Dissolved Oxygen Research Paper

Dissolved oxygen

Dissolved oxygen is oxygen gas molecules (O2) present in the water. Plants and animals cannot directly use the oxygen that is part of the water molecule (H2O) Oxygen enters streams from the surrounding air and as a product of photosynthesis from aquatic plants. Consistently high levels of dissolved oxygen are best for a healthy ecosystem. The Oxygen Level Vary Depending upon on factors including water temperature, time of day, season, depth, altitude, and rate of flow. Water at higher temperatures and altitudes will have less dissolved oxygen. Dissolved oxygen reaches its peak during the day. At night, it decreases as photosynthesis has stopped while oxygen consuming processes such as respiration, oxidation, and respiration

A chloride concentration in Nakkavagu Lake was noticed 50 mg/L. The highest chloride reported in winter was 79 mg/L due to frequent run-off loaded with contaminated water from the surrounding slum area and evaporation of water. The lowest value of chloride recorded during monsoon season was 98 mg/L due to the dilution of lake water by rain. Chloride. Range 50-600. 250

Nitrate

Nitrogen is abundant on earth, making up about 80% of our air as N2 gas .plants use nitrate to build protein and animals that eat plants also use organic nitrogen to build protein. When plants and animals die or excrete waste, this nitrogen is released into the environment as NH4+ (ammonium). This ammonium is eventually oxidized by bacteria into nitrite (NO2-) and then into nitrate. In this form it is relatively common in freshwater aquatic ecosystems. Nitrate thus enters streams from natural sources like decomposing plants and animal waste as well as human sources like sewage or fertilizer. It is measured in mg/L Natural levels of nitrate are usually less than 1 mg/L. Concentrations over 10 mg/L will have an effect on the freshwater aquatic Water with low dissolved oxygen may slow the rate at which ammonium is converted to nitrite (NO2-) and finally nitrate (NO3-). Nitrite and ammonium

The rate of oxygen consumption is affected by a number of variables: temperature, pH, the presence of certain kinds of microorganisms, and the type of organic and inorganic material in the water.

BOD is an important water quality parameter because it provides an index to assess the effect discharged wastewater will have on the receiving environment. The higher the BOD value, the greater the amount of organic matter or “food” available for oxygen consuming bacteria. The test for biochemical oxygen demand (BOD) is a bioassay procedure that measures the oxygen consumed by bacteria from the decomposition of organic matter

A water supply with a BOD level of 3-5 ppm is considered moderately clean. In water with a BOD level of 6-9 ppm, the water is considered somewhat polluted because there is usually organic matter present and bacteria are decomposing this waste.

The BOD/COD ratio for untreated wastewater is 0.5 or greater, the waste is considered to be easily treatable by biological means. If the ratio is below about 0.3, either the waste may have some toxic components or acclimated micro organisms may be required in its stabilization.