Table of Contents
- 1 Water Conservation and Management
- 1.1 EcoSan toilets
- 1.2 Bio-Toilets
- 1.3 Contour farming
- 1.4 Ground water conservation
- 1.5 Inter-basin transfer of water
- 1.6 Adoption of drip sprinkler irrigation
- 1.7 Management of growing pattern of crops
- 1.8 Selection of crop varieties
- 1.9 Nutritional management
- 1.10 Role of antitranspirants
- 1.11 Reducing evapotranspiration
- 1.12 Recycling of water
- 1.13 Reuse of wastewater
- 1.14 Reduce the loss of water due to evaporation
- 1.15 Water Treatment for Domestic Use
- 1.16 Watershed Management
- 1.17 Individual And Community Role
- 1.18 Government’s efforts on water conservation
- Primary source of water in India is south-west and north-east monsoons. Monsoon, however, is erratic and amount of rain fall is highly variable in different parts of our country. Hence, surface runoff needs be conserved.
- Can you imagine the amount of water that one can save if one didn’t have to flush the toilet? Well, this is already a reality. Ecological sanitation is a sustainable system for handling human excreta, using dry composting toilets.
- This is a practical, hygienic, efficient and cost-effective solution to human waste disposal.
- With this composting method, human excreta can be recycled into a resource (as natural fertilizer), which reduces the need for chemical fertilizers. There are working ‘EcoSan’ toilets in many areas of Kerala and Sri Lanka.
- Railways along with DRDO.
Why Bio Toilets in Rail?
- Direct discharge of human waste from the existing toilet system in trains causes corrosion of the tracks, costing crores to replace the rail tracks.
- The bio-toilets are fitted underneath the lavatories and the human waste discharged into them is acted upon by a particular kind of bacteria that converts it into non-corrosive neutral water.
- Bio-digesters: The term bio digester is used for the shells made up of steel for the anaerobic digestion of human waste.
- Bio tank: The term bio tank is used for the tanks made up of concrete for the anaerobic digestion of human waste.
- Aerobic Bacteria: Aerobic bacteria are those which flourish in the presence of free dissolved oxygen in the waste water and consume organic matter for their food, and thereby oxidizing it to stable end products.
- Anaerobic Bacteria: Anaerobic bacteria flourish in the absence of free dissolved oxygen, and survive by utilizing the bounded molecular oxygen in compounds like nitrates (NO3) and sulphates (SO4) etc. thereby reducing them to stable end products along with evolution of foul smelling gases like H2S (hydrogen sulphide), CH4 (methane)
- Facultative Bacteria: Facultative bacteria can operate either as aerobically or as anaerobically.
- Anaerobic Microbial inoculums: mixture of different types of bacteria (hydrolytic, Acidogenic, acetogenic and methanogenic groups) responsible for breakdown of complex polymers into simple sugars which are further broken down into low chain fatty acids and finally into biogas.
- Anaerobic digestion is a collection of processes by which microorganisms break down biodegradable material in the absence of oxygen.
The final waste are Methane and Carbon Dioxide.
- Forced aeration is essential which is energy intensive.
- Incomplete aeration (partial aerobic condition) leads to foul smell.
- Less effective pathogen inactivation.
- Cannot tolerate detergents
- Generate large amount of sludge.
- Repeated addition of bacteria/enzyme is required for the process.
- Maintenance & recurring cost is high.
- No aeration is required.
- Complete anaerobic conditions.
- More than 99% pathogen inactivation.
- Anaerobes can even degrade detergents/phenyl
- Sludge generation is very less.
- One time bacterial inoculation is enough.
- Minimal maintenance and no recurring cost.
With reference to bio-toilets used by the Indian Railways, consider the following statements:
- The decomposition of human waste in the bio-toilets is initiated by a fungal inoculum.
- Ammonia and water vapour are the only end products in this decomposition which are released into the atmosphere.
Which of the statements given above is/are correct?
- 1 only
- 2 only
- Both 1 and 2
- Neither 1 nor 2
Decomposition of human waste in bio-toilets is carried out by anaerobic bacteria.
The final waste is CO2 and CH4.
Answer: d) Neither 1 nor 2
- Contour farming is an example of harvesting technique involving water and moisture control at a very simple level.
- It often consists of rows of rocks placed along the contour of steps. Runoff captured by these barriers also allows for retention of soil, thereby serving as erosion control measure on gentle slopes.
- This technique is especially suitable for areas having rainfall of considerable intensity, spread over large part i.e. in Himalayan area, north east states and Andaman and Nicobar islands.
- In areas where rainfall is scanty and for a short duration, it is worth attempting these techniques, which will induce surface runoff, which can then be stored.
- Increasing the surface area for percolation, percolation tank construction etc. are some artificial recharge methods.
Catchment area protection (CAP)
- It helps in withholding runoff water albeit temporarily by a check bund constructed across the streams in hilly terrains to delay the run off so that greater time is available for water to seep underground.
- Such methods are in use in north-east states, in hilly areas of tribal belts. This technique also helps in soil conservation. Afforestation in the catchment area is also adopted for water and soil conservation.
- Western and peninsular regions have comparatively low water resources/cultivable land ratio. Northern and eastern region which are drained by Ganga and Brahmaputra have substantial water resources.
- Hence, the scheme of diverting water from region with surplus water to water deficit region can be adopted.
- Ganga-Cauvery link would enable the transfer of vast quantities of Ganga basin flood water running out to sea, to west and south west India.
- The transfer of the surplus Ganga water would make up for the periodical shortage in Son, Narmada, Godavari, Krishna and Cauvery.
- Surface irrigation methods leads to water loss due to evaporation and percolation.
- Drip irrigation is an efficient method of irrigation in which a limited area near the plant is irrigated by dripping water. This method is particularly useful in row crop.
- Similarly sprinkler method is also suitable for such water scarce areas. About 80% water consumption can be reduced by this method, whereas the drip irrigation can reduce water consumption by 50 to 70 %.
- In water scarce areas, the crop selection should be based on efficiency of the crop to utilize the water. Some of the plants suitable for water scarce areas are:
- plants with shorter growth period;
- high yielding plants that require no increase in water supply;
- plants with deep and well trenched roots and
- plants which cannot tolerate surface irrigation.
- Crop performance and yield are the results of genotype expression as modulated by continuous interactions with the environment.
- Generally, the new varieties of crop do not require more water than the older ones. However, they require timely supply of water because their productivity is high.
- Frequent light irrigation is more conductive than heavy irrigation at large intervals for obtaining high yields.
- Potassium plays a major role under stress conditions. It improves the tissue water potential by osmoregulation, ultimately increasing the water use efficiency.
- Experiments conducted at the Water Technology Centre, Coimbatore, indicated that foliar application of 0.5% potassium chloride can reduce the moisture stress in soyabean, sorghum and groundnut.
- Application of antitranspirants reduces transpiration maintaining thereby the tissue water potential. Plants then take up less water from soil.
- Antitranspirants can prolong the irrigation intervals by slowing down soil water depletion. Application of Kaolin (3%) and lime wash (2%) was found to maintain the water balance of plant and resulted in normal yield of sorghum under moisture stress conditions.
- Certain growth regulators reduce the plants susceptibility to water stress. Application of cycoel, a growth retardant increases the ability to withstand drought.
- Cycoel application also reduces production of gibberellic acid which leads to closing of stomata. Transpiration loss of water gets reduced.
- Evapotranspiration losses can be reduced by reducing the evaporation from soil surface and transpiration from the plants, in arid zones, considerable amount of water is lost in evaporation from soil surface.
- This can be prevented by placing water tight moisture barriers or water tight mulches on the soil surface. Non-porous materials like papers, asphalt, plastic foils or metal foils can also be used for preventing evaporation losses.
- Transpiration losses can be reduced by reducing air movement over a crop by putting wind breaks and evolving such types of crops which possess xerophytic adaptations.
- The wastewater from industrial or domestic sources can be used after proper treatment, for irrigation, recharging ground water, and even for industrial or municipal use. If agricultural lands are available close to cities, municipal waste water can be easily used for irrigation.
- Wastewater contains lots of nutrients. Its use for irrigation saves these nutrients. It improves the productivity of crops and soil fertility.
- Wastewater is a resource rather than a waste since it contains appreciable amount of nitrogen, phosphorus and potash.
- Stabilization ponds can be used for fish aquaculture. The effluent can also be used for cultivation of short-term and long term, ornamental, commercial and fodder crops.
The potential applications of reusing of treated wastewater are in the following fields or areas:
- Agricultural use through irrigation of crops as well as for improving river amenity;
- Industrial cooling especially in large industrial enterprises;
- Reuse in municipal public areas such as watering lawns, parks, play grounds and trees;
- Flushing toilets in hotels and residential districts;
- Reuse of the treated wastewater for urban landscape purposes.
- Treated waste water can also be used for groundwater recharging.
Grey water reuse
- Grey water is defined as untreated household wastewater, which has not come into contact with toilet waste. It can originate from the shower, bath, bathroom, washing basin, clothes washing machine and laundry trough. Grey water can be used in agriculture and many industries.
- The methods that reduce evaporation from water bodies are – installing wind breaks, reducing energy available for evaporation, constructing artificial aquifers, minimizing exposed surface through reservoir regulation, reducing ratio of area/volume of water bodies, locating reservoirs at higher altitudes and applying monomolecular firms.
- There are numerous methods to reduce losses due to evaporation and to improve soil moisture. Some of them are listed below:
- Mulching i.e. the application of organic or inorganic materials such as plant debris, compost, etc., slows down the surface run-off, improves soil moisture, reduces evaporation losses and improves soil fertility.
- Soil covered by crops, slow down run-off and minimize evaporation losses, hence, fields should not be left bare for long periods of time.
- Ploughing helps to move the soil around. As a consequence it retains more water thereby reducing evaporation.
- Shelter belt of trees and bushes along the edge of agricultural fields slow down the wind speed and reduce evaporation and erosion.
- Planting of trees, grass, and bushes breaks the force of rain and helps rainwater penetrate the soil.
- Fog and dew contain substantial amounts of water that can be used directly by adapted plant species. Artificial surfaces such as netting-surface traps or polythene sheets can be exposed to fog and dew; the resulting water can be used for crops.
- Contour farming is adopted in hilly areas and in lowland areas for paddy fields. Farmers recognize the efficiently of contour based systems for conserving soil and water.
- Salt-resistant varieties of crops have been also developed recently. Because these grow in saline areas, overall agricultural productivity is increased without making additional demands on fresh water sources. Thus, this is a good water conservation strategy.
- Desalination technologies such as distillation, electro-dialysis and reverse osmosis are available.
- Substances that are removed during the process of drinking water treatment include suspended solids, bacteria, algae, viruses, fungi, and minerals such as iron and manganese.
- The processes involved in removing the contaminants include physical processes such as settling and filtration, chemical processes such as disinfection and coagulation and biological processes such as slow sand filtration.
Coagulation / Flocculation
- Aluminium sulphate (alum) is the most common coagulant used for water purification. Other chemicals, such as ferric sulphate or sodium aluminate, may also be used.
- During coagulation, liquid aluminium sulfate (alum) is added to untreated water.
- This causes the tiny particles of dirt in the water to stick together or coagulate.
- Next, groups of dirt particles stick together to form larger particles called flocs.
- Flocs are easier to remove by settling or filtration.
- As the water and the floc particles progress through the treatment process, they move into sedimentation basins where the water moves slowly, causing the heavy floc particles to settle to the bottom.
- Floc which collects on the bottom of the basin is called sludge, and is piped to drying lagoons.
- In Direct Filtration, the sedimentation step is not included, and the floc is removed by filtration only.
- Water flows through a filter designed to remove particles in the water. The filters are made of layers of sand and gravel, and in some cases, crushed anthracite.
- Filtration collects the suspended impurities in water and enhances the effectiveness of disinfection. The filters are routinely cleaned by backwashing.
- Water is disinfected before it enters the distribution system to ensure that any disease-causing bacteria, viruses, and parasites are destroyed.
- Chlorine is used because it is a very effective disinfectant, and residual concentrations can be maintained to guard against possible biological contamination in the water distribution system.
- The addition of chlorine or chlorine compounds to drinking water is called chlorination.
- Chlorine can combine with certain naturally occurring organic compounds in water to produce chloroform and other potentially harmful byproducts. The risk of this is very small, however, when chlorine is applied after coagulation, sedimentation, and filtration.
- Ozone gas may also be used for disinfection of drinking water. However, since ozone is unstable, it cannot be stored and must be produced on-site, making the process more expensive than chlorination.
- Ozone has the advantage of not causing taste or odour problems. It also leaves no residue in the disinfected water.
- The lack of an ozone residue, however, makes it difficult to monitor its continued effectiveness as water flows through the distribution system.
- Solids that are collected and settled out of the water by sedimentation and filtration are removed to drying lagoons.
- Water fluoridation is the treatment of community water supplies for the purpose of adjusting the concentration of the free fluoride ion to the optimum level sufficient to reduce dental caries.
- Fluoride is generally present in all natural water. Its concentration up to certain level is not harmful. Beyond that level, the bones start disintegrating. This disease is called fluorosis.
- We have fluoride problem in many parts of our country. Bureau of Indian Standards prescribes 1.0 mg/l as desirable and 1.5 mg/l as maximum permissible limit for drinking water.
- Defluoridation at domestic level can be carried out by mixing water for treatment with adequate amount of aluminum sulphate (alum) solution, lime or sodium carbonate and bleaching powder depending upon its alkalinity (concentration of bicarbonates and carbonates in water) and fluoride contents.
- Lime is added to the filtered water to adjust the pH and stabilize the naturally soft water in order to minimise corrosion in the distribution system, and within customers’ plumbing.
Titbit: National Environmental Engineering Research Institute (NEERI) is at Nagpur.
Removal of iron
- In many parts of our country we have problem of excess iron in drinking water especially in North-East regions. Iron causes bad taste and odour to the drinking water. Bureau of Indian Standards prescribes desirable limit for iron as 0.3 mg/l.
- A major part of iron is oxidized. Then the water is made to react with oxidizing media (lime stone). By aeration and further oxidation the dissolved iron is converted to insoluble ferric hydroxide. The insoluble iron can thus be easily removed through filtration.
Removal of arsenic
- Arsenic is found in ground water in some parts of West Bengal. Arsenic is highly toxic in nature. It may cause a number of skin disorders or even cancer. Bureau of Indian Standards prescribes desirable limit for arsenic as 0.05 mg/l.
- Removal of arsenic is essential.
- Bleaching powder and alum are used for removal of arsenic.
- Watershed is an area that contribute water to a stream or a water body through run-off or underground path.
- That is the region from which surface water draws into a river, a lake, wet land or other body of water is called its watershed or drainage basin.
- Watershed management is a technique for conservation of water and soil in a watershed.
- The presence of water in soil is essential for the growth of plants and vegetation. Forests and their associated soils and litter layers are excellent filters as well as sponges, and water that passes through this system is relatively pure.
- Various kinds of forest disturbances can speed up the movement of water from the system and in effect, reduce the filtering action.
- In mountainous terrain the forests play a prominent role in prevention of soil erosion.
- Erosion threat can be tackled by the maintenance of continual cover. Ideally, this is achieved by single stem harvesting; only one tree is felled at any one point, and the small gap so created is soon sealed by the outward growth of its neighbors.
- Despite the uncertain balance of water gain and loss, forests offer the most desirable cover for water management strategies.
- In contrast to the rapid flows of short duration characteristics of sparsely vegetated land water yields are gradual, reliable and uniform in forests. Deforested land sheds water swiftly, causing sudden rises in the rivers below.
- Over a large river system, such as that of the Ganga and the Yamuna, forests are a definite advantage since they lessen the risk of floods. They also provide conditions more favourable to fishing and navigation than does un-forested land.
- All natural streams contain varying amounts of dissolved and suspended matter, although streams contain varying amounts of dissolved and suspended matter, although streams issuing from undisturbed watershed are ordinarily of high quality.
- Waters from forested areas are not only low in foreign substances, but they also are relatively high in oxygen and low in unwanted chemicals.
- The belief that forests increase rainfall has not been substantiated by scientific inquiry. Local effects can, however, prove substantial, particularly in semiarid regions where every millimeter of rain counts.
- The air above a forest, as contrasted with grassland, remains relatively cool and humid on hot days, so that showers are more frequent.
- Many areas in India used to get significant rainfall when they were forested are now facing severe draught due to denudation (example Rajasthan desert).
- Building check dams on seasonal rivers.
- Micro-watershed management project.
- Constructing percolation tanks in every residential and industrial complex.
- Roof top rain water collection for drinking purposes. [2/3rds of water is wasted in RO – reverse osmosis filtration]
- National Water Policy 2002 strongly emphasize conservation of water.
- Construction of large number of dams on various river systems.
- Interlinking of rivers (proposed).
- Promotion of bunds at village level.
- Promotion of rain water harvesting.
- Promotion of reuse and recycling of wastewater.
- Steps to protect water quality.
- Drought-proofing the future.
Permanent conservation measures may include:
- Subsidizing use of water-efficient faucets, toilets and showerheads
- Public education and voluntary use reduction.
- Billing practices that impose higher rates for higher amounts of water use
- Building codes that require water-efficient fixtures or appliances
- Leak detection surveys and meter testing, repair and replacement
- Reduction in use and increase in recycling of industrial water
Temporary cutbacks may include:
- Reduction of system-wide operating pressure
- Water use bans, restrictions, and rationing
- Strengthening of local or municipal bodies could help addressing the issue of water shortage and its management in cities.
Q3. Which one among the following industries is the maximum consumer of water in India?
- Paper and pulp
- Thermal power
Water consumption by various industries
- Thermal power
- Textile industry
- Paper and Pulp
- Iron and Steel industry
- Fertilizer Industry