Nitrogen Pathways in Nature ig. 2-7 Generalized nitrogen cycle in the aquatic and soil environment Decomposition by bacteria readily changes the organic form to ammonia. The age of wastewater is indicated by the relative amount of ammonia that is present The predominance of nitrate nitrogen in wastewater indicates that the waste has been stabilized with respect to oxygen demand. Nitrates, however, can be used by plants and animals to form protein
Nitrogen Pathways in Nature Fig. 2-7 Generalized nitrogen cycle in the aquatic and soil environment Decomposition by bacteria readily changes the organic form to ammonia. The age of wastewater is indicated by the relative amount of ammonia that is present. The predominance of nitrate nitrogen in wastewater indicates that the waste has been stabilized with respect to oxygen demand. Nitrates, however, can be used by plants and animals to form protein
Phosphorus Municipal wastewaters may contain from 4 to 16 mg/L of phosphorus as p The usual forms of phosphorus that are found in aqueous solutions include the orthophosphate, polyphosphate, and organic phosphate Polyphosphates undergo hydrolysis in aqueous solutions and revert to the orthophosphate forms, however, this hydrolysis is usually quite slow. The organically bound phosphorus can be an important constituent of industrial wastes and wastewater sludge The polyphosphates and organic phosphates must be converted to orthophosphates using an acid digestion step
Phosphorus Municipal wastewaters may contain from 4 to 16 mg/L of phosphorus as P. The usual forms of phosphorus that are found in aqueous solutions include the orthophosphate, polyphosphate, and organic phosphate. Polyphosphates undergo hydrolysis in aqueous solutions and revert to the orthophosphate forms; however, this hydrolysis is usually quite slow. The organically bound phosphorus can be an important constituent of industrial wastes and wastewater sludge. The polyphosphates and organic phosphates must be converted to orthophosphates using an acid digestion step
Sulfur The sul fate ion occurs naturally in most water supplies and is present in wastewater as well. Sulfur is required in the synthesis of proteins and is released in their degradation Hydrogen sulfide gas, which will diffuse into the headspace above the wastewater sewers that are not flowing full, tends to collect at the crown of the pipe. The accumulated h,s can then be oxidized biologically to sulfuric acid, which is corrosive to concrete sewer pipes This corrosive effect. known as "crown rot. can seriously threatened the structural integrity of the sewer pipe Sulfates may upset the biological process if the sulfide concentration exceeds 200 mg/L. If burned in gas engines the products of combustion can damage the engine
Sulfur The sulfate ion occurs naturally in most water supplies and is present in wastewater as well. Sulfur is required in the synthesis of proteins and is released in their degradation. Hydrogen sulfide gas, which will diffuse into the headspace above the wastewater sewers that are not flowing full, tends to collect at the crown of the pipe. The accumulated H2 S can then be oxidized biologically to sulfuric acid, which is corrosive to concrete sewer pipes. This corrosive effect, known as "crown rot," can seriously threatened the structural integrity of the sewer pipe . Sulfates may upset the biological process if the sulfide concentration exceeds 200 mg/L. If burned in gas engines, the products of combustion can damage the engine
Gases Gases commonly found in untreated wastewater include nitrogen (N, ), oxygen (O,), carbon dioxide (CO hydrogen sul fide (H,S), ammonia (NH methane(CHa). The latter three are derived from the decomposition of the organic matter present in wastewater and are of concern with respect to worker health and safety Environmental engineer must be familiar include chlorine (CI,) and ozone(O3), and the oxides of sulfur and nitrogen It will be useful to review the ideal gas law and to consider the solubility of gases in water and Henry's law as applied to the gases of interest
Gases Gases commonly found in untreated wastewater include nitrogen (N2 ), oxygen (O2 ), carbon dioxide (CO2 ), hydrogen sulfide (H2 S), ammonia (NH3 ), and methane(CH4 ). The latter three are derived from the decomposition of the organic matter present in wastewater and are of concern with respect to worker health and safety. Environmental engineer must be familiar include chlorine (Cl2 ) and ozone (O3 ) , and the oxides of sulfur and nitrogen . It will be useful to review the ideal gas law and to consider the solubility of gases in water and Henry's law as applied to the gases of interest
Solubility of gases in Water The actual quantity of a gas that can be present in solution is governed by (1) the solubility of the gas as defined by Henry's law (2)the partial pressure of the gas in the atmosphere (3)the temperature, and (4) the concentration of the impurities in the water(e. g linty, suspended solids, etc.) The ideal gas law Boyle's law(volume of a gas is inversely proportional to pressure at constant temperature Charles law(volume of a gas is directly proportional to temperature at constant pressure)
Solubility of Gases in Water The actual quantity of a gas that can be present in solution is governed by : (1) the solubility of the gas as defined by Henry's law, (2) the partial pressure of the gas in the atmosphere, (3) the temperature, and (4) the concentration of the impurities in the water (e.g., salinity, suspended solids, etc.). The Ideal Gas Law Boyle's law (volume of a gas is inversely proportional to pressure at constant temperature) Charles' law (volume of a gas is directly proportional to temperature at constant pressure)