Archive for December, 2009

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Constructed wetlands

December 19, 2009

Ecological way to manage wastewater

While natural wetlands should never receive wastewater from urban runoff, constructed wetlands can pick the city’s storm water runoff and waste water and biologically treat it to acceptable standards


EYE-CAPTURING: Constructed wetlands to treat wastewater.

Wetlands are areas like swamps and marshes typically subject to soil saturation and flooding during parts or whole of the year.

They have a unique variety of flora and fauna which can withstand the occasional full submergence as well as full dry conditions and are often referred to as the nurseries of life.

Wetlands have long been recognised as potential zones capable of handling various pollutants and being capable of absorbing or transforming them.

Many of the ‘tank’ ecosystem of south India are wetlands in the sense that they can be submerged during parts of the year and be dry during other times.

With tanks in urban areas losing their original purpose of providing agricultural water, their conversion to constructed wetlands has the potential to treat urban wastewater in a decentralised fashion, absorb and mitigate the impact of urban floods as well as provide a bio-diversity spot for flora and fauna.

Constructed wetlands

Constructed wetlands are artificially built wetlands designed to mimic the natural wetlands. Wetlands are different from pools or lakes primarily with more vegetation coverage and less water at shallow depths.

It is possible to design and classify the constructed wetlands as fully submerged wetland where the water is in contact with air and a subsurface horizontal flow constructed wetland where the water flows in a stone or brick bat medium and is not in contact with the air.

Constructed wetlands are typically shallow structures which are kept to depths of 1 meter or less. The bottom of the wetland is usually lined to prevent water from percolating down into the aquifer.

Constructed wetlands have shown tremendous potential of assisting in the biological digestion of human wastewater flows. The plant species can be of the variety that float on the surface, are completely submerged or are rooted at the bottom of the wetland.

Each plant species has a different role to play in the wetland by itself and also as host to other organisms such as bacteria.

In the home: A small constructed wetland can come up at the household level itself. Many sites and homes in the city’s periphery come up in places where there is no underground drainage facility. Here a modified septic tank called a baffled reactor can be built.

The wastewater from the home both from the kitchen and the bathroom is allowed to predigest in the baffled reactor and then allowed to flow into a constructed wetland.

This further treats the waste water as also allows a uniquely bio-diverse area spring up close to the home.

Bringing in a landscape feature

The Rajans have a house far away from the city and many homes in the layout had to take recourse to a septic tank and a leaching system for taking care of their waste water.

The Rajans chose to go for a baffle reactor and a constructed wetland instead and have therefore not only been able to treat wastewater well but also obtain a beautiful landscape feature on their plot

In layouts and apartments: Constructed wetlands can be designed to handle large volumes of wastewater and storm water emerging from these developments. Again a certain form of pre-treatment or pre-digestion of waste water is needed before the constructed wetlands take over and treat the water further.

By integrating it with parks and open spaces, walkways can be created with a palate of plants to enhance the visual appeal of the landscape while providing the functionality of treating wastewater.

At the city level: Constructed wetlands have treated wastewater flowing in canals in the city of Fuzhou,China.

Formerly a stinking 80 km network of flowing wastewater is now a lush green walkway around the city with no smell an with a clarity level in the canals which is much higher. The system was designed by John Todd and Ocean Arks international.

While natural wetlands should never receive wastewater from urban runoff, constructed wetlands can pick the city’s storm water runoff and waste water and biologically treat it to acceptable standards reducing turbidity levels, reducing bacteria , removing nutrients and increasing oxygen level of water while enhancing bio diversity.

Water wisdom calls for using nature and its bio-diversity as an ally in maintaining and enhancing the quality of life in our cities and homes.

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Water Bills- What they tell you.

December 17, 2009

WATERWISE

Water-bills- What they tell you

S.Vishwanath

www.rainwaterclub.org

zenrainman@gmail.com

080-23644690

A bill for water may seem a dull and uninteresting document. It can however be made quite interesting and informative.. In Bengaluru if you are connected to the Bangalore Water Supply and Sewerage Board mainline, you should receive a water bill every month.

Apart from the Subdivision name, Bill number, consumer i.d and type, one important item is the Last date of payment.  A small note is appended at the bottom of the bill which indicates that ‘If payment is not made before the due date steps for disconnection of supply will be initiated’. It is understood that not a single disconnection for domestic connections has been carried out so far. The penalty for late payment is also not indicated on the bill. A sign however urges you to pay on time and help BWSSB serve you better. The 24/7 kiosks of BWSSB for collection is however a global best practice which does not find mention in the bill.

Then comes the information on consumption. A ‘present reading’ in litres and a ‘previous reading’ in litres and the difference between the two indicates the consumption.  Sydney waters, when it gives a bill, compares it to the average consumption across the city and lets the household know whether they are above or below average. It also lets the household know how it is doing vis-à-vis standards by flagging a red or a green signal.

Next set of items is on Water charges. This has to be read with the back page of the bill which indicates the Increasing Block Tariff. The first slab of 0-8000 litres is charged at Rs 6 a kilo-litre and the next slab 8-25,000 litres  at Rs 9 per kilo-litre. That means if you have consumed 25,000 litres you pay 8 x 6 + 17 x 9 = Rs 201/- . The bill does not indicate the production cost of water which the BWSSB claims is around Rs 18 /- a kilo-litre. This would mean that the actual production cost of the 25,000 litres by the family would be Rs. 450/- and since the family pays Rs 201/- it receives a subsidy of Rs 249/- in that month. The vital information is important to let the consumer know actual costs and then to push for full cost recovery.

The next item is meter charges. Since the meter is paid for by the consumer during installation it is not clear what this meter charge is. Most probably it is the meter reading charge and if so must be clearly indicated.  Sanitary charges follow and read with the back page, it indicates a flat Rs 15/- for a domestic consumption up-to 25,000 litres . The actual cost of collection and treatment is not indicated. Once this is done it would be clear as to how much a family is subsidised for sewage collection and treatment. One estimate for collection puts it at Rs 600/- or Rs 24/- a kilo-litre. This means that the household gets a subsidy of Rs 585/- every month.

The interesting item is S.C for bore-well. This a Sanitary Charge for the water consumed from the bore-well and let into the sewage lines, which then the BWSSB has to treat. This is unique to any city in India. The back page of the bill indicates a flat rate of Rs 50/- per month per individual house and  for apartments also. If the BWSSB moves towards metering bore-wells it could then rationally charge on a volumetric basis incentivising less abstraction from groundwater.

Lessons: Institutions such as BWSSB and individual consumers could learn a lot from devising a communicative bill. Since a bill reaches the consumer every month it is a great communication tool for the BWSSB. Water wisdom demands that a water bill can be made interesting and a knowledge creator rather than a drab financial document.  Can we move towards water wisdom then?

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A turnaround in groundwater in a smart industrial area

December 12, 2009

WATER WISE

Managing water in an industrial unit

S. VISHWANATH

Thanks to a 10-year master plan, a water-scarce area sees a change of fortune


Proven method: Drip irrigation systems deliver water directly to the root zone of plants and reduce consumption

Located in a semi-arid area, the industrial unit spread over 343 acres depended solely on groundwater for its requirements. Borewells to a depth of 450 feet supplied the five lakh litres of water needed daily. In the year 2000, a disastrous year of rainfall, all the groundwater sources dried up and water had to be rationed. The plant had to shut operations and it became difficult to even supply water to the factory workers and their families resident in the colony.

The industrial unit resolved to consult experts from the ground water and forestry departments and came up with a comprehensive 10-year water management master plan involving watershed planning, rainwater harvesting, groundwater recharge and large-scale tree plantation.

Work began in right earnest that year itself with constant monitoring. More than 1,10,000 saplings of native trees which required little water were planted on campus. Percolation tank areas were identified and dug, recharge pits made and channels dug to link catchments to dried open wells.

A demand management strategy reduced water consumption to its optimum. Drip irrigation system was introduced to deliver water directly to the root zone of trees and reduce consumption.

Gradual change

A gradual change came over the area. Due to the recharge efforts the groundwater table rose by 250 feet and groundwater is now available in open wells also. Though the daily demand has gone up to eight lakh litres, a combination of reducing demand, recycling and reusing waste water and recharging groundwater has ensured that sustainable water is available right through the year.

Due to the rise in groundwater table, pumping costs have decreased and water is available at around Rs. 7 per kilo-litre. Energy costs and carbon emissions too have declined since the head to which water has to be pumped has reduced. The trees are fully grown, reducing ambient temperature by 2 degrees Celsius. Birds are flying in and biodiversity has increased and the industrial unit has become a bird-watchers’ paradise. Fruits from the mango, coconut, chikku, pomegranate and gooseberry trees fetch nearly Rs. 2 lakh a year. The entire ecosystem has been transformed and regenerated.

What began as a work to tackle water shortage has resulted in bio-diversity enhancement, a carbon footprint neutral plant, and an energy-efficient and water-efficient plant.

Award

The Mahindra and Mahindra unit at Zaheerabad won the excellent water management unit award and the innovative projects award for this remarkable work at the recent National Award for Excellence in Water Management 2009 organised by the CII at the CII-Sohrabji Godrej Green Building Centre in Hyderabad.

Industries like M & M Zaheerabad show that a dedicated team effort to overcome water adversity, combined with leadership, scientific planning, implementation and monitoring can transform a water-scarce region to a water-positive region. Since industrial demand for water is fast rising in India, solutions which show ‘water positivity’ are the need of the hour. That is water wisdom.

www.rainwaterclub.org

zenrainman@gmail.com

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Water management in apartments – a checklist

December 6, 2009

Ensuring water supply in apartments

A checklist of the factors apartment owners have to take note of

Apartments are the new reality of urban living. One of the key challenges is to meet the water supply demand to keep all the amenities working.

Here is a small checklist that apartment owners, associations and builders need to keep in mind so that the taps in the flats do not run dry

* Since multiple sourcing will be the order of the day, make sure that the sustainability of sources is kept in mind when connecting systems.

In simple terms, will water continue to come from the main pipelines? Will the borewells continue to give good quality of water for the next 20 years?

Is the apartment designed well for water tankers to come in and empty their loads systematically without disturbing the residents or the neighbourhood?

* Is there individual metering for each flat? Nobody likes to pay for the consumption of others. Individual metering to each flat rewards water conservation and punishes excess use. This should become the rule rather than the exception.

* Are the landscapes designed to be water efficient? The beautiful lawns and the exotic flowers are a delight to watch but can be huge water guzzlers. Is the landscape designed for water efficiency and less water consumption? Is treated wastewater of the right quality available for the landscape at all times?

* Is there a good leak detection system in the distribution network? Leaks can be surprisingly large and if undetected can cause huge water losses. Is there a system of metering and measuring at wholesale and retail levels to ensure that leaks are detected and fixed at regular intervals?

Facility manager

* Is there a good facility manager who is trained in water and wastewater management systems? Unless the right skills are available it will be impossible to manage the swimming pool, the landscape, the fire-fighting systems, the wastewater treatment and reuse systems et al. In short, without a well trained set-up, the system will collapse over time.

* Is there a good wastewater treatment and reuse system which is easy to operate, easy to repair and which reuses the bulk of wastewater for non-potable purposes such as toilet flushing and landscape demands?

* Is the rainwater and stormwater harvesting system designed well and in compliance with the law? Do they turn around the entire apartment block to a ‘zero runoff’ area and harvest every drop of rain?

* Are the borewells metered and monitored for quality and quantity? Is there a maintenance system for the borewells? Is a detailed hydro-geological data and the borewell log sheet available with the water facility manager?

* Is the water treatment system designed for BIS 10500, the drinking water standard for India?

Right devices

* Are all the devices in the bathroom, kitchen and other areas the most water-efficient in the business? Are all taps, showers, flushes, WCs of high quality and water efficient?

* Is the entire water and energy system well understood by the maintenance people? Are all pumps optimised for energy use and water delivery?

* Does the community meet often to discuss the water report card and become water and environment literate? Only by building the right communities and transferring the right knowledge through practice to the younger generation will we build a resilient and just society.

http://www.rainwaterclub.org

www.arghyam.org

e-mail:rainwaterclub@gmail.com

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Groundwater in Bangalore

December 6, 2009

WATER WISE

Understanding groundwater

S. VISHWANATH

There is no comprehensive legal or institutional framework for managing groundwater and prevent the digging of borewells in the city


Out of control: Borewells are being sunk without any restrictions

Borewells are everywhere in India and have become the lifeline for water. In Bangalore alone, the Bangalore Water Supply and Sewerage Board records the presence of about 100,000 borewells. Other estimates suggest that the city may have 400,000 borewells pumping out water to the tune of 100 million litres to 400 million litres per day. In any case new borewells are being dug by the hundreds every year all over the country.

New technologies for drilling are constantly emerging and borewells can now be dug to depths of 1,500 feet. The diameter of the drill also ranges from four-and-a-half inches 10 inches. Hydraulic drilling rigs make it possible to drill very fast and a drilling job can be completed in 10 to 12 hours’ time. Installing a pump usually requires two to four hours.

Typically a yield test should be done to optimise the selection of the appropriate pump and a water and energy-efficient pump which is maintenance free should be selected.

There is no comprehensive legal or institutional framework for managing groundwater in our city. Since the BWSSB manages piped water for the city and levies a Rs. 50 monthly sanitary cess on borewells, it is best placed to become the regulatory authority for groundwater. It can begin by insisting that all borewells in the city should be registered with it, not only those where it has given a water or sanitary connection. It can then begin a process of metering groundwater and charging on a volumetric basis rather than a flat rate. This will enable a better understanding of the volume of water being drawn from the aquifers.

No stipulation

There is no law currently which prevents the digging of borewells anywhere in the city. There is also currently no stipulation of any minimum distance between borewells. There is no law against the noise pollution created by borewells and their drilling at any time of night or day. The understanding of structural or other damage to adjacent buildings is limited. We need to insure from these risks in a comprehensive manner.

Maintaining a log of the successful and unsuccessful borewells, metering and measuring drawal on a monthly basis, keeping a log of the energy consumed per kilo-litre of water drawn, drawing up a maintenance schedule for the pumps, keeping regular track of water quality and ensuring recharge commensurate with drawal is the best way to go for apartments and layouts. A social ban on individual borewells, metered supply of water through common borewells, a tariff collection regime to ensure rainwater harvesting and recharge throughout the campus to ensure zero runoff of storm water is part of the best practices recommended for borewells.

www.rainwaterclub.org

www.arghyam.org

E-mail: zenrainman@gmail.com

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