Sustainable Management of Red Mud: Lifecycle Assessment and Treatment Techniques

Red mud is a strongly alkaline leaching solid hazardous waste material generated in the Bayer process of alumina production. India ranks 4 th place in alumina production. According to the Ministry of Mines (Oct 2022), India produces 9 million tonnes of red mud annually. In nature, red mud is highly alkaline. The high alkalinity and caustic content of red mud will contaminate the groundwater and fertile soil, and also there is a limitation on the utilization of red mud. Due to its low utilization ratio, large amounts of red mud are stacked in disposal areas, which may cause water pollution, soil salinization and heavy metal pollution. Red mud contains toxic metals such as arsenic, chromium, lead, nickel, zinc and radioactive elements such as thorium, potassium, and uranium, which cause severe effects on the environment and also on our health. The objective is to examine the environmental impact, utilization methods and treatment process of the red mud (bauxite residue). Also, scrutinize the biodegradation of heavy metals in red mud.


Ⅰ INDRODUCTION
Aluminum plays a vital role in day-to-day life.Aluminium is widely used in cans, foils, kitchen utensils, aeroplane parts.After oxygen, silica aluminium is third most abundant material in lithosphere.In 1854, the first production of aluminium is started.There are two steps in the alumina production one is Bayer process and other is hall-Heroult process.In the Bayer process, filtration after the addition of sodium hydroxide produces red mud. 1 ton of alumina production gives 1.5 tons of red mud.Currently about 4.6 billion tons of red mud is stored with an increase of 200mt per annum.Due to its high alkalinity, it causes serious effects to the environment such as human health effects due to the presence of heavy metals, soil pollution, leachate will also affect the ground water.
There is no proper utilization or treatment technique in India.The red mud is disposed as slurry form in sea or lake or it is disposed in dry form in land.In this paper the properties, environmental effects and its disposal and treatment techniques is highlighted.

Ⅱ BAUXITE:
Bauxite is a rock formed in the laterite soil.The French geologist Pierre Berthier named bauxite in 1821.bauxitecontains clay minerals, aluminium hydroxide, hydrous aluminium oxides.The insoluble minerals present in bauxite is hematite, quartz, magnetite, siderite, goethite.The specific gravity of bauxite is 2.6 to 3.5.

VI HEALTH IMPACTS ON HUMAN
Red mud contains toxic metals like arsenic, chromium, cadmium and nickel.The mud also contains radioactive elements and is highly alkaline, caustic enough to burn skin and eyes.Long-term exposure to arsenic from drinking-water and food can cause cancer and skin lesions.It has also been associated with cardiovascular disease and diabetes.In utero and early childhood exposure has been linked to negative impacts on cognitive development and increased deaths in young adults.
Adverse health effects associated with Cr(VI) exposure include occupational asthma, eye irritation and damage, perforated eardrums, respiratory irritation, kidney damage, liver damage, pulmonary congestion, upper abdominal pain, nose irritation and damage, respiratory cancer and skin irritation.
Breathing high levels of cadmium damages people's lungs and can cause death.Exposure to low levels of cadmium in air, food, water, and particularly in tobacco smoke over time may build up cadmium in the kidneys and cause kidney disease and fragile bones.Cadmium is considered a cancer-causing agent.
Nickel (Ni) is a hard, silvery-white metal that may cause irritation to the skin.Exposure can harm • Email: editor@ijfmr.com

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Volume 6, Issue 1, January-February 2024 4 the lungs, stomach, and kidneys.Exposure to nickel may lead to cancer.

VIIDISPOSAL TECHNIQUES Fig 4 Separation of liquid from bauxite
The environmental risk associated with the disposal of red mud is due to high alkalinity, presence of radionuclides and toxic elements.The traditional disposal technique includes slurry disposal, dry mud disposal, sea or lake disposal, closed cycledisposal, modified closed cycle disposal methods.Sea disposal: the slurry from the Bayer process is directly disposed to the sea through the pipeline.This may reduce the land pollution, but it increases the turbidity level in sea due to the formation of colloidal aluminium and magnesium compounds.Conventional wet disposal: by dewatering process the sodium hydroxide is separated from the redmud slurry.Due to the seepage

VIII UTILIZATION OF RED MUD
Now a days red mud is effectively used in engineering field.The red mud contains sufficient amount of silica, alumina, iron oxides so it can be used in the cement of alkaline content the groundwater got contaminated.Dry disposal: The slurry is dewatered and dried up to 48-58% of solids.This reduces the area of disposal.
In India mostly dry disposal is used.manufacturing.And in concrete red mud can be partially replaced in place of cement.In the wastewater treatment the red mud act as a adsorbent for the removal of heavy metals.It can be also used in brick manufacturing.

Fig
Fig 2 Aluminium plants in India

Fig 5
Fig 5 Utilization methods