The costs of wastewater management are greatly overweighed by the benefits to human health, economic development and environmental sustainability – providing new business opportunities and creating more ‘green’ jobs, WRITES ER. MOHAMMAD ASHRAF FAZILI
ER.MOHAMMAD ASHRAF FAZILI
Nature has provided us water in abundance. Water covers 72% of our globe. The land, animals including man indicate water origin of their original habitat. Besides human body has 70 to 85% water. The most of the world’s water is in oceans. A small proportion is bound up in ice sheets and glaciers, while a tiny fraction 1/10,000th exists in rivers and lakes. More than 90% of world water goes to agriculture, less than 3% accounts for domestic use, with a little more consumed by industry. Nearly half the world’s crop production, in terms of value, comes from irrigated land. Without irrigation many nations would find it impossible to feed their population or develop their economics.
Kashmir a century back was considered to have the purest form of water in the form of springs, lakes and rivers but the pressure of urbanization has had its adverse effect on these water bodies besides closure of the vital Nalla Mar Canal and its branch canals.
Sustainable Development Goal (SDG) target 6.3 requires us by 2030 to “improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and sustainability increasing recycling and safe refuse globally.”
Progress towards target 6.3 will also help achieve the SDGs on health and well-being (SDG 3), safe water and sanitation (SDG 6), affordable and clean energy (SDG 7), sustainable cities and communities (SDG 11), life below water (SDG 14), and life on land (SDG 15) among others.
Top line Messages
Globally, over 80% of the wastewater generated by society flows back into the ecosystem without being treated or reused.
1.8 billion people use a source of drinking water contaminated with faeces, putting them at risk of contracting cholera, dysentery, typhoid and polio. Unsafe water, poor sanitation, and hygiene cause around 8,42,00 deaths each year.
663 million people still lack improved drinking water sources.
By 2050, close to 70% of the world’s population will live in cities, compared to 50% today. Currently, most cities in developing countries do not have infrastructure and resources to address wastewater management in an efficient and sustainable way.
The opportunities from exploiting wastewater as a resource are enormous. Safely managed wastewater is an affordable and sustainable source of water, energy, nutrients and other recoverable materials.
The costs of wastewater management are greatly overweighed by the benefits to human health, economic development and environmental sustainability – providing new business opportunities and creating more ‘green’ jobs.
Wastewater and the Water cycle
Water has to be carefully managed during every part of the water cycle: from fresh water abstraction, pre-treatment, distribution, use, collection and post-treatment, to the use of treated wastewater and its ultimate return to the environment, ready to be abstracted to start the cycle again.
Due to population growth, accelerated urbanization and economic development, the quality of wastewater generated and the verall pollution load are increasing globally. However, wastewater management is being seriously neglected, and wastewater is grossly undervalued as a potentially affordable and sustainable source of water, energy, nutrients and other recoverable materials. It therefore needs to be seen as a source, rather than a burden to be disposed of.
There are many treatment processes and operational systems that will allow us to use wastewater to meet the growing water demand in growing cities, support sustainable agriculture, and enhance energy production and industrial development.
Wastewater and Cities
By 2030. global demand for water is expected to grow by 50%. Most of this demand for water will be in cities and will require new approaches to wastewater collection and management. Indeed, reused wastewater may help address other challenges including food production and industrial development.
Mainly in low-income areas of cities and towns within developing countries, a large proportion of wastewater is discharged directly into the closest surface water drain or informal drainage channel, sometimes without or with very little treatment. In addition to household effluent and human waste, urban-based hospitals and industries such as small-scale mining and motor garages, often dump highly toxic chemicals and medical waste into the wastewater system. Even in cities where wastewater is collected and treated, the efficiency of treatment may vary according to the system used. Traditional wastewater treatment plants may not remove certain pollutants, such as endocrine disruptors, which can negatively affect people and the ecosystem.
Examples
Here in Srinagar the Dal lake waters are being pumped to the treatment plant at Nishat and the treated water is supplied to the city. Besides the treated effluents from the STPs at Lam, Hazratbal, Habak and Brari-numal are allowed to flow into the lake which may be a cause of concern to those who closely monitor their water quality. In addition, the problem of the direct disposal of faecal matter from house boats into the lake remains unattended till date. Similarly, almost the entire untreated sewage and drainage of the towns and the city finds its way into river Jhelum being the only drainage channel of the valley. At a few places its water is used for drinking purposes after treatment or even without treatment (like Malroo village at the tail end of the city.)
Water conservation
Water conservation includes all the policies, strategies, and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand. Population, household size, and growth and affluence all affect how much water is used. Factors such as climate change have increased pressures on natural water resources especially in manufacturing and agricultural irrigation. Many US cities have already implemented policies aimed at water conservation, with much success.
The goals of water conservation efforts include:
Ensuring availability of water for future generations where the withdrawal of freshwater from an ecosystem does not exceed its natural replacement rate.
Energy conservation as water pumping, delivery and wastewater treatment facilities consume a significant amount of energy. In some regions of the world over 15% of total electricity consumption is devoted to water management.
Habitat conservation where minimizing human water use helps to preserve freshwater habitats for local wildlife and migrating waterfowl, but also water quality.
Strategies
The key activities that benefit water conservation (save water) are as follows:
Any beneficial reduction in water loss, use and waste of resources.
Avoiding any damage to water quality.
Improving water management practices that reduce the use or enhance the beneficial use of water.
One strategy in water conservation is rainwater harvesting. Digging ponds, lakes, canals, expanding the water reservoir, and installing rainwater catching ducts and filtration systems on homes are different methods of harvesting rainwater. Many people in many countries keep clean containers so they can boil it and drink it, which is useful to supply water to the needy. Harvested and filtered rainwater can be used for toilets, home gardening, lawn irrigation, and small-scale agriculture.
Another strategy in water conservation is protecting groundwater resources. When precipitation occurs, some infiltrates the soil and goes underground. Water in this saturation zone is called groundwater. Contamination of groundwater causes the groundwater water supply to not be able to be used as a resource of fresh drinking water and the natural regeneration of contaminated groundwater can take years to replenish. Some examples of potential sources of groundwater contamination include storage tanks, septic systems, uncontrolled hazardous waste, landfills, atmospheric contaminants, chemicals, and road salts. Contamination of groundwater decreases the replenishment of available freshwater so taking preventative measures by protecting groundwater resources from contamination is an important aspect of water conservation.
An additional strategy to water conservation is practicing sustainable methods of utilizing groundwater resources. Groundwater flows due to gravity and eventually discharges into streams. Excess pumping of groundwater leads to a decrease in groundwater levels and if continued it can exhaust the resource. Ground and surface waters are connected, and overuse of groundwater can reduce and, in extreme examples, diminish the water supply of lakes, rivers, and streams. In coastal regions, over pumping groundwater can increase saltwater intrusion which results in the contamination of groundwater water supply. Sustainable use of groundwater is essential in water conservation.
A fundamental component to water conservation strategy is communication and education outreach of different water programs. Developing communication that educates science to land managers, policy makers, farmers, and the public is another important strategy utilized in water conservation. Communication of the science of how water systems work is an important aspect when creating a management plan to conserve that system and is often used for ensuring the right management plan to be put into action.
Social solutions
Drip irrigation system
Water conservation programs involved in social solutions are typically initiated at the local level, by either municipal water utilities or regional governments. Common strategies include public outreach campaigns, tiered water rates (charging progressively higher prices as water use increases), or restrictions on outdoor water use such as lawn watering and car washing. Cities in dry climates often require or encourage the installation of xeriscaping or natural landscaping in new homes to reduce outdoor water usage. Most urban outdoor water use in California is residential, illustrating a reason for outreach to households as well as businesses.
One fundamental conservation goal is universal metering. The prevalence of residential water metering varies significantly worldwide. Recent studies have estimated that water supplies are metered in less than 30% of UK households, and about 61% of urban Canadian homes (as of 2001). Although individual water meters have often been considered impractical in homes with private wells or in multifamily buildings, the U.S. Environmental Protection Agency estimates that metering alone can reduce consumption by 20 to 40 percent. In addition to raising consumer awareness of their water use, metering is also an important way to identify and localize water leakage. Water metering would benefit society, in the long run, it is proven that water metering increases the efficiency of the entire water system, as well as help unnecessary expenses for individuals for years to come. One would be unable to waste water unless they are willing to pay the extra charges, this way the water department would be able to monitor water usage by the public, domestic and manufacturing services.
Some researchers have suggested that water conservation efforts should be primarily directed at farmers, because crop irrigation accounts for 70% of the world’s freshwater use. The agricultural sector of most countries is important both economically and politically, and water subsidies are common. Conservation advocates have urged removal of all subsidies to force farmers to grow more water-efficient crops and adopt less wasteful irrigation techniques.
New technology poses a few new options for consumers, features such as full flush and half flush when using a toilet are trying to make a difference in water consumption and waste. Also available are modern shower heads that help reduce wasting water: old shower heads are said to use 5-10 gallons per minute, while new fixtures available use 2.5 gallons per minute and offer equal water coverage. Another method is to recycle the water of the shower directly, by means a semi-closed system which features a pump and filter. Such a setup (called a “water recycling shower”) has also been employed at the VIRTUE LINQ house. Besides recycling water, it also reuses the heat of the water (which would otherwise be lost).
Household applications
The Home Water Works website contains useful information on household water conservation. Contrary to the popular view that the most effective way to save water is to curtail water-using behaviour (e.g., by taking shorter showers), experts suggest the most efficient way is replacing toilets and retrofitting washers as demonstrated by two household end use logging studies in the U.S.
Water-saving technology for the home includes:
Low-flow shower heads sometimes called energy-efficient shower heads as they also use less energy.
Low-flush toilets and composting toilets. These have a dramatic impact in the developed world, as conventional Western toilets use large volumes of water.
Dual flush toilets created by Caroma includes two buttons or handles to flush different levels of water. Dual flush toilets use up to 67% less water than conventional toilets.
Faucet aerators, which break water flow into fine droplets to maintain “wetting effectiveness” while using less water. An additional benefit is that they reduce splashing while washing hands and dishes.
Raw water flushing where toilets use sea water or non-purified water.
Wastewater reuse or recycling systems, allowing:
Reuse of greywater for flushing toilets or watering gardens
Recycling of wastewater through purification at a water treatment plant.
Rainwater harvesting
High-efficiency clothes washers
Weather-based irrigation controllers
Garden hose nozzles that shut off the water when it is not being used, instead of letting a hose run.
Low flow taps in wash basins.
Swimming pool covers that reduce evaporation and can warm pool water to reduce water, energy and chemical costs.
Automatic faucet is a water conservation faucet that eliminates water waste at the faucet. It automates the use of faucets without the use of hands.
Commercial applications
Many water-saving devices (such as low-flush toilets) that are useful in homes can also be useful for business water saving. Other water-saving technology for businesses includes:
Waterless urinals
Waterless car washes
Infrared or foot-operated taps, which can save water by using short bursts of water for rinsing in a kitchen or bathroom.
Pressurized water brooms, which can be used instead of a hose to clean sidewalks.
X-ray film processor re-circulation systems
Cooling tower conductivity controllers
Water-saving steam sterilizers, for use in hospitals and health care facilities
Rainwater harvesting
Water to Water heat exchangers.
Agricultural applications
Overhead irrigation, centre pivot design
For crop irrigation, optimal water efficiency means minimizing losses due to evaporation, runoff or subsurface drainage while maximizing production. An evaporation pan in combination with specific crop correction factors can be used to determine how much water is needed to satisfy plant requirements. Flood irrigation, the oldest and most common type, is often very uneven in distribution, as parts of a field may receive excess water in order to deliver sufficient quantities to other parts. Overhead irrigation, using centre-pivot or lateral-moving sprinklers, has the potential for a much more equal and controlled distribution pattern. Drip irrigation is the most expensive and least used type but offers the ability to deliver water to plant roots with minimal losses. However, drip irrigation is increasingly affordable, especially for the home gardener and considering rising water rates. Using drip irrigation methods can save up to 30,000 gallons of water per year when replacing irrigation systems that spray in all directions. There are also cheap effective methods like drip irrigation such as the use of soaking hoses that can even be submerged in the growing medium to eliminate evaporation. As, changing irrigation systems can be a costly undertaking, conservation efforts often concentrate on maximizing the efficiency of the existing system. This may include chiselling compacted soils, creating furrow dikes to prevent runoff, and using soil moisture and rainfall sensors to optimize irrigation schedules. Usually, large gains in efficiency are possible through measurement and more effective management of the existing irrigation system. The 2011 UNEP Green Economy Report notes that “improved soil organic matter from the use of green manures, mulching, and recycling of crop residues and animal manure increases the water holding capacity of soils and their ability to absorb water during torrential rains”, which is a way to optimize the use of rainfall and irrigation during dry periods in the season.
Water Reuse
Water shortage has become an increasingly difficult problem to manage. More than 40% of the world’s population live in a region where the demand for water exceeds its supply. The imbalance between supply and demand, along with persisting issues such as climate change and population growth, has made water reuse a necessary method for conserving water. There are a variety of methods used in the treatment of wastewater to ensure that it is safe to use for irrigation of food crops and/or drinking water.
Seawater desalination requires more energy than the desalination of fresh water. Despite this, many seawaters desalination plants have been built in response to water shortages around the world. This makes it necessary to evaluate the impacts of seawater desalination and to find ways to improve desalination technology. Current research involves the use of experiments to determine the most effective and least energy intensive methods of desalination.
Sand filtration is another method used to treat water. Recent studies show that sand filtration needs further improvements, but it is approaching optimization with its effectiveness at removing pathogens from water. Sand filtration is very effective at removing protozoa and bacteria but struggles with removing viruses. Large-scale sand filtration facilities also require large surface areas to accommodate them.
The removal of pathogens from recycled water is of high priority because wastewater always contains pathogens capable of infecting humans. The levels of pathogenic viruses have to be reduced to a certain level in order for recycled water to not pose a threat to human populations. Further research is necessary to determine more accurate methods of assessing the level of pathogenic viruses in treated wastewater.
Wasting of water
Leaking garden hose bib: Wasting of water (also called “water waste” in the U.S.) is the flip side of water conservation and, in household applications, it means causing or permitting discharge of water without any practical purpose. Inefficient water use is also considered wasteful. By EPA estimate, household leaks in the U.S. can waste approximately 900 billion gallons (3.4 billion cubic meters) of water annually nationwide. Generally, water management agencies are reluctant or unwilling to give a concrete definition to the somewhat fuzzy concept of water waste. However, definition of water waste is often given in local drought emergency ordinances. One example refers to any acts or omissions, whether wilful or negligent, that are “causing or permitting water to leak, discharge, flow or run to waste into any gutter, sanitary sewer, watercourse or public or private storm drain, or to any adjacent property, from any tap, hose, faucet, pipe, sprinkler, pond, pool, waterway, fountain or nozzle.”. In this example, the city code also clarifies that “in the case of washing, “discharge,” “flow” or “run to waste” means that water in excess of that necessary to wash, wet or clean the dirty or dusty object, such as an automobile, sidewalk, or parking area, flows to waste. Water utilities (and other media sources) often provide listings of wasteful water-use practices and prohibitions of wasteful uses. Examples include utilities in San Antonio, Texas. Las Vegas, Nevada, California Water Service company in California, and City of San Diego, California. The City of Palo Alto in California enforces permanent water use restrictions on wasteful practices such as leaks, runoff, irrigating during and immediately after rainfall, and use of potable water when non-potable water is available. Similar restrictions are in effect in the State of Victoria, Australia. Temporary water uses bans (also known as “hosepipe bans”) are used in England, Scotland, Wales and Northern Ireland.
Strictly speaking, water that is discharged into the sewer, or directly to the environment is not wasted or lost. It remains within the hydrologic cycle and returns to the land surface and surface water bodies as precipitation. However, in many cases, the source of the water is at a significant distance from the return point and may be in a different catchment. The separation between extraction point and return point can represent significant environmental degradation in the watercourse and riparian strip. What is “wasted” is the community’s supply of water that was captured, stored, transported and treated to drinking quality standards. Efficient use of water saves the expense of water supply provision and leaves more fresh water in lakes, rivers and aquifers for other users and also for supporting ecosystems. A concept that is closely related to water wasting is “water-use efficiency.” Water use is considered inefficient if the same purpose of its use can be accomplished with less water. Technical efficiency derives from engineering practice where it is typically used to describe the ratio of output to input and is useful in comparing various products and processes. For example, one showerhead would be considered more efficient than another if it could accomplish the same purpose (i.e., of showering) by using less water or other inputs (e.g., lower water pressure). However, the technical efficiency concept is not useful in making decisions of investing money (or resources) in water conservation measures unless the inputs and outputs are measured in value terms. This expression of efficiency is referred to as economic efficiency and is incorporated into the concept of water conservation.
Er.Mohammad Ashraf Fazili is a former Chief Engineer.
