RIVER GANGA

A Project on Environmental Science focused on wastewater and sewage treatment for a clean River Ganga in future. -By Pranav, Sagar, Vikas and Mayank

IntroductionThe Ganga (गग��) is a major river of the Indian subcontinent rising in the Himalaya Mountains and flowing about 2,510 km (1,560 mi) generally eastward through a vast plain to the Bay of Bengal. On its 1,560-mi (2,510-km) course, it flows southeast through the Indian states of Uttar Pradesh, Bihar, and West Bengal. In central Bangladesh it is joined by the Brahmaputra and Meghna rivers. Their combined waters (called the Padma River) empty into the Bay of Bengal and form a delta 220 mi (354 km) wide, which is shared by India and Bangladesh. Its plain is one of the most fertile and densely populated regions in the world. The Ganges alone drains an area of over a million square km with a population of over 407 million. Millions depend on water from the holy river for several things: drinking, bathing, agriculture, industry and other household chores.Ganga river known as Ganga Maata (गग�� मा�ता�) or Mother Ganges is revered as a goddess whose purity cleanses the sins of the faithful and aids the dead on their path toward heaven. In most Hindu families, a vial of water from the Ganga is kept in every house. It is believed that drinking water from the Ganga with one's last breath will take the soul to heaven. Hindus also believe life is incomplete without bathing in the Ganga at least once in their lifetime. Some of the most important Hindu festivals and religious congregations are celebrated on the banks of the river Ganga such as the Kumbh Mela or the Kumbh Fair and the Chhat Puja. Kumbh Mela is the largest religious gathering on Earth for Hindu peoples, where around 70 million Hindus from around the world participated in the last Kumbh Mela at the Hindu Holy city Prayaga (also known as Allahabad).

Map of Ganga

Pollution in Ganga RiverToday, over 29 cities, 70 towns, and thousands of villages extend along the Ganga banks. Nearly all of their sewage - over 1.3 billion liters per day - goes directly into the river, along with thousands of animal carcasses, mainly cattle. Another 260 million liters of industrial waste are added to this by hundreds of factories along the rivers banks. Municipal sewage constitutes 80 per cent by volume of the total waste dumped into the Ganga, and industries contribute about 15 percent. The majority of the Ganga pollution is organic waste, sewage, trash, food, and human and animal remains. Over the past century, city populations along the Ganga have grown at a tremendous rate, while waste-control infrastructure has remained relatively unchanged. Recent water samples collected in Varanasi revealed fecal-coliform counts of about 50,000 bacteria per 100 milliliters of water, 10,000% higher than the government standard for safe river bathing. The result of this pollution is an array of water-borne diseases including cholera, hepatitis, typhoid and amoebic dysentery. An estimated 80% of all health problems and one-third of deaths in India are attributable to water-borne diseases.The sacred practice of depositing human remains in the Ganga also poses health threats because of the unsustainable rate at which partially cremated cadavers are dumped. Hundreds of corpses burn on the line of wooden pyres. Soot-covered men bustle about, raking in the still-glowing ashes, sweeping them into the river. Ganga is getting polluted day-by-day. Nearly 170 factories and tanneries located between Kannauj and Varanasi, covering an area of 450 km, were found responsible for polluting the river by discharging wastes into it without treatment,” Union Minister for Environment and Forests Jairam Ramesh told reporters on August 28, 2010. There is an urgent need to aware people and get started to stop its pollution and degradation.

Ganga Action PlanAfter two Ganga Action Plans failed to deliver the goods, seven major IITs of the country have joined hands to find ways to clean up the national river. The Ganga Action Plan (GAP) was initiated by the late Prime Minster Indira Gandhi, who called for a comprehensive survey of the situation in 1979. In 1985, the government of India launched the Ganga Action Plan, which was devised to clean up the river in selected areas by installing sewage treatment plants and threatening fines and litigation against industries that pollute. The 2006 official audit of the Ganga Action Plan has revealed that it has met only 39 per cent of its sewage treatment target. The 2006 official audit of the Ganga Action Plan has revealed that it has met only 39 per cent of its sewage treatment target. Moreover, the plan is behind schedule by over 13 years. According to the legal counsel, Central Pollution Control Board, Mr Vijay Panjawani, even after spending Rs 24,000 crore, the Ganga remains as dirty as everA total of 146 industries are reported to be located along the river Ganga between Rishikesh and Prayagraj. 144 of these are in Uttar Pradesh (U.P.) and 2 in Uttrakhand. Of the grossly polluting industries in U.P., 82 industries have installed Effluent Treatment Plants (ETPs) and are reported to be complying with the standards, 27 industries, though have installed ETPs are not reported to be complying with the prescribed standards and 35 industries are reported to have been closed.

Industrial Wastewater TreatmentIndustrial wastewater treatment covers the mechanisms and processes used to treat waters that have been contaminated in some way by anthropogenic industrial or commercial activities prior to its release into the environment or its re-use.Treatment of industrial wastewater:Solids removal: Most solids can be removed using simple sedimentation techniques with the solids recovered as slurry or sludge. Very fine solids and solids with densities close to the density of water pose special problems. In such case filtration or ultrafiltration may be required. Although, flocculation may be used, using alum salts or the addition of polyelectrolytes.Oils and grease removal: The wastewaters from large-scale industries such as oil refineries, petrochemical plants, chemical plants, and natural gas processing plants commonly contain gross amounts of oil and suspended solids. Those industries use a device known as an API oil-water separator which is designed to separate the oil and suspended solids from their wastewater effluents. The API separator is a gravity separation device designed is based on the specific gravity difference between the oil and the wastewater because that difference is much smaller than the specific gravity difference between the suspended solids and water. The suspended solids settles to the bottom of the separator as a sediment layer, the oil rises to top of the separator and the cleansed wastewater is the middle layer between the oil layer and the solids. Typically, the oil layer is skimmed off and subsequently re-processed or disposed of, and the bottom sediment layer is removed by a chain and flight scraperThe water layer is sent to further treatment consisting usually of a Electroflotation module for additional removal of any residual oil.

Activated sludge process: Activated sludge is a biochemical process for treating sewage and industrial wastewater that uses air (or oxygen) and microorganisms to biologically oxidize organic pollutants, producing a waste sludge (or floc) containing the oxidized material. In general, an activated sludge process includes:(1) An aeration tank where air (or oxygen) is injected and thoroughly mixed into the wastewater.(2) A settling tank (usually referred to as a "clarifier" or "settler") to allow the waste sludge to settle. Part of the waste sludge is recycled to the aeration tank and the remaining waste sludge is removed for further treatment and ultimate disposal.Trickling filter process: A trickling filter consists of a bed of rocks, gravel, slag, peat moss, or plastic media over which wastewater flows downward and contacts a layer (or film) of microbial slime covering the bed media. Aerobic conditions are maintained by forced air flowing through the bed or by natural convection of air. The process involves adsorption of organic compounds in the wastewater by the microbial slime layer, diffusion of air into the slime layer to provide the oxygen required for the biochemical oxidation of the organic compounds. The end products include carbon dioxide gas, water and other products of the oxidation. As the slime layer thickens, it becomes difficult for the air to penetrate the layer and an inner anaerobic layer is formed.

Sewage TreatmentSewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff (effluents) and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants.

Process:Sewage can be treated close to where it is created, a decentralised system, (in septic tanks, biofilters or aerobic treatment systems), or be collected and transported via a network of pipes and pump stations to a municipal treatment plant, a centralised system, (see sewerage and pipes and infrastructure). Sewage collection and treatment is typically subject to local, state and federal regulations and standards. Industrial sources of wastewater often require specialized treatment processes (see Industrial wastewater treatment).Sewage treatment generally involves three stages, called primary, secondary and tertiary treatment.Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. The settled and floating materials are removed and the remaining liquid may be discharged or subjected to secondary treatment.Secondary treatment removes dissolved and suspended biological matter. Secondary treatment is typically performed by indigenous, water-borne micro-organisms in a managed habitat. Secondary treatment may require a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment.Tertiary treatment is sometimes defined as anything more than primary and secondary treatment in order to allow rejection into a highly sensitive or fragile ecosystem (estuaries, low-flow rivers, coral reefs,...). Treated water is sometimes disinfected chemically or physically (for example, by lagoons and microfiltration) prior to discharge into a stream, river, bay, lagoon or wetland, or it can be used for the irrigation of a golf course, green way or park. If it is sufficiently clean, it can also be used for groundwater recharge or agricultural purposes.

Sewage Treatment Plant

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