Table of contentsSummaryIntroductionSituation in Tamil NaduUnavoidable food waste towards defluoridationCharred pomegranate seedsPhyllanthus Emblica seedsConclusionSummaryAir, water and food are the three basic needs for survival of the humanity. The Earth's surface is covered with two thirds of water. But the availability of quality fresh water is one of the most critical environmental problems. Pollutants are the main cause of water pollution. Fluorine is the 13th richest element found in the earth's crust. Fluoride is considered a “double-edged sword” because its deficiency leads to dental caries while an excessive amount leads to dental and skeletal fluorosis. Adsorption is considered an effective process for defluoridating water. On the other hand, food waste is increasing. Around 1.3 billion tonnes of food are lost or wasted each year, representing almost a third of the food produced globally for human consumption. The main objective of this chapter is to highlight the inevitable food waste to the society so that it can be used as an adsorbent. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essayKeywords: Defloration, Adsorbent, Fluoride, Food waste, Food wasteIntroduction “Not all waste is waste. Can also be transformed into treasures. » Water is the most abundant and constitutes an essential element of our vital system. Water is present in every cell of our body, in various tissues and compartments. Therefore, the nutritional recommendation of water is higher during the growing period. Water acts as a solvent, reaction medium, reactant and reaction product. Water is necessary for cellular homeostasis because it transports nutrients to cells and removes waste products from cells. It is the environment in which all the transport systems operate allowing exchanges between cells, interstitial fluid and capillaries. Water quality is affected by different pollutants. Additionally, prolonged discharge of industrial effluents, domestic sewage, use of fertilizers and pesticides, and landfills cause groundwater pollution and health problems. Food waste is defined as waste generated during meal preparation and any uneaten food. This also includes food that has been thrown away, unused, or partially used. It does not include packaging materials. Food waste can exclude meat, i.e. vegetable peelings, leftover fruit, tea bags, coffee grounds, egg shells, etc. Alternatively, food waste may include meat and therefore include cooked food, meat, fish, bones, etc. The types of food waste can be summarized as avoidable, potentially avoidable and unavoidable food waste. 60% is avoidable food waste (for example: plate scrapings, leftovers, missing fruits and vegetables, out-of-date perishables, etc.). 20% are potentially avoidable foods. waste (e.g. bread crusts, potato skins, etc.). 20% is unavoidable food waste (e.g. general rubbish, banana peels, chicken bones, etc.). This food waste can be reduced, reused and recycled. Literature analysis shows that unavoidable food waste also has health benefits and functional properties. So this wasteinevitable food can be used effectively. One of the properties of some unavoidable food waste is their ability to fluoridate. Fluoride is considered a natural contaminant for groundwater resources globally. Fluorine is the 17th most abundant element in the earth's crust. It is a gas and is never found free in nature. Fluoride is essential for normal bone mineralization and the formation of tooth enamel. Fluoride is often considered a "double-edged sword" because insufficient fluoride intake leads to dental caries, while excessive consumption leads to dental and skeletal fluorosis. According to the World Health Organization, the maximum acceptable limit for fluoride concentration in drinking water is 1.5 mg/l. The maximum limit of fluoride in drinking water intended for human consumption is 1.0 mg/l. According to the National Fluorosis Prevention and Control Program, high fluoride levels have been reported in 230 districts of 20 states (after the bifurcation of Andhra Pradesh in 2014). Fluoride enters the human body mainly through drinking water and also partly through food. It is absorbed through the gastrointestinal and respiratory tracts; distributed by the blood and deposited in bones and teeth. Acute toxicity occurs after ingestion of a few fluorinated compounds for a short period of time which then leads to poisoning. Symptoms include nausea, vomiting, increased salivation, abdominal pain and diarrhea. In severe or fatal cases, these symptoms are followed by seizures, cardiac arrhythmias and coma. Other symptoms include collapse with pallor, weakness, shallow breathing, faint heart sounds, cold damp skin, cyanosis, dilated pupils, hypocalcemia and hyperkalemia, and even death within two to four hours. Other possible effects include muscle paralysis, carpopedal spasms, and extremity spasms. Chronic exposure causes dental fluorosis and skeletal fluorosis. Dental fluorosis is characterized by discoloration, mottling of the teeth, dull, opaque white spots in the enamel, which can become colored yellow to dark brown and, in severe forms, cause marked pitting and brittleness of the teeth . Prolonged exposure to fluoride results in brittle bones with low tensile strength, known as skeletal fluorosis. High fluoride toxicity leads to thyroid changes, growth retardation, kidney changes, and even urolithiasis. Like lead, even a tiny dose of fluoride buildup damages children's brains and development. Also produces abnormal behavior in animals and also reduces the IQ of humans. Situation in Tamil NaduAmong the drinking water samples tested for fluoride, 14% of them had levels above 3 ppm/l and 86% had fluoride levels above 1.5 ppm/l, which were above authorized levels. In Tamil Nadu, water samples collected from districts like Dharmapuri, Krishnagiri and Dindigul yielded fluoride content above 1.5 mg/l. Defluoridation methods are divided into three basic types of modes of action. Chemical reaction with fluoride – Nalgonda Technique Adsorption process e.g. Charcoal prepared from bones, activated charcoal, activated magnesia, tamarind gel, serpentine, activated alumina, plant matter, burnt clay. Ion Exchange Process – Anion/Cation Exchange Resins. Unavoidable food waste to defluorinationA biosorbent was prepared by loading Al/Fe oxide. on thetea waste. It has been tested against drinking water containing fluoride. It was found that the combination of Tea and Al or Tea-Al and Fe could effectively reduce the fluoride concentration below 1.5 mg/l in drinking water as well as the residual concentrations of Al and Fe in the drinking water. Drinking water after Tea-Al-Fe treatment was below WHO standards at pH values ​​ranging from 5 to 10. The maximum fluoride adsorption capacities for the original tea biosorbents, Tea-Fe, Tea-Al and Tea-Al-Fe were 3.83, 10.47, 13.79 and 18.52. mg/g, respectively. Ganvir and colleagues studied the effect of rice husk ash in removing fluoride from drinking water. Rice husk ash, an abundantly available material, was prepared by burning rice/paddy husks. Adsorption experiments were carried out using 0.1 g of adsorbent concentration per liter of water containing fluoride in the range of 10 to 60 mg/L at pH 7. All experiments were conducted at 27° C for 1 hour. The adsorption capacities of modified rice husk ash and column study for defluorination were found to be 15.08 and 9.5 mg/g. It was concluded that fluoride removal depends on a high pH value. Potato peel in combination with rice husk ash was used as an adsorbent for the removal of As and F from contaminated water. It was found that the maximum adsorption capacity of the adsorbents for As and F− was 2.17 µg g−1 and 2.91 mg g−1, respectively. Fluoride removal was observed between pH 7 and 9. Thus, it was concluded that in fluoride-contaminated waterways, these adsorbents can be used to filter both arsenic and fluoride. In batch and column tests, chemically modified rice husk and corn cob activated carbon were studied for fluoride removal. It has been tested in three variants such as 100% corn cob activated carbon and 50% rice husk + 50% corn cob activated carbon. The adsorption capacities were found to be 7.9, 5.0 and 5.2 mg/g. In the batch test, the maximum adsorption capacity of rice husk and corn cob activated carbon was 7.9 and 5.8 mg/g, and the removal efficiency was 91% and 89%. was reached. In batch mode, corn husk fly ash was tested for its ability to remove fluoride from water. The greatest fluoride removal was 86% under ideal conditions. This maximum evacuation was observed at a stirring speed of 250 rpm at pH 2, 2.0 g/50 ml dosage and an equilibrium time of 120 minutes. Christina and Viswanathan investigated saponified orange peel residue (SOPR) and immobilized Fe3O4 nanoparticles SOPR (FNPSOPR) for the effective removal of fluoride from water. The maximum adsorption capacity of FNPSOPR was found to be 80.33 mg/g at a sorbent concentration of 0.25 gL−1. Nasr and colleagues observed cuttlefish bones as an adsorbent material (available in Tunisia) for water defluoridation. It was concluded that cuttlefish bone exhibits excellent efficiency for fluoride removal. So, cuttlefish bones are 80% effective in removing fluoride from water. It was obtained at pH 7.2, 1 h contact time, 15 g/L adsorbent dose and 5 mg/L initial fluoride concentration. A research study shows that sawdust powder from Indian rose (Dalbergia sissoo), wheat straw (Triticum spp.), and sugarcane bagasse provided better removal of fluoride in water. The material was dried in an oven at 105 °C for 24 h and then sieved in a size range of 20 to 50 mesh ASTM. The fluoride concentration was significantly reduced from 3.14 to 1.31, 1.59 and 1.71 mg L−1, respectively.for sugarcane bagasse, sawdust and wheat straw. The coir ash was prepared by drying the coir in a muffle furnace at 423 K for one and a half hours, then it was washed with distilled water and dried in the sun. The dried fiber was then dried in an oven at 353 K overnight. It was sieved on a 150 mm mesh. Then it was impregnated with aluminum (AICFA) to remove fluoride from drinking water. The effect of the adsorbent to remove fluoride from groundwater was carried out without adjusting the pH of the experimental samples at the rate of 0.5 g/L AICFA under experimental conditions identical to those in the adsorption study in batches to equilibrium. The fluoride level was reduced from 6.01 ± 0.11 to < 0.96 mg/L.rch on eggshell powder as an adsorbent for the removal of fluoride from aqueous solution in using the discontinuous technique. Maximum fluoride adsorption was achieved at pH 2.0–6.0. Approximately 94% defluorination was achieved at an initial metal ion concentration of 5 mg/l at an optimal dose of 2.4 g/100 ml and an optimal duration of 120 minutes. Using shrimp shell waste, the initial fluoride concentration of 8 mg/L was removed approximately 80% at pH 11 within 15 minutes of contact time and adsorbate dose of 8 mg/L. The research also shows that the removal percentage of F increased with increasing adsorbent dose from 3.2 g/L to 64 g/L, but there was no difference between 48 g/L and 64 g/L. Banana peels, peanut shells, and sweet lemon peels have been used as adsorbents to remove fluoride from industrial wastewater. It was found that the defluoridation efficiency of banana peel, peanut shell and sweet lemon peel was 94.34, 89.9 and 59.59%, respectively. The collected banana peel was washed with deionized water and dried in a hot air oven at 50 °C. C for 12 hours. The dried barks were cut into small pieces and dried again in a hot air oven maintaining a temperature of 60 °C for 24 h. In the column study, a removal percentage of 86.5% was observed. The adsorbent for Java plum (S. cumini) seeds was prepared by drying the seeds in the sun for 2 days and then dried in a hot air oven in the range of 80–100 °C for 36 hours. This experiment was carried out in an SS tube reactor column. The reactor is filled with a weighted amount of Java plum seed adsorbent having a particle size of 2 to 4 mm as a fixed bed absorber. The bed was supported by cotton and sealed with rubber, to prevent flow of adsorbent with the effluent. The experimental results were encouraging and indicate that Java plum seeds can be used as a bio-adsorbent to remove fluoride in a fixed bed adsorption process. The optimal dose for the batch system was 3.9 g/50 ml. Charred pomegranate seeds. Pomegranate seeds were dried, charred and ground to fine sizes. It was found that adsorbents with a particle size of 55 µm, optimal dosage of 0.75 g, pH 5.5 and contact time of 75 min can act as good adsorbents. They also studied the adsorption of a different solution having initial fluoride concentrations of 2, 4, 6, 8 and 10 mg/L. It was found that when the fluoride concentration is 2 mg/L, the efficiency of the adsorbent is 88%, but when the fluoride concentration increases to 10 mg/L, the efficiency is reduced at 47%. The collected lemon peels were sun-dried for 5-6 days, then oven-dried at 80 ± 5°C for 24 hours, ground into powder, then activated.