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Case Studies | Chemistry | India | Volume 8 Issue 6, June 2019 | Popularity: 6.7 / 10

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Aquaponics - Self Sustainable Ecosystem

Dr Vaishali Mishra

Abstract: Since the Green Movement, and our modern methods of farming, comes the use of fertilizers and pesticides, which, along with water pollution, have been causing air pollution. Fumes from nitrogen-rich fertilizers and animal waste combine in the air with pollutants -nitrogen oxides and sulfates from vehicles, power plants and industrial processes—to create tiny solid particles, or aerosols which can penetrate deep into lungs, causing heart or pulmonary diseases. Instead of the conventional method of agriculture, a sustainable ecosystem aquaponics can be adopted which does not depend on the chemical fertilizers and synthetic pesticides and combats all sorts of pollution at the same time. Aquaponics combines hydroponics with aquaculture. Hydroponics is the science of growing plants without soil in organic nutrient-rich water. Aquaculture is the breeding and farming of aquatic organisms, such as fish, shellfish, and aquatic plants, usually for human consumption In aquaponic system production of fish and plants does not dependent on rainfall and even water use is minimum. Fish, sustainable food production and air purifier plants growth per unit area in this sustainable system is much faster and healthier than others. The air purifier plants grown from aquaponics are able to maintain the oxygen to carbon-dioxide ratio very efficiently, and is thereby able to reduce the carbon footprint, PM 2.5 , PM10. In an aquaponics system, the fish provide nutrients in the form of their waste, or excrement. This waste contains nitrogen in the form of ammonia, along with a variety of nutrients like potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P) and sulfur (S), and some other micronutrients like chlorine (Cl), iron (Fe), manganese (Mn), boron (B), zinc (Zn), copper (Cu) and molybdenum (Mo). Nitrifying bacteria that live in the hydrotol in the fish tank and on the tank walls convert the ammonia first into nitrites and then to nitrates as natural fertilizes, which uses by the plants. The water in the tank is continuously pumped into a grow bed where the plants are located. The plants remove the nutrients from this water, and nitrifying bacteria in the grow bed, clean the water by converting excess ammonia into nitrates. The grow bed and plants act as a biofilter, cleansing the water. The clean water is then recycled and sent back into the fish tank, so that the fish remain healthy. The chemical reaction for nitrification are as NH_3+O_2 - (?- (Nitrosomonas bacteria)) NO_2^-+3H^++2e^- NO_2^-+H_2 O - (?- (Nitrobacter)) NO_3^-+2H^++2e^- . Applying Law of Mass Action to the given elementary reactions: Rate_1= -d [NH_3]/dt=-d [O_2]/dt=k_1 [NH_3] [O_2]=k_1^' [NH_3] Rate_2=-d [NO_2^-]/dt=-d [H_2 O]/dt=k_2 [NO_2^-] [H_2 O]=k_2^' [NO_2^-] k_1^'=k_1 [O_2] k_2^'=k_2 [H_2 O] The concentration of oxygen (O2) and water (H2O) are at much higher than ammonia and nitrite hence the concentrations of oxygen and water remain constant throughout the reaction and the reactions can be treated as pseudo-first order reactions, with the rate efficiency being controlled by the respective bacteria, i. e. Nitrosomonas and Nitrobacter. This is reasonable because ammonia and nitrite are dissolved in a large amount of water in the plant bed. Also, the plant bed is well-oxygenated due to the flood and drain process. Hence, the percentages of oxygen and water consumed by the reaction will be negligible compared to their total concentrations. India is an agriculture based country, so implementing the Aquaponics system- a self-sustaining ecosystem on a large scale could have corresponding increase in the economy, recycling and reuse of water and mitigating air pollution, thus emphasizing on the need of eco-sustainability.

Keywords: Ammonia, Aquaponics, Bio filter, Fiber glass, Hydrotol, plants, fis

Edition: Volume 8 Issue 6, June 2019

Pages: 1248 - 1257

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