculationby a process of bioflocculation.

Setup: The GWA would be manually added to waste stream every week. Addition is done before

aerobic and anaerobic stages to achieve best performance.


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Solids SeparationThe next critical step in the pro

designed on the basis of a high r

Flocculation is a process in wh

polyelectrolytes. These chains

separated from the solution in a

The sludge settled at the botto

one before the belt filter. Enou

this liquid passes on to the belt

goes to the next step which inclu

The use of bio flocculating b

reduce the amount of flocculan

The order of a few grams pewater processed.

Design: Flocculants are m

wastewater emerging from

allowed to settle in a tank cont

moving paddles. These paddles

to the bottom of tank and

would overflow from the top of

can take anywhere between

minutes for the flocs to form.

The return from ultrafiltration s

pumped to points of turbulence

Features:

Low cost design and con Very fast flocculation an Small footprint and mai Removal of colloids whic

ess is separation of solids. This step is carried

ate thickener of small capacity.

ich a colloidal system is destabilized by addin

ind colloidal particles and create agglomerate

settling tank.

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h settling time is provided to allow formation

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des Ultrafiltration.

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r tonne of

ixed with

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10 to 30

stem is mixed with flocculent to form a dilute s

to mix with wastewater before the settling tank.

struction, low running costs (a low power motor

d separation of solids and liquid.

tenance cost.

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certain long chain

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in the first step, the

of large flocs. When

d off. The overflow

lution which is then

required).

ter.


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UltrafiltrationThis is a filtering process which stops particles of size 0.01 microns and large. It can stop the passage

of bacteria, virus, colloids and larger particles. The particles it cannot stop are certain dyes, salts,

sugars and ions, most of which are easily removed by the aforementioned treatment methods. A

higher pressure at inlet compared to the effluent side helps transfer of liquid through themembrane.

Design: Our design seeks to improve the performance of the membranes used in ultrafiltration by

using ultrasonic vibrations. These vibrations would prevent the particles from settling inside the

pores of the filter and a longer life is expected. These filters greatly reduce the amount of harmful

microbes in the water and it should be bath able.

After some UV treatment, this water could be used for bathing, laundry, sinks etc.

Features:

Membrane has very fine pore sizes to prevent microbes from crossing over. The very few microbes that do cross over are removed by a UV or ozonation. Moderately long service life and costs. Low operating costs. High through flow, low filtration time required. Compact, small footprint, moderate power consumption. No prefiltration required Automated operation High quality effluent in a single step Ultrasonic vibrator prevents fouling of membrane and reduction in efficiency. Periodic back flushing is usually incorporated in the design to clean the membranes Modular construction Environment friendly materials used in membranes.


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Novelty and feasibilityIdea 1

We have used Temp tank and Belt filter to remove sludge from clear greywater. The tank is

equipped with a sensor, similar to the one found in flush tanks, modified to automatically switch onthe belt filter as soon as it is full. This takes care of surges in water collection system.

If we use a continuously running belt filter, most efficient capacity would be around 1000 lph.

Without a temp tank acting as a buffer, it will get overwhelmed in the mornings when everybody

bathes and releases lots of greywater.

The proposed system uses buffer temp tank. This allows intermittent use of belt filter. The filter can

be used of higher capacity to beat the morning rush. We can use the belt filter at 2500 lph for half

the time required, maintaining efficiency as well as accommodating surges. It is very practical and

feasible.

The tank could be made of easily available Sintex canisters and the sensor mechanism is a slight

modification of the regular toilet flush mechanism.

Idea 2

We have used equilibrium in the system with fixed input, output and recirculating loads. Our system

is designed in a cyclic fashion as opposed to linear design of most technologies.

The recirculating load in our design may exceed 100% and this helps in making the system more

stable and resistant to daily fluctuations in load and chemical shocks. It also helps in sustainingproper bacterial distribution throughout the system.

This design is very feasible as all we have to do is recirculate the unfiltered water from the

ultrafiltration step.

Continual removal of unfiltered water helps in maintaining a low load on the dirty side of ultrafilter

and increases filtration efficiency by a significant amount.

It also reduces the amount of greywater additives required as most bacteria are recirculated.

This ensures a very high recovery of greywater that is simply not possible in other techniques. Thetotal amount of greywater entering is roughly equal to the clean water recovered. Addition of

rainwater results in a greater yield than total input. The only water lost is a very small fraction in

sludge. We can recover over 95 % of greywater generated through this method.

Idea 3

We have added Grey water additives during aerobic and anaerobic stages to assist growth of

microbes.

Micronutrients in GWA contain traces of Fe, Cu, Zn, Mo, Co, etc which are not found in required

quantities in greywater but are necessary for growth, enzymatic action, degradation of waste.


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GWA also contains certain specialized bacteria that can quickly remove certain difficult to degrade

substances resulting in a very high BOD, COD, TSS and inorganic removal.

Certain bacteria can bio flocculate. Addition of such species results in reduction in the usage of costly

flocculants.

The GWA are very costly, order of Rs5000 per kg or more. But the need of only a few grams of it

every week makes it a relatively inexpensive proposition. Hence it is highly feasible.

Idea 4

Use of anaerobic Baffled reactors over other anaerobic methods

ABRs are modifications of the common septic tanks and are passive in operation. They can be easily

and cheaply constructed and require no energy to operate. They require cleaning a couple of times

an year. They have almost no operating costs apart from GWA and very long lives.

Idea 5

Use of RBCs over other aerobic treatment techniques

RBC is moderately costly but their life is in the order of decades. They require electricity to drive

motors, means relatively high operating costs. But the low RPM means very low power consumption

and small motors.

They provide large surface area and proper aeration. They are most efficient in breaking down

difficult to degrade substances.

Idea 6

Use of Ultrasound assisted ultrafiltration

Use of ultrasound increases filtration efficiency at low pressure differences across the membrane.

(Mechanisms for the enhancement of ultrafiltration and membrane cleaning by different ultrasonic

frequencies; Ming Cai, Shuna Zhao, Hanhua Liang)

The study has shown that for low pressure difference across membrane (0.4 atm) and low ultrasonic

frequencies (28 KHz), the cake resistance decreases significantly. This results in an increased fluxcompared to normal process and significantly increases self cleaning.

It is highly feasible as an ultrasonic transducer can be purchased for $10 or so. Manufacturers would

need to integrate it into their designs.

Idea 7

Removal of accumulated heavy metals and non degradable compounds from the process

Some of the organic compounds and heavy metals are difficult to degrade biologically and may pass

through the ultrafilteration system. These substances are harmful to people if consumed in large


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quantities. To prevent these substances from reaching the food cycle, the following measures in

design have been taken.

Diverting a fraction of greywater to blackwater cycle. This helps in attaining an equilibriumin the system wherein the amount of these substances entering the system becomes equal

to the amount exiting it. The overall increase in the amount of these substances in purified

water would be negligible compared to other sources.

Addition of greywater additives containing bacteria specially created to degrade and removethe harmful substances.

The potable water is made available through an RO system. This system would be installed inevery home and not in a centralized facility due to inherent problems of bulk purification,

handling, metering, cleaning, and maintenance of highly pure water distribution system. RO

systems are highly efficient in removing TDS, TSS and most other harmful substances

present still remaining in the ultrafiltered water. Due to low drinking and cooking water

requirement, RO systems can be installed in homes easily.

Alternately, activated charcoal based filters also reduce the amount of TSS, TDS and larger

molecules through adsorption. These systems can be made available to each household at a

low price. TATA SWACH costs around Rs 300 and provides 3 000 l of drinking water, enough

for nearly 6 months of average family water consumption.

No extra cost is to be incurred as most people prefer installing their own water purification

systems.


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Cost AnalysisThe cost analysis done here is tentative and may vary depending on origin, construction and capacity

of devices used and use pattern. The per capita water consumption has been calculated based on

assumption that current average per capita water consumption in a developing city is 91.56 51.51

litres per day (Source: Water consumption patterns in Domestic households in major cities: AShaban, R N Sharma figures of 2005). The target consumers are middle to upper middle class families

with assumed spending capacity of Rs 30,000 per month or more. This brackets our operating costs

to around Rs 1500 per month (5% of average monthly expenditure).

Our proposed system uses more efficient plumbing and fittings. This can reduce wastage by a

theoretical 40%. For all our cost considerations, we shall assume the following:

Number of people per family (normalised)= 4 Number of families in a complex= 50 (200 heads) Average per person consumption without using efficient practices= 120 l (mean +variable/2) Average actual per person consumption of water (efficient use)= 80 l Total greywater generated per person= 65 l (rest is blackwater or lost) Total greywater generated per day = 13 000 litres Total freshwater supplied per day = 16 000 litres Temp storage tank capacity = 3 000 litres (1 sqm area) Filter press capacity = 2500 litres per hour(recirculation,intermittent) (2 sqm) Settling tank capacity = 5000 litres (5 sqm) ABR capacity = 20 000 litres (residence time of 15 -24 hours) (20 sqm) RBC capacity = 10 000 litres (residence time of 4-10 hours) (10 sqm) Flocculation tank capacity = 1200 litres (residence time 10-30 minutes) (2 sqm) Ultrafilter capacity = 700 litres per hour (2sqm) Pump capacity to supply to overhead tanks = 700 litres per hour UV tube capacity = 700 lph/3 gpm

Components:

1. The cost of ultra filtration system is the largest cost component in the system. The capacityassumed lies in the range of 700 lph

The installation cost seems to be in the range of Rs 150 000 (data for 1-3m3 per hour

ultrafiltration system)

The operational cost is in terms of electricity at 1 KW. The price can be assumed Rs 3.5 per

KWh resulting in 31 000 as electricity charges per year adding a maintenance cost to make a

total operating cost Rs 50 000 per annum.

Per capita expenditure on ultrafiltration = Rs 250 per annum.

2. The cost of RBC is second largest in the operation.The DIY RBCs cost around Rs 50 000 to assemble. We can assume a commercial low cost

product would cost Rs 100 000 for installation. This is spread over a period of couple of

decades.


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Operating cost would be in terms of 100 W of electricity. Investment required = Rs 25 per

head

3. The third cost would be of ABR system.Installation of a typical septic tank in India is usually around Rs 50 000. An additional cost for

modifying would increase the total cost to Rs 100 000. This is also a long term investment.

No operating cost is required as the flow is entirely passive.

4. Cost of Belt FilterInstallation cost of a small belt filter would be in the range of Rs 100 000 for a life of around

1 decade.

The operational costs would reach the tune of 750 W for half a day daily. Adding to it the

cost of maintenance, we could be looking at a cost of Rs 100 per head per annum.

5. Cost of additives.Flocculants cost Rs 5 000 per kg and are added in the ratio of 1-4 kg per tonne of sludge

created. Since greywater is very dilute, it would produce no more than 2 kg of sludge daily.

Flocculants required = 5- 10 g daily or Rs 15,000 per annum or Rs 80 per head per annum.GWA costs around Rs 5 000 per kg and is required in similar amounts. Rs 80 per head per

annum added.

6. UV irradiation tubes can be procured at a price of Rs 20 000 and an annual operational costof Rs 2500 including power and maintainence. Its life is over three decades

7. Other costs can be assumed to be Rs 100 per head per annum as miscellaneous expenditure.8. Pumping costs are not extra as they would be in design anyway.

Total annual expenditure per head = Rs 250+ 25 +100+ 80 +80 +100 =Rs 635 per head per annum.

Even if we add extra costs the design would result in 43 000 litres of water supplied for Rs 700 per

year at less than 2 paisa per litre operating cost.

The total installation cost would be Rs 450 000 for a period of say 5 years resulting in a per capita

installation cost of Rs 2500.

Since 80% of total greywater is recycled, and our rainwater harvesting measures result in supply of

freshwater for, say, 4 months in a year. We need municipal supply for 8 months only

Total water purchased from the municipality = 3000 lpd (16000-13000)* 8*30 =720 000 litres at a

rate of 3.5 paisa per litre = Rs 25 200 in an year

In absence of this method, total water purchased would have been 16000*365*3.5=Rs 204 400 per

year

This indicates that the proposed method is very cost effective and can return its investment in less

than 5 years.


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Summarising the features of this design, we can conclude that

The aforementioned design is very cost effective The cost of water generated is comparable to municipal water supply in terms of cost The system is resilient to variations in loading and chemical shock The degree of reclamation is very high, reaching over 95% Low area required. Design is very compact. Low cost construction and simple design Easy maintenance Low operating costs Installation cost very low Less retention time- small volume required Easy to stop and restart if required High purity of effluent, near potable quality. Reduced dependence on municipal water supply and waste disposal.


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ConclusionAssuming the worst case scenario and increasing price of everything accordingly, we get the

following table:

System Installation cost Per capitainstallation cost Operating costPer annum Per capita annualoperating cost

Ultrafiltration 160 000 800 50 000 250

RBC 100 000 500 10 000 50

ABR 100 000 500 600 3

Belt filter 100 000 500 20 000 100

Flocculant 0 0 30 000 80

GWA 0 0 30 000 80

UV 20 000 100 4400 22

Miscellaneous 20 000 100 35 000 175

Total 500 000 2500 180 000 900

Item Volume per

person per

day

Per annum (L) Installation

Cost

Operating cost Total operating

cost of water

per litre

Total water

Required

80 5 840 000 1 100 000 203 000 3.48 paisa

Recirculated

greywater

65 4 745 000 500 000

(ROI 5 year)

180 000 3.8 paisa

Freshwater

required

15 1 095 000 600 000 23 000 2.1 paisa

Freshwatersupplied by rain

10 730 000 600 000(ROI 10 year)

10 000 1.5 paisa

Municipal

freshwater

5 365 000 0 12 775 3.5 paisa

Scenario without

treatment

80 5 840 000 0 204 400 3.5 paisa

We can hereby conclude that use of the aforementioned techniques would result in an insignificant

rise in cost of water for common people compared to municipality supplied water. If used efficiently,

it can even lead to a reduction in cost of water.

We can also conclude that existing decentralized water purification systems can achieve municipality

grade price point while still remaining green. Our system is very eco friendly and can actually prove

more cost effective if made in bulk and marketed in form of integrated systems. Much of the cost of

water is shaved off by reclaiming water at the site itself.

The very low residence time allows a compact design covering as little as 45 square meter of area.

The whole system can be built in the basement of any one of the 5 buildings.

We have, thoroughly analysed possible variations of this system and have concluded that this one

offers best price to performance ratio. This system has potential to change the current greywater

treatment scenario.


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Section 2: Rainwater Harvesting

IntroductionRainwater harvesting is an ancient practice of collecting and storing rainwater for later use.

Rainwater is a very important part of the hydrological cycle on earth. Hydrological cycle represents

the path through which water circulates between atmosphere, lithosphere and hydrosphere. There

is essentially an intricate balance in this cycle. Human activities tend to divert water from its natural

course and this affects the health of the planet. However, human population has grown to an extent

where it cannot sustain without disrupting the natures balance. We should, therefore, strive to

approach the problem of water scarcity in such a way natures cycles get minimally disrupted.

Rainwater harvesting is one such process. In this process, a part of the rainfall is diverted for human

use. This reduces the amount of stormwater generated in cities and as a result, fewer pollutantsreach the rivers and lakes. It also reduces the amount of water removed from the rivers and

minimizes the impact on natural water bodies. Thirdly it reduces the amount of water we purchase

from municipality. Lastly, it provides a much cleaner source of water than any other natural source.

Rainwater consists of certain particulate matter, dust particles, dissolved gases such as SO2, NO2,

CO2 and a few other compounds. They can be removed easily and the water would become near

potable without any energy or cost intensive step.

Our process aims to reduce the dependence on municipal water supply by storage of rainwater in

underground artificial aquifers and making the system a part of the building water supply. The

novelty of our report is the emphasis laid upon the design and cost effectiveness of the system.


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Needs Being AddressedOur design primarily focuses on the use of collected rainwater to reduce the dependence on

municipal water supply. A significant amount of independence from the grid can be achieved at a

low cost if rainwater is used with our greywater purification system.

Our design addresses the problem of high cost of water storage systems by introducing a more cost

effective system. Our design also addresses the problem of long term storage, proper collection,

filtration, wash water management, landscaping, etc.

The features of rainwater is that it is soft water, needs less purification, is free, and seems as a more

natural water source.

Existing Solutions1. The natural solution was to allow rainwater to seep through the ground and form groundwater. It is a part of natural hydrological cycle and requires no effort on human part other

than pumping it out. It used to be the best process available until cities grew up and covered

the ground with impervious concrete and chemicals began to be released in rural farms.

2. Farming utilizes rainwater. The collection of rainwater in paddy fields has been practiced formillennia.

3. People in urban locations collect rainwater in buckets and barrels to use for toilet flushingand gardening.

4. Storage of rainwater in ponds for use in agriculture has been practiced for a long time.5. PVC underground tanks of thousand gallon capacity are used to store rainwater for non

potable needs. Primary filteration is usually enough to make rainwater fit for such uses.

6. Matrix storage systems use PVC matrix cubes stacked to form a storage matrix for millions ofliters of storage capacity. The water proofing is done by PVC water proof liners

7. Above the ground storage in huge steel tanks or in unused spaces.8. Diversion of urban rainwater into recharge pits lined with gravel or wells to recharge

groundwater.


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Proposed SolutionThe proposed rainwater solution utilizes the following components:

Catchment Surface: A well designed catchment surface can result in a higher water recoveryand a lower level of contamination of collected water.

Gutters and Downspouts for transfer of collected rainwater from catchment to storage First flush diverter to remove the First flush water which may contain urban dust and various

contaminants. The first flush can be reused for toilet flushing.

Filtration system to remove impurities from water and make it suitable for long termstorage. Our system is passive and based on sand-charcoal-gravel filters.

Storage system to store water for long periods of time. It would be cheap, easy to construct,high capacity and strong. It must not allow degradation of water quality due to storage.

Pumping system to transfer collected water to greywater purification system for transfer tohomes and reduce municipality bills.

For all considerations, we can assume each apartment of of 2 bhk being 100 m2(1076 sq ft).

Total catchment area, (two apartments on every floor of 5 five storey buildings,) = 1000m2

Annual average rainfall = 120 cm.

Collection efficiency = 70% (losses in wash water, inefficiency)

Total volume of tank necessary for storage of this water = 840 000 l

Total area required for collection of this water (assuming a tank of height 2.5 m) = 336 m

2

Efficient tank area under required = 300 m2 (rain is spread over 3 months)

Area under the basement of each apartment = 100 m2

Total basement area = 1000 m2

Area required for one vehicle = 12 m2 (Wikipedia)

Total parking area considering 1 vehicle per household = 600 m2

Area wasted = 400 m2


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The Catchment SurfaceThe catchment Surface is the collection surface that is used for collecting rainwater. The things to

consider are that airborne dust, dirt, chemicals bird droppings etc are accumulated over the surface.

Water from these surfaces could be potentially harmful. Some types of roof attract dust more than

others; some absorb water and can cause moulds to grow; the slope plays a major role in timerequired to wash the roof. Various roofing materials being used are asbestos, galvanized steel,

concrete, thatch etc.

The most suitable catchment surface for urban environment would be an application of StableCrete

over a smooth layer of roofing concrete. It is a chemical that penetrates the surface of the concrete

and seals it, preventing entry of water.

Features:

Low cost Watertight, does not absorb water Smooth surface means easier removal of contaminants by wash water Widely used and easily available Long life, 10 - 15 years Environment friendly, low VOC Increases the life of roof by preventing corrosion Easy to apply. No problem of peeling, eroding Repels stain Light in color, reduces heat gain during summers

Feasibility

Total Roof area = 10760 sq ft. Cost of StableCrete per foot = $0.35 per sq foot Total cost of system = 169 500 spread over 15 years without any operational cost Reduction in cost of roof repairs and extended life of roof.


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Transfer of waterThe rainwater is transferred from rooftop via cement/PVC pipes. The method is tried and tested and

most cost effective of all systems.

However, attention must be paid to design in such a way that all the water exits on the side of the

filter.

Primary filtration would remove leaf and larger particles. Simple, removable strainer baskets placed

at strategic points in the system would be adequate.

The downspout would release its contents in to the filtering mechanism placed under non porous

surface.

First Flush divertersThe first few 1 mm of rain usually contains the airborne wastes settled on the catchment area. It is

rich in heavy metals such as lead and mercury. It also contains soot, organic compounds, bird

droppings etc. These materials are difficult to treat in greywater treatment systems and thus

primarily useless.

First flush diverters are simple mechanically,

electrically or manually operated devices to

divert a fixed volume of water before allowing it

to go on to its destination. A simple design uses a

floating plastic ball to divert the flow of water

once the wash water tank is full.

The design can be attached to the downspout at

the rooftops itself.

The water accumulated in wash water tank can be used for car washing and the like. Up to 5% of

total rainfall can end up as wash water. A small amount of wash water must be diverted if the

rainfall is more than 3-4 days overdue.

The cost of this system is very small and would be under 25 000 Rs for the most sophisticated one.


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Filtering of rainwaterThe contaminants of rainwater are mostly tiny suspended particles that need a small amount of

filtration to make it suitable for long term storage. The filter that we designed for our system is a

basic charcoal filter 2 m deep and a large surface.

Features:

The filter is a slight modification of anancient filtration device shown here.

The total depth of the filter would be

nearly 2 m.

The first 30 cm would be gravel, next30 would be coconut charcoal

followed by 50 cm sand and 70 cm

gravel

The filter would be enclosed in aplastic waterproofing material laid

over the wall of the building and the

storage tank.

The filtered water collected at the bottom of the filter would rise up a PVC pipe and feedinto the tanks.

A diffuser would distribute the water from the downspout throughout the length of thefilter.

A few relief valves would provide an exit to water during overflow. The overflow would bechanneled to regular drains.

Feasibility and cost analysis

The filter can be assumed to be 15 m long, 0.5 m wide and 2 m deep (15m3 total) The design incorporates 4 such systems. Less may be required. Cost of river sand = Rs 1600/t Volume required = (2600 Kg/ m3) 3.5 m3 =10 t (Rs 16 000) Cost of charcoal = Rs 13500/t Volume required = (208 Kg/ m3) 2.5 m3 = 0.600 t (Rs 8 000) Cost of gravel = Rs 4500/t Volume required = (2600 kg/ m3) 7.5 m3 = 20 t (Rs 90 000) Installation cost = Rs 150 000 for several years with no maintenance


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Layout showing storage tanks and unde

Design of Filter and Storage tanks

rground parking spaces. All the elements shown here are below ground level


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Rainwater StorageThe usual method of storing rainwater in PVC tanks is very costly even if the life of the tank is in

several decades. The matrix method of rainwater storage includes the creation of an underwater

aquifer filled with small cubes with 95% empty space. Stacking these cubes on top of each other and

on the sides inside a layer of water proof shell creates sturdy aquifers. The cost is, however, high at$16 000 for a 20 000 l tank. Our water storage capacity should be 300 000 l and this would cost a

fortune

We also noticed that a large amount of parking space in the basement remains unused. Our system

utilizes some of this unused space.

Our design tries to minimize the cost required to make such aquifers in two ways:

Basement storage tankBasement storage tank would be made by creating a concrete tank inside the basementitself. The tank would be from ceiling to floor and all sides would be made of reinforced

concrete. A PVC liner on the inside of the tank would prevent any water from seeping

through the foundation. This tank would be fed directly by the filtering mechanism.

The feasibility of the idea is high as no excavation would have to be done, the building

material would be easily available at the time of construction, and the life of the tank would

be nearly equal to the life of the building.

Underground storage tanksUnderground storage tanks are useful in reclaiming the wasted space between the buildings

maintaining the soil cover and landscape at the same time.

Our design utilizes PVC columns to support a 6 inch reinforced concrete ceiling which in turn

supports 1 foot of soil layer above it.

The design can easily be replaced by concrete columns and a thicker ceiling as required.

However, PVC would support a thinner ceiling better than cement columns. Use of PVC

liners would reduce the chances of water leakage. PVC is waterproof; hence extra

waterproofing of pillars would not be necessary.

Lets assume 5 pillars to support 1 sqm of ceiling. Total load on the top ceiling would be of 1

foot of soil, people and occasional light vehicles (motorcycles/cycles). The pillars would have

to be strong enough to support 2.5 m3

of water + 0.2 m3

of concrete + 0.5 m3

of soil and an

assumed load of 1200 N at any time.

Total loading of the tank per m2= (2500+520+1300)*9.8N +1500N= approx 45 000 N

Compressive strength of PVC = 65 000 000 N/ m2

Assuming a 20% loading, area of PVC required = 6.9 * 10-4 m2 = 1.5 cm radius pillar

Amount of PVC required per 2.5 m3 storage capacity = 2.53 kg

Total amount of PVC required = 310 kg (Rs 20 000 @Rs 65 per kg)


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Novelty and feasibilityIdea 1

Use of StableCrete in catchment area

The StableCrete compound is designed to enter the pores of concrete and seal the points of entry of

water. Our catchment area is made up of smooth, light colored concrete and coated with

StableCrete. This creates an impervious surface that allows dust and other contaminants to be

washed off easily with the wash water.

It is a better measure than PVC sheets, rubber layers, and asphalt in many ways. Firstly, it does not

peel off, has longer life, is more durable and cost effective than other methods.

Cost of installation is around Rs 200 000 on a 10760 sq ft roof spread over 15 years and no

maintenance cost

Idea 2

Use of First Flush diverted water for washing cars and similar activities. The water is not fit for

consumption but can always be used for other jobs before sending it down the drain. This idea is

very feasible as a single pipe is enough to provide for the job required.

Idea 3

Use of ancient charcoal based filtration device. The filtration device is designed to be completely

passive and enclosed. Maintenance would be required once every few years as the filtering area is

very large to get clogged soon.

The cost of filters arrive at Rs 150 000 for several years of trouble free operation

Idea 4

Use of Basement area for water storage. Our calculations show that a fraction of basement area can

easily be used for storing water for long term. Simple concrete tanks would be made at the time of

building design at not much extra cost. The cost of PVC liners would however fall at a maximum of Rs

100 000 for a life of several decades.

Idea 5

Use of underground space for water storage

Our technique also focuses on an underground artificial aquifer for water storage made out of

reinforced concrete and PVC columns. They can be placed underground in the spaces between

buildings. This design can support a layer of soil over the tank and thus store water at no loss of

landscape.

This design is much less pricier than Matrix storage systems and is very cost effective. It can be built

at under Rs 100 000 excluding the cost of concrete as concrete Is easily available during constructionand prices vary.


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Cost AnalysisThe cost of installing this harvesting system is as follows:

Extra cost for roof preparation = Rs 170 000 over 15 years

Extra cost for piping = 0

Cost for wash water diverters = 100 000 over 10 years of life

Cost of filtering = 150 000 over 5 years of life

Cost of PVC used in tanks = 50 000 over 20 years

Cost of making tanks and reinforced concrete = 200 000 over 40 years.

Total cost of system = nearly Rs 700 000 (based on conservative accounts)

ConclusionWe have presented a system that can store over six months supply of freshwater in a very cost

effective manner. The system is simple, cheap, robust, and long lasting.

The total cost of the system comes under Rs 700 000 spread over a period of several decades. This is

cheaper than municipal water supply. The operational and maintenance costs are negligible in our

design. Assuming Rs 10 000 spent on maintenance per year, we have a water source at less than 1.5

paisa per liter operational cost.

This design provides significant reduction in cost of collecting and storing huge quantities of

rainwater in a very cost effective manner.


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Section 3: Blackwater Reclamation

IntroductionBlack water can be defined as wastewater derived from toilets. This kind of water is rich in organic

content, nitrogen and has a near perfect composition for survival of microbes. It contains certain

pathogens, pharmaceutical wastes and other substances that make it unfit for use before proper

treatment.

Our design focuses on the blackwater system as a natural extension of the nutrient cycle. The human

wastes generated are usually derived from farms. It is only right that the effluents produced return

to the source. However, it is essential to understand that the effluent produced is harmful if it comes

directly in contact with human food, etc. A number of human pathogens can easily transmit if these

effluents are directly applied to plants.

The good news is, however, that the return of fecal matter to farms is an age old agriculturalpractice and most of the human bacteria cannot survive in the harsh, aerobic environment outside

their human host. However, our system is designed to eliminate the risk that still remains.

The blackwater is a dilute solution of human feces, urine and other substances flushed down the

toilets. The most harmful components are pathogens such as E coli that normally reside in our

digestive tracts. Several other communicable diseases can also spread if untreated human waste

reaches water bodies or farms.


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Needs being addressedOur system addresses the following concerns:

Return of nutrients to the source to complete the nutrient cycle by returning the wastesback into the farms.

Generation of Biogas to extract residual energy from our wastes. Removal of pathogens before returning the fecal matter to the farms Reclamation of a portion of blackwater to achieve a greater pulp density for biogas plants as

well as reduction in the amount of freshwater used.

Use of Urine diverting toilets to divert urine from biological processes and later addition toeffluent to achieve a perfect manure composition.

Current TechnologiesCurrently available technologies are:

1. Direct excretion in farms to return nutrients back to the source. It occurs predominantly inrural areas.

2. Use of composting toilets, pits dug in the ground and filled after several months of usage toallow composting.

3. UASB, MBR etc are very costly and unnatural treatment technologies4. Use of biogas plants to generate biogas and reuse of effluent in farms5. Use of septic tanks to leach nutrients in effluent water which is then sent to farms, municipal

treatment, stagnation ponds, groundwater filtration etc to remove transfer nutrients to

biomass.


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Proposed SolutionThe proposed solution tries to minimize the risk of pathogen transfer inherent in the process of

using human fecal matter as manure.

The first step is to install urine diverting toilets and waterless urinals to separate the urine from fecalmatter. The high nitrogen content of urine slows down the decomposition of nutrients inside the

biogas plant. The bacteria residing in biogas plants are affected by urine as nitrogen is not crucial for

anaerobic breakdown of nutrients.

The next step is to reclaim a certain portion of blackwater through microfiltration/activated charcoal

filtration to divert it to greywater circuit. A two stage filtration with pore sizes 1 mm and 1 m to

remove particulates and bacteria respectively would be installed. This will reduce the volume of

blackwater to be sent to biogas and improve its performance. For every 100 liter of blackwater

generated, 40 l would be sent to biogas plant and remaining 60 l to greywater cycle.

This is followed by a traditional bio digester tank containing thermophilic bacteria. These bacteria

operate at 50-70C and remove a lot of pathogens found in human waste. However, these bacteria

are sensitive to minor fluctuations in chemical changes and care must be put to use non bactericidal

cleaning liquids in latrines. The residence time for slurry in this system is approx 15-20 days.

Assuming a daily 15 l black water generated and 40% volume reduction, we have 1800 l slurry per

day. Required tank volume would be 36 000 l. Adding slurry from greywater treatment containing

kitchen waste would further increase the output. This biogas generated can be used to power

electric generators by modifying them to accept gaseous fuel. This method is currently used at a few

locations.

Biogas produced per person per day 0.02 m3 (Total 4 m3 per day) (24 KWh per day) (Rs 80 saved per

day @Rs 3.5 per KWh)

The slurry produced would be removed weekly and sent to farms to be used as organic manure.

After taking out the slurry from the bio digester, lime can be added to stabilize the manure and

make its application easier. It also kills remaining pathogens. The manure thus formed is odorless

and hence can be easily used anywhere. The collected urine can be added after this step so as to

balance the nutrients. The slurry thus prepared can be used for hydroponics after clarification, in

drip irrigation, composting and can be directly applied to plants before fruiting season. This fertilizer

is a slow release one and improves soil quality.

The only requirement would be a dumping truck to pump the slurry out and take it to the fields. The

transport cost can easily be recovered in terms of soil quality, manure composition etc. A lot of

entrepreneurs actually use these manures to fertilize their soils. This slurry must still be treated as

potentially hazardous and handled carefully.


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Novelty and FeasibilityIdea 1

Diverting urine at the source by using urine diverting toilets and waterless urinals

The proposed system uses thermophilic bacteria which struggle to survive under high nitrogen load.

We can bypass this potential downside by using waterless urinals and urine diverting latrines. The

urine can later be used as manure.

The cost of this system would not be too great compared to benefits as the system would consume

less water. It is also easier and cost effective to install in the long run.

Idea 2

Use of filter to divert a portion of blackwater to greywater circuit

The proposed system would use a microfiltration/ charcoal/ sand based filter to allow nutrients to

flow to greywater circuit without the bacteria crossing over. This would increase the nutrient load of

greywater system and result in better performance. This would also replenish any water lost in the

system due to evaporation/ spilling etc.

The filters need to be sturdy and can be had for less than 5 dollars for cleaning 2000 l water

(compared to TATA Swach) or Rs 75 000 for activated charcoal per annum. Slow sand filters can

achieve similar results for a fraction of the cost and require less maintenance. Cost = Rs 20 000 per

annum.

The key is to pass fresh blackwater through the filtration circuit. This would not give the bacteriamuch time to propagate and contaminate the system to an extent where cleaning becomes

impossible.

Idea 3

Use of thermophilic bacteria to degrade the waste

The bacteria in human bodies are acclimated to 37C. Hence to neutralize them, we can use

thermophilic bacteria which can survive in temperatures over 50C, the point where human bacteria

die off.

The thermophilic bacteria also have lesser retention periods and can digest the material in 50-20

days instead of 60-100 days with traditional biogas plants.

The tanks are very cost effective as the biogas produces a value of about Rs 80 per day, enough to

recover the construction costs in a few years. Add to it the price of manure, and it will become the

only process that actually creates value instead of gobbling money and electricity. The biogas is used

to run retrofitted gensets to provide electricity to households or street lighting.


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Idea 4

Preparation of good manure

The effluent of biogas plant can be used as a highly fertile compost material to improve soil

properties, as a liquid manure, in hydroponics and drip irrigation and numerous other ways.

To improve the properties of this manure, lime can be added. It stabilizes the soil and kills harmful

microbes. Further improvement can be done by adding freshly diverted urine. This process would

create unparalleled manure with all the desired properties in a good fertilizer.

The feasibility of the idea lies in the fact that it generates value as opposed to other systems using

energy and money to operate. The catch of this method is the fact that farmers do not like

humanure and the difficulty in transport the liquid fertilizer. That said, humanure is odor free and

stable. It must, however be handled carefully and treated as blackwater. It must not be applied

directly to edible plant parts. Slurry transport services can easily take it to farms in sealed canisters.

It can also be commercially marketed in pouches after pasteurization.

Idea 5

Use of biogas plant instead of other techniques

The biogas plant can actually generate value if marketed properly. This process is a lot better than

other energy and cost intensive methods of blackwater treatment. Concerns about water wastage

can be addressed by the fact that some amount of water must leave the system to avoid

accumulation of harmful substances in the system.

This system can generate a value of Rs 80 per day. Assuming a 40% efficiency, each day can save 10

KWh per day, around Rs 12 000 savings per year. This can easily pay for installation costs in 10 years.


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Cost AnalysisThe installation costs can be addressed as follows:

Extra cost involved in urine diverting latrines = Rs 500 000 (Rs 2500 per apartment) over 2 decades

Cost of filters Rs 50 000 per annum (Filtration may be omitted altogether)

Cost of biogas tank = Rs 150 000 (add govt subsidy) for a 3600 l tank

Cost of manure preparation and delivery = 0 paid for by the farm

Total cost of installation = Rs 700 000 (Rs 3 500 per person)

Value recovery every year = Rs 12 000 (enough to pay for maintenance)

ConclusionThe proposed method aims to change the way we view the blackwater around us. The blackwater is

loaded with nutrients. We can easily transfer it to Mother Nature from where it was originally

borrowed. No other method seems as natural to us as the proposed one due to the ease of

installation, maintenance, operation, compactness and value generated.

This system can be installed underground and the gas holding tank can be designed to give a modern

look to the landscape.


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Section 4: Smart Metering and Billing

IntroductionWater metering is a common feature of all modern buildings. Installation of water meters allow

water supply companies to bill their customers based on the amount they consume, thus providingan incentive for conserving water. It comes handy during rationing of water and can be used to

detect leakage in supply lines. It is rightly said in this context, if you cant measure it, you cant

manage it. For effective management of the scarce water resources, we will need better measuring

and management technologies

Water meters are based on various principles such as turbine, paddle, venturi, orifice, ultrasound,

Magnetism, etc. The different techniques adopted can vary according to the accuracy desired.

Water billing systems currently involve a meter reader to go to each meter and read it. Then he

sends the data to the utility company which then bills the customers as desired.

Needs Being AddressedOur design addresses the issues concerning water metering and billing.

A centralized design would eliminate the need of meter reader to go to each household to measure.

The system would be designed to send near real time data directly to the servers from where

centralised billing and other services would be provided. The primary issues that affect the cost of

water metering are installation costs and recurrent costs to read the meters.

It is also noticed that the knowledge of the consumption patterns leads to a more responsible

approach to usage. In some cases, the total consumption of water decreased by up to 20 % as a

result of putting the live water usage data at prominent places. Our system enables the consumers

to get detailed report on usage pattern of water which is fed to a monitor right in their apartments.

Another approach is the concept of submetering, where the building management puts up small,

low cost meters at every apartment to measure the water consumption by each of the homeowners.

This reduces the load on the utility company and is better for the management as most of the water

supplied to the households is not from municipality.

Use of smart meters is a recent trend in households. It utilizes microcontrollers to gather data from

different sources such as gas meters, water meters, electricity meters, HVAC meters and sending it

to the utility companies. It is the evolution of automatic metering system.


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Existing SolutionsThe current practices in place are

No metering. Instead a flat charge is levied on the consumers by the companies Analog meters fitted to measure the supply to each apartment, coupled with monthlyreadings by paid meter readers. Use of Automatic metering systems to send daily, weekly, monthly usage data automatically

over long distances by wireless or wired communication

Use of smart meters to monitor usage patterns several times a day to better manage usage.Some even provide real time usage data.

Proposed SystemThe proposed system contains digital water meters to measure the flow rates to the apartments.These meters are capable of transmitting near real time data to microcontroller which shows the

information on a display placed in a

prominent location in the apartment.

Microcontrollers can be used to collate the

data provided by the water meter and a

display attached to it can be used to

provide accurate visual representation of

usage patterns as shown here. This

information has the potential to make theuser realise his/her usage pattern and

result in a more conscious use of

resources.

These microcontrollers can be attached to other meters too and they can provide real time data

about all the aspects of the house. Electricity meters, gas meters, alarm systems, Cable TV, HVAC

systems can all be integrated with the smart meter. All the meters can be located in the apartment

or anywhere else but it must be connected to the network.

The data from the smart meter installed in each household can be transferred to the owners forproper billing. The smart meters situated in different apartments would use a star topology to

connect to the central servers.

Facilities that can be integrated with Smart Meters

Water meters. Digital water meters can be purchased for Rs 5000. These come withbatteries and can function independent of the system for years before their batteries need

recharge. They can also transfer data to microcontroller in real time.

Electricity meter are already digital, a simple modification can enable them to send dataover to microcontroller


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Alarm systems can be connected to this system. The microcontroller would determine anybreach and can act accordingly by notifying the authorities over the network. The alarm

systems currently in use are similar in function with the exception of being independent of

other meters

HVAC systems can be attached to the microcontroller. It would receive temperature datafrom different parts of the house and actively control the flow of air in different parts of the

apartment by a set of valves and distribution system. This can result in more precise climate

control of the house and aid in making more precise billing. Pitot tubes would measure cold

air being used in real time. Smart meters would replace existing systems and thus carry no

extra cost. The ability to program the microcontroller would allow precise climate control of

the apartment

Cable TV and broadband connections can also be incorporated with the microcontroller. Smart display attached to the microcontroller would provide detailed graphical usage data

to the homeowners.

Central billing server can connect to different smart meters in a LAN in star topology andprovide billing data. It would remove the need of meter readers. When coupled with the

internet, it would provide a cost effective metering and billing solution. The cost effective

Ethernet would be more than enough to support all the meters as well as provide high speed

broadband to the consumers.

The design of microcontrollers can be derived from testing on Arduino boards. These boards can be

programmed to gather data from meter and communicate it over RJ45 socket on Ethernet.

Alternately, it can display the data on an LCD screen. After testing, the desired microcontroller can

be mass produced in desired form factor. These require about 1 watt and can be powered by

electricity, rechargeable batteries or over the network itself using Power over Ethernet technology.


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Novelty feasibility and cost analysisIdea 1

Use of digital meters

Use of digital meters reduces the dependence on meter readers to go and read the meters. Digital

data can easily be transferred over long distances by using wireless or wired methods.

Digital meters are a bit costly due to expensive sensors and battery and LCD display but bulk

purchase would put the prices somewhere between 1 to 3 times that of analog meters. Hence

projected cost for low capacity meters is Rs 5000 per piece, 3000 more than analog meters.

The feasibility lies in the fact that the cost of manual reading every month is not present anymore.

Besides, digital meters are considered more precise than their analog counterparts. This would lead

to more accurate billing.

Idea 2

Use of Microcontrollers

Microcontrollers bestow the power of smartness in the network. They can receive input from single

or multiple sources, analyse it and convert into any format desired, audio, display, digital signal,

Ethernet etc. The cheapest of these can be had for Rs 500 apiece. Arduino is an example of

reprogrammable microcontroller circuit for about Rs 1500. Permanent microcontrollers can cost

much less.

In case different meters are located far away from the display, each meter can get an IP address of

its own and transfer its data over the network. The display, also connected to the network, can

identify the meters installed for a single owner and display its data. Data is protected by AES 128 bit

encryption.

Idea 3

Aggregation of multiple meters in one reduces individual measurement by a very large amount, The

system automatically syncs its data with servers located in the management and eliminates the need

to do separate measurement of HVAC, electricity, Water, gas, etc. The microcontroller can also

process the costs involved and return estimated costs incurred for the utility availed.

Idea 4

The method of installing the digital display at prominent place inside an apartment would result in

the generation of resource consciousness in consumers. This information has the potential to make

the user realise his/her usage pattern and result in a more efficient and cost effective use of

resources.


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ConclusionThe cost of employing this system would be largely offset by reduction in manual reading of these

meters. Plus integration of many services in one would lead to an insignificant increase in total cost

of the system. Microcontrollers can be purchased at throwaway prices. Companies such as Iltron

manufacture smart meters. Slight modifications in the basic design can allow data from multiplemeters to be displayed on an integrated display.

The system uses modern smart meters to measure the usage of various utilities. This provides the

user with a better control over his usage and detailed info provided would enable him to make

better decisions.


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Section 5: Deploying supporting infrastructureThe systems mentioned in this report do not stand in void. They need supporting infrastructure and

proper care to serve their true purpose. The residents would need to understand the intricate

relationship between humans and nature. The consciousness about the resources nature provides is

very crucial. We must understand that each resource that we are currently using belongs to thefuture generations. If we take more than our fair share or waste these resources, we would be

stealing from our own kids and putting them in a far more unsecure future.

The following measures could help increase the effectiveness of the systems mentioned in the long

run. It is not an exhaustive list and amends must be made as and when required.

We have assumed an average national consumption of 120 l per capita daily water consumption. In

the urban rich, it can easily go up to 500-600 l per person per day.

Low flow faucet aerators: These aerators fit over the regular faucets and reduce the flowrate of water passing through it. To compensate for loss in volume, it adds air bubbles formsurrounding air to the flow. This results in a thick stream but uses less than half of water

usually required.

Low flow Showerheads: These showerheads can reduce the flow rate of water by more thanhalf. It compensates for it by evenly distributed droplets and a higher flow pressure, creating

an illusion of regular shower.

Pre rinse kitchen faucets with spray heads are much more efficient in washing utensils. Theyare flexible and can be switched on only while washing, not while scrubbing. This is provided

in addition to regular taps. It can reduce water used to wash utensils by a large amount

Use of 4 or 5 star rated washing machines and dishwashers. The higher the rating, the betterwater utilization. Also, these must be used only with full loads as half loads are a waste of

resources.

Use of electronic kitchen sink grinder would break down food and other organic waste andprevent system from being clogged. No separate organic waste disposal system would be

required as all necessary microbes are in the greywater reclamation system itself.

Use of Organic or biodegradable soaps, detergents, cosmetics, cleaning liquids etc. Thiswould prevent chemical shock in the anaerobic tanks and result in better performance.

All these features can pay for themselves in a period of time in form of water savings.

The proposals made in this report are efficient enough to provide good

quality water at costs lower than municipal rates, if only operating costs

are considered. The installation costs arrive at nearly Rs 10 000 per person.

We can hereby conclude our report by stating that it is possible to manage

water resources more efficiently only if the public is concerned about it.

Any system would fail if its users overlook its fragility and its importance.


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References:

Characteristics of grey wastewater by Eva Eriksson, Karina Auffarth, Mogens Henze, Anna

Ledin

http://www.gruptefsa.com/

http://sswm.info/

http://www.cseindia.org/

http://www.ovivowater.com

Grey water characterisation and its impact on the selection and operation of technologies

for urban reuse by B. Jefferson, A. Palmer, P. Jeffrey, R. Stuetz and S. Judd

http://ezinearticles.com/?Grey-Water-Additive&id=850659

http://www.biosystemssa.co.za

http://www.college.ucla.edu/webproject/micro7/studentprojects7/rader/asludge2.htm

http://www.outotec.com/

http://www.thewatertreatments.com/waste-water-treatment-filtration-purify-sepration-

sewage/flocculation-basin-waste-water-treatment

And many many more

Documents

Final EcoDes Project